Lipoprotein(a) and cardiovascular prognosis of familial dyslipidemias: data from a 10-year follow-up study

Abstract

Abstract Background Familial dyslipidemias, such as heterozygous familial hypercholesterolemia (FH) and familial combined hyperlipidemia (FCH) are associated with premature cardiovascular (CV) disease. On the other hand, increased lipoprotein(a) [Lp(a)] is considered as the most prevalent monogenic lipid disorder in the general population. Purpose This study aimed to longitudinally follow up two specific populations with familial dyslipidemias associated with increased CV risk, namely FH and FCH, and compare them with reference to their CV prognosis, investigating in parallel the effect of Lp(a) levels. Methods 433 patients with FH (34% males, mean age 44.2±12.8 years) and 476 patients with FCH (57% males, mean age 49.0±11.1 years) from the outpatient lipid clinic of our hospital, without history of CV disease, who fulfilled the FH and FCH criteria, respectively, participated in the study. Participants were evaluated for a mean follow-up period of 9.6±7.6 years, with at least one annual visit. Venous blood samples were obtained at baseline in all patients for the determination of lipid profile and levels of Lp(a). All subjects were on lipid-lowering medication during the follow-up period. The endpoint of our study was the composite of major CV events (coronary artery disease events and stroke). Results The incidence of the composite endpoint of major CV events during the follow-up period in the total population was 6.5%, while it was greater in patients with FH compared to patients with FCH (8.1% vs 5.5%, p=0.03). Regarding CV risk factors, FCH compared to FH patients had greater prevalence of baseline hypertension (36% vs 9.7%, p<0.001) and diabetes (11% vs 2%, p<0.001), whereas FH patients had greater Lp(a) levels (37.4±40.3 vs 29.7±34.6 mg/dl, p<0.01). Multiple Cox regression analysis revealed that FH patients had greater CV risk compared to FCH patients (HR 2.17, 95% CI 1.10-4.26, p=0.02). Moreover, in FH patients, increased baseline Lp(a) levels (≥30mg/dl) were an independent predictor of major adverse CV events (HR 2.37 95% CI 1.41-4.90, p=0.02), whereas in FCH patients increased Lp(a) was not an independent predictor. In FCH patients the presence of diabetes at baseline was a strong independent prognosticator of adverse CV events (HR 3.56 95% CI 1.19-11.33, p=0.03), after adjustment for confounding factors. Conclusions FH patients have greater CV risk compared to FCH patients. In FH patients, the presence of increased Lp(a) doubles the CV risk, beyond low density lipoprotein cholesterol levels. On the other hand, in FCH patients the presence of diabetes triples the CV risk, whereas Lp(a) does not convey an independent prognostic value.