Effect of Cardiac Rehabilitation in Preventing Implantable Cardioverter Defibrillator Therapy in Patients with Reduced Left Ventricular Ejection Fraction

In patients with implantable cardioverter defibrillators(ICD)or cardiac resynchronization therapy defibrillators(CRT-D), appropriate and inappropriate shocks lead to a higher risk of mortality. Cardiac rehabilitation(CR)is an established therapy for patients with ischemic heart disease and/or congestive heart failure. However, it is unclear whether CR could reduce the need for device therapies. The purpose of the present study was to investigate whether CR reduces device therapies and mortality in patients with severe cardiac dysfunction and ICD or CRT-D. Of the 390 patients who were implanted with an ICD or CRT-D between 1998 and 2015, 222(178 men, 44 women)with a low ejection fraction(EF; <45%)were investigated in this present study. The study cohort was divided into two groups, the CR group(n=70)and the non-CR group (n=152), and baseline clinical characteristics of the two groups were compared. Furthermore, the number of all device therapies, appropriate therapies, inappropriate therapies, and mortality for 1 year after ICD or CRT-D implantation were compared. There were no significant differences in baseline characteristics between the CR and non-CR groups(e.g. age 68.5 vs 66.2 years[P=0.16]; EF 27.9% vs 29.7%[P=0.14]). Kaplan-Meier analysis revealed that all device therapy events and inappropriate therapy events were lower in the CR than non-CR group(P=0.01 and P=0.03, respectively). Appropriate therapy events and mortality did not differ significantly between the two groups(5.7% vs 13.1%[P=0.09]and 11.4% vs 17.0%[P=0.28], respectively). CR may have beneficial effects in preventing therapy events, especially inappropriate therapy, in patients with an ICD or CRT-D.