Comparison of ventricular arrhythmia burden, therapeutic interventions, and survival, in patients < 75 and patients ≥ 75 years of age treated with implantable cardioverter defibrillators

Aim: Implantable cardioverter defibrillators (ICD) reduce arrhythmic mortality in a wide range of patients with poor left ventricular (LV) function. However, whether ICD therapy is equally effective in younger and older patients remains uncertain. To address this question, we compared ICD-documented ventricular tachyarrhythmia burden in patients, <75 years of age (Group 1) and >75 years of age (Group 2). Methods: Data were obtained from 208 consecutive ICD-treated patients: 159 Group 1 (mean age 59±12), and 49 Group 2 (mean age 79±3). Demographic and clinical features including presenting arrhythmias, LV ejection fraction, and nature of heart disease were similar. Medications were comparable except that amiodarone use was more frequent in Group 2. Results: The numbers of combined ventricular tachycardia (VT) and ventricular fibrillation (VF) episodes per month were 0.4±2 and 0.3±2 for groups 1 and 2, respectively (P = 0.7). Individually, VT episodes per month were 0.4±2 and 0.3±2 (P = 0.7) and VF episodes per month were 0.003±0.01 and 0.03±0.2 (P = 0.2) for the two groups, respectively. The mean duration and average cycle length of arrhythmias were 3.1±20.4 s and 275±119 ms in Group 1, and 6±45 s and 285±114 ms in Group 2 (P values, 0.6 and 0.8). The mean time between the ICD implantation and the first episode of a devicetreated arrhythmia was comparable in the two groups. Thirty-six patients died during follow-up; 22 (14%) Group 1 and 14 (29%) Group 2 (P = 0.02), almost exclusively on a non-sudden cardiac basis. Thus, despite higher ultimate mortality in older patients, both the nature and characteristics of spontaneous arrhythmia recurrence, and the time to first apparently bene.cial therapy, were similar during follow-up in the two groups. Conclusion: In terms of reversing potentially life-threatening arrhythmias, the rationale for ICD therapy is comparable in older and younger individuals.