Implantable cardioverter-defibrillator therapy in patients with ventricular fibrillation out of hospital cardiac arrest secondary to acute coronary syndrome

BACKGROUND: Survivors of ventricular fibrillation out of hospital cardiac arrest (VF-OHCA) due to a potentially reversible cause such as acute myocardial infarction (MI) or ischemia are considered to be at low risk of recurrent arrhythmia. Implantable cardioverter defibrillators (ICD) are not routinely recommended in such patients. However, the outcome of these patients in the era of rapid coronary revascularization and ICD therapy is not known.

METHODS AND RESULTS: We examined the outcome of 114 consecutive survivors of VF OHCA due to acute MI or ischemia in Olmsted County, MN from 1990 to 2011. An ICD was implanted in 45/114 patients. ICD recipients had lower EF [median (IQR) 38 (26 to 54) versus 48 (35 to 58) %, P=0.04]. During a median (IQR) follow-up of 9.9 (4.4 to 14.6) years, ICD implantation was associated with reduced cardiac mortality (HR 0.24 [0.07 to 0.88], P=0.031) and a trend towards reduced all-cause mortality (HR 0.56 [0.30 to 1.02], P=0.059) after adjusting for the first principal component. One or more appropriate ICD therapies were delivered in 19/45, with half of the patients receiving therapy within 1 year. Patients with EF ≤35% at discharge continued to be at long-term risk for ICD therapy compared with those with EF >35% who were at increased risk predominantly in the first 8 months. EF and revascularization were not significantly associated with ICD therapy in the multivariable analysis.

CONCLUSIONS: Patients with VF-OHCA in the setting of acute MI or myocardial ischemia remain at high risk of recurrent ventricular arrhythmias, particularly if EF ≤35%. This suggests that ICD implantation may be reasonable if EF ≤35%.