Pharmacologic and surgical treatment of dyslipidemic children and adolescents

Emerging antidyslipidemic drugs

BACKGROUND

Many patients at high risk for coronary heart disease (CHD) fail to reach target lipid levels with currently available medications, and a small but clinically relevant proportion of patients experience adverse effects. Thus, additional pharmaceutical strategies are required to fill these gaps in efficacy and tolerability.

OBJECTIVE

To provide an overview of both current and emerging antidyslipidemic drugs.

METHODS

For the current antidyslipidemic drugs, we focus primarily on statins, bile acid sequestrants, fibrates, ezetimibe, and niacin. Emerging antidyslipidemic drugs herein discussed were identified by searching the Pharmaprojects database for 'hypercholesterolemia drugs' (Phase II or Phase III), 'HDL-based therapies', and 'PCSK9 inhibition'.

RESULTS/CONCLUSIONS

Combinations of currently existing medications are most easily applicable. Meanwhile, strategies to raise HDL-C rely on a deep understanding of the complexity of HDL metabolism. Furthermore, novel approaches to further reduce LDL-C warrant careful evaluation of benefit-risk ratio. Finally, the medical community will have to rely on late-phase CHD outcome studies as the final arbiter of clinical application for any new antidyslipidemia treatment.

Novel non-systemic inhibitor of ileal apical Na+-dependent bile acid transporter reduces serum cholesterol levels in hamsters and monkeys

1-{7-[(1-(3,5-Diethoxyphenyl)-3-{[(3,5-difluorophenyl)(ethyl)amino]carbonyl}-4-oxo-1,4-dihydroquinolin-7-yl)oxy]heptyl}-1-methylpiperidinium bromide, R-146224, is a potent, specific ileum apical sodium-dependent bile acid transporter (ASBT) inhibitor; concentrations required for 50% inhibition of [3H]taurocholate uptake in human ASBT-expressing HEK-293 cells and hamster ileum tissues were 0.023 and 0.73 microM, respectively. In bile-fistula rats, biliary and urinary excretion 48 h after 10 mg/kg [14C]R-146224, were 1.49+/-1.75% and 0.14+/-0.05%, respectively, demonstrating extremely low absorption. In hamsters, R-146224 dose-dependently reduced gallbladder bile [3H]taurocholate uptake (ED50: 2.8 mg/kg). In basal diet-fed hamsters, 14-day 30-100 mg/kg R-146224 dose-dependently reduced serum total cholesterol (approximately 40%), high density lipoprotein (HDL) cholesterol (approximately 37%), non-HDL cholesterols (approximately 20%), and phospholipids (approximately 20%), without affecting serum triglycerides, associated with reduced free and esterified liver cholesterol contents. In normocholesterolemic cynomolgus monkeys, R-146224 specifically reduced non-HDL cholesterol. In human ileum specimens, R-146224 dose-dependently inhibited [3H]taurocholate uptake. Potent non-systemic ASBT inhibitor R-146224 decreases bile acid reabsorption by inhibiting the ileal bile acid active transport system, resulting in hypolipidemic activity.

Severe supravalvar aortic stenosis in familial homozygous hypercholesterolemia

Familial homozygous hypercholesterolemia is a rare disease with diverse clinical presentations. Patients often present with cutaneous xanthomas, particularly in the Achilles' tendon. They may have significant cardiovascular involvement, including premature atherosclerotic coronary artery disease and valvar and supravalvar aortic stenosis. Standard therapy includes diet modulation, pharmacotherapy, and lipid apheresis. Rarely, patients require surgical intervention for coronary artery bypass grafting and/or relief of the aortic stenosis. We present the case of a patient with severe progressive supravalvar aortic stenosis that ultimately required surgical resection despite aggressive medical therapy.

Plasma exchange and heart-liver transplantation in a patient with homozygous familial hypercholesterolemia

A female patient born in 1950 underwent plasma exchange and concomitant drug therapy for 20 yr due to homozygous familial hypercholesterolemia. Plasma exchange reduced total cholesterol levels from 25-30 mmol/L (967-1160 mg/dL) before treatment to 9.5 mmol/L (363 mg/dL) with regression of xanthomas and no side effects of long-term treatment. Due to end-stage calcific left ventricular outflow tract obstruction not amenable to standard valve reconstructive surgery, a combined heart-liver transplantation was successfully performed in 1996. She is without symptoms and living a normal life 4 yr after transplantation. Total cholesterol value is normal (4.7 mmol/L [182 mg/dL]) using a moderate dose of statins. Selective coronary angiography is without signs of graft vascular disease and the liver function is normal.

Statins in children: what do we know and what do we need to do?

Children have been tested and treated for hypercholesterolemia for more than 30 years. Although most treatment regimens have been limited to dietary intervention, statin use is increasing. Statins have been used in children since 1987, but published sources have only reported on small numbers of children with severe hypercholesterolemia. The available data indicates that statins can be useful and well tolerated. New data will be available in the next few years that will lead to the wider use of these drugs. Although statin drugs have proven to be safe in the adult population, physicians will be obliged to follow pediatric patients closely when these agents are widely used in the first few years. The use of highly effective safe drugs such as statins will allow for the assessment of the best time to initiate therapy in younger populations and what benefits may be found over the long term.

Liver transplantation for homozygous familial hypercholesterolaemia

Homozygous familial hypercholesterolaemia is a rare inherited condition with an incidence of approximately one in a million. It is associated with severe premature atherosclerosis and early death from cardiovascular complications. The results of liver transplantation reported to date have suggested only partially effective reduction of the hypercholesterolaemia. Three boys with familial hypercholesterolaemia, aged 10.0 to 15.1 years, received liver grafts at Addenbrooke's Hospital. Their untreated fasting lipid concentrations were grossly raised. All three had angiographic evidence of coronary atheroma and two had exertional angina. One child had such severe atheroma that coronary artery bypass surgery was considered necessary before liver transplantation. All three had straightforward operative and postoperative courses and their lipid concentrations returned rapidly to normal. One boy developed chronic rejection requiring retransplantation. Currently all three boys are well, on normal diets, and with normal liver function. It is concluded that (1) liver transplantation offers highly effective treatment for this lethal condition, (2) timing the operation is difficult but it should be undertaken before coronary artery disease has progressed too far (when combined liver and heart transplantation may be the only possibility), and (3) in well grown children with no previous abdominal surgery the immediate risks of liver transplantation are low but chronic rejection remains a danger.

Guidelines for screening, evaluating, and treating children with hypercholesterolemia

Hypercholesterolemia is the most frequently identified coronary heart disease risk factor in childhood, with 25% or more of children in the United States reported to have borderline high or high levels. This article provides a summary of current recommendations for cholesterol screening, evaluation, treatment, and follow-up in the pediatric office or clinic setting. Detection and treatment of pediatric dyslipidemia, however, is only one component of preventive cardiology and should be addressed in routine well child and adolescent care along with major efforts to prevent cigarette smoking, obesity, inactivity, and hypertension.

Familial hypercholesterolemia and intracavernous venous spilling of cholesterol in a child with large suprasellar dermoid cyst. Case report

A unique case of suprasellar dermoid cyst and familial hypercholesterolemia in a child is reported. Such an association, which strengthens the congenital hypothesis of dermoid cysts, could be a manifestation of a complex dyslipidemic inherited syndrome, at least in children. Surgical removal of the dermoid cyst which spilled cholesterol into the cavernous and intercavernous sinuses, allowed reduction of cholesterol levels in the postoperative period.

Familial combined hyperlipidemia in children: clinical expression, metabolic defects, and management

The first evidence that elevation of plasma levels of cholesterol is a risk factor for the development of atherosclerosis in children came from the Bogalusa Heart Study in 1986, which reported an association between aortic fatty streaks in 3- to 26-year-old subjects and increased plasma levels of low-density lipoprotein cholesterol (LDL-C). The most compelling evidence of a cause-and-effect relationship has come from the multicenter cooperative study called the Pathobiological Determinants of Atherosclerosis in Youth. When the investigators examined the abdominal aorta and the right coronary artery of adolescents and young adults who had died of trauma, they found a significant relationship between the sum of the very low density lipoprotein (VLDL) plus LDL-C level and both fatty streaks and raised atherosclerotic lesions. They also found an inverse relationship between those lesions and increased high-density lipoprotein cholesterol (HDL-C) levels. In addition, their studies showed that smoking (as assessed by the serum thiocyanate level) promotes atherogenesis in children as young as age 15 years. Thus many pediatricians have now accepted the importance of identifying children with significant hypercholesterolemia so that appropriate dietary and life-style modifications can be recommended. This is especially important because there is often a major genetic component to the hyperlipidemia seen in children.

Dyslipoproteinemia and other risk factors for atherosclerosis in children and adolescents

The early lesions of atherosclerosis in youth are strongly related to antemortem levels of total and low density lipoprotein (LDL) cholesterol, very low density lipoprotein (VLDL) cholesterol, and triglyceride, to ponderal index and to systolic and diastolic blood pressure. The major apolipoproteins of LDL and high density lipoprotein (HDL), apo B and apo A1, respectively, as well as levels of Lp(a) lipoprotein are often abnormal in children born to a parent with coronary artery disease (CAD). Other risk factors for CAD include obesity, high blood pressure, cigarette smoking, diabetes mellitus, positive family history of CAD and physical inactivity. Children from families with premature CAD, familial dyslipidemia or hypertension, and/or two other risk factors should have a lipoprotein profile determined. The first form of treatment is a diet low in total fat, saturated fat and cholesterol, combined with treatment of overnutrition and obesity, if necessary, and regular habits of aerobic physical activity. Children with inherited disorders of LDL metabolism may require the addition of lipid lowering therapy. The early detection and treatment of youth at risk for premature CAD offers the greatest promise to decrease morbidity and mortality.

Detection and quantitation of calcific atherosclerosis by ultrafast computed tomography in children and young adults with homozygous familial hypercholesterolemia

Ultrafast computed tomography (CT) is a new method for detecting calcific lesions in the coronary arteries. The ability of CT to detect and quantify coronary artery atherosclerosis in children and young adults at risk for malignant atherogenesis was evaluated. A total of 11 consecutive familial hypercholesterolemic (FH) homozygotes (3 to 37 years old) participated. Untreated total cholesterol concentrations were 488 to 1277 mg/dL (12.7 to 33.2 mmol/L). Angiography detected significant lesions in 7 of 11 patients. CT detected calcific atherosclerosis in all 9 of the patients older than 12 years of age, including all those with angina. CT was more sensitive in detecting aortic root and coronary ostial lesions, where atherosclerosis first appears in homozygous FH. The volume of calcification (in cubic millimeters) correlated with the severity and duration of the hypercholesterolemia (r = .62, P < .05) as well as with the presence of angina (P < .05). All patients with angina (7 of 7) had > 150 mm3 of calcified volume, whereas only 1 of 4 asymptomatic patients had a volume score > 150 mm3. We conclude that (1) coronary and aortic calcium phosphate deposits are common in young FH homozygotes; (2) these deposits are associated with the presence of angiographic stenoses, as has been seen in adults with coronary atherosclerosis; and (3) aortic calcific deposits are more common than calcific coronary lesions.

Familial combined hyperlipidemia in children: clinical expression, metabolic defects, and management

Familial combined hyperlipidemia (FCHL) is a dominantly inherited hyperlipidemia that occurs in at least 1% of the adult population and is responsible for 10% of premature coronary artery disease. In families referred for evaluation because of primary hyperlipidemia in a child, FCHL is expressed three times more commonly than familial hypercholesterolemia and half of the siblings are affected. Several metabolic defects apparently are associated with the FCHL phenotype. Most commonly, excess production of very low density lipoprotein apolipoprotein B can be demonstrated. In other families, reduced lipoprotein lipase activity is associated. One allele at a locus influencing apolipoprotein B levels predicts FCHL in a large proportion of families ascertained through affected children. Whether this allele is responsible for the excess of very low density lipoprotein apolipoprotein B detected in metabolic studies has not been elucidated. Management of FCHL in children begins with dietary modification. A bile acid sequestrant may be considered as well if diet cannot reduce the plasma low-density lipoprotein cholesterol level to less than 4.13 mmol/L (160 mg/dl) after the age of 10 years. Although the hydroxymethylglutaryl-coenzyme A reductase inhibitors are not currently recommended for children younger than 19 years of age, we speculate that they will be increasingly utilized for the management of FCHL in teenage boys who continue to have low density lipoprotein cholesterol levels greater than 4.13 mmol/L (160 mg/dl) after dietary modification.