Reevaluating Modality of Cardiopulmonary Exercise Testing in Patients with Heart Failure and Resynchronization Therapy: Relevance of Heart Rate-Adaptive Pacing

BACKGROUND: Chronotropic incompetence (CI) in heart failure (HF) patients with cardiac resynchronization therapy (CRT) and activity sensors may vary according to exercise modality. We hypothesized that chronotropic response and exercise capacity differ when HF patients with CRT and heart rate (HR) adaptive pacing are exercised on cycloergometer versus treadmill. METHODS AND RESULTS: This is a crossover study in which stable HF patients with CRT and HR-adaptive pacing triggered by activity sensors underwent maximal symptom-limited cardiopulmonary exercise testing on both a cycloergometer and treadmill. Adjusted percent of HR reserve (%HRR) was calculated as HRR/age-predicted HRR. CI was defined as ≤62% of age-predicted HRR. Among 16 patients (59 ± 10 years, ejection fraction 27 ± 12%, 87% on beta-blockers), prevalence of CI was high irrespective of exercise modality (87.5% on cycloergometer vs 62.5% on treadmill; P = .12). Chronotropic responses were better on the treadmill; %HRR was higher on a treadmill vs cycloergometer (61 ± 26% vs 22 ± 31%; P = .003). Peak oxygen consumption was increased by 24% on a treadmill vs cycloergometer (15.8 vs 12.7 mL/kg/min; P < .0001). CONCLUSIONS: In HF patients with CRT and HR-adaptive pacing, treadmill cardiopulmonary exercise testing enhances chronotropic response, HRR, and peak oxygen consumption compared with a cycloergometer. These findings may have implications in exercise prescription and thresholds for advanced therapies such as heart transplantation and ventricular assist devices.