Oxygen Consumption – ABC CARDIOL

ABC

Editorial

Is There an Association Between Timed Up and Go Test Performance Results and Directly Measured Peak Oxygen Consumption in Patients with Heart Disease?

Filipe Ferrari et al. Ricardo Stein

Functional capacity, the ability to perform daily activities independently, is commonly assessed using standardized tests like the 6-minute walk test, Timed Up and Go Test (TUGT), and one-minute sit-to-stand test. However, the gold standard for evaluating functional or cardiorespiratory capacity is cardiopulmonary exercise testing (CPET), which measures peak oxygen consumption (VO₂peak). CPET involves gradually increasing exercise intensity until exhaustion or symptom onset.

Numerous studies consistently demonstrate a strong inverse association between VO₂peak and cardiovascular events, cardiovascular mortality, and all-cause mortality,^, underscoring the pivotal role of functional capacity in the context of cardiovascular diseases. Moreover, in heart failure, regardless of ejection fraction status, poor performance on the 6-minute walk test has been linked to elevated risks of all-cause mortality and heart failure.

[…]

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Original Article

Prediction of Peak Oxygen Consumption in Patients with Heart Disease Based on Performance on the Timed Up and Go Test

Danilo Silva dos Santos et al. Ciro Oliveira Queiroz Cristiane Maria Carvalho Costa Dias Gerson Cipriano Junior … Queila Oliveira Borges Luiz Eduardo Fonteles Ritt

Abstract

Background

The use of the timed up and go (TUG) test to assess cardiorespiratory fitness in patients with heart disease has not been well defined in the literature.

Objectives

Test the association between TUG and peak oxygen consumption (VO₂peak), construct an equation based on TUG to predict VO₂peak, and determine a cutoff point to estimate VO₂peak ≥ 20 mL/kg/min.

Methods

This cross-sectional study included 201 patients with coronary artery disease or heart failure, between 36 and 92 years of age, who underwent TUG and cardiopulmonary exercise test. Correlation, ROC curve, multiple linear regression, and Bland-Altman analyses were performed. The significance level was set at p < 0.05.

Results

The mean age of the total sample was 67 ± 13 years, and 70% of participants were male. The mean VO₂peak was 17 ± 6 mL/kg/min, and the mean TUG time was 7 ± 2.5 seconds. The correlation between VO₂peak and TUG was r = −0.54 (p < 0.001), and R² was 0.30. The following equation was developed based on ; a value of 0 was assigned to the male sex and 1 to the female sex (adjusted R: 0.41; adjusted R²: 0.40). The VO₂peak estimated by the equation was 18.81 ± 3.2 mL/kg/min, and the VO₂peak determined by cardiopulmonary exercise test was 18.18 ± 5.9 mL/kg/min (p > 0.05). The best cutoff point in the TUG for VO₂peak ≥ 20 mL/kg/min was ≤ 5.47 seconds (area under the curve: 0.80; 95% confidence interval: 0.74 to 0.86).

Conclusions

TUG and VO₂peak showed a significant association. A prediction equation for VO₂peak was developed and validated internally with good performance. The cutoff point in the TUG to predict VO₂peak ≥ 20 mL/kg/min was ≤ 5.47 seconds.

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IJCS

Editorial

Cardiorespiratory Optimal Point: A New Kid in the Block or an Established Star?

Summary

COP researchers have already conducted very important research that must be expanded, including larger and more diverse and better defined populations, with patients around the world, different cardiovascular and non-cardiovascular diseases, tests using a treadmill (more experience with treadmill CPET is needed), and evaluation of the prognostic values of sub-maximal parameters, such as COP and eventually VO ₂ at VT1, versus the maximal parameters, such as pVO ₂ , VE/VCO ₂ slope, and OUES.

A clear answer is needed: Is the information obtained from a submaximal CPET enough, or should it be considered only as an alternative when it is not possible to perform a maximal CPET or when peak VO ₂ was not reached?

[…]

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Original Article

Predictive Ability of Cardiopulmonary Exercise Test Parameters in Heart Failure Patients with Cardiac Resynchronization Therapy

João Ferreira Reis et al. António Valentim Gonçalves Pedro Garcia Brás Rita Ilhão Moreira … Pedro Rio Ana Teresa Timóteo Rui M. Soares Rui Cruz Ferreira

Abstract

Background

There is evidence suggesting that a peak oxygen uptake (pVO₂) cut-off of 10ml/kg/min provides a more precise risk stratification in cardiac resynchronization therapy (CRT) patients.

Objective

To compare the prognostic power of several cardiopulmonary exercise testing (CPET) parameters in this population and assess the discriminative ability of the guideline-recommended pVO₂cut-off values.

Methods

Prospective evaluation of consecutive heart failure (HF) patients with left ventricular ejection fraction ≤40%. The primary endpoint was a composite of cardiac death and urgent heart transplantation (HT) in the first 24 follow-up months, and was analysed by several CPET parameters for the highest area under the curve (AUC) in the CRT group. A survival analysis was performed to evaluate the risk stratification provided by several different cut-offs. p values <0.05 were considered significant.

Results

A total of 450 HF patients, of which 114 had a CRT device. These patients had a higher baseline risk profile, but there was no difference regarding the primary outcome (13.2% vs 11.6%, p =0.660). End-tidal carbon dioxide pressure at anaerobic threshold (P_ETCO_2AT)had the highest AUC value, which was significantly higher than that of pVO₂in the CRT group (0.951 vs 0.778, p =0.046). The currently recommended pVO₂cut-off provided accurate risk stratification in this setting (p <0.001), and the suggested cut-off value of 10 ml/min/kg did not improve risk discrimination in device patients (p =0.772).

Conclusion

P_ETCO_2ATmay outperform pVO₂’s prognostic power for adverse events in CRT patients. The current guideline-recommended pVO2 cut-off can precisely risk-stratify this population.

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Editorial

NYHA Classification and Cardiopulmonary Exercise Test Variables in Patients with Heart Failure

Ricardo Vivacqua Cardoso Costa

Heart failure (HF) is considered a prevalent disease, limiting survival and constituting one of the leading causes of hospitalization or death in several countries, including Brazil. Therefore, clinical classification in patients with HF can be considered important as an initial reference, as it informs the functional condition of these patients. Classically, the subjective classification of the New York Heart Association (NYHA) and the objective classification of Weber are the most used. The NYHA functional classification and oxygen consumption at peak exertion were decisive in determining the functional condition of patients with Chagas disease. However, certain patients with minor symptoms are at high risk of hospitalization or death.

In patients with HF, the 6-minute walk test is also considered in assessing functional and prognostic capacity. This test has a predictive value for mortality in patients with HF functional class II and III (NYHA).

[…]

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Case Report

The Effect of Respiratory Protective Surgical Mask on Physiological Markers of Endurance Performance in a Recreational Runner

Danilo Marcelo Leite do Prado et al. Valmir Oliveira Silvino Ewerton Gomes Vieira Bruno Viana Rosa … Acácio Salvador Veras e Silva Marcos Antonio Pereira dos Santos

Introduction

The advent of the Coronavirus 19 (COVID-19) pandemic, which has quickly spread worldwide, has raised the attention regarding the use of respiratory protective face masks (PFM) not only by healthcare personnel, but also the general population. In this context, wearing a PFM during physical exercise in an external environment can reduce COVID-19 infection risks. On the other hand, the use of PFM can increase the subjective perception of breathing difficulty through the formation of microclimates inside the face mask (i.e., temperature and humidity) and airflow restriction.

In recent years, the number of amateur runners has significantly increased among many populations around the world, as running can be performed with minimal equipment, and by a broad variety of people. Interestingly, during endurance exercise, the adaptability of the cardiorespiratory system is of paramount importance, as it increases both convective and diffusive oxygen transport, thus enabling the body to meet the demands for oxygen, substrate delivery, and carbon dioxide removal. Moreover, the so-called physiological markers of endurance performance, such as ventilatory anaerobic threshold, respiratory compensation point, running economy, and maximal oxygen uptake, also seem to be important in determining absolute exercise intensity (i.e., pace, power output).

[…]

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Original Article

The Six-Minute Step Test as a Predictor of Functional Capacity according to Peak VO2 in Cardiac Patients

Luiz Eduardo Fonteles Ritt et al. Eduardo Sahade Darzé Gustavo Freitas Feitosa Jessica Santana Porto … Gabriela Bastos Renata Braga Linhares de Albuquerque Cristiane Miura Feitosa Thaissa Costa Claro Eloisa Ferreira Prado Queila Borges de Oliveira Ricardo Stein

Abstract

Background:

Six-minute step test (6MST) is a simple way to evaluate functional capacity, although it has not been well studied in patients with coronary artery disease (CAD) or heart failure (HF).

Objective:

Analyze the association between the 6MST and peak oxygen uptake (VO_2peak) and develop an equation for estimating VO_2peak based on the 6MST, as well as to determine a cutoff point for the 6MST that predicts a VO_2peak ≥20 mL.Kg^-1.min^-1

Methods:

In 171 patients who underwent the 6MST and a cardiopulmonary exercise test, correlation, regression, and ROC analysis were used and a p < 0.05 was admitted as significant.

Results:

mean age was 60±14 years and 74% were male. Mean left ventricle ejection fraction was 57±16%, 74% had CAD and 28% had HF. Mean VO_2peak was 19±6 mL.Kg^-1.min^-1 and mean 6MST performance was 87±45 steps. Association between 6MST and VO_2peak was r 0.69 (p <0.001). The model VO_2peak =19.6 + (0.075 x 6MST) – (0.10 x age) for men and VO_2peak =19.6 + (0.075 x 6MST) – (0.10 x age) – 2 for women could predict VO_2peak based on 6MST results (adjusted R 0.72; adjusted R² 0.53). The most accurate cutoff point for 6MST to predict a VO_2peak ≥20 mL.Kg^-1.min^-1 was >105 steps (AUC 0.85; 95% CI 0.79 -0.90; p <0.001).

Conclusion:

An equation for predicting VO_2peak based on 6MST results was derived, and a significant association was found between 6MST and VO_2peak. The cutoff point for 6MST, which predicts a VO_2peak ≥20 mL.Kg^-1.min^-1, was >105 steps. (Arq Bras Cardiol. 2021; 116(5):889-895)

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Original Article

Maximal Oxygen Uptake and Ventilation Improvement Following Sacubitril-Valsartan Therapy

António Valentim Gonçalves et al. Tiago Pereira-da-Silva Ana Galrinho Pedro Rio … Rui Soares Joana Feliciano Rita Ilhão Moreira Sofia Silva Sandra Alves Eunice Capilé Rui Cruz Ferreira

Abstract

Background

Sacubitril/valsartan had its prognosis benefit confirmed in the PARADIGM-HF trial. However, data on cardiopulmonary exercise testing (CPET) changes with sacubitril-valsartan therapy are scarce.

Objective

This study aimed to compare CPET parameters before and after sacubitril-valsartan therapy.

Methods

Prospective evaluation of chronic heart failure (HF) patients with left ventricular ejection fraction ≤40% despite optimized standard of care therapy, who started sacubitril-valsartan therapy, expecting no additional HF treatment. CPET data were gathered in the week before and 6 months after sacubitril-valsartan therapy. Statistical differences with a p-value <0.05 were considered significant.

Results

Out of 42 patients, 35 (83.3%) completed the 6-month follow-up, since 2 (4.8%) patients died and 5 (11.9%) discontinued treatment for adverse events. Mean age was 58.6±11.1 years. New York Heart Association class improved in 26 (74.3%) patients. Maximal oxygen uptake (VO₂max) (14.4 vs. 18.3 ml/kg/min, p<0.001), VE/VCO₂slope (36.7 vs. 31.1, p<0.001), and exercise duration (487.8 vs. 640.3 sec, p<0.001) also improved with sacubitril-valsartan. Benefit was maintained even with the 24/26 mg dose (13.5 vs. 19.2 ml/kg/min, p=0.018) of sacubitril-valsartan, as long as this was the highest tolerated dose.

Conclusions

Sacubitril-valsartan therapy is associated with marked CPET improvement in VO₂max, VE/VCO₂slope, and exercise duration. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)

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Original Article

Prognostic Prediction of Cardiopulmonary Exercise Test Parameters in Heart Failure Patients with Atrial Fibrillation

António Valentim Gonçalves et al. Tiago Pereira-da-Silva Rui Soares Joana Feliciano … Rita Ilhão Moreira Pedro Rio Ana Abreu Rui Cruz Ferreira

Abstract

Background:

Atrial fibrillation (AF) is associated with increased mortality in heart failure (HF) patients.

Objective:

To evaluate whether the risk of AF patients can be precisely stratified by relation with cardiopulmonary exercise test (CPET) cut-offs for heart transplantation (HT) selection.

Methods:

Prospective evaluation of 274 consecutive HF patients with left ventricular ejection fraction ≤ 40%. The primary endpoint was a composite of cardiac death or urgent HT in 1-year follow-up. The primary endpoint was analysed by several CPET parameters for the highest area under the curve and for positive (PPV) and negative predictive value (NPV) in AF and sinus rhythm (SR) patients to detect if the current cut-offs for HT selection can precisely stratify the AF group. Statistical differences with a p-value <0.05 were considered significant.

Results:

There were 51 patients in the AF group and 223 in the SR group. The primary outcome was higher in the AF group (17.6% vs 8.1%, p = 0.038). The cut-off value of pVO₂ for HT selection showed a PPV of 100% and an NPV of 95.5% for the primary outcome in the AF group, with a PPV of 38.5% and an NPV of 94.3% in the SR group. The cut-off value of VE/VCO₂ slope showed lower values of PPV (33.3%) and similar NPV (92.3%) to pVO₂ results in the AF group.

Conclusion:

Despite the fact that AF carries a worse prognosis for HF patients, the current cut-off of pVO₂ for HT selection can precisely stratify this high-risk group.

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IJCS

Original Article

Classification System for Cardiorespiratory Fitness Based on a Sample of the Brazilian Population

Antonio Eduardo Monteiro de Almeida et al. Igor Rafael Miranda Ferreira Santander Maria Izabel Macedo Campos Jorge René Garcia Arévalo … João Agnaldo do Nascimento Luiz Eduardo Fonteles Ritt Karlyse Claudino Belli Jorge Pinto Ribeiro Ricardo Stein

Abstract

Background:

Peak oxygen consumption (VO_2peak) is an important prognostic marker and its classification helps the cardiologist in the therapeutic decision-making process. The most commonly used cardiorespiratory fitness (CRF) classification has not been validated for the Brazilian population.

Objective:

To elaborate a CRF classification using a Brazilian sample and to compare it with the American Heart Association (AHA), Cooper and UNIFESP classifications.

Methods:

A total of 6,568 healthy subjects were analyzed through cardiopulmonary exercise testing (CPET). They were distributed by sex and the following age groups (years): 7-12, 13-19, 20-79 (per decades) and > 80 years. After measurement of the VO_2peak, participants were distributed into quintiles of CRF in very poor, poor, moderate, high and very high (AEMA Table). The CRF classifications by AEMA, AHA, Cooper, and UNIFESP were compared using the Wilcoxon, Kappa and concordance percentages.

Results:

VO_2peak presented an inverse and moderate correlation with age considering both sexes (R = -0.488, p < 0.001). All paired comparisons between CRF classification systems showed differences (p < 0.001) and disagreement percentage – AEMA versus AHA (k = 0.291, 56.7%), AEMA versus Cooper (k = 0.220, 62.4%) and AEMA versus UNIFESP (k = 0.201, 63.9 %).

Conclusion:

The AEMA table showed important discrepancies in the classification of CRF when compared to other tables widely used in our setting. Because it was obtained from a large sample of the Brazilian population, the AEMA table should be preferred over other classification systems in our population.

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IJCS

Original Article

Comparative Analysis of Direct and Indirect Methods for the Determination of Maximal Oxygen Uptake in Sedentary Young Adults

Alfredo Moreira da Rocha Neto et al. Artur Haddad Herdy Pablo de Souza

Abstract

Background:

Maximal oxygen uptake is a powerful prognostic indicator and a reliable measure of physical conditioning. It can be measured directly by cardiopulmonary exercise testing (CPET) or indirectly by formulas derived from conventional protocols.

Objective:

We compared the VO₂ max obtained by formula using exercise testing with Bruce protocol (BP) with the VO₂ max obtained by CPET on the treadmill.

Methods:

We selected 41 healthy, non-obese, physically inactive young volunteers, aged between 21 and 50 years, residents of Florianópolis, Brazil.

Results:

Twenty-one women (52%) with mean age of 35.62 ± 8.83 years, and 20 males, with mean age of 32.5 ± 7.18 years participated in the study. Statistically significant differences were found for VO₂ max between the two methods (BP – 42.31 ± 5.21 ml/kg.min vs. CPET – 30.46 ± 5.50 ml/kg.min., p < 0.0001). The Bruce formula overestimated the result by 34.1% (BP – 45.95 ± 3.94 ml/kg.min vs. CPX – 34.27 ± 4.20 ml/kg.min, p < 0.0001) for men, and by 44.8% (BP – 38.84 ± 3.72 ml/kg.min vs. CPX – 26.83 ± 3.90, p < 0.0001) for women. A moderate correlation was observed between the methods (r = 0.65). When classifying the results according to the table of aerobic capacity of the American Heart Association, the agreement was null (kappa = 0.0034; Pearson chi2 = 0.001).

Conclusion:

VO₂ estimated by BP is not capable of demonstrating the true aerobic capacity in these individuals, while CPET is an important tool for early detection of diminished functional capacity in sedentary young men and women.

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Original Article

Correlation between Exercise Stress Test and Echocardiographic Parameters in Elderly Individuals

Liz Andréa Villela Baroncini et al. Camila Varotto Baroncini Juliana Ferreira Leal

Abstract

Background:

Maximum oxygen consumption (VO₂ max) in healthy individuals decreases approximately 10% per decade of life, and such decrease is more pronounced after the seventh decade.

Objectives:

To assess functional capacity of individuals aged 75 years or older, submitted to ergometric test and transthoracic echocardiogram exam, by means of metabolic equivalent (MET) and VO₂ max measurements.

Methods:

A total of 381 patients (205 women; 79 ± 3.7 years) were evaluated. Exclusion criteria were: presence of left ventricular (LV) systolic dysfunction, LV diastolic dysfunction grade II and III, significant valve disease, or coronary artery disease with systolic LV dysfunction or dilatation. Associations between quantitative variables were analyzed by Pearson and Spearman correlation coefficients, and comparisons of quantitative data by Student’s t-test for independent samples.

Results:

Increasing age was associated with a progressive decrease in the distance covered (p = 0.021), in the expected increase in HR (p < 0.001), in VO₂ max (p < 0.001), and METs (p < 0.001) in both genders. There was no correlation of exercise test parameters with the echocardiographic parameters.

Conclusions:

Relatively healthy older individuals, with global systolic and diastolic functions of the left ventricle preserved, presented a progressive decrease in their functional capacity due to their natural aging process, comorbidities related to their age range and physical deconditioning.

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IJCS

Original Article

Influence of Pulmonary Rehabilitation on Clinical Characteristics in Patients with Chronic Heart Failure and Chronic Obstructive Pulmonary Disease

Ganna S. Smyrnova et al. Tetiana M. Babkina Gennadii G. Taradin Mykola T. Vatutin

Abstract

Background:

The improvement of treatment strategies in patients with chronic obstructive pulmonary disease (COPD) and especially with comorbid pathology should provide rational conversion of standard schemes of therapy and rehabilitation in accordance with their clinical, pathogenic, functional and economic feasibility.

Objective:

To assess the influence of pulmonary rehabilitation on clinical characteristics in patients with chronic heart failure (CHF) and concomitant COPD.

Methods:

The study included 102 patients with CHF and concomitant COPD (males, 62%; mean age, 68.2 ± 4.5 years). All patients were divided into two groups: control group (CG) (n = 54), received only standard therapy of CHF and COPD; and intervention group (IG) (n = 48) were additionally taught the full yogic breathing as a program of pulmonary rehabilitation. Calculation of points by clinical evaluation scale (CES), assessment of CHF functional class (FC) (NYHA) and 6-minute walk test (6MWT – with the evaluation of dyspnea by the Borg scale) were performed in all patients on admission to the department and at discharge. Significant association was defined by p value < 0.05.

Results:

At baseline, there were no significant differences in clinical characteristics of the patients and studied parameters between the groups. At discharge both groups showed significant reduction of dyspnea by the Borg scale (in CG: from 7.2 ± 0.8 points to 5.2 ± 0.3; in IG: from 7.4 ± 0.6 points to 3.2 ± 0.4), the number of points by CES (in CG: from 10.8 ± 0.3 points to 7.2 ± 0.4; in IG: from 10.7 ± 0.6 points to 5.9 ± 0.6). Increase in exercise tolerance (by the distance of 6MWT) was observed in both groups (in CG: from 215 ± 24 m to 275 ± 22 m; in IG: from 219 ± 21 m to 308 ± 24 m). The changes were more significant in IG compared to CG. We observed the prominent decrease in CHF FC and length of hospital stay in IG.

Conclusions:

Application of full yogic breathing as the program of pulmonary rehabilitation in addition to standard therapy of the patients with CHF and COPD is associated with a significant decrease in CHF FC, an increase in exercise tolerance and a reduced length of hospital stay.

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Original Article

Pre-Participation Physical Fitness does not Influence Adherence to a Supervised Exercise Program

Fábio Akio Nishijuka et al. Christina Grüne de Souza e Silva Carlos Vieira Duarte Claudio Gil Soares de Araújo

Abstract

Background:

Exercise-based cardiac rehabilitation tends to reduce mortality. However, it requires medium/long-term adherence to regular physical exercise. It is relevant to identify the variables that affect adherence to an supervised exercise program (SEP).

Objective:

To evaluate the influence of pre-participation levels of aerobic and non-aerobic physical fitness components in medium-term adherence to SEP.

Methods:

A total of 567 SEP participants (65 ± 12 years) (68% men) were studied. Participants adherent to the program for less than 6 months (48%) (non-adherent – NAD) were compared with 52% of participants who were adherent for 6 months or more (adherents – AD). In the non-aerobic fitness, flexibility (FLX) (Flexitest) and muscle power (MPW)/body weight in standing rowing (watts/kg) were evaluated while aerobic fitness was obtained by direct measure of VO₂max/body weight (VO₂). These measurements were normatized for sex and age based on percentiles (P) (P-FLX/P-MPW) of reference data or percentages of predicted (P-VO₂). Additionally, AD and NAD with extreme results (tertiles) were simultaneously compared for the three variables.

Results:

There was no difference between AD and NAD for non-aerobic results, in median [P25-P75], P-FLX: 30 [13-56] and 31 [9-52], respectively, (p = 0.69) and P-MPW: 34 [17-58] and 36 [16-62], respectively (p = 0.96), and for aerobic results (mean ± standard error) P-VO₂ (75.9 ± 1.3% and 75.0 ± 1.3%, respectively) (p = 0.83). When comparing extreme tertiles, a difference was found for P-MPW in the lower tertile only, with a slight advantage of AD over NAD- 9 [5-16] versus 4 [1-11] (p = 0.04).

Conclusion:

Although awareness of the pre-participation levels of aerobic and non-aerobic physical fitness components is useful for individualized exercise prescription, these variables do not seem to influence medium-term adherence to SEP.

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IJCS

Original Article

Cardiopulmonary Exercise Testing in Patients With Left Bundle Branch Block and Preserved Ejection Fraction

Milena dos Santos Barros et al. Rívia Siqueira Amorim Romerito Oliveira Rocha Enaldo Vieira de Melo … José Augusto Barreto-Filho Antônio Carlos Sobral Sousa Romeu Sérgio Meneghelo Joselina Luzia Menezes Oliveira

Abstract

Background:

Left bundle branch block (LBBB) has prognostic significance in patients with congestive heart failure. However, its influence is not well established in patients with preserved systolic ventricular function.

Objective:

To evaluate the implications of LBBB presence in the cardiovascular performance of patients with preserved left ventricular systolic function (LVEF).

Methods:

26 LBBB patients (61.3 ± 8.2 years of age) and 23 healthy individuals (58 ± 6.8 years of age) with LVEF > 0.5 underwent cardiopulmonary exercise testing (CPET).

Results:

CPET analysis revealed: peak oxygen consumption (VO₂) predicted in the LBBB group was 87.2 ± 15.0% versus 105.0 ± 15.6% (p < 0.0001); peak oxygen pulse predicted in LBBB group was 98.6 ± 18.6% vs 109.9 ± 13.5% (p = 0.02); VO₂ predicted anaerobic threshold in LBBB group was 67.9 ± 13.6% vs 70.2 ± 12.8% (p = 0.55); ΔVO₂/Δload in the LBBB group was 15.5 ± 5.51 versus 20.7 ± 7.3 ml.min^-1.watts^-1 (p = 0.006); ventilation / carbon dioxide production (VE/VCO₂ slope) in LBBB group was 29.8 ± 2.9 versus 26.2 ± 2.9 (p = 0.0001) and VO₂ recovery time in the LBBB group was 85.2 ± 11.8 vs. 71.5 ± 11.0 seconds (p = 0.0001). LBBB was an independent marker for VE/VCO₂ slope increase.

Conclusion:

LBBB presence in individuals with preserved LVEF did not affect cardiovascular performance, but there was an increase of the VE/VCO₂ slope in comparison to the control group.

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Review Article

Cardiopulmonary Exercise Test: Background, Applicability and Interpretation

Artur Haddad Herdy et al. Luiz Eduardo Fonteles Ritt Ricardo Stein Claudio Gil Soares de Araújo … Mauricio Milani Romeu Sérgio Meneghelo Almir Sérgio Ferraz Carlos Hossri Antonio Eduardo Monteiro de Almeida Miguel Morita Fernandes-Silva Salvador Manoel Serra

Abstract

Cardiopulmonary exercise test (CPET) has been gaining importance as a method of functional assessment in Brazil and worldwide. In its most frequent applications, CPET consists in applying a gradually increasing intensity exercise until exhaustion or until the appearance of limiting symptoms and/or signs. The following parameters are measured: ventilation; oxygen consumption (VO₂); carbon dioxide production (VCO₂); and the other variables of conventional exercise testing. In addition, in specific situations, pulse oximetry and flow-volume loops during and after exertion are measured. The CPET provides joint data analysis that allows complete assessment of the cardiovascular, respiratory, muscular and metabolic systems during exertion, being considered gold standard for cardiorespiratory functional assessment.^–

The CPET allows defining mechanisms related to low functional capacity that can cause symptoms, such as dyspnea, and correlate them with changes in the cardiovascular, pulmonary and skeletal muscle systems. Furthermore, it can be used to provide the prognostic assessment of patients with heart or lung diseases, and in the preoperative period, in addition to aiding in a more careful exercise prescription to healthy subjects, athletes and patients with heart or lung diseases.

Similarly to CPET clinical use, its research also increases, with the publication of several scientific contributions from Brazilian researchers in high-impact journals.

Therefore, this study aimed at providing a comprehensive review on the applicability of CPET to different clinical situations, in addition to serving as a practical guide for the interpretation of that test.

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Original Article

Brazilian Cardiorespiratory Fitness Classification Based on Maximum Oxygen Consumption

Artur Haddad Herdy et al. Ananda Caixeta

Abstract

Background:

Cardiopulmonary exercise test (CPET) is the most complete tool available to assess functional aerobic capacity (FAC). Maximum oxygen consumption (VO₂ max), an important biomarker, reflects the real FAC.

Objective:

To develop a cardiorespiratory fitness (CRF) classification based on VO₂ max in a Brazilian sample of healthy and physically active individuals of both sexes.

Methods:

We selected 2837 CEPT from 2837 individuals aged 15 to 74 years, distributed as follows: G1 (15 to 24); G2 (25 to 34); G3 (35 to 44); G4 (45 to 54); G5 (55 to 64) and G6 (65 to 74). Good CRF was the mean VO₂ max obtained for each group, generating the following subclassification: Very Low (VL): VO₂ 105%.

Results:

Conclusions:

This chart stratifies VO₂ max measured on a treadmill in a robust Brazilian sample and can be used as an alternative for the real functional evaluation of physically and healthy individuals stratified by age and sex.

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Original Article

Reduction in Post-Marathon Peak Oxygen Consumption: Sign of Cardiac Fatigue in Amateur Runners?

Ana Paula Rennó Sierra et al. Anderson Donelli da Silveira Ricardo Contesini Francisco Rodrigo Bellios de Mattos Barretto … Carlos Anibal Sierra Romeu Sergio Meneghelo Maria Augusta Peduti Dal Molin Kiss Nabil Ghorayeb Ricardo Stein

Abstract

Background:

Prolonged aerobic exercise, such as running a marathon, produces supraphysiological stress that can affect the athlete’s homeostasis. Some degree of transient myocardial dysfunction (“cardiac fatigue”) can be observed for several days after the race.

Objective:

To verify if there are changes in the cardiopulmonary capacity, and cardiac inotropy and lusitropy in amateur marathoners after running a marathon.

Methods:

The sample comprised 6 male amateur runners. All of them underwent cardiopulmonary exercise testing (CPET) one week before the São Paulo Marathon, and 3 to 4 days after that race. They underwent echocardiography 24 hours prior to and immediately after the marathon. All subjects were instructed not to exercise, to maintain their regular diet, ingest the same usual amount of liquids, and rest at least 8 hours a day in the period preceding the CPET.

Results:

The athletes completed the marathon in 221.5 (207; 250) minutes. In the post-marathon CPET, there was a significant reduction in peak oxygen consumption and peak oxygen pulse compared to the results obtained before the race (50.75 and 46.35 mL.kg^-1 .min^-1; 19.4 and 18.1 mL.btm, respectively). The echocardiography showed a significant reduction in the s’ wave (inotropic marker), but no significant change in the E/e’ ratio (lusitropic marker).

Conclusions:

In amateur runners, the marathon seems to promote changes in the cardiopulmonary capacity identified within 4 days after the race, with a reduction in the cardiac contractility. Such changes suggest that some degree of “cardiac fatigue” can occur.

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Original Article

Sex-Specific Equations to Estimate Maximum Oxygen Uptake in Cycle Ergometry

Christina G. de Souza e Silva et al. Claudio Gil S. Araújo

Abstract

Background:

Aerobic fitness, assessed by measuring VO₂max in maximum cardiopulmonary exercise testing (CPX) or by estimating VO₂max through the use of equations in exercise testing, is a predictor of mortality. However, the error resulting from this estimate in a given individual can be high, affecting clinical decisions.

Objective:

To determine the error of estimate of VO₂max in cycle ergometry in a population attending clinical exercise testing laboratories, and to propose sex-specific equations to minimize that error.

Methods:

This study assessed 1715 adults (18 to 91 years, 68% men) undertaking maximum CPX in a lower limbs cycle ergometer (LLCE) with ramp protocol. The percentage error (E%) between measured VO₂max and that estimated from the modified ACSM equation (Lang et al. MSSE, 1992) was calculated. Then, estimation equations were developed: 1) for all the population tested (C-GENERAL); and 2) separately by sex (C-MEN and C-WOMEN).

Results:

Measured VO₂max was higher in men than in WOMEN: -29.4 ± 10.5 and 24.2 ± 9.2 mL.(kg.min)^-1 (p < 0.01). The equations for estimating VO₂max [in mL.(kg.min)^-1] were: C-GENERAL = [final workload (W)/body weight (kg)] x 10.483 + 7; C-MEN = [final workload (W)/body weight (kg)] x 10.791 + 7; and C-WOMEN = [final workload (W)/body weight (kg)] x 9.820 + 7. The E% for MEN was: -3.4 ± 13.4% (modified ACSM); 1.2 ± 13.2% (C-GENERAL); and -0.9 ± 13.4% (C-MEN) (p < 0.01). For WOMEN: -14.7 ± 17.4% (modified ACSM); -6.3 ± 16.5% (C-GENERAL); and -1.7 ± 16.2% (C-WOMEN) (p < 0.01).

Conclusion:

The error of estimate of VO₂max by use of sex-specific equations was reduced, but not eliminated, in exercise tests on LLCE.

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Original Article

An Equation for the Prediction of Oxygen Consumption in a Brazilian Population

Antonio Eduardo Monteiro de Almeida et al. Charles de Moraes Stefani João Agnaldo do Nascimento Narla Miranda de Almeida … Amilton da Cruz Santos Jorge Pinto Ribeiro (in memoriam) Ricardo Stein

Background:

The equations predicting maximal oxygen uptake (VO_{2max or peak}) presently in use in cardiopulmonary exercise testing (CPET) softwares in Brazil have not been adequately validated. These equations are very important for the diagnostic capacity of this method.

Objective:

Build and validate a Brazilian Equation (BE) for prediction of VO_2peak in comparison to the equation cited by Jones (JE) and the Wasserman algorithm (WA).

Methods:

Treadmill evaluation was performed on 3119 individuals with CPET (breath by breath). The construction group (CG) of the equation consisted of 2495 healthy participants. The other 624 individuals were allocated to the external validation group (EVG). At the BE (derived from a multivariate regression model), age, gender, body mass index (BMI) and physical activity level were considered. The same equation was also tested in the EVG. Dispersion graphs and Bland-Altman analyses were built.

Results:

In the CG, the mean age was 42.6 years, 51.5% were male, the average BMI was 27.2, and the physical activity distribution level was: 51.3% sedentary, 44.4% active and 4.3% athletes. An optimal correlation between the BE and the CPET measured VO_2peak was observed (0.807). On the other hand, difference came up between the average VO_2peak expected by the JE and WA and the CPET measured VO_2peak, as well as the one gotten from the BE (p = 0.001).

Conclusion:

BE presents VO_2peak values close to those directly measured by CPET, while Jones and Wasserman differ significantly from the real VO_2peak.

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Artigo Original

Cardiorespiratory optimal point: a submaximal variable of the cardiopulmonary exercise testing

Plínio Santos Ramos et al. Djalma Rabelo Ricardo Claudio Gil Soares de Araújo

BACKGROUND: At the maximal Cardiopulmonary Exercise Testing (CPET), several ventilatory variables are analyzed, including the ventilatory equivalent for oxygen (VE/VO2). The minimum VE/VO2 value reflects the best integration between the respiratory and cardiovascular systems and may be called “Cardiorespiratory Optimal Point (COP)”. OBJECTIVE: To determine the behavior of the COP according to gender and age in healthy adults and verify its association with other CPET variables. METHODS: Of 2,237 individuals, 624 were selected (62% men and 48 ± 12 years), non- athletes, healthy, who were submitted to maximal CPET. COP or minimum VE/VO2 was obtained from the analysis of ventilation and oxygen consumption in every minute of CPET. We investigated the association between age and COP for both genders, as well as associations with: VO2max, VO2 at anaerobic threshold (VO2AT), oxygen uptake efficiency slope (OUES) and with maximum VE. We also compared the intensity of exertion (MET) at the COP, AT and VO2max. RESULTS: COP increases with age, being 23.2 ± 4.48 and 25.0 ± 5.14, respectively, in men and women = (p < 0.001). There are moderate and inverse associations with VO2max (r = -0.47; p < 0.001), with VO2AT (r = -0.42; p < 0.001) and with OUES (r = -0.34; p < 0.001). COP occurred, on average, at 44% do VO2max and before AT (67% of VO2max) (p < 0.001). CONCLUSION: COP, a submaximal variable, increases with age and is slightly higher in women. Being modestly associated with other ventilation measures, there seems to be an independent contribution to the interpretation of the cardiorespiratory response to CPET.

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Artigo Original

Cardiorespiratory fitness of a Brazilian regional sample distributed in different tables

Karlyse Claudino Belli et al. Carine Calegaro Cleusa Maria Richter Jonatas Zeni Klafke … Ricardo Stein Paulo Ricardo Nazario Viecili

BACKGROUND: Most classification tables of cardiorespiratory fitness (CRF) used in clinical practice are international and have not been validated for the Brazilian population. That can result in important discrepancies when that classification is extrapolated to our population. OBJECTIVE: To assess the use of major CRF tables available in a Brazilian population sample of the Central High Plan of the state of Rio Grande do Sul (RS). METHODS: This study assessed the retrospective data of 2,930 individuals, living in 36 cities of the Central High Plan of the state of RS, and considered the following: presence of risk factors for cardiovascular disease and estimated maximum oxygen consumption (VO2peak) values obtained through exercise test with Bruce protocol. To classify CRF, the individuals were distributed according to sex, inserted in their respective age groups in the Cooper, American Heart Association (AHA) and Universidade Federal de São Paulo (Unifesp) tables, and classified according to their VO2peak. RESULTS: Women had lower VO2peak values as compared with those of men (23.5 ± 8.5 vs. 31.7 ± 10.8 mL.kg-1.min-1, p < 0.001). Considering both sexes, VO2peak showed an inverse and moderate correlation with age (R = -0.48, p < 0.001). An important discrepancy in the CRF classification levels was observed between the tables, ranging from 49% (Cooper x AHA) to 75% (Unifesp x AHA). CONCLUSION: Our findings indicate important discrepancy in the CRF classification levels of the tables assessed. Future studies could assess whether international tables could be used for the Brazilian population and populations of different regions of Brazil.

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Artigo Original

Effects of the continuous positive airway pressure on the airways of patients with chronic heart failure

João Carlos Moreno de Azevedo et al. Edison Ramos Migowisk de Carvalho Luis Augusto Feijó Fátima Palha de Oliveira … Sara Lúcia Silveira de Menezes Henrique Murad

BACKGROUND: Heart failure can present with asymptomatic dysfunction at decompensation, with limitations and decrease in the productive capacity. The Continuous Positive Airway Pressure (CPAP) is a non-pharmacological means to decrease afterload. OBJECTIVE: To analyze the effects of CPAP (10 cmH2O), for 30 days in patients with chronic heart failure. METHODS: We assessed 10 patients with heart failure (6 males, 4 females) of several etiologies, with a mean age of 54 ± 14 years, with a BMI of 21 ± 0.04 kg/m². The therapy was applied for 60 min., 5 times a week for 30 days, during the daytime. The echocardiogram and the ergospirometry were analyzed, before and 30 days after the therapy. RESULTS: There was a 19.59% increase in the left ventricular ejection fraction (LVEF): 23.9 ± 8.91 vs 27.65 ± 9.56%; p = 0.045. At the ergospirometry, the exercise time (ET) showed a significant increase from 547 ± 151.319 vs 700 ± 293.990 sec., p = 0.02; oxygen consumption (VO2) was 9.59 ± 6.1 vs 4.51 ± 2.67 ml.kg-1.min.-1, p = 0.01, whereas the carbon dioxide production (VCO2) at rest (9.85 ± 4.38 vs 6.44 ± 2.88 ml.kg-1.min.-1, p = 0.03) decreased. CONCLUSION: The CPAP resulted in an increase in the LVEF and ET, decreased the oxygen consumption and the carbon dioxide production at rest.

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Artigo Original

Cardiorespiratory and perceptual responses to walking and running at the same speed

Walace David Monteiro et al. Claudio Gil Soares de Araújo

BACKGROUND: It is possible that different forms of locomotion, when carried out at the same speed, may have a distinct influence on the physiological and perceptual responses to exercise. OBJECTIVE: To compare the cardiorespiratory responses and the subjective perception of the effort to walk and run at the same speed, as determined from the walk-run transition speed (WRTS). METHODS: From an initial sample of 453 subjects enrolled in the compulsory military service, 12 young adult men were selected and carefully homogenized as to age, sex, anthropometric characteristics, aerobic condition and experience in a treadmill. In preliminary sessions, the individual WRTS was determined. Thereafter, on three different days, the subjects walked and ran in balanced order, in each of the following speeds: WRTS; WRTS – 0.5 km/h; WRTS + 0.5 km/h, so as to obtain exhaled gases, heart rate (HR) and perception of effort measurements. RESULTS: The protocol for WRTS detection was highly reproducible (r = 0.92, p <0.05). In an intensity of exercise above the WRTS, the perceived effort, the HR, and the ventilatory variables-VE, VO2, VCO2 and R-showed higher values during walking than during running (p 0.05). CONCLUSION: Walking at a speed above the WRTS tends to be more stressful to the subject, from a physiological and perceptual point of view. It seems appropriate to individualize the WRTS and standardize the form of locomotion for determining a more accurate and physiological intensity of the aerobe exercises.

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