The impact of high-density lipoprotein cholesterol levels on long-term outcomes after non-ST-elevation myocardial infarction

Background: Low serum high-density lipoprotein cholesterol (HDL-C) level is a potent risk factor for developing atherosclerosis, yet it is uncertain if HDL-C level at the time of non-ST-segment elevation myocardial infarction (NSTEMI) has downstream prognostic importance. Methods: We evaluated 24,805 patients with NSTEMI aged ≥ 65 years enrolled at 434 Can Rapid Stratification of Unstable Angina Patients Suppress Adverse Outcomes with Early Implementation of the American College of Cardiology/American Heart Association Guidelines (CRUSADE) participating hospitals between February 15, 2003, and December 30, 2006, who had clinical data linked to Medicare files through December 31, 2008. Unadjusted and adjusted hazard ratios (HRs) were calculated to determine the association between HDL-C level at initial hospitalization and all-cause mortality, as well as a combined outcome of all-cause mortality or recurrent myocardial infarction (MI). Results: Overall, 50% of patients had low HDL-C (≤40 mg/dL) and 18% had very low HDL-C (≤30 mg/dL). The rate of all-cause mortality was 39.5% during a median follow-up of 2.9 years; death or recurrent MI occurred in 43% in this older population with NSTEMI. Compared with patients who had normal HDL-C, those with very low HDL-C had a modest but significantly higher long-term mortality risk (adjusted HR 1.12, 95% CI 1.06-1.19, P =.0001). The adjusted HR for mortality or recurrent MI was the same. When modeled as a continuous variable, every 5-mg/dL decrement in HDL-C below 40 mg/dL was associated with a 5% increased risk of long-term mortality, as well as the combined end point. Conclusions: Older patients with NSTEMI with low levels of HDL-C are at increased risk for downstream mortality or recurrent MI. Future studies are needed to evaluate strategies to reduce this residual risk.