abc Arquivos Brasileiros de Cardiologia Arq. Bras. Cardiol. 0066-782X 1678-4170 Sociedade Brasileira de Cardiologia - SBC São Paulo, SP, Brazil mrnNcH9K6Y6dRWPbC7vz9Hr 00012 S0066-782X2005000500012 S0066-782X(05)08400512 10.1590/S0066-782X2005000500012 Artigo Original Tendência temporal de letalidade hospitalar por infarto agudo do miocárdio: 1994-2003 Mattos Marco Antonio de Toledo Daniele Gusmão Mattos Carlos Eduardo de Tura Bernardo Rangel Gadelha Diego Neri Benevides Siqueira Filho Aristarco Gonçalves de Rio de Janeiro Rio de Janeiro Universidade Federal do Rio de Janeiro Brazil Instituto Nacional de Cardiologia Laranjeiras 05 2005 84 5 416 421 23 11 2004 19 07 2004 This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

OBJETIVO: Analisar a tendência temporal de letalidade atribuída ao infarto agudo do miocárdio (IAM) e se a mudança de conduta interferiu diretamente nesta letalidade. MÉTODOS: Avaliaram-se 1055 pacientes não selecionados internados em unidade coronariana de 1994-2003. Foram analisadas variáveis relacionadas ao perfil clínico e terapêutico. A análise estatística utilizou o amortecimento exponencial de séries temporais e outras técnicas como a regressão linear logística. RESULTADOS: A letalidade média foi de 10,8%, sendo 12% em 1994 e 7% em 2002 (p=0,000), uma redução relativa de 58%. Não houve variação significativa do perfil de risco dos pacientes. Eram 67,4% homens e 32,4% mulheres, com idade média de 60,93 e 64,84 anos, respectivamente e observou-se aumento significativo no percentual de cateterismos cardíacos (de 14% para 51%), na angioplastia realizada após 24 horas do infarto (de 2% para 33%), na cirurgia de revascularização miocárdica (de 4% para 7%) e na angioplastia primária (de 4% para 11%) com p=0,000, p=0,021, p=0,000 e p=0,000, respectivamente, para tendência linear. Nas primeiras 24 horas houve aumento do uso de aspirina e betabloqueadores, de 78% para 100% e, de 33% para 76% (p=0,003 e p=0,004, respectivamente) ao longo dos anos. Após a análise, persistiram como determinantes de letalidade a terapia de reperfusão miocárdica, a utilização de aspirina e de betabloqueador nas primeiras 24 horas do IAM (p=0,010, p=0,024 e p=0,035, respectivamente). CONCLUSÃO: Houve queda da letalidade e a mudança de conduta no tratamento do IAM ao longo dos anos foi responsável pela redução da letalidade nesta série temporal.

 tendência temporal letalidade hospitalar infarto agudo do miocárdio 24 05 2005

ARTIGO ORIGINAL

Tendência temporal de letalidade hospitalar por infarto agudo do miocárdio. 1994-2003

Marco Antonio de Mattos; Daniele Gusmão Toledo; Carlos Eduardo de Mattos; Bernardo Rangel Tura; Diego Neri Benevides Gadelha; Aristarco Gonçalves de Siqueira Filho

Rio de Janeiro, RJ

Instituto Nacional de Cardiologia Laranjeiras e Universidade Federal do Rio de Janeiro - Rio de Janeiro

Endereço para correspondência

RESUMO

OBJETIVO: Analisar a tendência temporal de letalidade atribuída ao infarto agudo do miocárdio (IAM) e se a mudança de conduta interferiu diretamente nesta letalidade.

MÉTODOS: Avaliaram-se 1055 pacientes não selecionados internados em unidade coronariana de 1994-2003. Foram analisadas variáveis relacionadas ao perfil clínico e terapêutico. A análise estatística utilizou o amortecimento exponencial de séries temporais e outras técnicas como a regressão linear logística.

RESULTADOS: A letalidade média foi de 10,8%, sendo 12% em 1994 e 7% em 2002 (p=0,000), uma redução relativa de 58%. Não houve variação significativa do perfil de risco dos pacientes. Eram 67,4% homens e 32,4% mulheres, com idade média de 60,93 e 64,84 anos, respectivamente e observou-se aumento significativo no percentual de cateterismos cardíacos (de 14% para 51%), na angioplastia realizada após 24 horas do infarto (de 2% para 33%), na cirurgia de revascularização miocárdica (de 4% para 7%) e na angioplastia primária (de 4% para 11%) com p=0,000, p=0,021, p=0,000 e p=0,000, respectivamente, para tendência linear. Nas primeiras 24 horas houve aumento do uso de aspirina e betabloqueadores, de 78% para 100% e, de 33% para 76% (p=0,003 e p=0,004, respectivamente) ao longo dos anos. Após a análise, persistiram como determinantes de letalidade a terapia de reperfusão miocárdica, a utilização de aspirina e de betabloqueador nas primeiras 24 horas do IAM (p=0,010, p=0,024 e p=0,035, respectivamente).

CONCLUSÃO: Houve queda da letalidade e a mudança de conduta no tratamento do IAM ao longo dos anos foi responsável pela redução da letalidade nesta série temporal.

Palavras-chave: tendência temporal, letalidade hospitalar, infarto agudo do miocárdio

O infarto agudo do miocárdio (IAM) é o maior problema de saúde pública nos países industrializados. A sua incidência vem aumentando, assustadoramente, nos países em desenvolvimento1,2.

Um declínio progressivo e constante na taxa de mortalidade por IAM tem sido observado ao longo das últimas 4 décadas, de 30% para, aproximadamente, 15%3. Nos primórdios da década de 80, esforços significativos foram desenvolvidos na tentativa de limitar o tamanho do IAM, com a introdução dos fibrinolíticos e os betabloqueadores4-6. O uso disseminado do ácido acetilsalicílico e o desenvolvimento da angioplastia transluminal coronariana (ATC) em sua totalidade, contribuíram para a redução da taxa de mortalidade, a curto prazo, para 6,5%7-10.

Apesar da tendência de maior utilização das terapias, estas ainda são subutilizadas11-13. Alguns estudos demonstraram que o conhecimento de diretrizes nacionais ou internacionais não garantem uma prática médica baseada em evidências científicas14.

Diversas explicações existem para as mudanças verificadas na letalidade do IAM, registradas ao longo dos anos: melhora da monitorização, alteração da taxa de hospitalização por IAM, mudança do perfil de risco dos pacientes e melhora do tratamento farmacológico e intervencionista15-17.

Estudos que analisam a incidência, a evolução e a mortalidade por IAM ainda são escassos no Brasil. No Estado do Rio de Janeiro, existe publicado apenas um estudo sobre a letalidade hospitalar por IAM, em 1995, não havendo nenhum estudo sobre a tendência temporal de letalidade por IAM, em unidade coronariana (UC)18.

Dentro desta perspectiva, o presente estudo tem por objetivos estudar a tendência temporal da letalidade atribuída ao IAM, na UC e avaliar se a mudança de conduta interferiu diretamente nesta letalidade.

Métodos

Foram incluídos no estudo todos os pacientes com diagnóstico de IAM, não selecionados, independente da faixa etária, internados consecutivamente na Unidade Coronariana de 01/03/1994 a 01/03/2003, acompanhados prospectivamente durante a internação e os dados sobre as características do infarto e a evolução foram armazenados em um programa de banco de dados. Os critérios diagnósticos para IAM foram os estabelecidos pela Organização Mundial de Saúde19. A partir do ano de 2000 utilizou-se a troponina I quantitativa como marcador sérico de infarto.

Foram investigados os fatores de risco clássicos para a doença arterial coronariana e considerou-se como antecedente de infarto do miocárdio a documentação em prontuário hospitalar ou a presença de onda Q patológica20.

Os critérios de elegibilidade para terapia de reperfusão miocárdica foram os recomendados pelo AHA/ACC21. Para a terapia farmacológica foi utilizada a estreptoquinase e a angioplastia primária (ATC P) foi introduzida na Instituição a partir de 1998. As complicações cardíacas avaliadas na UC foram a insuficiência cardíaca (classificação de Killip-Kimball22) à admissão hospitalar ou durante a internação, o reinfarto, a angina pós-IAM23 e as arritmias comuns no curso do IAM.

O cateterismo cardíaco (cine) era indicado na presença de isquemia persistente ou recorrente, insuficiência cardíaca, complicações mecânicas e arritmias ventriculares graves. A partir de 1998, a rotina da unidade coronariana passou a indicar cine com mais freqüência para os pacientes que evoluíam com insuficiência cardíaca, angina pós-IAM, IAM sem onda Q de alto risco e a angioplastia de resgate mais precocemente na falência da estreptoquinase (ATC seletiva/ATC-S).

As medicações adjuvantes utilizadas na fase aguda do infarto incluíram ácido acetilsalicílico, betabloqueadores intravenoso e oral, inibidores da enzima conversora da angiotensina, estatinas, inibidores da glicoproteína IIb/IIIa (com ATC P), ticlopidina, nitroglicerina e heparinas não fracionada e de baixo peso molecular, utilizadas de acordo com as condutas da rotina da unidade coronariana, já previamente publicadas24. As condutas sofreram atualização em 1998 e 2002 com utilização mais ampla de cine, ATC S, ácido acetilsalicílico, betabloqueadores e estatinas.

Para fins de cálculo da letalidade hospitalar, contabilizaram-se apenas os óbitos ocorridos durante a internação na UC por IAM25,26.

Após revisão dos valores contidos na base de dados, foi calculada a letalidade por IAM geral e de acordo com o tipo de IAM (com Q ou sem Q), a localização (anterior ou inferior), a idade (65 anos e < 65 anos), sexo, uso ou não de reperfusão, infarto prévio, insuficiência cardíaca, diabetes e outras variáveis.

Para averiguar se havia diferença significativa entre os valores destas variáveis com o passar dos anos, foi utilizado o método do qui-quadrado, seguido pelo qui-quadrado para tendência linear a fim de verificar se a mudança era consistente com uma reta ascendente ou descendente. Para avaliar as diferenças entre médias foi utilizado o teste T de Student e a ANOVA. Para avaliar a importância de mudanças no perfil de risco dos pacientes ao longo dos anos que pudessem interferir com a letalidade, foi utilizada a análise multivariada. Foi realizada a análise de regressão logística para as variáveis que apresentaram diferenças significativas em 3 momentos distintos: global (1994-2002), 1º período (1994-1998) e 2º período (1998-2002). Esta análise visou avaliar se a mudança da forma de tratamento determinou ou não uma mudança do comportamento destes preditores. Para analisar quais fatores foram determinantes independentes da mudança da letalidade, foi feito um ajuste múltiplo das características clínicas relacionadas a letalidade, através da regressão linear múltipla. Antes de cada variável ser acrescida ao modelo original, avaliou-se sua correlação com todas as outras para evitar colinearidade. Em seguida, foi realizado o amortecimento exponencial da série temporal, visando avaliar a tendência linear e a importância da letalidade do ano anterior no ano seguinte e estimar os resultados dos 2 anos futuros. A análise temporal é de março/1994 a março/2003.

Foram utilizados os software STATISTICA 6.0 para a realização do qui-quadrado e para as regressões logística e linear, e o R system 1.7.2 para o amortecimento exponencial.

Resultados

Foram incluídos consecutivamente, 1.055 pacientes com diagnóstico de IAM. Da amostra 713 (67,4%) eram homens. O IAMQ representou 76,5%. O número médio de pacientes com IAM foi de 105 (fig. 1). A idade média foi de 62,20±12,23 anos, sendo 60,93±12,4 para os homens e 64,84±11,5 para as mulheres.

A parede anterior foi acometida em 287 casos. Infarto prévio em 23,9% dos casos. Os fatores de risco mais freqüentes foram hipertensão arterial sistêmica (60,8%), história familiar (40,5%), tabagismo (38,4%), dislipidemia (31,6%) e diabetes mellitus (22,4%). A angina pós-IAM ocorreu em 268 pacientes, classe Killip-Kimball >2 em 290 pacientes e o reinfarto em 42. A letalidade média foi de 10,8%, sendo de 12% em 1994 e de 7% em 2002 (p=0,000), representando uma redução relativa de 58% (fig. 2).

Dos pacientes com supradesnivelamento do segmento ST, 35% (282) foram submetidos à terapia de reperfusão miocárdica, sendo 26,4% por trombolítico e 8,5% por ATC P. A cine foi realizada em 32,4% dos trombolizados e, destes, 11,7% submetidos à angioplastia de resgate (quase totalidade a partir de 1998). A letalidade foi de 10,8% nos trombolizados e de 10,1% nos submetidos a ATC P.

Foram encaminhados a cine 351 pacientes. A ATC S teve um crescimento significativo (p<0,004), de duas (1,7%) realizadas em 1994, para 31 (19,5%) em 2002. A cirurgia de revascularização miocárdica (CRM) foi realizada em 55 pacientes.

Houve aumento da incidência de IAM sem onda Q (IAMSQ) e menor acometimento da parede anterior, respectivamente, p=0,000 e p=0,008 (tab. I). As mulheres eram 3,92 anos mais velhas que os homens.

De 1994 a 2003, aumentou a realização de cine (de 14% para 51%), de ATC S (de 2% para 33%) e da CRM (de 4% para 7%) com p=0,000, p=0,021 e p=0,000, respectivamente, para tendência linear.

Houve aumento da terapia de reperfusão miocárdica de 1994 para 2002 (p=0,000, para tendência linear) (fig. 3). Vale lembrar que 2003 é representado apenas pelos 3 primeiros meses do ano.

Conforme figura 4, ocorreu aumento significativo, nas primeiras 24 horas, na utilização de ácido acetilsalicílico e betabloqueadores.

A insuficiência cardíaca e a angina pós-IAM apresentaram redução significativa de suas incidências, de 1994 para 2003, de 31% para 15% e de 21% para 11%, respectivamente.

A tabela II demonstra as variáveis que compõem o perfil de risco dos pacientes. Apenas o acometimento da parede anterior e o IAMSQ apresentaram mudança ao longo dos anos (p=0,008 e p=0,000, respectivamente, para tendência linear). Para avaliar a influência na letalidade do IAM, realizou-se a análise das mesmas ao longo dos anos (tab. III). Fica clara a importante redução da letalidade após o ano de 1998. A importância dessas variáveis na letalidade hospitalar encontra-se na tabela IV. Em momento algum, o IAMSQ foi preditor independente de letalidade.

No caso da parede anterior, houve diminuição de sua frequência ao longo dos anos, acompanhada de queda da letalidade. Ao se analisar este dado em 3 períodos distintos, demonstra-se que a parede anterior foi preditora independente no período global do estudo (1994-2002) e de 1994-1998. Entretanto, no período de 1998-2002 deixa de ser preditora independente de letalidade hospitalar.

Para analisar quais os fatores determinantes independentes na mudança da letalidade hospitalar do IAM empregou-se a regressão linear múltipla.

Observou-se correlação entre o IAM de parede anterior e o IAMQ (R=0,9173 e p=0,000), escolhendo-se o IAM de parede anterior por motivos biológicos e clínicos. Após a análise, os determinantes de letalidade hospitalar foram: a terapia de reperfusão miocárdica, a utilização de ácido acetilsalicílico e de betabloqueador nas primeiras 24 horas do IAM (p=0,010, p=0,024 e p=0,035, respectivamente).

Discussão

As principais razões relacionadas às mudanças na letalidade hospitalar por IAM são a alteração da taxa de hospitalização, a mudança do perfil de risco dos pacientes e a melhora do tratamento farmacológico e intervencionista15-17.

Nesta pesquisa, nota-se na figura 1, que a taxa de internação média anual do IAM, ao longo de todo o período, foi de 105 pacientes, com menor número de internação em 1996 e 1999 (90 e 100, respectivamente). Entretanto, quando se avaliou a tendência geral de letalidade por IAM, a taxa de letalidade em 1996 foi a mais alta de todo o período e em 1998 e 1999 ocorreu um platô na curva de tendência. Este declínio na letalidade, com taxa de hospitalização estável ou aumentada é consistente com outros estudos publicados, que sugerem a melhora do tratamento como responsável pela tendência favorável na letalidade do IAM17,21,27.

A letalidade hospitalar por IAM depende do perfil de risco dos pacientes. As variáveis utilizadas nesta amostra (tab. II) também foram utilizadas em diversos trabalhos publicados28-34. Pode-se verificar que apenas o IAMSQ e a localização do infarto na parede anterior apresentaram mudanças de freqüência significativas ao longo dos anos, enquanto as outras variáveis não se alteraram. A regressão logística multivariada demonstrou que o IAMSQ não foi preditor independente de letalidade.

Segundo Burke e cols.35 a mudança no perfil de risco explica-se, em parte, por alterações na política de admissão hospitalar e pela melhora nas técnicas diagnósticas, criando-se condições para a detecção de pequenos infartos. A utlização da troponina pode ter levado a admissão de infartos menos graves, assim como no aumento da incidência de IAMSQ. Corroborando com a regressão logística na análise da tendência temporal de letalidade por tipo de IAM, observamos que esta permaneceu praticamente estável ao longo do tempo para o IAMSQ, enquanto para o IAMQ, houve queda significativa. Tal fato deve-se ao incremento das intervenções farmacológicas e invasivas empregadas no IAMQ, a partir de 1998 (figs. 3 e 4), o que refletiu na letalidade global por IAM. Resultado semelhante foi publicado em 2001, em 22 anos de estudo, em que se verificaram redução da incidência do IAMQ e aumento do IAMSQ. A letalidade hospitalar do IAMQ diminuiu com os anos (de 24% em 1975 para 14% em 1997) a do IAMSQ permaneceu estável, em 12%36.

No atual estudo, a freqüência do IAM anterior variou significativamente (p=0,008, para tendência linear), de 49,1% em 1994 para 30,2% em 2002, fato este que poderia ter influenciado a letalidade hospitalar. Associado à queda da freqüência também se observou declínio significativo da letalidade, de 16,4% para 8,3%, que poderia ser resultado direto do menor número de pacientes internados. Para avaliar o possível confundimento, empregou-se a regressão logística em 3 períodos distintos, demonstrando-se que no período de 1998 a 2002 a parede anterior deixa de ser preditora independente, com odds ratio de 1,39 (0,72 - 2,71, tab. IV). Período que coincide com a utilização mais intensiva de intervenções com efeito benéfico na letalidade, como a terapia de reperfusão (inclusão da ATC primária), a ATC S e a terapia farmacológica (figs. 3 e 4) como em outros estudos21,37, 38.

No presente trabalho não encontramos diferença significativa na freqüência de classe Killip > 2 ao longo dos anos (p=0,07), corroborando com o fato que a redução da letalidade não se acompanha necessariamente da redução da gravidade dos pacientes internados39.

Alexander e cols.40 relataram que a letalidade hospitalar por IAM está diretamente relacionada à idade mais elevada. No presente estudo, a proporção de idosos (em torno de 45%) não variou significativamente (p=0,977) ao longo dos anos

Este trabalho é o primeiro a analisar a tendência temporal de letalidade hospitalar por IAM, em 9 anos, na UC, e a influência das modalidades terapêuticas em uma população não selecionada. A letalidade hospitalar é um indicador tradicional de desempenho de qualidade da assistência, tendo sido recentemente destacada por Dubois41.

Mudanças terapêuticas ocorreram no tratamento do IAM nas últimas 2 décadas e, diversos estudos controlados, randomizados, investigaram o impacto da farmacoterapia adjunta e da reperfusão na letalidade hospitalar42-45. Heidenreich e cols.46 concluíram que a principal razão para o declínio da letalidade hospitalar precoce estava relacionada a ampliação da terapia adjuvante (ácido acetilsalicílico, IECA, betabloqueadores), as técnicas de reperfusão miocárdica, assim como a angioplastia seletiva (resgate, de urgência) e a CRM.

No registro francês, a proporção de utilização do ácido acetilsalicílico aumentou de 63% para 89% e de betabloqueadores de 41% para 64% no período de 1994 para 1995 com queda da letalidade 12,1% para 7,7%28. No Registro Americano do IAM, de 1990 a 1999, demonstrou-se crescente utilização desses fármacos nas primeiras 24h da admissão hospitalar47.

Nota-se no atual trabalho um aumento significativo na utilização da ácido acetilsalicílico e betabloqueadores (fig. 4), principalmente a partir de 1998, corroborando para o fato que a introdução e a ampliação destas terapias benéficas participaram da redução da letalidade hospitalar.

Uma parcela significativa da redução da letalidade está relacionada às intervenções (ATC P, CRM precoce, angioplastia de resgate, cinecoronariografia nos pacientes de alto risco) realizadas durante a fase aguda37,48.

Nesta amostra observamos aumento da cine e da ATC S (p=0,000 e p=0,021, para tendência linear). Isto se deu a despeito de não ter havido alteração do perfil de risco mas por ter ocorrido uma mudança na condução do tratamento do infarto na fase aguda pela rotina médica que se instalou a partir de 1998, intervindo mais agressivamente e precocemente nos pacientes de alto risco e com complicações. Durante recente simpósio latino-americano de terapia intensiva, nos pacientes da nossa UC submetidos a ATC P, a letalidade foi de 2%49.

No Estado do Rio de Janeiro, dos 23108 pacientes com diagnóstico de IAM, avaliados através das autorizações de internação hospitalar, entre 1995 e 2000 encontrou-se pequena tendência decrescente, porém significativa da letalidade hospitalar, de 18,4% para 16,9%, com média de 18%, sendo que a utilização da terapia trombolítica quase que dobrou, passando de 6,6% para 11,8% (r2=0,69 e p<0,05). Para o Município do Rio de Janeiro, a letalidade hospitalar do mesmo período não sofreu mudança significativa, de 16,5% para 15,8%50.

De acordo com diversos autores existe uma importante variação nos perfis de utilização das tecnologias aplicadas no IAM, com indicações e eficácia já plenamente investigadas, debatidas e estabelecidas51-53. Este fato é devido à existência de graus variáveis de adesão ou de conhecimento dos protocolos baseados em evidência científica14,54. Na UC, a equipe reúne-se periodicamente para atualização das condutas de acordo com as necessidades e a disponibilidade dos recursos terapêuticos disponíveis. Depois de atualizadas, estas passam a ser plenamente empregadas pela equipe médica, mantendo a uniformidade e adesão à rotina.

Uma das limitações deste estudo é o baixo poder de generalização e, portanto, suas conclusões só devem ser aplicadas a populações com um perfil de IAM semelhante a este. A segunda limitação refere-se ao fato que este tipo de estudo analisou os dados gerais e não a informação individual de cada paciente. Por causa disto, a avaliação de casualidade ficou prejudicada, tendo sido minimizada com a análise de série temporal, aplicada no presente estudo.

Em conclusão, neste estudo, observou-se que houve redução da letalidade hospitalar por IAM, em ambos os sexos e que o declínio da letalidade se deveu à implementação, na prática diária, de medidas clínicas farmacológicas e intervencionistas.

Marco Antonio de Mattos

Rua General Rabelo, 64/202

22451-010 - Rio de Janeiro, RJ

E-mail:

demattos@cardiol.br

Enviado em 19/07/2004 - Aceito em 23/11/2004

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Intravenous short-term infusion of streptokinase in acute myocardial infarction. Circulation. 1983; 67:536-48. Intravenous short-term infusion of streptokinase in acute myocardial infarction Circulation. 1983 536 48 67 Schroder R Biamino G Brooks-Brunn JA 11. Kizer JR, Cannon CP, McCabe CH, et al. Trends in the use of pharmacotherapies for acute myocardial infarction among physicians who design and/or implement randomized trials versus physicians in routine clinical practice: The MILIS-TIMI experience. Multicenter Investigation on Limitation of Infarct Size. Thrombolysis in Myocardial Infarction. Am Heart J. 1999; 137:79-92. Trends in the use of pharmacotherapies for acute myocardial infarction among physicians who design and/or implement randomized trials versus physicians in routine clinical practice: The MILIS-TIMI experience. Multicenter Investigation on Limitation of Infarct Size. Thrombolysis in Myocardial Infarction Am Heart J. 1999 79 92 137 Kizer JR Cannon CP McCabe CH 12. Goldberg RJ, Gurwitz JH. Disseminating the results of clinical trials to community-based practitioners: Is anyone listening? Am Heart J. 1999;137:4-7. Disseminating the results of clinical trials to community-based practitioners: Is anyone listening? Am Heart J 1999 4 7 137 Goldberg RJ Gurwitz JH 13. GRACE, for the GRACE Investigators. Management of acute coronary syndromes: variation in practice and outcome: findings from Global Registry of Acute Coronary Events. Eur Heart J. 2002; 23:1177-89. the GRACE Investigators. Management of acute coronary syndromes: variation in practice and outcome: findings from Global Registry of Acute Coronary Events Eur Heart J. 2002 1177 89 23 GRACE, for 14. Ryan TJ, Antman EM, Brooks NH, et al. 1999 update: ACC/AHA guidelines for the management of patients with acute myocardial infarction: executive summary and recommendations: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Acute Myocardial Infarction). Circulation. 1999; 100:1016-30. 1999 update: ACC/AHA guidelines for the management of patients with acute myocardial infarction: executive summary and recommendations: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Acute Myocardial Infarction) Circulation. 1999 1016 30 100 Ryan TJ Antman EM Brooks NH 15. Fang J, Alderman M. Dissociation of hospitalization and mortality trends for myocardial infarction in the United States from 1988 to 1997. Am J Cardiol. 2001; 113:208-14. Dissociation of hospitalization and mortality trends for myocardial infarction in the United States from 1988 to 1997 Am J Cardiol. 2001 208 14 113 Fang J Alderman M 16. McGovern PG, Pankow JS, Shahar E, et al for The Minnesota Heart Survey Investigators. Recent trends in acute coronary disease: mortality, morbidity, medical care, and risk factors. N Engl J Med. 1996; 334:884-90. for The Minnesota Heart Survey Investigators: Recent trends in acute coronary disease: mortality, morbidity, medical care, and risk factors N Engl J Med. 1996 884 90 334 McGovern PG Pankow JS Shahar E 17. Rosamond WD, Chambless LE, Folsom AR, et al. Trends in the incidence of myocardial infarction and in mortality due to coronary heart disease, 1987 to 1994. N Engl J Med. 1998; 339:861-7. Trends in the incidence of myocardial infarction and in mortality due to coronary heart disease, 1987 to 1994 N Engl J Med. 1998 861 7 339 Rosamond WD Chambless LE Folsom AR 18. Escosteguy CC, Medronho PR, Portela MC. Avaliação da letalidade hospitalar do infarto agudo do miocárdio no estado do Rio de Janeiro através do uso do Sistema de Informações Hospitalares/SUS. Cad Saúde Colet. 1998; 7:39-59. Avaliação da letalidade hospitalar do infarto agudo do miocárdio no estado do Rio de Janeiro através do uso do Sistema de Informações Hospitalares/SUS Cad Saúde Colet. 1998 39 59 7 Escosteguy CC Medronho PR Portela MC 19. World Health Organization, Working Group on the Establishment of Ischaemic Heart Disease Registers. Report of the Fifth Working Group, Copenhagen. In: Report no. Eur 8201 (5). World Health Organization, Geneva, 1971. Report no. Eur 8201 1971 5 20. Prineas RJ, Crow RJ, Blackburn H. The Minnesota Code Manual of Eletrocardiographic Findings: Standards and Procedures for Measurement and Classification In: Wright J, ed. Boston: John Wright, PSG Inc, 1-229, 1982. 1982 1 229 Prineas RJ Crow RJ Blackburn H Wright J 21. AHA, Medical/Scientific Statement Special report: ACC/AHA guidelines for the management of patients with acute myocardial infarction. Circulation. 1990; 82:664-707. AHA, Medical/Scientific Statement Special report: ACC/AHA guidelines for the management of patients with acute myocardial infarction Circulation 1990 664 707 82 22. Killip T, Kimball J. Treatment of myocardial infarction in a coronary care unit. A two year experience with 250 patients. Am J Cardiol. 1967;20:457-64. Treatment of myocardial infarction in a coronary care unit: A two year experience with 250 patients Am J Cardiol 1967 457 64 20 Killip T Kimball J 23. Braunwald E. Unstable angina: A classification. Circulation. 1989; 80: 410-4. Unstable angina: A classification Circulation. 1989 410 4 80 Braunwald E 24. Brasileiro ALS. Rotinas do Serviço - Unidade Coronária, Hospital de Cardiologia de Laranjeiras. 2.ed. Rio de Janeiro: Revinter, 1997. Rotinas do Serviço - Unidade Coronária, Hospital de Cardiologia de Laranjeiras 1997 25. Desharnais S. Current uses of large data sets to assess the quality of providers. Int J Tecch Assess Health Care. 1990;6:229-38. Current uses of large data sets to assess the quality of providers Int J Tecch Assess Health Care. 1990 229 38 6 Desharnais S 26. Jencks SF. Assessing hospital associated deaths from discharge data: The role of length of stay and comorbidity. JAMA. 1988; 260:2240-6. Assessing hospital associated deaths from discharge data: The role of length of stay and comorbidity JAMA. 1988 2240 6 260 Jencks SF 27. Kostis JB, Wilson AC, Lacy CR, et al. Time trends in the ocurrence and outcome of acute myocardial infarction and coronary heart disease death between 1986 and 1996 (A New Jersey Statewide Study), for the Myocardial Infarction Data Acquisition System (MIDAS) Study Group. Am J Cardiol. 2001;88:837-41. Time trends in the ocurrence and outcome of acute myocardial infarction and coronary heart disease death between 1986 and 1996 (A New Jersey Statewide Study), for the Myocardial Infarction Data Acquisition System (MIDAS) Study Group Am J Cardiol. 2001 837 41 88 Kostis JB Wilson AC Lacy CR 28. Danchin N, Vaur L, Genès N, et al. Management of acute myocardial infarction in intensive care units in 1995: A Nationwide French survey of practice and early hospital results. J Am Coll Cardiol. 997; 30:1598-605. Management of acute myocardial infarction in intensive care units in 1995: A Nationwide French survey of practice and early hospital results J Am Coll Cardiol. 1997 1598 605 30 Danchin N Vaur L Genès N 29. Moreno R, Garcia E, Soriano J, et al. Angiographic and clinical reasons for the higher in-hospital mortality in diabetic patients with acute myocardial infarction treated with primary angioplasty. Eur Heart J. 1999;20 (Abstr Suppl):615. Angiographic and clinical reasons for the higher in-hospital mortality in diabetic patients with acute myocardial infarction treated with primary angioplasty Eur Heart J. 1999 615 20 Moreno R Garcia E Soriano J 30. GUSTO III, Investigators. The Global Use of Strategies to Open Occluded Coronary Arteries. A comparison of reteplase with alteplase for acute myocardial infarction. N Engl J Med. 1997;337:1118-23. The Global Use of Strategies to Open Occluded Coronary Arteries: A comparison of reteplase with alteplase for acute myocardial infarction N Engl J Med. 1997 1118 23 337 GUSTO III Investigators 31. Brieger DB, Mak KH, White HD, et al. The benefit of early sustained reperfusion in patients with acute myocardial infarction superimposed on prior infarction. Insights from the GUSTO-I trial. Am J Cardiol. 1998;81:282-7. The benefit of early sustained reperfusion in patients with acute myocardial infarction superimposed on prior infarction: Insights from the GUSTO-I trial Am J Cardiol. 1998 282 7 81 Brieger DB Mak KH White HD 32. Barakat K, Wilkinson P, Deaner A, et al. How should age affect management of acute myocardial infarction? A prospective cohort study. Lancet. 1999;353:955-9. How should age affect management of acute myocardial infarction? A prospective cohort study Lancet. 1999 955 9 353 Barakat K Wilkinson P Deaner A 33. Goldberg RJ, McCormick D, Gurwitz JH, et al. Age-related trends in short- and long-term survival after acute myocardial infarction: a 20-year population-based perspective (1975-1995). Am J Cardiol. 1998;82:1311-7. Age-related trends in short- and long-term survival after acute myocardial infarction: a 20-year population-based perspective (1975-1995) Am J Cardiol. 1998 1311 7 82 Goldberg RJ McCormick D Gurwitz JH 34. Hochman JS, Tamis JE, Trevor D, et al, for the Global Use of Strategies to Open Coronary Arteries in Acute Coronary Síndromes IIb Investigators. Sex, clinical presentation, and outcome in patients with acute coronary syndromes. N Engl J Med. 1997; 341:226-32. for the Global Use of Strategies to Open Coronary Arteries in Acute Coronary Síndromes IIb Investigators: Sex, clinical presentation, and outcome in patients with acute coronary syndromes N Engl J Med. 1997 226 32 341 Hochman JS Tamis JE Trevor D 35. Burke GL, Edlavitch SA, Gregor RD, et al. The effects of diagnostic criteria on trends in coronary heart disease morbidity: The Minnesota Heart Survey. J Clin Epidemiol. 1989; 42:17-24. The effects of diagnostic criteria on trends in coronary heart disease morbidity: The Minnesota Heart Survey J Clin Epidemiol 1989 17 24 42 Burke GL Edlavitch SA Gregor RD 36. Furman MI, Dauerman HL, Goldberg RJ, et al. Twenty-two year (1975 to 1997) trends in the incidence, in-hospital and long-term case fatality rates from initial Q-wave and non-Q-wave myocardial infarction: a multi-hospital community-wide perspective. J Am Coll Cardiol. 2001; 37:1571-80. Twenty-two year (1975 to 1997) trends in the incidence, in-hospital and long-term case fatality rates from initial Q-wave and non-Q-wave myocardial infarction: a multi-hospital community-wide perspective J Am Coll Cardiol. 2001 1571 80 37 Furman MI Dauerman HL Goldberg RJ 37. Dellborg M, Eriksson P, Riha M, et al. Declining hospital mortality in acute myocardial infarction. Eur Heart J. 1994;15:5-9. Declining hospital mortality in acute myocardial infarction Eur Heart J. 1994 5 9 15 Dellborg M Eriksson P Riha M 38. Gottlieb S, Goldbourt U, Boyko V, et al. Mortality trends in men and women with acute myocardial infarction in coronary care units in Israel. A comparison between 1981 1;83:422-37. Mortality trends in men and women with acute myocardial infarction in coronary care units in Israel A comparison between 1981 422 37 1 83 Gottlieb S Goldbourt U Boyko V 44. Fuster V, Dyken ML, Vokonas PS. Aspirin as a therapeutic agent in cardiovascular disease. Circulation. 1993;87:659-75. Aspirin as a therapeutic agent in cardiovascular disease Circulation. 1993 659 75 87 Fuster V Dyken ML Vokonas PS 45. Mahon NG, O'Horke C, Codd MB, et al. Hospital mortality of acute myocardial infarction in the thrombolytic era. Heart. 1999;81:478-82. Hospital mortality of acute myocardial infarction in the thrombolytic era Heart. 1999 478 82 81 Mahon NG O'Horke C Codd MB 46. Heidenreich PA, McClellan M. Trends in treatment and outcomes for acute myocardial infarction: 1975-1995. Am J Med. 2001;37:1571-80. Trends in treatment and outcomes for acute myocardial infarction: 1975-1995 Am J Med. 2001 1571 80 37 Heidenreich PA McClellan M 47. Rogers WJ, Canto JG, Lambrew CT, et al. Temporal trends in the treatment of over 1.5 million patients with myocardial infarction in the US from 1990 through 1999: the National Registry of Myocardial Infarction 1, 2 and 3. J Am Coll Cardiol. 2000;36:2056-63. Temporal trends in the treatment of over 1. 5 million patients with myocardial infarction in the US from 1990 through 1999: the National Registry of Myocardial Infarction 1, 2 and 3 J Am Coll Cardiol. 2000 2056 63 36 Rogers WJ Canto JG Lambrew CT 48. Tavazzi L. Clinical epidemiology of acute myocardial infarction. Am Heart J. 1999; 138 (2 Pt 2): 48-54. Clinical epidemiology of acute myocardial infarction Am Heart J. 1999 48 54 2 Pt 2 138 Tavazzi L 49. Mattos MA, Toledo DG, Mattos CE, et al. Primary angioplasty in a public hospital: initial results. In: 2nd international symposium on intensive care and emergency medicine for latin america, 2003, São Paulo. Critical Care. 2003; 7 (suppl 3):S1-S64. 2003 S1 S64 Mattos MA Toledo DG Mattos CE 50. Penna MG. Avaliação da assistência hospitalar ao infarto agudo do miocárdio no estado do rio de janeiro. Orientador: Cláudia Caminha Escosteguy. Rio de Janeiro HSE, 2002, 102 p. Dissertação (Monografia de conclusão da Residência Médica). Avaliação da assistência hospitalar ao infarto agudo do miocárdio no estado do rio de janeiro 2002 102 Penna MG 51. Becker RC, Terrin M, Ross R, et al. Comparison of clinical outcomes for women and men after acute myocardial infarction. Ann Intern Med. 1994;120:638-45. Comparison of clinical outcomes for women and men after acute myocardial infarction Ann Intern Med. 1994 638 45 120 Becker RC Terrin M Ross R 52. O'Connor GT, Quinton HB, Traven ND, et al. Geographic variation in the treatment of acute myocardial infarction: the Cooperative Cardiovascular Project. JAMA. 1999; 281: 627-33. Geographic variation in the treatment of acute myocardial infarction: the Cooperative Cardiovascular Project JAMA. 1999 627 33 281 O'Connor GT Quinton HB Traven ND 53. Venturini F, Romero M, Tognoni G. Patterns of practice for acute myocardial infarction in a population from ten countries. Eur J Clin Pharmacol. 1999; 54: 877-86. Patterns of practice for acute myocardial infarction in a population from ten countries Eur J Clin Pharmacol. 1999 877 86 54 Venturini F Romero M Tognoni G 54. Smith SC, Blair SN, Bonow RO et al. AHA/ACC Scientific Statement: AHA/ACC guidelines for preventing heart attack and death in patients with atherosclerotic cardiovascular disease: 2001 update. A statement for healthcare professionals from the American Heart Association and the American College of Cardiology. Circulation. 2001;104:1577-9. AHA/ACC Scientific Statement: AHA/ACC guidelines for preventing heart attack and death in patients with atherosclerotic cardiovascular disease: 2001 update. A statement for healthcare professionals from the American Heart Association and the American College of Cardiology. Circulation 2001 1577 9 104 Smith SC Blair SN Bonow RO Original Articles Temporal tendency of in-hospital lethality due to acute myocardial infarction: 1994-2003

OBJECTIVE: To analyze the temporal tendency of lethality due to acute myocardial infarction (AMI) and if the change in behavior directly interfered in such lethality. METHODS: 1055 non-selected patients, who were hospitalized in coronary unit from 1994 to 2003, were assessed. Clinical and therapeutic profile-related variables were analyzed. The statistic analysis used the exponential damping of temporal series and other techniques, such as the logistic linear regression. RESULTS: The average lethality was 10.8%, being 12% in 1994 and 7% in 2002 (p=0.000), a relative reduction of 58%. There was no significant variation in the risk profile of the patients. There were 67.4% of men and 32.4% of women, with an average age of 60.93 and 64.84 years old, respectively. It was observed a significant increase in the percentage of cardiac catheterization (from 14% to 51%), in the angioplasty carried out 24 hours after the infarction (from 2% to 33%), in the surgery for myocardial revascularization (from 4% to 7%) and in the primary angioplasty (from 4% to 11%) with p=0.000, p=0.021, p=0.000 and p=0.000, respectively, for linear tendency. In the first 24 hours there was an increase of the use of aspirin and beta-blockers, from 78% to 100% and, from 33% to 76% (p=0.003 and p=0.004, respectively) along the years. After the analysis, the myocardial reperfusion therapy, the use of aspirin and beta-blocker in the first 24 hours of the AMI (p=0.010, p=0.024 and p=0.035, respectively) kept on being lethality determiners. CONCLUSION: There was a decrease in lethality and the change of behavior in the treatment of AMI along the years was responsible for the reduction of lethality in that temporal series.

 temporal tendency in-hospital lethality acute myocardial infarction

ORIGINAL ARTICLE

Temporal tendency of in-hospital lethality due to acute myocardial infarction. 1994-2003

Marco Antonio de Mattos; Daniele Gusmão Toledo; Carlos Eduardo de Mattos; Bernardo Rangel Tura; Diego Neri Benevides Gadelha; Aristarco Gonçalves de Siqueira Filho

Rio de Janeiro, RJ - Brazil

National Institute of Cardiology Laranjeiras - Rio de Janeiro and Federal University of Rio de Janeiro - Rio de Janeiro

Correspondence

ABSTRACT

OBJECTIVE: To analyze the temporal tendency of lethality due to acute myocardial infarction (AMI) and if the change in behavior directly interfered in such lethality.

METHODS: 1055 non-selected patients, who were hospitalized in coronary unit from 1994 to 2003, were assessed. Clinical and therapeutic profile-related variables were analyzed. The statistic analysis used the exponential damping of temporal series and other techniques, such as the logistic linear regression.

RESULTS: The average lethality was 10.8%, being 12% in 1994 and 7% in 2002 (p=0.000), a relative reduction of 58%. There was no significant variation in the risk profile of the patients. There were 67.4% of men and 32.4% of women, with an average age of 60.93 and 64.84 years old, respectively. It was observed a significant increase in the percentage of cardiac catheterization (from 14% to 51%), in the angioplasty carried out 24 hours after the infarction (from 2% to 33%), in the surgery for myocardial revascularization (from 4% to 7%) and in the primary angioplasty (from 4% to 11%) with p=0.000, p=0.021, p=0.000 and p=0.000, respectively, for linear tendency. In the first 24 hours there was an increase of the use of aspirin and beta-blockers, from 78% to 100% and, from 33% to 76% (p=0.003 and p=0.004, respectively) along the years. After the analysis, the myocardial reperfusion therapy, the use of aspirin and beta-blocker in the first 24 hours of the AMI (p=0.010, p=0.024 and p=0.035, respectively) kept on being lethality determiners.

CONCLUSION: There was a decrease in lethality and the change of behavior in the treatment of AMI along the years was responsible for the reduction of lethality in that temporal series.

Key words: temporal tendency, in-hospital lethality, acute myocardial infarction

The acute myocardial infarction (AMI) is the greatest public health problem in industrialized countries. Its incidence has been dramatically increasing in developing countries1,2.

A progressive and steady decrease in the mortality rate through AMI has been observed in the last 4 decades, from 30% to, approximately, 15%3. In the early 1980s, significant efforts were developed to try to limit the size of AMI, with the introduction of fibrinolysin and beta-blockers4-6. The disseminated use of the acetylsalicylic acid and the full development of the percutaneous coronary intervention (PCI), have contributed for the short-term reduction of the mortality rate to 6.5%7-10.

Despite the tendency of greater use of therapies, they still have been underused11-13. Some studies have demonstrated that the understanding of national or international guidelines does not guarantee a scientific evidence-based medical practice14.

There were many explanations for the changes seen in the lethality of AMI, recorded along the years: improvement of monitoring, change in hospitalization rate due to AMI, change of the risk profile of the patients and improvement of the pharmacological and interventionist treatment15-17.

There are only a few studies that analyze the incidence, evolution and mortality due to AMI in Brazil. In the State of Rio de Janeiro, there is only one study on the in-hospital lethality due to AMI published, in 1995, and there is no study on temporal tendency of lethality due to AMI, in a coronary care unit (CCU)18.

Within such perspective, the present study aims at studying the temporal tendency of lethality attributed to AMI, in CCU and assess whether the change of conduct has directly interfered in such lethality.

Methods

All non-selected AMI-diagnosed patients were included in the study, regardless of age, consecutively hospitalized at the Coronary Care Unit from 03/01/1994 to 03/01/2003, prospectively followed during the hospitalization. The data on the characteristics and evolution of the infarction were stored in a database program. The diagnostic criteria for AMI were those established by the World Health Organization19. From the year 2000, quantitative troponin I was used as infarction serum marker.

The classic risk factors for the coronary artery disease were investigated and the in-hospital record documentation or the presence of the pathologic Q wave was regarded as myocardial infarction antecedent20.

The eligibility criteria for myocardial reperfusion therapy were those recommended by the AHA/ACC21. For the pharmacotherapy the streptokinase was used and the primary angioplasty (P PCI) was introduced in the Institution from 1998. The cardiac complications assessed at CCU were the cardiac insufficiency (classification of Killip-Kimball22) to the hospital admission or during the hospitalization, the reinfarction, the post-AMI angina23 and the ordinary arrhythmias in the course of AMI.

The cardiac catheterization (cine) was indicated in the presence of persistent or recurring ischemia, cardiac insufficiency, mechanical complications and serious ventricular arrhythmias. From 1998, the routine of the coronary unit began to indicate a higher frequency of cine for the patients who evolved with cardiac insufficiency, post-AMI angina, AMI without high-risk Q wave and the earliest rescue angioplasty in the failure of streptokinase (selective PCI/S PCI).

The adjuvant medications used in the acute stage of the infarction included acetylsalicylic acid, intravenous and oral beta-blockers, inhibitors of angiotensin converter enzyme, statins, inhibitors of IIb/IIIa glycoprotein (with P PCI), ticlopidine, nitroglycerin, and non-fractioned and low molecular weight heparins, used in accordance to the previously published conducts of the routine of the coronary unit24. The conducts were updated in 1998 and 2002 with a wider use of cine, S PCI, acetylsalicylic acid, beta-blockers and statins.

For the objective of calculation of in-hospital lethality, the deaths occurred during the CCU hospitalization due to AMI were accounted25,26.

After a review of the values contained in the database, the lethality due to general AMI and in accordance to the type of AMI (with Q or without Q), the location (anterior or lower), the age (65 years old and < 65 years old), sex, with or without the use of reperfusion, previous infarction, cardiac insufficiency, diabetes and other variables was calculated.

In order to check if there was a significant difference among the values of those variables along the years, the chi-square method was used. It was followed by the chi-square for linear tendency, aiming to check if the change was consistent with an ascending or descending straight line. In order to assess the differences among means, the T test of Student and ANOVA were used. To measure the importance of changes in the risk profile of patients along the years, which could interfere with lethality, the multivariable analysis has been used. The logistic regression analysis was performed for the variables that showed significant differences in three distinct moments: global (1994-2002), 1st period (1994-1998) and 2nd period (1998-2002). That analysis aimed at assessing whether the treatment way determined a change in the behavior of those predictors. Through multiple linear regressions, a multiple adjustment of lethality-related clinical characteristics was done to analyze which factors were determinant, regardless of lethality change. Before each variable was added to the original model, its correlation to all other variables was assessed in order to avoid co-linearity. Then, the exponential damping of the temporal series was done, aiming at assessing the importance of lethality in the previous year in the following year and estimate the results in the 2 future years. The temporal analysis is from March/1994 to March/2003.

The STATISTICA 6.0 software was used for the chi-square and the logistic and linear regressions, and the R System 1.7.2 software was used for the exponential damping.

Results

1,055 AMI-diagnosed patients were consecutively included. From the sample, 713 (67.4%) were men. AMIQ represented 76.5%. The average number of AMI patients was 105 (fig. 1). The average age was 62.20±12.23 years old, being 60.93±12.4 for men and 64.84±11.5 for women. The anterior wall was affected in 287 cases. Previous infarction occurred in 23.9% of the cases. The most frequent risk factors were systemic hypertension (60.8%), familial history (40.5%), smoking (38.4%), dyslipidemia (31.6%) and diabetes mellitus (22.4%). The post-AMI angina occurred in 268 patients, Killip-Kimball class >2 in 290 patients and the re-infarction in 42. The average lethality was 10.8%, being 12% in 1994 and 7% in 2002 (p=0.000), representing a relative reduction of 58% (fig. 2).

From the patients with ST-segment elevation, 35% (282) were submitted to the myocardial reperfusion therapy, being 26,4% through thrombolytic and 8.5% through P PCI. The cine was performed in 32.4% of the thrombolised patients and, from those, 11.7% were submitted to rescue angioplasty (almost 100% from 1998). The lethality rate was 10.8% among the thrombolised and 10.1% in those submitted to P PCI.

351 patients were sent to the cine. S PCI had a significant growth (p <0.004), from two (1.7%) performed in 1994, to 31 (19.5%) in 2002. The myocardial revascularization surgery (MRS) was performed in 55 patients.

There was an increase of the incidence of AMI without Q wave (AMIWQ) and a lower onset of the anterior wall, respectively, p=0.000 and p=0.008 (tab. I). Women were 3.92 years older than men.

From 1994 to 2003, there were increases in the performance of cine (from 14% to 51%), of S PCI (from 2% to 33%) and MRS (from 4% to 7%) with p=0.000, p=0.021 and p=0.000, respectively, for linear tendency.

There was an increase therapy of myocardial reperfusion from 1994 to 2002 (p=0.000, for linear tendency) (fig. 3). It is important to remember that the year 2003 is represented by only the first three months in the year.

According to figure 4, a significant increase occurred in the first 24 hours in the use of acetylsalicylic acid and beta-blockers.

The cardiac insufficiency and the post-AMI angina showed significant reduction in their incidences, from 1994 to 2003, from 31% to 15% and from 21% to 11%, respectively.

Table II demonstrates the variables that compose the risk profile of the patients. Only the onset of the anterior wall and the AMIWQ showed some change along the years (p=0.008 and p=0.000, respectively, for linear tendency). In order to assess the influence of AMI on lethality, their analyses were performed along the years (tab. III). It is clear the important lethality reduction after 1998. The importance of such variables in in-hospital lethality is found on table IV. At no moment was the AMIWQ an independent predictor of lethality.

In the case of anterior wall, there was a decrease of its frequency along the years, followed by a fall in lethality rate. When analyzing that datum in three different periods, it is demonstrated that the anterior wall was an independent predictor in the global period of the study (1994-2002) and from 1994-1998. However, in the 1998-2002 period, it is not an independent predictor of in-hospital lethality.

In order to analyze which factors are independent and determinant in the change of AMI in-hospital lethality the multiple linear regression was used.

A correlation between the anterior wall AMI and the AMIQ (R=0.9173 and p=0.000) was observed, and the anterior wall AMI was chosen for biological and clinical reasons. After the analysis, the determinants of in-hospital lethality were: the therapy of myocardial reperfusion, the use of acetylsalicylic acid and beta-blocker in the first 24 hours of AMI (p=0.010, p=0.024 and p=0.035, respectively).

Discussion

The main reasons related to the changes in in-hospital lethality due to AMI are the change in hospitalization rate, change in the risk profile of patients and the improvement of the pharmacological and interventionist treatment15-17.

It is noted in figure 1 in this research that the average yearly hospitalization rate of AMI, along the whole period was 105 patients, with a lower number of hospitalization in 1996 and 1999 (90 and 100, respectively). However, when the general tendency of lethality due to AMI was assessed, the lethality rate in 1996 was the highest in the whole period. In 1998 and 1999 there was a plateau in the tendency curve. Such decrease of lethality, with a stable or increased hospitalization rate, is consistent with other studies published, which suggest the improvement in the treatment as responsible for the favorable tendency in lethality of AMI17,21,27.

The in-hospital lethality due to AMI depends on the risk profile of the patients. The variables used in this sample (tab. II) were also used in many works published28-34. It is possible to verify that only the AMIWQ and the location of the infarction in the anterior wall showed significant frequency changes along the years, whereas the other variables did not change. The multivariable logistic regression demonstrated that the AMIWQ was not an independent predictor of lethality.

According to Burke et al.35 the change in the risk profile is partly explained through changes in the policy of hospital admission and for the improvements in diagnostic techniques, by creating conditions for the detection of little infarctions. The use of troponin could have led to the admission of less serious infarctions, as well as the increase of incidence of AMIWQ. Corroborating with the logistic regression in the analysis of temporal tendency de lethality per type of AMI, we observed that it remained was practically stable along the time for the AMIWQ, whereas there was a significant decrease for the AMIQ. Such fact is due to the increase of the pharmacological and invasive interventions employed in the AMIQ, from 1998 (figs. 3 and 4), which reflected in the global lethality due to AMI. A similar result was published in 2001, in 22 years of study, in which a reduction of incidence of AMIQ and an increase of AMIWQ were verified. The in-hospital lethality of AMIQ diminished along the years (from 24% in 1975 to 14% in 1997) and the AMIWQ remained stable in 12%36.

In the current study, the frequency of anterior AMI varied significantly (p=0.008, for linear tendency), from 49.1% in 1994 to 30.2% in 2002, a fact that could have influenced the in-hospital lethality. Associated to the decrease of frequency, a significant decrease of lethality, from 16.4% to 8.3%, was also observed, which could be a direct result from the lower number of admitted patients. In order to assess the possible confusion, the logistic regression was employed in 3 different periods, which demonstrated that in the period from 1998 to 2002 the anterior wall is not an independent predictor any longer, with an odds ratio of 1.39 (0.72 -2.71, tab. IV). That is a period that coincides with the most intensive use of interventions with a benefic effect on the lethality, as the reperfusion therapy (inclusion of primary PCI), the S PCI and the pharmacotherapy (figs. 3 and 4) as in other studies21,37, 38.

In the current work we did not find any significant difference in the frequency of Killip class > 2 along the years (p=0.07), corroborating with the fact that the reduction of lethality is not necessarily connected with the reduction of seriousness of the admitted patients39.

Alexander et al.40 reported that the in-hospital lethality due to AMI is directly related to the older age. In the present study, the proportion of elderly (around 45%) did not vary significantly (p=0.977) along the years.

This work is the first to analyze the temporal tendency of in-hospital lethality due to AMI, in 9 years, in the CCU, and the influence of therapeutic modalities in a non-selected population. The in-hospital lethality is a traditional indicator of performance of quality of attendance, and it has recently been highlighted by Dubois41.

Therapeutic changes have occurred in the treatment of AMI in the last 2 decades and many controlled, randomized studies investigated the impact of the adjunct pharmacotherapy and the reperfusion in the in-hospital lethality42-45. Heidenreich et al.46 concluded that the main reason for the decrease of early in-hospital lethality was related to the amplification of adjuvant therapy (acetylsalicylic acid, IACE, beta-blockers), the myocardial reperfusion techniques, as well as the selective angioplasty (rescue, urgency) and the MRS.

In the French records, the proportion of the use of acetylsalicylic acid increased from 63% to 89%, and the beta-blockers from 41% to 64% in the period from 1994 to 1995, with a decrease in lethality, from 12.1% to 7.7%28. In the American records of AMI, from 1990 to 1999, it was demonstrated a growing use of those pharmaceuticals in the first 24 hours of hospital admission47.

A significant increase in the utilization of acetylsalicylic acid and beta-blockers (fig. 4) was noted, especially from 1998, which corroborates to the fact that the introduction and amplification of those benefic therapies participated in the reduction of in-hospital lethality.

A significant part of the reduction of lethality is related to the interventions (P PCI, early MRS, rescue angioplasty, cinecoronariography in high risk patients) performed during the acute stage37,48.

In this sample, we noted an increase of cine and S PCI (p=0.000 and p=0.021, for linear tendency). This occurred despite of not having a change in the risk profile, but for having occurred a change in the conduct of the treatment of infarction at the acute stage through the medical routine that was introduced from 1998, by intervening more aggressive and earlier in high risk patients and in those with complications. During a recent Latin-American symposium of intensive therapy in P PCI-submitted patients from our CCU, the lethality rate was 2%49.

In the State of Rio de Janeiro, from 23,108 AMI-diagnosed patients, assessed through authorizations for hospitalization, between 1995 and 2000, a small decreasing, but significant, tendency of in-hospital lethality, from 18.4% to 16.9%, with an average of 18%, was found, and the use of thrombolytic therapy almost doubled, going from 6.6% to 11.8% (r2=0.69 and p<0.05). In the City of Rio de Janeiro, the in-hospital lethality did not have a significant change in the same period, going from 16.5% to 15.8%50.

According to many authors, there is an important variation in the usage profiles of the technologies applied in AMI, with already investigated, debated and clarified indications and efficacy51-53. That fact is due to the existence of variable levels of adhesion or knowledge of the scientific evidence-based protocols14,54. At CCU the team periodically meets for the updating of the conducts in accordance to the needs and availability of therapeutic resources available. After updated, they start to be fully used by the medical team, keeping the uniformity and adhesion to the routine.

One of the limitations in this study is the low power of generalization and, therefore, its conclusions must only be applied to populations with an AMI profile similar to this one. The second limitation refers to the fact that this kind of study analyzed the general data and not the individual information of each patient. Because of that, the casualty assessment was impaired, having been minimized with the analysis of the temporal series, applied in the present study.

In conclusion, in this study it was observed that there was a reduction of in-hospital lethality due to AMI, in both sexes, and that the decrease of lethality was due to the implementation of pharmacological and interventionist clinical measures in the daily practice.

References

Marco Antonio de Mattos

Rua General Rabelo, 64/202

Cep 22451-010 - Rio de Janeiro, RJ - Brazil

E-mail:

demattos@cardiol.br

Sent for publishing on 07/19/2004

Accepted on 11/23/2004