Abstract 12579: Aerobic Exercise Training After an ICD: Primary Results of the Anti-Arrhythmic Effects of Exercise After an ICD Trial
Background: Aerobic exercise after an implantable cardioverter defibrillator (ICD) has not been extensively studied for efficacy and safety. Clinicians are reluctant to prescribe exercise because of concern for causing arrhythmias. ICD patients are afraid to exercise because of fear in getting an ICD shock. The purposes were to determine the effects of 8 weeks of aerobic exercise on the primary outcome of cardiopulmonary function [peak VO2, EX time, VO2 at AT, O2 pulse, METS, Maximum HR], and to determine if exercise increased ICD shocks or hospitalizations.
Methods: 160 subjects (80/group) with a prior ICD implant (40% primary and 60% secondary prevention), mean age 55 ±12 years, 77.5% male, 84% Caucasian, 100% beta-blocked, and EF%=40%, entered a RCT comparing aerobic exercise to usual care after an ICD. Baseline and 8 week cardiopulmonary exercise tests were done using a modified Balke treadmill protocol. Aerobic exercise (EX) = 8 weeks of home walking 1 hour/day on 5 days/week at 60-80% of maximum HR using the Karvonen formula vs. usual care (UC). ICD shocks were monitored with ICD interrogations. Hospitalizations were verified with medical records. Analysis of variance was used to determine group x time effects on study outcomes.
Results: Exercise significantly increased peak VO2 ml/kg/min, p=0.01 (EX 26.4±7.1, UC 24.0±6.6), EX time, p=0.001 (EX 16:03± 6:13; UC13:37±6:03), VO2 at AT ml/kg/min, p=0.008 (EX 22.4±6.1; UC 20.0±5.5), O2 pulse, p=0.054 (EX 18.4±5.2; UC 17.1±5.0), and METS, p=0.005 (EX 7.6±2.0; UC 6.8±1.9). Maximum HR was not significantly changed. Average RPR was 1.12/group. No ICD shocks were attributed to exercise: 3 in UC and 0 in exercise received an ICD shock or ATP. There were 11 hospitalizations in each group, none were related to exercise. Of these: 0 in EX and 1 in UC were due to heart failure, 2 in EX and 1 in UC to chest pain, and 1 in EX and 0 in UC were due to VT.
Conclusions: Exercise, strenuous enough to achieve significant impact on cardiopulmonary function after an ICD, is safe without increasing ICD shocks or cardiac hospitalizations. This study outlines safe parameters for clinician use in prescribing exercise after an ICD. Patients with ICDs can be assured that participation in aerobic exercise is safe and improves their overall CV health.
- © 2013 by American Heart Association, Inc.