Long-term Mortality and Shock-rate in Patients Surviving Out-of-Hospital Cardiac Arrest with and without early implantation of an Implantable Cardioverter Defibrillator.

INTRODUCTION: In patients who survive out-of-hospital cardiac arrest (OHCA), guidelines for implantation of an implantable cardioverter-defibrillator (ICD) are not unequivocal. METHODS: Patients resuscitated from OHCA of cardiac cause, without a reversible cause and an expected survival >1 year were identified (year 2007-2011). Patients with acute coronary syndrome (ACS) and primary arrhythmia were compared with respect to; (1) incidence of early ICD-implantation prior to hospital discharge, (2) first shock- and anti-tachycardia (ATP) therapy up to 5 years, and (3) 5-year mortality rate assessed by Cox-regression analyses. RESULTS: ACS-patients (n = 256) less often had an ICD implanted compared to primary arrhythmia patients (n = 258) (30% vs. 82%). Cumulative 5-year incidence of appropriate ICD-therapy did not differ (ATP; ACS: 28% vs. primary arrhythmia: 27%, shock; ACS: 22% vs. primary arrhythmia: 29%). Crude 5-year mortality was lower in ICD-patients; ACS: No ICD: 22% vs. ICD: 13%; primary arrhythmia: No ICD; 66% vs. ICD: 16%. No difference in mortality between patients was noted (adjusted hazard ratio (HRACS): 0.91, 95% CI: 0.50-1.67). ICD-implantation was independently associated with lower 5-year mortality risk in both patient groups after adjusting for cause of arrest, age > 65 years, left ventricular ejection fraction (LVEF) ≤35%, sex, and successful revascularization (in ACS only) (HRACS: 0.35, CI: 0.17-0.73, HRPA: 0.15, CI: 0.08-0.27). CONCLUSIONS: Cumulative incidences of appropriate therapy did not differ according to cause of arrest. Implantation of an early ICD after OHCA was significantly and independently associated with a lower 5-year mortality risk in both ACS and primary arrhythmia patients.