Goldraich L, Ross HJ, Foroutan F, Walker M, Braga J, McDonald
J Card Fail. 2017 May;23(5):422-426.
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.