Impact of baseline heart failure burden on post-implantable cardioverter-defibrillator mortality among medicare beneficiaries

Abstract

Objectives: This study sought to assess the impact of baseline heart failure (HF) burden on survival with primary implantable cardioverter-defibrillator (ICD) among Medicare recipients.

Background: Survival after primary ICD implantation may differ between trial and Medicare populations.

Methods: Linking data from the CMS (Centers for Medicare and Medicaid Services) ICD registry and the Medicare files (2005 to 2009), we identified primary ICD recipients age ≥66 years with ejection fraction ≤35%. Number of previous HF hospitalizations (prev-HF-hosp) and length of hospitalization prior to implantation were used to define HF burden. Crude all-cause mortality was estimated. Adjusted hazard ratios (HR) were derived from Cox models.

Results: Of 66,974 ICD recipients (73% men, 88% white, mean age 75 years), 11,876 died (average follow-up = 1.4 years), with 3-year mortality of 31%. Among patients with no prev-HF-hosp, 3-year mortality was 27% compared with 63% in those with ≥3 prev-HF-hosp (adjusted HR: 1.8). Among patients with same-day implantation, 3-year mortality was 25% compared with 53% in those with >1-week hospitalization days prior to implantation (adjusted HR: 1.9). Mortality at 3-year follow-up among the 31,685 ICD recipients with no prev-HF-hosp and same-day implantation (low HF burden) was similar to that in trials (22%).

Conclusions: Nearly one-third of Medicare ICD recipients died within 3 years, reflecting a population with more advanced age and disease than seen in trial populations for primary prevention ICD. Nearly one-half of Medicare recipients had a low HF burden and had a survival similar to trial ICD recipients. Future research is warranted to understand the effectiveness of primary ICD implantation among Medicare beneficiaries with heavy HF burdens.

Figure 1. Kaplan-Meier cumulative crude mortality by the number of prior HF hospitalizations

After ICD placement, mortality at three years increased from 27% in patients without prior HF hospitalization to 63% in those with three or more prior HF hospitalizations. Among patient who had more than three prior HF hospitalizations, more than half died by two years of implantation.

Figure 2. Kaplan-Meier cumulative crude mortality by the number of days from admission to ICD implantation

Mortality at three years was more than twice as high, from 25% in patients with same-day implantation to 53% in the patients hospitalized for eight or more days before implantation. Among patients who had more than eight hospital-days before implantation, more than half died by three years.

Figure 3. Post-implantation Mortality among Medicare Populations with Low Burden of HF (N=31, 685)

Patient who had no HF hospitalization in the year before ICD implantation and received the device on the admission day (47%, N=31, 685) had similar mortality after ICD implantation as those in the major trials (Mortality at three-year in patients with low HF burden=22% versus 16–22% in SCD-HeFT and MADIT II).