Background: Clinical and epidemiological studies have shown an inverse and independent association between high-density lipoproteins (HDL) and risk of developing coronary artery disease. The aim of this study was to estimate the prevalence of the phenotype characterized by low HDL values and to assess the impact of HDL plasma levels on the prognosis of patients hospitalized in the cardiologic unit of our Institute, during 30 months of follow-up.
Methods: Between February 1999 and February 2002, 1169 patients (778 men and 391 women) who had undergone hospitalization, were enrolled in a cardiovascular registry. The lipid profile was evaluated for all patients; a subgroup (n = 626) underwent coronary angiography. Patients were followed up for a mean period of 30 months, during which the frequency of revascularization procedures (coronary angioplasty or bypass), myocardial infarction and death were recorded.
Results: Nearly half of the subjects (45%, of which 77% men) showed HDL values < 40 mg/dl, and 25% of the population (80% men) were characterized by extremely reduced HDL concentrations (< or = 35 mg/dl). Patients with coronary atherosclerosis showed HDL levels lower than those of subjects with negative angiography (41.0 +/- 10.8 vs 46.6 +/- 10.9 mg/dl, p < 0.0005). An inverse relationship was found between HDL and coronary artery disease: the risk of developing the illness decreased by 4% for each increase of 1 mg/dl in HDL (p < 0.005); in males < 60 years and females < 65 years, the coronary artery disease risk association increased by 3% (p < 0.005). The risk of interventions decreased by 2% for each increase of 1 mg/dl in HDL (p < 0.01), both in the total population and in males < 60 years and females < 65 years. Finally, patients with HDL < 40 mg/dl showed a higher risk of revascularization interventions (+25%, p < 0.01) in comparison to the subjects with HDL > 40 mg/dl.
Conclusions: This study demonstrates: a) the high prevalence of the phenotype characterized by low plasma concentrations of HDL among patients hospitalized in a cardiologic unit; b) lower HDL values in subjects with coronary atherosclerosis compared to subjects with normal coronary angiography; c) the inverse relationship between HDL and coronary atherosclerosis; d) the prognostic value of HDL as a predictor of surgical revascularization.