Exercise-Based Cardiac Rehabilitation Improves Exercise Capacity Regardless of the Response to Cardiac Resynchronization Therapy in Patients with Heart Failure and Reduced Ejection Fraction

Background: In patients with chronic heart failure with reduced ejection fraction (HFrEF), cardiac resynchronization therapy (CRT) improves left ventricular ejection fraction (LVEF) and exercise-based cardiac rehabilitation (ECR) enhances exercise capacity. This study examined the relationship between the 2 responses. Methods and Results: Sixty-four consecutive HFrEF patients who participated in a 3-month ECR program after CRT were investigated. Patients were categorized according to a median improvement in peak oxygen uptake (PV O2) after ECR of 7% as either good (n=32; mean percentage change in PV O2 [%∆PV O2]=23.2%) or poor (n=32; mean %∆PV O2=2.5%) responders. There was no significant difference in baseline characteristics between the good and poor responders, except for PV O2 (51% vs. 59%, respectively; P=0.01). The proportion of good CRT responders was similar between the good and poor responders (%∆LVEF ≥10%; 53% vs. 47%, respectively; P=NS). Overall, there was no significant correlation between %∆LVEF after CRT and %∆PV O2 after ECR. Notably, among poor CRT responders (n=32), the prevalence of atrial fibrillation (0% vs. 29%; P<0.03) and baseline PV O2 (48% vs. 57%; P<0.05) were significantly lower among those with a good (n=15) than poor (n=17) response to ECR. Conclusions: In patients with HFrEF, good ECR and CRT responses are unrelated. A good PV O2 response to ECR can be achieved even in poor CRT responders, particularly in those with a sinus rhythm or low baseline PV O2.