Serum bilirubin levels in familial hypercholesterolemia: a new risk marker for cardiovascular disease?

Low concentrations of bilirubin are associated with an increased risk for cardiovascular disease (CVD). Possibly, bilirubin exerts its effect through the protection of LDL from oxidation. Therefore, we examined whether low bilirubin might also be a risk marker for CVD in patients with familial hypercholesterolemia (FH) and whether statins influence serum bilirubin levels. Patients with FH were recruited from 37 lipid clinics. After a washout period of 6 weeks, all patients were started on monotherapy with simvastatin 80 mg for a period of two years. A total of 514 patients were enrolled. Bilirubin at baseline was inversely associated with the presence of CVD, also after adjustment for age, gender, presence of hypertension, and HDL cholesterol levels. Moreover, bilirubin levels were significantly raised, by 7%, from 10.0 to 10.8 µmol/L after treatment with simvastatin 80 mg. We hypothesize first that high bilirubin levels might protect patients with FH from CVD. Furthermore, bilirubin levels were significantly increased after treatment with simvastatin 80 mg, independent of changes in liver enzymes, which might confer additional protection against CVD. Whether this is also true for lower doses of simvastatin or for other statins remains to be investigated.

Clinical, diagnostic, and therapeutic aspects of familial hypercholesterolemia.

Heterozygous familial hypercholesterolemia (FH) is a common inherited disorder of lipoprotein metabolism. FH is characterized by elevated levels of low-density lipoprotein cholesterol, the presence of tendon xanthomas, and premature cardiovascular disease. The underlying molecular defect of FH consists of mutations in the gene coding for the low-density-lipoprotein-receptor protein, detection of which provides the only unequivocal diagnosis. Although the cause of FH is monogenic, there is wide variation in the onset and severity of atherosclerotic disease in these patients. Additional atherogenic risk factors of environmental, metabolic, and genetic origin are presumed to influence the clinical phenotype in FH. Criteria used to identify individuals with FH include a combination of clinical characteristics, personal and family history of early coronary artery disease, and biochemical parameters. Since the introduction in 1989 of statins, which have been shown to be effective and to delay or prevent the onset of cardiovascular disease, drug treatment of FH has greatly improved. New lipid-lowering agents are presently being developed for clinical use. This review provides an update on the clinical, diagnostic, and therapeutic aspects of heterozygous familial hypercholesterolemia.

Regression of carotid and femoral artery intima-media thickness in familial hypercholesterolemia: treatment with simvastatin.

OBJECTIVE: To investigate whether high-dose simvastatin therapy could reduce carotid and femoral artery intima-media thickness (IMT) in patients with familial hypercholesterolemia (FH) to prevent cardiovascular disease. BACKGROUND: Imaging of arterial walls with B-mode ultrasonography is increasingly used as a noninvasive surrogate marker of cardiovascular disease. Intervention trials using this modality have shown that by reducing risk factors, progression of atherosclerosis was inhibited. METHODS: After a washout period of 6 weeks, all patients with FH started monotherapy with simvastatin, 80 mg/d, for 2 years. The primary end point was the change (in millimeters) of the mean combined far-wall IMT of predefined carotid and femoral arterial segments at 2 years. RESULTS: We included a total of 153 patients with FH. Mean +/- SD combined baseline IMT was 1.07 +/- 0.23 mm. After treatment with simvastatin for 2 years, this IMT decreased by a mean of 0.081 mm (95% confidence interval, -0.109 to -0.053; P<.001), with its largest reduction in the femoral artery (-0.283 mm; P<.001). An actual decrease of combined IMT was seen in 69.8% of all patients. CONCLUSIONS: High-dose simvastatin therapy reduces arterial wall IMT in more than two thirds of the patients, with its largest effect on the femoral artery. Furthermore, patients with FH who were treated with both statin and antihypertensive medication experienced a significantly greater benefit in terms of IMT reduction.

Consumption of tall oil-derived phytosterols in a chocolate matrix significantly decreases plasma total and low-density lipoprotein-cholesterol levels.

In a randomized, double-blind, placebo-controlled trial we evaluated the effect of dietary chocolates enriched with a wood-based phytosterol-phytostanol mixture, containing 18 % (w/w) sitostanol, compared with placebo dietary chocolates in seventy subjects with primary hypercholesterolaemia (total cholesterol levels below 8 mmol/l). For 4 weeks, participants consumed three servings of the phytosterol-enriched chocolate/d that provided 1.8 g unesterified phytosterols/d or a placebo chocolate in conjunction with a low-fat, low-cholesterol diet. Plasma total and LDL-cholesterol levels were statistically significantly reduced by 6.4 % (-0.44 mmol/l) and 10.3 % (-0.49 mmol/l), respectively, after 4 weeks of phytosterol-enriched-chocolate treatment. Plasma HDL-cholesterol and triacylglycerol levels were not affected. Consumption of phytosterol-enriched chocolates significantly increased plasma lathosterol concentration (+20.7 %), reflecting an increased endogenous cholesterol synthesis in response to phytosterol-induced decreased intestinal cholesterol absorption. Furthermore, the chocolates enriched with phytosterols significantly increased both plasma sitosterol (+95.8 %) and campesterol (+64.1 %) levels, compared with the placebo chocolate group. However, the absolute values of plasma sitosterol and campesterol remained within the normal range, that is, below 10 mg/l. The chocolates with phytosterols were palatable and induced no clinical or biochemical side effects. These findings indicate that dietary chocolate enriched with tall oil-derived phytosterols (1.8 g/d) is effective in lowering blood total and LDL-cholesterol levels in subjects with mild hypercholesterolaemia and thus may be helpful in reducing the risk of CHD in these individuals.

Baseline lipid values partly determine the response to high-dose simvastatin in patients with familial hypercholesterolemia. The examination of probands and relatives in Statin studies with familial hypercholesterolemia (ExPRESS FH).

Statins decrease low-density lipoprotein cholesterol (LDL-C), and additionally, reduce triglycerides (TG) and raise high-density lipoprotein cholesterol (HDL-C) levels. This study evaluated the frequency of abnormal TG and HDL-C levels in patients with classical familial hypercholesterolemia (FH) and assessed therapeutic response at different baseline levels of these lipoproteins after 1 year of statin therapy. A total of 508 FH patients were included and mean LDL-C levels (8.37+/-2.12 mmol l(-1)) were severely elevated. After a washout period of 6 weeks, all patients started monotherapy with 80 mg simvastatin. Remarkably, LDL-C reduction was dependent on baseline LDL-C levels ranging from 51.1 to 45.5% in the top versus the bottom third of the LDL-C distribution. Unexpected in FH, elevated baseline TG levels were seen in 30% and low HDL-C levels in 15% of all patients. Also, changes in these lipoproteins were dependent on baseline levels; TG reduction was 40.7 versus 22.2% in patients with elevated versus normal levels, while HDL-C increase was 29.1 versus 11.4% in patients with low versus normal HDL-C levels. In conclusion, FH patients with the worst lipoprotein profile showed the greatest benefit from high-dose simvastatin treatment, since changes in these parameters were partly determined by baseline lipid levels.

Elevated remnant-like particles in heterozygous familial hypercholesterolemia and response to statin therapy.

BACKGROUND: Remnant lipoproteins (RLP-C) are considered important in atherogenesis. Hence, this study was designed to assess RLP-C levels and the effect of statin therapy in patients with familial hypercholesterolemia (FH). Elevated RLP-C levels have been associated with the presence and progression of atherosclerotic disease, and their presence in FH patients has been proposed but never established in a large cohort, nor has their response to statin therapy been confirmed. METHODS AND RESULTS: FH patients were recruited from 36 lipid clinics. After a washout period of 6 weeks, all patients were started on monotherapy with 80 mg of simvastatin for 2 years. RLP-C levels were assessed by an immune-separation assay. In 327 FH patients, RLP-C measurements could be performed before and after treatment. Mean total cholesterol (10.55+/-2.17 mmol/L), mean LDL cholesterol (8.40+/-2.13 mmol/L), and median RLP-C (0.47 mmol/L) levels were all severely elevated at baseline. After treatment, RLP-C levels were reduced by 49% (0.24 mmol/L; P<0.0001). Even patients with normal triglyceride levels had elevated RLP-C levels at baseline, and those with high RLP-C levels were generally characterized by a very atherogenic lipoprotein profile. CONCLUSIONS: Baseline RLP-C levels are severely elevated in FH patients and are reduced by simvastatin but do not return to normal. These elevated RLP-C levels could be the consequence of impaired function of the LDL receptor in FH. RLP-C levels in FH contribute to an atherogenic lipoprotein profile and could identify patients who require additional treatment.