Variations in Assessment Methods of Heterogeneous Exercise Capacity Response After Cardiac Rehabilitation

Background: Cardiac rehabilitation (CR) improves the prognosis of patients with cardiac diseases by, among other measures, improving exercise capacity (EC) as assessed according to different parameters. Objective: This study aimed to evaluate the effects of phase II of CR on the different measurements of EC and to assess the distribution of changes in these measurements among patients who underwent the intervention. Methods: From a single-center retrospective registry, records of 295 patients who underwent the six-minute walk test (6MWT) and cardiopulmonary exercise testing twice during CR were evaluated. The distance of the 6MWT, peak oxygen uptake (VO2) expressed in absolute values and as a percentage of predicted values, and workload on a cycle ergometer were assessed before and after CR and then analyzed. Results: Among the 295 patients (228 men, mean age 62 years [range: 55–69 years]), CR resulted in improvements in the median value of peak VO2 (approximately 1 mL/kg/min, 3% of the predicted value), workload (by approximately 5 watt), and 6MWT distance (by approximately 24 m, 5% of the predicted value). A total of 53.6% of the patients achieved an improvement in peak VO2 of ≥1 mL/kg/min and 44.1% of the patients achieved an improvement in 6MWT distance of >30 m. Simultaneous improvement in both peak VO2 and 6MWT distance was observed in 23% of the participants, whereas 26% did not achieve clinically meaningful improvement in either parameter. Conclusions: CR improved exercise capacity, although the proportion of patients who achieved clinically meaningful improvement differed substantially across the exercise capacity measurements.