Exercise After an ICD | Journal Scan

Study Questions:

What are the effects of a home aerobic exercise training and maintenance program (EX) on aerobic performance, implantable cardioverter-defibrillator (ICD) shocks, and hospitalizations in ICD recipients?

Methods:

One hundred sixty patients with ICD for primary (43%) or secondary (57%) prevention were randomly assigned to a home aerobic exercise training and maintenance program (EX) or usual care. EX consisted of 8 weeks of home walking 1 hour/day, 5 days/week at 60-80% of heart rate reserve, followed by 16 weeks of maintenance home walking for 150 minutes/week. Adherence to EX was determined from exercise logs, ambulatory HR recordings of exercise, and weekly telephone calls. Usual care patients received no exercise directives and were monitored by monthly telephone. The primary outcome was peak oxygen consumption (peakVO2), measured with cardiopulmonary exercise testing at baseline, and 8 and 24 weeks. Adverse events were identified by ICD interrogations, and patient and medical records.

Results:

ICD patients were 55 ± 12 years old and had left ventricular ejection fraction of 41 ± 16. All were taking beta-blockers. Patients in the exercise arm increased their peakVO2 from 24.6 ± 5.7 mg/kg/min to 26.8 ± 7.0 at 8 weeks, which was maintained at 24 weeks. Patients in the usual care group did not improve their peakVO2. The difference between the groups was statistically significant. ICD shocks were infrequent (exercise 4, usual care 8), and there were no differences in hospitalizations or deaths between the groups.

Conclusions:

The authors concluded that prescribed home exercise is safe and significantly improves cardiovascular performance in ICD recipients without causing shocks or hospitalizations.

Perspective:

Exercise has unquestioned benefits related to overall health and quality of life, and has been found to be beneficial in patients after myocardial infarction, coronary bypass grafting, and those with heart failure. Unfortunately, many patients and physicians are uncertain about the safety of moderate exercise in patients with ICDs for fear of appropriate shock for ventricular tachycardia or inappropriate therapy for sinus tachycardia. The current study demonstrates safety and efficacy of moderate aerobic exercise in patients with ICDs. The risk of ICD shock was not increased by exercise, and patients in the exercise arm had significantly improved peakVO2 at 8 and 24 weeks compared with controls. A unique feature of this trial was that all exercise (except peakVO2 assessments) was performed at home, which probably contributed to the high adherence rates. In other patient populations, exercise is also associated with improved quality of life, and it would be interesting to see if quality-of-life scores would improve with exercise in this patient group.

Clinical Topics: Arrhythmias and Clinical EP, Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Exercise

Keywords: Arrhythmias, Cardiac, Defibrillators, Implantable, Death, Sudden, Cardiac, Exercise, Exercise Test, Hospitalization, Heart Failure, Heart Rate, Medical Records, Oxygen Consumption, Quality of Life, Telephone, Walking, Primary Prevention, Secondary Prevention


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