Coronary flow reserve in young men with familial combined hyperlipidemia

Background-Familial combined hyperlipidemia (FCHL) is a common hereditary d isorder of lipoprotein metabolism estimated to cause 10% to 20% of prematur e coronary heart disease. We investigated whether functional abnormalities exist in coronary reactivity in asymptomatic patients with FCHL. Methods and Results-We studied 21 male FCHL patients (age, 34.8+/-5.4 years ) and a matched group of 21 healthy control subjects. Myocardial blood flow (MBF) was measured at baseline and during dipyridamole-induced hyperemia w ith PET and O-15-labeled water. The baseline MBF was similar in patients an d control subjects (0.79+/-0.19 versus 0.88+/-0.20 mL.g(-1).min(-1), P=NS). An increase in MBF was seen in both groups after dipyridamole infusion, bu t MBF at maximal vasodilation was lower in FCHL patients (3.54+/-1.59 versu s 4.54+/-1.17 mL.g(-1).min(-1), P=0.025). The difference in coronary flow r eserve (CFR) was not statistically significant (4.7+/-2.2 versus 5.3+/-1.6, P=NS, patients versus control subjects). Considerable variability in CFR v alues-was detected within the FCHL group. Patients with phenotype IIB (n=8) bad lower now during hyperemia (2.5+/-1.2versus 4.2+/-1.5 mL.g(-1).min(-1) , P<0.05) and lower CFR (3.4+/-2.1 versus 5.4+/-2.0, P<0.05) compared with phenotype IIA (n=13). Conclusions-Abnormalities in coronary flow regulation exist in young asympt omatic FCHL patients expressing phenotype IIB (characterized by abnormaliti es in both serum cholesterol and triglyceride concentrations). This is in l ine with previous observations suggesting that the metabolic abnormalities related to the pathophysiology of FCHL are associated with the phenotypes I IB.