Importance of HDL cholesterol levels and the total/ HDL cholesterol ratio as a risk factor for coronary heart disease in molecularly defined heterozygous familial hypercholesterolaemia

Aims To assess the relationship of the lipid profile to coronary heart disease in a group of heterozygous familial hypercholesterolaemic subjects with similar age, sex, body mass index, prevalence of angiotensin converting enzyme DD genotype and type of low density lipoprotein receptor mutation. Methods and Results A total of 66 molecularly defined heterozygous familial hypercholesterolaemic subjects, 33 of whom had coronary heart disease, were studied. Clinical features, cardiovascular risk factors and lipid parameters were compared in both groups. Familial hypercholesterolaemic patients with coronary heart disease showed significantly lower values of mean plasma HDL cholesterol and a higher total/HDL cholesterol ratio as compared with familial hypercholesterolaemic subjects free of coronary heart disease. Total and LDL cholesterol concentrations were higher in patients with coronary heart disease, without reaching statistical significance. No differences in plasma lipoprotein(a) levels on absolute and log-transformed values were observed between the two groups. In the whole familial hypercholesterolaemia group, plasma HDL cholesterol levels were related to plasma triglyceride values and to LDL receptor gene ‘null mutations’. Conclusions In familial hypercholesterolaemic subjects of similar age, gender, body mass index, systolic and diastolic blood pressure, and genetic factors that could influence coronary heart disease risk, plasma HDL cholesterol values and total/HDL cholesterol ratios are two important coronary risk factors. Hence, treatment of familial hypercholesterolaemia should focus not only on lowering total and LDL cholesterol levels, but also on increasing HDL cholesterol values for coronary heart disease prevention. More prospective and intervention trials should be conducted to establish the relationship of HDL cholesterol levels and coronary heart disease in familial hypercholesterolaemia.