BACKGROUND: Studies on the relationship between left ventricular reverse remodeling and cardiopulmonary exercise capacity in heart failure patients undergoing cardiac resynchronization therapy (CRT) are scarce and inconclusive.
METHODS AND RESULTS: Eighty-four patients with a 1st-time CRT-defibrillator (mean age 65 ± 11; 73% male) underwent echocardiography and cardiopulmonary exercise testing (CPX) before implantation (baseline) and 6 months after implantation. At baseline, patients also completed a set of questionnaires measuring mental and physical health. The association between echocardiographic response (left ventricular end-systolic volume decrease ≥15%) and a comprehensive set of CPX results was examined. Echocardiographic responders (54%) demonstrated higher peak oxygen consumption and better exercise performance than nonresponders at baseline and at 6-month follow-up. Furthermore, only echocardiographic responders showed improvements in ventilatory efficiency during follow-up. Multivariable repeated measures analyses revealed that, besides reverse remodeling, New York Heart Association functional class II and good patient-reported health status before implantation were the most important correlates of higher average oxygen consumption during exercise, and that nonischemic etiology and smaller pre-implantation QRS width were associated with better ventilatory efficiency over time.
CONCLUSIONS: During the first 6 months of CRT there was a significant positive association between reverse remodeling and cardiopulmonary exercise capacity.