A MAPA é indicada para todo hipertenso e normotenso? Existem evidências para tanto?
Universidade de São Paulo - São Paulo, SP
A hipertensão arterial é responsável diretamente por 80% dos casos de acidentes vasculares encefálicos e 40% dos casos de doença isquêmica do coração no Brasil, sendo essas duas condições responsáveis por 40% dos óbitos em nosso meio1. Apesar de não existirem estudos epidemiológicos de abrangência nacional, o Ministério da Saúde estima, baseado em levantamentos isolados, que a prevalência de hipertensão na população adulta brasileira é de pelo menos 20%2. Portanto, o combate à hipertensão deve ser visto como uma prioridade em termos de Saúde Pública.
Dentro dessa visão, é mais do que óbvio dizer que tudo começa com um correto diagnóstico da hipertensão. Tradicionalmente, o diagnóstico da hipertensão é baseado em medidas de consultório, preferencialmente em duas ou mais ocasiões diferentes, de acordo com o preconizado nas IV Diretrizes Brasileiras de Hipertensão3. A informação prognóstica de que pessoas com valores de pressão arterial de consultório acima de 140/90mmHg estão sob maior risco cardiovascular é inquestionável em termos populacionais4. No entanto, algumas questões precisam ser levantadas.
Mesmo tomando-se todos os cuidados necessários para uma correta medida da pressão no consultório, que vão desde o correto posicionamento do paciente até o uso de esfigmomanômetros calibrados, dois aspectos inerentes a características biológicas da pressão arterial podem levar a medidas equivocadas: sua conhecida variabilidade em 24 horas, ou seja, uma medida isolada não representa necessariamente o comportamento da pressão durante todo o dia, e o efeito do avental branco, uma reação de alarme na presença do médico, que pode elevar significativamente a pressão arterial5.
A monitorização ambulatorial da pressão arterial (MAPA), pelas próprias características do método, além de sobrepujar tais limitações da pressão arterial de consultório, fornece uma série de outras informações sobre o comportamento da pressão arterial, tais como valores de média de pressão arterial em diferentes períodos do dia, pressão arterial durante o sono, carga pressórica e análises diversas sobre a variabilidade da pressão arterial (desvio-padrão,
A superioridade da MAPA em relação à medida da pressão arterial de consultório não é apenas teórica. Em diversos estudos transversais, ao menos uma das variáveis obtidas na MAPA mostrou-se superior às medidas de consultório quando correlacionada com as mais diversas lesões em órgãos-alvo, seja hipertrofia miocárdica, infartos cerebrais lacunares, proteinúria, graus de retinopatia hipertensiva e espessura mio-intimal de carótidas9.
Vários estudos prospectivos tiveram como objetivo primário avaliar o papel da MAPA em prognosticar a ocorrência de eventos cardiovasculares em hipertensos não tratados, sendo que pelo menos duas variáveis da MAPA, a saber, as médias de pressão arterial e o descenso noturno da pressão arterial, demonstraram inequívocas vantagens da MAPA em identificar com mais propriedade aqueles pacientes que estavam sob maior risco10,11. À semelhança dos estudos prospectivos realizados em hipertensos não tratados, já dispomos de ao menos um estudo de
Mais recentemente, dois estudos de
As críticas que poderiam existir acerca de extrapolação desses resultados para uma população ocidental e predominantemente urbana, como a brasileira, foram dissipadas com os resultados de um estudo dinamarquês que realizou a MAPA em 1.700 pessoas da população geral da cidade de Copenhague, que após um período médio de seguimento de 9,5 anos, também apontou informações prognósticas adicionais advindas da MAPA14. Assim como para a pressão de consultório, o estudo mostrou uma correlação positiva e linear entre a média de pressão arterial de 24 horas e o risco de mortalidade cardiovascular.
Portanto, apesar de a MAPA não estar presente no algoritmo diagnóstico de hipertensão de nenhuma sociedade internacional que tenha publicado uma diretriz relacionada ao tema, em um futuro não muito distante, dadas as vantagens da MAPA em relação à medida da pressão de consultório aqui colocadas, a indicação da MAPA para confirmar o diagnóstico de hipertensão poderá tornar-se obrigatória, sob pena de estarmos negando as melhores evidências disponíveis15.
Sem dúvida nenhuma, o grande empecilho para a imediata implantação dessa conduta é o custo proibitivo que tal abordagem traria para qualquer gestor de saúde que viesse a sustentá-la, seja ele público ou privado. No entanto, com o barateamento progressivo da tecnologia, o custo/efetividade desta abordagem ficará evidente.
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1. Lotufo PA. Why Brazil does not have an outbreak of chronic diseases: lessons from cardiovascular diseases? Ciênc Saúde Coletiva 2004;9: 844-7.
2. Guimaraes AC. Hypertension in Brazil. J Hum Hypertens 2002;16(Suppl 1):S7-S10.
3. IV Brazilian guidelines in arterial hypertension. Arq Bras Cardiol 2004;82(Suppl 4):7-22.
4. Prospective Studies Collaboration. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analisys of individual data for one million adults in 61 prospective studies. Lancet 2002;360:1903-13.
5. Pickering TG, DPhil, Hall JE et al. Recommendations for Blood Pressure Measurement in Humans and Experimental Animals Part 1: Blood Pressure Measurement in Humans A Statement for Professionals From the Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research. Hypertension 2005;45:142-61.
6. Ohkubo T, Hozawa A, Yamaguchi J et al. Prognostic significance of the nocturnal decline in blood pressure in individuals with and without high 24-h bloodpressure: the Ohasama study. J Hypertens 2002;20:2183–89.
7. Kario K, Pickering TG, Umeda Y et al. Morning surge in blood pressure as a predictor of silent and clinical cerebrovascular disease in elderly hypertensives: a prospective study. Circulation 2003;107:1401-6.
8. Redon J, Liao Y, Lozano JV et al. Ambulatory blood pressure and microalbuminuria in essential hypertension: Role of circadian variability. J Hypertens 1994;12:947–53.
9. Verdecchia P, Angeli F, Gattobigio R. Clinical usefulness of ambulatory blood pressure monitoring. J Am Soc Nephrol 2004;15(Suppl 1):S30-3.
10. Perloff D, Sokolov M, Cowan R. The prognostic value of ambulatory blood pressure. JAMA 1983; 248: 2792-8.
11. Staessen J, Thijs L, Fagard R et al. For the Systolic Hypertension in Europe Trial Investigators. Prediccting cardiovascular risk using conventional vs ambulatory blood pressure in older patients with systolic hypertension. JAMA 1999;282:539-46.
12. Clement DL, Buyzere ML, Bacquer DA et al. For the Office vs Ambulatory Pressure Study Investigators. Prognostic value of ambulatory blood-pressure recordings in patients with treated hypertension. N Engl J Med 2003;348: 2407-15.
13. Kikuya M, Ohkubo T, Asayama K et al. Ambulatory blood pressure and 10-year risk of cardiovascular and noncardiovascular mortality: the Ohasama study. Hypertension 2005;45:240-5.
14. Hansen TW, Jeppesen J, Rasmussen S, Ibsen H, Torp-Pedersen C. Ambulatory blood pressure and mortality: a population-based study. Hypertension 2005;45:499-504.
15. Myers MG. Ambulatory blood pressure monitoring for routine clinical practice. Hypertension 2005;45:483-4.
16. Verdecchia P. Prognostic value of ambulatory blood pressure. Current evidence and clinical implications. Hypertension 2000;35:844-51.
Décio Mion Júnior Av. Dr. Enéas de Carvalho Aguiar, 255 05403-000 – São Paulo, SP E-mail:
Recebido em 01/05/05
Aceito em 01/07/05
Is ABPM indicated for all hypertensives and normotensives? Is supportive evidence available?
Universidade de São Paulo - São Paulo, SP - Brazil
Hypertension is directly responsible for 80% of stroke occurrences, and for 40% of heart ischemia conditions in Brazil. The two conditions account for 40% of deaths in our country1. Although there are no nationwide epidemiologic studies available, the Ministry of Health – based on non-pooled data – estimates hypertension prevalence in Brazilian adult population to be at least 20%2. Therefore, fighting hypertension must be seen as a priority in Public Health.
From that angle, it is redundant to say that it all starts with the correct diagnosis of hypertension. Traditionally, hypertension diagnosis is based on doctor's office records, preferably at two or more different occasions, as recommended by the IV Brazilian Guidelines on Hypertension3. The prognostic information that individuals with blood pressure values above 140/90mmHg when measured at the doctor's office have shown to be under higher cardiovascular risk is unquestionable in populational terms4. However, some issues deserve further discussion.
Even if all care is taken for accurate measuring of blood pressure at the office – from proper positioning of patient up to the use of calibrated sphygmomanometers – two aspects related to the very nature of blood pressure biological characteristics may lead to non-correct measuring: BP renowned variability in the 24-hour period, which means to say, one measure – isolatedly - is not necessarily representative of pressure behavior all day long. Additionally, the "white coat effect" – an alarm reaction when in the presence of the doctor - may significantly raise blood pressure5.
Based on the very nature of the method, in addition to exceeding the very limitations of blood pressure office measuring, ambulatory blood pressure monitoring (ABPM) provides quite a number of data on blood pressure behavior, such as mean blood pressure values at different points of time in the day, blood pressure during sleep, pressure load, and different analyses on blood pressure variability (standard deviation, early morning surge, etc.), which, at lower or higher relevance, have also shown to be useful in identifying patients at high cardiovascular risk 6,7,8.
A higher efficiency as compared to BP measured at the office has proven not to be based on theoretical grounds only. In a number of cross-sectional studies, at least one of the variables obtained from ABPM showed to be superior to doctor's office measures when correlated to the various lesions in target organs: myocardial hypertrophy, lacunal cerebral infarctions, proteinuria, levels of hypertensive retinopathy, and myointimal thickness of carotid arteries9.
A number of prospective studies had the purpose of analyzing the role played by ABPM in the prognosis of cardiovascular events in non-treated hypertensives. At least two AMBP variables - blood pressure means and nocturnal blood pressure fall - showed to be ABPM inequivocal advantages in more properly identifying patients under higher risk10,11. Similarly to the prospective studies carried out with non-treated hypertensives, at least one cohort study is already available, analyzing AMBP in patients under drug treatment. Results were again favorable to ABPM12.
More recently, two cohort studies have validated those results for the general population as well. The Ohasama study published data on a 10-year follow-up with 1,332 individuals from a Japanese rural community. Those data confirmed observations already carried out when circumscribed to the five first years of follow-up: ABPM blood pressure means (awake, during sleep, and in the 24-hour period) are better markers for cardiovascular prognosis when compared to doctor's office measuring of BP, particularly mean blood pressure values during sleep13.
Any criticism against extrapolating those results to a Western, predominantly urban population - as the Brazilian population - was dissipated by the results of a Danish study that had ABPM records of 1,700 individuals from the general population in Copenhagen. After a 9 ½-year period of follow up, that population also showed additional prognosis through ABPM14. Just as pressure taken at the office, the study showed a positive and linear correlation between 24-hour mean blood pressure and the risk of cardiovascular mortality.
Threfore, although ABPM has not yet been included as a diagnostic algorithm for hypertension by any of the international societies that have published related guidelines, ABPM indication to confirm hypertension diagnosis may be made compulsory at no distant future due to the benefits it offers as compared to meausures taken at the doctor's office, as pointed out earlier. Otherwise, the best evidence available will have been denied15.
The major obstacle for immediate implementation of such conduct is undoubtedly the prohibitive cost it would represent to any health manager trying to support it, whether at the public or private environment. However, with technology progressively becoming more affordable, cost/effectiveness of such approach will be evident.
Illustration 1, adapted from a suggestion made by Verdecchia16, exemplifies how ABPM may be useful to diagnose hypertension, also providing additional stratification of cardiovascular risk, as well as acting as a guide for therapeutic orientation.
1. Lotufo PA. Why Brazil does not have an outbreak of chronic diseases: lessons from cardiovascular diseases? Ciênc Saúde Coletiva 2004;9: 844-7.
2. Guimaraes AC. Hypertension in Brazil. J Hum Hypertens 2002;16(Suppl 1):S7-S10.
3. IV Brazilian guidelines in arterial hypertension. Arq Bras Cardiol 2004;82(Suppl 4):7-22.
4. Prospective Studies Collaboration. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analisys of individual data for one million adults in 61 prospective studies. Lancet 2002;360:1903-13.
5. Pickering TG, DPhil, Hall JE et al. Recommendations for Blood Pressure Measurement in Humans and Experimental Animals Part 1: Blood Pressure Measurement in Humans A Statement for Professionals From the Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research. Hypertension 2005;45:142-61.
6. Ohkubo T, Hozawa A, Yamaguchi J et al. Prognostic significance of the nocturnal decline in blood pressure in individuals with and without high 24-h bloodpressure: the Ohasama study. J Hypertens 2002; 20:2183–89.
7. Kario K, Pickering TG, Umeda Y et al. Morning surge in blood pressure as a predictor of silent and clinical cerebrovascular disease in elderly hypertensives: a prospective study. Circulation 2003;107:1401-6.
8. Redon J, Liao Y, Lozano JV et al. Ambulatory blood pressure and microalbuminuria in essential hypertension: Role of circadian variability. J Hypertens 1994;12:947–53.
9. Verdecchia P, Angeli F, Gattobigio R. Clinical usefulness of ambulatory blood pressure monitoring. J Am Soc Nephrol 2004;15(Suppl 1):S30-3.
10. Perloff D, Sokolov M, Cowan R. The prognostic value of ambulatory blood pressure. JAMA 1983; 248: 2792-8.
11. Staessen J, Thijs L, Fagard R et al. For the Systolic Hypertension in Europe Trial Investigators. Prediccting cardiovascular risk using conventional vs ambulatory blood pressure in older patients with systolic hypertension. JAMA 1999;282:539-46.
12. Clement DL, Buyzere ML, Bacquer DA et al. For the Office vs Ambulatory Pressure Study Investigators. Prognostic value of ambulatory blood-pressure recordings in patients with treated hypertension. N Engl J Med 2003;348: 2407-15.
13. Kikuya M, Ohkubo T, Asayama K et al. Ambulatory blood pressure and 10-year risk of cardiovascular and noncardiovascular mortality: the Ohasama study. Hypertension 2005;45:240-5.
14. Hansen TW, Jeppesen J, Rasmussen S, Ibsen H, Torp-Pedersen C. Ambulatory blood pressure and mortality: a population-based study. Hypertension 2005;45:499-504.
15. Myers MG. Ambulatory blood pressure monitoring for routine clinical practice. Hypertension 2005;45:483-4.
16. Verdecchia P. Prognostic value of ambulatory blood pressure. Current evidence and clinical implications. Hypertension 2000;35:844-51.
Décio Mion Júnior Av. Dr. Enéas de Carvalho Aguiar, 255 05403-000 – São Paulo, SP - Brazil E-mail:
Received on 5/01/05
Accepted on 7/01/05