Maximal functional capacity, ejection fraction, and functional class in Chagas cardiomyopathy. Are these indices related?

Abstract

Objective: Left ventricular ejection fraction (LVEF) and maximal functional capacity (VO2max) have both been shown to be related to a poor long-term survival in Chagas' disease patients. The aim of this study was to estimate the potential association of VO2max, LVEF, and NYHA functional class in patients with Chagas' disease cardiomyopathy. Methods: One hundred four male patients, aged 40.3±9.0 years (range, 18 to 65), with a definite diagnosis of Chagas disease cardiomyopathy were studied. LVEF and VO2max were both classified into 3 degrees: LVEF ≤0.30, 0.30< LVEF ≤0.50, and LVEF > 0.50 and VO2max ≤10, 10 20 ml.kg-1.min -1, respectively. Results: Thirty-one patients (29.8%) were in NYHA functional class II, 41 (39.4%) in functional class III, and 32 (30.8%) in functional class IV. The corresponding values of VO2max and LVEF for functional classes II, III, and IV were 21.5±4.0 ml.kg -1.min-1, 18.3±5.8 ml.kg-1.min -1, and 14.7±4.9 ml.kg-1.min-1 and 0.50±0.6, 0.35± 0.9, and 0.29±0.7, respectively. LVEF= ≤0.30 and VO2max = ≤10 ml.kg-1.min-1 were found in the majority of patients in NYHA functional class IV. Conversely, patients in functional class II were mostly those with LVEF >0.50 as well as VO2max >20 ml.kg-1.min-1. Conclusion: A convincingly good association exists between NYHA functional class, functional capacity and LVEF in patients with Chagas' disease cardiomyopathy. These data may be helpful in the management of heart failure in Chagas' disease patients.