Implantable Cardioverter-Defibrillator Use Among Medicare Patients With Low Ejection Fraction After Acute Myocardial Infarction

Abstract

Importance: Implantable cardioverter-defibrillators (ICDs) are not recommended within 40 days of myocardial infarction (MI); thus, ICD implantation might not be considered during the post-MI care transition.

Objective: To examine ICD implantation rates and associated mortality among older MI patients with low ejection fraction (EF).

Design, setting, and participants: Retrospective observational study of Medicare beneficiaries with an EF of 35% or less after MI, treated at 441 US hospitals between 2007 and 2010, excluding patients with prior ICD implantation. Follow-up data were available through December 2010.

Exposures: ICD implantation within 1 year of MI vs no ICD implantation within 1 year of MI.

Main outcomes and measures: Patient characteristics associated with receiving an ICD within 1 year after discharge and 2-year mortality associated with ICD implantation.

Results: Among 10,318 MI patients with EF of 35%or lower, the cumulative 1-year ICD implantation rate was 8.1% (95%CI, 7.6%-8.7%). Patients with ICD implantation were more likely to have prior coronary artery bypass graft procedures, higher peak troponin levels, in-hospital cardiogenic shock, and cardiology follow-up within 2 weeks after discharge relative to patients who did not receive an ICD within 1 year. Implantation of ICD was associated with lower 2-year mortality (15.3 events per 100 patient-years [128 deaths in 838 patient-years] vs 26.4 events per 100 patient-years [3033 deaths in 11 479 patient-years]; adjusted HR, 0.64; 95%CI, 0.53-0.78). [table: see text]

Conclusions and relevance: In this large registry study of older patients who experienced MI from 2007-2010, fewer than 1 in 10 eligible patients with low EF received an ICD within 1 year after MI, although ICD implantation was associated with lower risk-adjusted mortality at 2 years. Additional research is needed to determine evidence-based approaches to increase ICD implantation among eligible patients.