Low LDL-Cholesterol at Time of Myocardial Infarction Means Higher Long-Term Mortality

Patients with low levels of low-density lipoprotein (LDL) cholesterol at the time of a myocardial infarction (MI) have decreased 3-year survival, according to data reported here on November 7th at the American Heart Association Scientific Sessions 2004.

The findings were reported by Mouaz H. Al-Mallah, MD, staff cardiologist, Henry Ford Heart & Vascular Institute, Detroit, Michigan.

Dr. Al-Mallah and colleagues tested the hypothesis that patients who develop nonST segment elevation MI despite a low level of LDL cholesterol have a worse outcome in the long-term.

"Hyperlipidemia has been shown to be an independent risk factor for the development of coronary artery disease," Dr. M Al-Mallah explained. "Randomized controlled trials have demonstrated that lipid-lowering therapy improves mortality and morbidity in patients with and without coronary artery disease."

While lower lipid profiles after the development of congestive heart failure have been associated with worse long-term outcomes, the prognostic value of LDL cholesterol at admission has not been established in patients with acute coronary syndrome.

The present analysis included 517 patients admitted to the coronary intensive care unit in a tertiary care center over a recent 3-year period with a diagnosis of nonST segment MI, who were enrolled prospectively in a data registry.

Lipid profiles, including total cholesterol, LDL cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyceride levels were measured within the first 24 hours of admission.

Patients were divided into 2 groups based on their LDL-cholesterol levels - below or above the median LDL of 105 mg/dL.

The primary endpoint of the study was 3-year mortality.

At 3 years, patients with a LDL-cholesterol level of 105 mg/dL or less had a higher unadjusted mortality rate compared to patients with LDL-cholesterol greater than 105 mg/dL (14.8% vs 7.1%, odds ratio [OR] = 2.3).

After adjusting for race, prior MI, hypertension, diabetes, lipid-lowering therapy, smoking, prior aspirin and beta-blocker use, diastolic blood pressure, and admission HDL-cholesterol level, mortality remained worse in the group with LDL-cholesterol levels of 105 mg/dL or less (OR = 1.8, P =.05).

Dr. Al-Mallah said that the results demonstrate that patients with low LDL-cholesterol levels at the time of their MI have a higher long-term mortality at 3 years. Whether this is a result of biologic effects or of subsequent therapy is not clear.

He added that atherosclerotic plaque rupture in the setting of lower cholesterol may be a marker of more complex atherosclerotic disease that portends worse long-term prognosis in patients with nonST segment MI.