Prevalence of elevated lipoprotein(a) [Lp(a)] in patients with familial hypercholesterolemia (FH)

Background

To estimate the prevalence of elevated lipoprotein(a) [Lp(a)] in patients with familial hypercholesterolemia (FH) diagnosed using Dutch Lipid Clinic Network (DLCN) criteria and to assess the correlation of variables (age, gender, diabetes mellitus, hypertension etc.) with elevated Lp(a) in FH patients.

Purpose

Coronary artery disease (CAD) is a leading cause of mortality worldwide, presenting at an earlier age and with increased severity among South Asian population. Premature CAD (i.e.

diagnosed before the age of 55 years for men and 60 years for women) is two to three times more prevalent in Indian population, not fully explained by conventional risk factors, thus, highlighting the role of non-conventional risk factors like Lp(a) in aggravating the CAD risk especially among South Asian population. FH is genetically inherited disorder predisposing to premature coronary artery disease. Elevated Lp(a) i.e., plasma levels of more than 50 mg/dL, is also an independent risk factor for premature CAD. There is no data from Indian population regarding the prevalence of elevated Lp(a) in FH patients.

Methods

Study included 229 patients diagnosed as potential FH (probable and definite) using DLCN criteria (score ≥6). Demographic details, CAD risk factors, and complete lipid profile were noted. Pre-treatment levels of LDL-C was obtained after calculating correction factor for patients on lipid lowering therapy to calculate DLCN score. Patients with premature CAD with DLCN criteria score of ≥6 were included. Lp(a) estimation was done using immuno-turbidimetric method.

Results

A total of 229 potential FH patients [Males-176 (76.8%); females-53(23.1%)] with definite FH- 58 (25.3%); probable FH- 171 (74.6 %) with mean age- 46.75±9.2 years were included. Mean LDL-C was 154.07±67.18 mg/dL. Combined prevalence of elevated Lp(a) in potential FH patients was 49.3%. No significant correlation of variables was seen with elevated Lp(a).

Conclusion

Prevalence of FH in young acute coronary syndrome in our country is more than 15%. Prevalence of elevated Lp(a) in general population is 25% and in CAD is 35%. Combined prevalence of FH and elevated Lp(a) in premature CAD patients is 49.3% in Indian population. Thus, elevated Lp(a) is more common in FH patients and has synergistic role in severity and early onset of CAD.