Age Predicts 90-Day Mortality in PPCI Patients

Age was the strongest predictor of 90-day mortality among patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI) for reperfusion, according to results of a recent study [Arch Intern Med. 2011;171(6):559-567]. Because older patients with STEMI are usually not candidates for pharmacologic reperfusion, PPCI is often the preferred alternative in this patient population. However, clinical trials of PPCI in older patients have consisted of relatively small numbers. Christopher B. Granger, MD, of Duke University Medical Center, and his colleagues conducted a subanalysis of data from APEX-AMI (Assessment of Pexelizumab in Acute Myocardial Infarction) to examine the association between age and 90-day outcomes among patients with STEMI undergoing PPCI. APEX-AMI was a multicenter, randomized, double-blind, placebo-controlled trial conducted from July 2004 until May 2006 that compared intravenous pexelizumab with placebo in high-risk STEMI patients planning to undergo PPCI for reperfusion. The researchers’ analysis included data on 5745 patients, 1358 of whom were 65 to 74 years of age and 977 were ≥75 years of age. The primary end point was all-cause 30-day mortality; secondary end points included the composite incidence of congestive heart failure (CHF), cardiogenic shock, or death through days 30 and 90. The researchers determined adjusted and unadjusted 90-day outcomes by age with the use of Kaplan-Meier curves and rates, and multivariable Cox proportional hazards models to predict 90-day mortality rates. Patients ≥75 years of age who underwent PPCI experienced higher rates of in-hospital clinical events, including electrical and mechanical complications, renal failure, hypotension, stroke, recurrent ischemic events, and bleeding compared with PPCI patients <75 years of age. Stroke rates by day 90 were 2.8% for those ≥75 years of age compared with 0.7% and 1.5% for patients <65 years of age and between the ages of 65 and 74, respectively. Stroke occurred within 7 days of randomization in 0.4%, 1.1%, and 1.5% of patients <65 years of age, ages 65 to 74, and ≥75 years of age, respectively (P<.001). Among 69 patients who underwent PPCI and subsequently had a stroke, 18 (26.1%) experienced stroke within 24 hours of PPCI. The median length of time to stroke from PPCI was 4 days. The researchers found recurrent in-hospital myocardial infarction (MI) rates to be 2.6%, 4.1%, and 4.8%, respectively, for patients <65, 65 to 74 years, and ≥75 years of age. The mortality rate for patients ≥75 years of age increased steadily from 30 to 90 days, a 2.3% change compared with a 0.5% change for patients <75 years of age. After adjustment, age was shown to be the strongest independent predictor of mortality. For every 10-year increase in age, the hazard of 90-day mortality doubled (hazard ratio, 2.07 per 10-year increase; 95% confidence interval, 1.84-2.33). The adjusted hazard ratio for 90-day mortality was >5 times higher among patients ≥75 years of age versus those <65 years of age. The researchers also found a Killip class of 3 to be an independent predictor, with hazard of 90-day mortality increased more than 4 times. Other factors linked to mortality included heart rate, serum creatinine level, ST-segment deviation, and high-risk inferior MI. A possible limitation of the analysis was its observational design; unmeasured confounders may have impacted results.