OUTCOME WITH IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR THERAPY FOR SURVIVORS OF VENTRICULAR-FIBRILLATION SECONDARY TO IDIOPATHIC DILATED CARDIOMYOPATHY OR CORONARY-ARTERY DISEASE WITHOUT MYOCARDIAL-INFARCTION

Patients with idiopathic dilated cardiomyopathy (IDC) constitute a min ority among implantable cardioverter-defibrillator (ICD) recipients; h ow these patients fare versus those with coronary artery disease (CAD) is not well defined, nor is the mechanism of cardiac arrest recurrenc e, which may involve a more significant role of bradyarrhythmias. A re trospective multicenter study regarding outcome of ICD therapy was con ducted in 224 patients with either IDC (n = 69; 31%) or CAD (n = 155; 69%) presenting exclusively with ventricular fibrillation (VF) unassoc iated with acute myocardial infarction. Patients with IDC were signifi cantly younger (mean age 57 vs 61 years in patients with CAD, p <0.04) and less male predominant (64 vs 79% in patients with CAD, p <0.02). There was no significant difference in mean left ventricular ejection fraction (0.27 in IDC patients vs 0.29 in CAD patients), but sustained ventricular tachycardia was induced less often in patients with IDC ( 21 vs 58% in CAD patients, p <0.001). Bradycardia pacing, either by an ICD with bradycardia pacing ability or a separate bradycardia pacemak er, was available in only 15% of ICD implantees. During a median follo w-up duration of 1.7 years for patients with IDC and 1.9 years for pat ients with CAD, estimated cumulative event rates were similar for any type shock (2-year incidence of 74% in IDC patients, 69% in CAD patien ts) as well as for appropriate shock (2-year incidence of 46% in IDC p atients, 40% in CAD patients). Over the follow-up period, estimated su dden death rates were not significantly different (actuarial 2-year ra te: 3.7% in IDC patients, 4.7% in CAD patients); nor did we identify d ifferences in cardiac mortality (actuarial 2-year rate: 9.7% in IDC pa tients, 11.3% in CAD patients) or total mortality (actuarial 2-year ra te: 11.5% in IDC, 15.1% in CAD). Thus, despite major differences in un derlying pathophysiology, baseline characteristics and inducibility st atus, we observed comparably high-device utilization rates and low sud den death rates among survivors of ICD-treated VF with either IDC or C AD, the majority of whom lacked bradycardia pacing capability. Indirec tly, this suggests that, in patients with IDC and a history of VF, bra dyanhythmic sudden deaths are uncommon, ventricular tachyarrhythmias, however, as inferred from the similarly high ICD discharge rates, may be as important a mechanism for cardiac arrest recurrence as in patien ts with CAD.