Long-Term Mortality of Older Patients With Acute Myocardial Infarction Treated in US Clinical Practice

Abstract

Background: There is limited information about the long-term survival of older patients after myocardial infarction (MI).

Methods and results: CRUSADE (Can rapid risk stratification of unstable angina patients suppress adverse outcomes with early implementation of the ACC/AHA guidelines) was a registry of MI patients treated at 568 US hospitals from 2001 to 2006. We linked MI patients aged ≥65 years in CRUSADE to their Medicare data to ascertain long-term mortality (defined as 8 years post index event). Long-term unadjusted Kaplan-Meier mortality curves were examined among patients stratified by revascularization status. A landmark analysis conditioned on surviving the first year post-MI was conducted. We used multivariable Cox regression to compare mortality risks between ST-segment-elevation myocardial infarction and non-ST-segment-elevation myocardial infarction patients. Among 22 295 MI patients ≥ age 65 years (median age 77 years), we observed high rates of evidence-based medication use at discharge: aspirin 95%, β-blockers 94%, and statins 81%. Despite this, mortality rates were high: 24% at 1 year, 51% at 5 years, and 65% at 8 years. Eight-year mortality remained high among patients who underwent percutaneous coronary intervention (49%), coronary artery bypass graft (46%), and among patients who survived the first year post-MI (59%). Median survival was 4.8 years (25th, 75th percentiles 1.1, 8.5); among patients aged 65-74 years it was 8.2 years (3.3, 8.9) while for patients aged ≥75 years it was 3.1 years (0.6, 7.6). Eight-year mortality was lower among ST-segment-elevation myocardial infarction than non-ST-segment-elevation myocardial infarction patients (53% versus 67%); this difference was not significant after adjustment (hazard ratio 0.94, 95% confidence interval, 0.88-1.00).

Conclusions: Long-term mortality remains high among patients with MI in routine clinical practice, even among revascularized patients and those who survived the first year.

Keywords: elderly; mortality; myocardial infarction; revascularization; survival.

Figure 1

Patient flow diagram. CMS indicates Centers for Medicare and Medicaid Services; CRUSADE, Can rapid risk stratification of unstable angina patients suppress adverse outcomes with early implementation of the ACC/AHA guidelines; NSTEMI, non–ST‐segment–elevation myocardial infarction; STEMI, ST‐segment–elevation myocardial infarction.

Figure 2

Cumulative Kaplan–Meier mortality estimates during an 8‐year follow‐up period in the overall population (blue line) and landmark population, conditional on surviving 1 year from the index MI hospitalization (dashed red line). n is the number of patients at risk. MI indicates myocardial infarction; N/A, not applicable.

Figure 3

Median survival in years, stratified by age group at presentation for the index MI. The black bars reflect post‐MI patients in the CRUSADE‐CMS‐linked data set. The gray bars represent expected lifespan from the United States National Vital Statistics Report.9 The largest difference in survival is noted among the relatively younger patients. Data from the 2004 National Vital Statistics Report are presented to provide context. The gray bars reflect expected lifespan of adults by ascending order of age: 65, 70, 75, 80, 85, and 90 years. Direct comparisons cannot be made between the median survival among our cohort and the expected lifespan because of the differences in age categorization. The sample sizes for the post‐MI patients depicted in the black bars are provided in Table S1. CMS indicates Centers for Medicare and Medicaid Services; MI, myocardial infarction.

Figure 4

Cumulative Kaplan–Meier mortality estimates stratified by subgroup. A, MI type, NSTEMI (red) vs STEMI (blue). B, Revascularization strategy, Medical Management (red), PCI (blue), CABG (green); n is the number of patients at risk. CABG indicates coronary artery bypass grafting; MI, myocardial infarction; NSTEMI, non–ST‐segment–elevation myocardial infarction; PCI, percutaneous coronary intervention; STEMI, ST‐segment–elevation myocardial infarction.

Figure 5

Probability of mortality as a function of time since index MI in years stratified by medically managed STEMI (red line), revascularized (PCI or CABG) STEMI (blue line), medically managed NSTEMI (green line), and revascularized NSTEMI (black line). n is the number of patients at risk. CABG indicates coronary artery bypass grafting; MI, myocardial infarction; NSTEMI, non–ST‐segment–elevation myocardial infarction; PCI, percutaneous coronary intervention; STEMI, ST‐segment–elevation myocardial infarction.