Implantable cardioverter defibrillator implantation rates after out of hospital cardiac arrest: are the rates guideline-concordant?

Background — Clinical practice guidelines recommend implantable cardioverter defibrillators (ICDs) for the secondary prevention of sudden death after a cardiac arrest not from a reversible cause, but "real world" implantation rates are not well described.

Methods — Adults with out of hospital cardiac arrest attended by Emergency Medical Services are captured in the Toronto Regional RescuNET database. We analyzed those who survived to hospital discharge and collected data on age, sex, initial rhythm, ST-elevation myocardial infarction (STEMI) on presenting electrocardiogram (ECG), in-hospital revascularization, neurologic status (Modified Rankin Scale [MRS]) at discharge, and admission hospital type. To estimate 'indicated' ICD implantation rates, "likely ICD-eligible" patients were defined as having an initial shockable rhythm, no STEMI on presenting ECG, no revascularization, and good neurologic status (MRS 0-3). "Not likely ICD-eligible" patients were defined as having a STEMI on presenting ECG, revascularization, or poor neurologic status (MRS 4-5).

Results — In the 1238 adults (2011-2014) analyzed, the overall ICD implantation rate was 23.9%. Two hundred fifty-six patients were "likely ICD-eligible," of whom 146 (57.0%) received an ICD. The implantation rate for "not likely ICD-eligible" patients was 16.7% (112 of 670). ICD eligibility could not be determined for 312 patients, of whom 38 (12.2%) received an ICD. Admission to a hospital with ICD implantation facilities was associated with a higher probability of ICD implantation (odds ratio, 2.85; 95% confidence interval, 1.40-5.82).

Conclusions — Postcardiac arrest ICD implantation rates in eligible patients are lower than expected. Implementation strategies to monitor guideline adherence after out of hospital cardiac arrest are warranted.