No association between high-density lipoprotein levels and ventricular repolarization indexes in subjects with primary hypercholesterolemia

OBJECTIVE: Data regarding the effect of lipid parameters on repolarization are sparse. Recent data indicate that reconstituted HDL administration shortens repolarization in cardiomyocytes as well as the corrected QT (QTc) interval in human subjects. We investigated the potential association of high-density lipoprotein cholesterol (HDL-C) levels with conventional and novel electrocardiographic markers of ventricular repolarization in patients with hypercholesterolemia. METHODS: Consecutive subjects with primary hypercholesterolemia were recruited. We recorded clinical and laboratory parameters as well as electrocardiographic indexes. With regard to ventricular repolarization, we calculated the QTc interval, the T peak-to-end (Tpe) interval, and the Tpe/QT ratio. RESULTS: The study population consisted of 440 patients (199 men) with a median age of 56 [48-65] years. The correlation analysis (Spearman's) failed to show any association between HDL-C and any of the studied electrocardiographic parameter. Moreover, no correlation between other lipid parameters and the electrocardiograhic indexes was evident. Also, a comparison of the ventricular repolarization parameters between different HDL-C quartile groups (HDL-Q1: ≤ 1.11 mmol/L; HDL-Q2: 1.12-1.29 mmol/L; HDL-Q3: 1.30-1.53 mmol/L; HDL-Q4: ≥ 1.54 mmol/L) was performed. Specifically, the differences in QTc (p: 0.372), Tpe in leads II (p: 0.356), V2 (p: 0.372), V5 (p: 0.112), and Tpe/QT in leads II (p: 0.348), V2 (p: 0.162), V5 (p: 0.122) were not significant. CONCLUSION: HDL-C levels are not associated with the QTc interval or indexes of repolarization dispersion in patients with primary hypercholesterolemia. The potential antiarrhythmic efficacy of HDL should be further evaluated in the setting of myocardial ischemia where dynamic changes in the heterogeneity of ventricular repolarization ensue.