The feasibility and safety of stepwise protocol in cardiopulmonary exercise testing-exercise stress echocardiography for subjects with heart failure.

Abstract

Exercise stress testing using a ramp protocol has been favored for cardiopulmonary exercise testing (CPX) in patients with heart failure (HF). However, the stepwise protocol for CPX was preferred for its possible combination with exercise stress echocardiography (ESE). We, therefore, investigated the feasibility and safety of using a stepwise protocol for CPX-ESE in patients with HF. Ambulatory outpatients with chronic HF were enrolled for a symptom-limited stepwise bicycle exercise test in the semi-supine position on a cycle ergometer. The test was started at a workload of 30 W and increased by 15 W every 3 minutes until maximal exertion. The echocardiographic and respiratory variables and any complications during the exercise were recorded. Among a total of 36 participants (age 61.2 ± 12.4 years; 69.4% men), all subjects achieved anerobic threshold during CPX-ESE and reached 72.3% of the age-predicted peak heart rate. The peak oxygen consumption was 14.7 mL/kg/min, and the peak RER was 1.25. There were no severe adverse complications, and only two minor rhythmic events were reported: nonsustained supraventricular tachycardia and isolated ventricular premature beats. The echocardiographic images acquired at each stage were of good quality in 92.6% of all acquisitions, and the intra-observer and interobserver repeatability was >80%. The stepwise protocol, with an initial workload of 30 W, followed by 15 W increments every 3 minutes, was feasible and provided an adequate stress load for patients with HF. This exercise stress modality was safe and well-tolerated.