Weber classification in cardiac rehabilitation

Abstract

Objective Upon beginning cardiac rehabilitation after a cardiac event, stationary cycle exercise ergometry is commonly performed to determine maximum exercise aerobic capacity (peak oxygen uptake [peak VO2]) and anaerobic threshold. The Weber classification stratifies patients based on peak VO2 and anaerobic threshold to define functional physical capacity. The purpose of the present study was to evaluate the Weber classification in patients entering cardiac rehabilitation.Methods and results In 275 consecutive patients entering cardiac rehabilitation from January 2009 to March 2010, peak VO2 and anaerobic threshold were measured before and after cardiac rehabilitation. Consecutive patients with different cardiac conditions were compared, including percutaneous intervention (PCI) without myocardial infarction, myocardial infarction, coronary artery bypass graft (CABG), and heart failure. The Weber class of most patients entering cardiac rehabilitation was low, usually Weber class C for women and class B for men (peak VO2 was 13 ± 4 ml/kg/min in women and 15 ± 3 ml/kg/min in men). Before the cardiac rehabilitation the greatest values of peak VO2 were associated with PCI and the lowest values with heart failure, with significantly greater average values for patients with PCI than heart failure before cardiac rehabilitation (PCI, 16 ± 2 ml/kg/min versus heart failure, 11 ± 3 ml/kg/min, P< 0.05). There was no statistical difference between the CABG and heart failure groups in mean peak VO2 before cardiac rehabilitation (CABG, 13 ± 2 ml/kg/min versus heart failure, 11 ± 3 ml/kg/min, NS) and between the PCI and myocardial infarction groups (PCI, 16 ± 2 ml/kg/min versus myocardial infarction, 15 ± 4 ml/kg/min, NS). At the end of cardiac rehabilitation, the Weber class was improved of one class for patients with PCI, myocardial infarction, CABG, and women with heart failure but not for men with heart failure.Conclusions The Weber classification was useful to monitor improvement in functional capacity from the beginning to the end of cardiac rehabilitation. Cardiac rehabilitation improved physical function. But the Weber classification in itself because of the low classes found among many patients after a cardiac event and before a cardiac rehabilitation could underestimate the results of this one.