Early ICD implantation in cardiac arrest survivors with acute coronary syndrome - predictors of implantation, ICD-therapy and long-term survival

Abstract

Objectives. Implantable cardioverter defibrillator (ICD) implantation in patients resuscitated from out-of-hospital cardiac arrest (OHCA) due to acute myocardial infarction (AMI) is controversial. Design. Consecutive OHCA-survivors due to AMI from two Danish tertiary heart centers from 2007 to 2011 were included. Predictors of ICD-implantation, ICD-therapy and long-term survival (5 years) were investigated. Patients with and without ICD-implantation during the index hospital admission were included (later described as early ICD-implantation). Patients with an ICD after hospital discharge were censored from further analyses at time of implantation. Results. We identified 1,457 consecutive OHCA-patients, and 292 (20%) of the cohort met the inclusion criteria. An ICD was implanted during hospital admission in 78 patients (27%). STEMI and successful revascularization were inversely and independently associated with ICD-implantation (OR_STEMI = 0.37, 95% CI: 0.14-0.94, OR_revasc = 0.11, 0.03-0.36) whereas age, sex, LVEF <35%, comorbidity burden or shockable first OHCA-rhythm were not associated with ICD-implantation. Appropriate ICD-shock therapy during the follow-up period was noted in 15% of patients (n = 12). Five-year mortality-rate was significantly lower in ICD-patients (18% vs. 28%, p_logrank = 0.02), which was persistent after adjustment for prognostic factors (HR = 0.44 (95% CI: 0.23-0.88)). This association was no longer found when using first event (death or appropriate shock whatever came first) as outcome variable (p_logrank = 0.9). Conclusions. Mortality after OHCA due to AMI was significantly lower in patients with early ICD-implantation after adjustment for prognostic factors. When using appropriate shock and death as events, ICD-patients had similar outcome as patients without an ICD, which may suggest a survival benefit due to appropriate device therapy.

Keywords: Out-of-hospital cardiac arrest; acute myocardial infarction; implantable cardioverter defibrillator; outcome; sudden cardiac death.