Work-rate affects cardiopulmonary exercise test results in heart failure

Aims: Cardiopulmonary exercise test (CPET) is used to evaluate patients with chronic heart failure (HF) usually by means of a personalized ramp exercise protocol. Our aim was to evaluate if exercise duration or ramp rate influences the results. Methods and results: Ninety HF patients were studied (peak V-O2 > 20 ml/min/kg, n=28, 15-20 ml/min/kg, n=39 and < 15 ml/min/kg, n=23). Each patient did four CPET studies. The initial study was used to separate the subjects into three groups, according to their exercise capacity. In the remaining studies, work-rate was increased at three different rates designed to have the subjects reach peak exercise in 5, 10 and 15 min from the start of the ramp increase in work-rate, respectively. The order was randomized. The work-rate applied for the total population averaged 22.7 +/- 8.0, 11.6 +/- 3.7, 7.5 +/- 2.9 W/min with effective loaded exercise duration of 5 min and 16s +/- 29 s, 9 min and 43s +/- 49 s and 14 min and 32 s +/- 1 min and 12 s for the 5-, 10- and 15-min tests, respectively. Peak 10, averaged 16.9 +/- 4.3*, 18.0 +/- 4.4 and 18.0 +/- 5.4 ml/min/ kg for the 5-, 10- and 15-min tests, (*=p < 0.001 vs. 10 min). The shortest test had the lowest peak heart rate and ventilation and highest peak work-rate. Peak V-O2 and heart rate were lowest in 5-min tests regardless of HF severity. The Delta V-O2/Delta work-rate was lowest in 5-min tests and highest in 15-min tests. At all ramp rates, Delta V-O2/Delta work-rate was lower for the subjects with the lower peak V-O2. The V-E/V-CO2 slope and V-O2 at anaerobic threshold were not affected by the protocol for any grade of HF. Conclusions: In chronic HF, exercise protocol has a small effect on peak V-O2, and Delta V-O2/Delta work but does not affect V-O2, at anaerobic threshold and V-E/V-CO2, slope. (c) 2004 European Society of Cardiology. Published by Elsevier B.V All rights reserved.