Incidence of cardiovascular disease in familial combined hyperlipidemia: A 15-year follow-up study

Background and aims: Familial combined hyperlipidemia (FCHL) is a complex dyslipidemia associated with premature cardiovascular disease (CVD). The present study was conducted to 1) determine the incidence of CVD in FCHL in this era of protocolled, primary prevention; and 2) examine whether cardiovascular risk estimation based on the Systemic Coronary Risk Estimation (SCORE) chart, as proposed in the 2016 ESC/EAS guidelines for the management of dyslipidemia, is justified in FCHL.

Methods: FCHL patients, their normolipidemic (NL) relatives and spouses originally included in our baseline cohort in 1998-2005 (n = 596) were invited for a follow-up visit to determine the incidence of CVD, defined as (non-) fatal coronary artery disease, ischemic stroke and peripheral artery disease requiring invasive treatment.

Results: Follow-up data (median: 15 years) was acquired for 85% of the original cohort. The cumulative incidence of CVD was significantly higher in FCHL patients than in spouses (23.6% versus 4.7%; hazard ratio (HR): 5.4, 95% CI: 2.0-14.6; HR after adjustment for risk factors included in SCORE: 4.7, 95% CI: 1.6-13.8), but not in NL relatives compared to spouses (5.8% versus 4.7%). The SCORE chart tended to overestimate CVD risk in the spouses (observed [O]/expected [E] ratio: 0.2, p = 0.01), but not in FCHL patients (O/E: 1.3, p = 0.50).

Conclusions: Risk of primary CVD is still substantially increased in FCHL patients, despite preventive measures. The overestimation of CVD risk by the SCORE chart -a nowadays frequently observed phenomenon thanks to improved primary prevention - was not seen in FCHL. These results suggest that more aggressive treatment is justified to avoid excessive CVD in FCHL.