Exercise performance and training in patients with implantable cardioverter-defibrillators and coronary heart disease

The aim of this preliminary study was to compare exercise performance and the effect of exercise training in cardiac patients with and without an implantable cardioverter-defibrillator (ICD). There are few data on exercise performance and on the effect of exercise training in patients with an ICD. Data in patients with an ICD (n = 8) were compared with those from a matched control group (n = 16). Patients performed maximal cycle-ergometer testing before and after 3 months of exercise training. All patients had to stop the exercise test for reasons of exhaustion. The predetermined heart rate threshold in ICD patients, set at the detection rate of the ICD minus 30 beats/min, was not reached. Before training, peak oxygen uptake was not different in the ICD patients compared with the control group (21.0 +/- 6.9 vs 21.9 +/- 5.0 ml oxygen standard temperature pressure dry/min/kg). Exercise training increased peak oxygen uptake to a similar extent in both groups, 20% and 24%, respectively. One ICD patient developed uneventful ventricular tachycardia at the end of the post-training exercise test, and another during training. Thus, exercise performance and the favorable response to a 3-month exercise training program are comparable in patients with ICD and matched control patients. However, tachyarrhythmias may occur during exercise testing or training and require special attention. Selected patients with ICD can be encouraged to participate in medically supervised exercise training programs. The results of this study should be confirmed with additional studies on larger numbers of subjects.