Reassessment of Cardiac Function and Implantable Cardioverter-Defibrillator Use Among Medicare Patients with Low Ejection Fraction After Myocardial Infarction
Background—Guidelines recommend that patients with low ejection fractions (EF) post-myocardial infarction (MI) have their EF reassessed 40 days after MI for implantable cardioverter-defibrillator (ICD) candidacy. This study examines rates of EF reassessment and their association with 1-year ICD implantation in post-MI patients with low EF.
Methods—We examined rates of post-discharge EF reassessment and ICD implantation among 10,289 Medicare-insured patients ≥65 years with an EF≤35% during the index MI admission from 1/2007-9/2010 in ACTION Registry-GWTG. Multivariable Cox models tested the association between time-dependent EF reassessment and 1-year ICD implantation, stratified by revascularization status during the index MI admission.
Results—Among patients with EF≤35% during the index MI admission, 66.8% (95% CI 65.9%-67.8%) had EF reassessment within the next year. Revascularized patients were more likely to have EF reassessment (76.9% [95% CI 75.8%-78.0%)] vs. 53.7% [95% CI 52.2%-55.2%], p <0.001) and had shorter times to EF reassessment (median 67 vs. 84 days, p<0.001) than non-revascularized patients. Among patients with EF reassessment, only 11% received an ICD within 1 year. Reassessment of EF was associated with higher likelihood of ICD implantation for both revascularized (unadjusted 12.1% vs. 2.4%, p<0.001, adjusted HR 10.6, 95% CI 7.7-14.8) and non-revascularized patients (unadjusted 10.0% vs. 1.7%, p<0.001, adjusted HR 6.1, 95% CI 4.1-9.2).
Conclusions—In US practice, EF reassessments are commonly performed among MI patients with an initially reduced EF. While 1-year EF reassessment is associated with increased likelihood of ICD implantation, 1-year ICD implantation rates remain very low even among patients with EF reassessment, regardless of revascularization status.
- Received March 3, 2016.
- Revision received September 25, 2016.
- Accepted October 21, 2016.