Abstract 16722: HDL Cholesterol Subclasses and Mortality after Acute Myocardial Infarction: The TRIUMPH Prospective Multi-Center Registry

Abstract

Introduction: Although differentiation of HDL cholesterol (HDL-C) by its subclasses may add information on its function, current data on risk stratification are contradictory. We sought to determine the relative prognostic importance of HDL-C subclasses after acute myocardial infarction (AMI).

Methods: We examined the 2,465 patients who participated in lipid testing in TRIUMPH; a prospective, 24-center U.S. study of AMI outcomes. Patients underwent direct measurement of lipoprotein cholesterol subfractions during AMI hospitalization by density gradient ultracentrifugation. We stratified patients by tertiles of HDL-C and its two major subclasses (HDL2-C and HDL3-C), then compared 2-year mortality rates, and hazard ratios adjusted for age, sex, race, and GRACE score, the most validated clinical method for risk-stratifying post-AMI survival.

Results: Patients were 58±12 years old (mean±SD) and 68% were men. After 2 years of follow-up, 226 (9%) died. For total HDL-C, there was a nonsignificantly higher mortality rate (10.9%) in the lowest tertile, as compared with the middle and highest tertiles (mortality rates 8.2% and 8.5%; P=0.12). Within subfractions, there was a higher mortality rate (13.7%) in the lowest HDL3-C tertile, as compared with the middle (7.7%) and highest (7.2%) tertiles (P<0.0001) and an opposite, but non-significant, pattern for HDL2-C (mortality rates, 8.6%, 8.1%, and 10.9% in the lowest, middle, and highest tertiles; P=0.10). In multivariable-adjusted Cox regression models, total HDL-C levels were inversely associated with mortality, with an even stronger association for HDL3-C (Table). There was no association with HDL2-C and mortality.

Conclusion: Increased mortality at 2 years after AMI was strongly associated with lower HDL3-C, but not HDL2-C levels, resulting in a blunted association for total HDL-C. Once replicated, these data highlight the value of subclassification of HDL-C to better risk-stratify prognosis after AMI.