The association of exercise test variables with long-term mortality in patients with chronic Chagas disease.

Background: The identification of variables obtained in the exercise test (ET) associated with increased risk of death is clinically relevant and would provide additional information for the management of Chagas disease (CD). The objective of the present study was to evaluate the association of ET variables with mortality in patients with chronic CD. Methods: This retrospective longitudinal observational study included 232 patients (median age 46.0 years; 50% women) with CD that were followed at the Evandro Chagas National Institute of Infectious Diseases (Rio de Janeiro, Brazil) and performed an ET between 1989 and 2000. The outcome of interest was all-cause mortality. Results: There were 103 deaths (44.4%) during a median follow-up of 21.5 years (IQR 25-75% 8.0-27.8), resulting in 24.5 per 1,000 patients/year incidence rate. The ET variables associated with mortality after adjustments for potential confounders were increased maximal (HR 1.02; 95% CI 1.00-1.03 per mmHg) and change (HR 1.03; 95% CI 1.01-1.06 per mmHg) of diastolic blood pressure (DBP) during ET, ventricular tachycardia at rest (HR 3.95; 95% CI 1.14-13.74), during exercise (HR 2.73; 95% CI 1.44-5.20), and recovery (HR 2.60; 95% CI 1.14-5.91), and premature ventricular complexes during recovery (HR 2.06; 1.33-3.21). Conclusion: Our findings suggest that ET provides important prognostic value for mortality risk assessment in patients with CD, with hemodynamic (increased DBP during exercise) and electrocardiographic (presence of ventricular arrhythmias) variables independently associated with an increased mortality risk in patients with CD. The identification of individuals at higher mortality risk can facilitate the development of intervention strategies (e.g., close follow-up) that may potentially have an impact on the longevity of patients with CD.

Could peak oxygen uptake be estimated from proposed equations based on the six-minute walk test in chronic heart failure subjects?

OBJECTIVES: To evaluate the agreement between the measured peak oxygen uptake (VO2peak) and the VO2peak estimated by four prediction equations based on the six-minute walk test (6MWT) in chronic heart failure patients. METHOD: Thirty-six chronic heart failure patients underwent cardiopulmonary exercise testing and the 6MWT to assess their VO2peak. Four previously published equations that include the variable six-minute walk distance were used to estimate the VO2peak: Cahalin, 1996a (1); Cahalin, 1996b (2); Ross, 2010 (3); and Adedoyin, 2010 (4). The agreement between the VO2peak in the cardiopulmonary exercise testing and the estimated values was assessed using the Bland-Altman method. A p-value of <0.05 was considered statistically significant. RESULTS: All estimated VO2peak values presented moderate correlation (ranging from 0.55 to 0.70; p<0.001) with measured VO2peak values. Equations 2, 3, and 4 underestimated the VO2peak by 30%, 15.2%, and 51.2%, respectively, showing significant differences from the actual VO2peak measured in the cardiopulmonary exercise testing (p<0.0001 for all), and the limits of agreement were elevated. The VO2peak estimated by equation 1 was similar to that measured by the cardiopulmonary exercise testing, and despite the agreement, bias increased as VO2peak increased. CONCLUSIONS: Only equation 1 showed estimated VO2peak similar to the measured VO2peak; however, a large limits of agreement range (∼3 METs) does not allow its use to estimate maximal VO2peak.

Capacidade funcional máxima "normal"em pacientes com insuficiência cardíaca por miocardiopatia chagásica / "Normal" Maximal Functional Capacity in Patients with Congestive Heart Failure Due to Chagas' Cardiomyopathy

OBJETIVO: Comparar portadores de miocardiopatia chagásica com insuficiência cardíaca congestiva (ICC) e consumo máximo de oxigênio (VO2 max) acima de 20mL/kg-1/min-1 com grupo normal, e rediscutir o conceito de normalidade do método.MÉTODOS: Foram estudados 104 pacientes com ICC. O grupo controle (G2) constituiu-se de 23 indvíduos normais sedentários. Analisamos os pacientes pela VO2max e fraçäo de ejeçäo (FE) de ventrículo esquerdo. As médias foram comparadas utilizando o teste t. RESULTADOS: Dos 104 pacientes, 37 (35,6por cento) apresentaram VO2max acima de 20 mL/kg-1/min-1(GI), com valores entre 20,5 e 30,5 (24,5+/-2,9) e FE entre 19 e 63 (42+/-11,7). G2 apresentou VO2max entre 21 e 42 mL/kg-1/min-1 (33,3+/-5,6) e FE entre 70 e 82 (75,1+/-3,2). Näo houve diferença significante (p=0,1136) entre as idades. Houve diferença entre as médias de VO2max e FE (p<0,0001).CONCLUSAO: Estes pacientes atingiram VO2max acima de 20mL/kg-1/min-1, e apresentaram