Patients with ACS and low HDL cholesterol levels are at increased risk

Patients with acute coronary syndrome (ACS) and low baseline levels of high-density lipoprotein (HDL) cholesterol are at increased risk of death and adverse cardiac events, irrespective of levels of low-density lipoprotein (LDL) cholesterol. These patients are therefore likely to benefit from therapeutic strategies aimed at raising HDL cholesterol.1

This observational study included 1,032 patients who undergone angioplasty with drug-eluting stent implantation for ACS. The endpoints of the study were death, Q-wave myocardial infarction, target lesion revascularisation and a composite of major adverse cardiac events (MACEs) at 30 days and one year. Low baseline HDL cholesterol was defined as < 40 mg/dL (< 1.0 mmol/L) in men and < 45 mg/dL (< 1.2 mmol/L) in women.

At admission, 86% of patients were treated for hypercholesterolaemia, and 98% were discharged on a statin (atorvastatin 40 mg/day). Only 37 (6.7%) patients with low HDL cholesterol were discharged on combination lipid-modifying therapy (either statin plus nicotinic acid or a fibrate, or other combination therapy). The incidence of MACEs was significantly higher among patients with low HDL cholesterol compared with those with high levels, both at 30 days (3.2% vs. 0.3%, p=0.002) and up to one year (27% vs. 12%, p=0.005). Significantly more deaths occurred among patients with low HDL cholesterol compared with those with higher levels (14 vs. 4 deaths at one year, p=0.033).

Kaplan-Meier survival analysis showed that patients with high HDL cholesterol levels had a significantly higher survival rate over the one-year follow-up period than those with low HDL cholesterol levels. Increasing HDL cholesterol levels by 1 mg/dL (0.026 mmol/L) was associated with a 4% decrease in the risk of target lesion revascularisation or MACEs. Multivariate regression analysis identified low HDL cholesterol at baseline as one of the key independent predictors for these adverse outcomes at one year (Hazard ratio 2.61, 95%CI 1.33 to 5.12).

These observations were consistent with data from the MIRACL (Myocardial Ischemia Reduction with Aggressive Cholesterol Lowering) trial, which showed that even with aggressive lowering of LDL cholesterol, HDL cholesterol – but not LDL cholesterol - influenced short-term outcome in patients with ACS.2