DISCUSSION
Our study showed a significant increase in exercise capacity among patients undergoing outpatient cardiac rehabilitation, as reported in other clinical studies [11–13]. Resting spirometry parameters including FEV1 and FEV1/FVC also improved. Our study indicates a strong relationship between physical activity and improvement of exercise capacity. Thus, an interesting issue is the effect of improved exercise capacity on patient outcomes. A positive association between improved exercise capacity and reduction of overall and CV mortality was found in a group of coronary artery disease patients undergoing cardiac rehabilitation [14–17]. The key to success seems, however, to maintain exercise capacity at a high level. Comprehensive rehabilitation with continuous patient support and advice to maintain exercise capacity are
key factors promoting mortality reduction among patients with coronary artery disease undergoing outpatient or in-hospital exercise training. An interesting analysis was performed by Lee et al. [18] who compared the effect of body weight reduction and exercise capacity on overall and CV mortality. This study included 14,345 men in whom baseline exercise capacity in MET and body mass index (BMI) were evaluated. Changes in BMI and exercise capacity during 6.3 years of
follow-up were categorised as a decrease, increase, or no change. During 11.4 years of follow-up, 914 noncardiac deaths and 300 CV deaths were noted. Hazard ratios (with 95% confidence intervals [CI]) for total and CV mortality in comparison to patients with a decrease in exercise capacity were 0.70 (0.59–0.83) and 0.73 (0.54–0.98), respectively, among patients with no change of exercise capacity, and 0.61 (0.51–0.73) and 0.58 (0.42–0.80), respectively, among patients with an increase in exercise capacity. This means that overall mortality was reduced by 39% among patients in whom an increase in exercise capacity was noted. An increase in exercise capacity by 1 MET was associated with a reduction in total and CV mortality by 15–19%. BMI changes did not correlate significantly with total mortality, while CV mortality among men with an increase in body weight was 39% higher compared to men with a decrease in body weight. When adjusted for maximum change in exercise capacity, this associa-tion was attenuated and lost statistical significance. A decrease in exercise capacity was associated with increased total and CV mortality. These findings indirectly indicate a major role of increased exercise capacity in the effects cardiac rehabilitation, while body weight reduction is of lesser importance.