Effect of Ezetimibe Plus Simvastatin Versus Simvastatin Alone on Atherosclerosis in the Carotid Artery (ENHANCE)(P02578)

Inclusion Criteria: * Genotype-confirmed heterozygous familial hypercholesterolemia with written documentation of the genetic diagnosis at the time of screening and LDL-C \>=210 mg/dL (5.43 mmol/L), or clinical diagnosis of heterozygous familial hypercholesterolemia, defined as LDL-C \>=210 mg/dL (5.43 mmol/L) and at least one of the following: * tendinous xanthoma * child \<18 years of age with hypercholesterolemia (LDL-C \>159 mg/dL (4.11 mmol/L) * has a sibling with hypercholesterolemia (LDL-C \>190 mg/dL \[4.91 mmol/L\]) and tendinous xanthoma * family history with an LDL-C value distribution pattern compatible with dominant autosomal transmission and at least one relative presenting fasting total cholesterol values \>348 mg/dL (9.0 mmol/L) after exclusion of secondary causes of dyslipidemia * LDL-C \>=210 mg/dL (5.43 mmol/L) 1 week before randomization * plasma triglyceride level \<=400 mg/dL (4.52 mmol/L) Exclusion Criteria: * pregnancy or any other situation, condition, or illness that, in the opinion of the investigator, may interfere with optimal participation in the study * presence of an apolipoprotein B gene mutation with confirmed absence of an LDL receptor mutation in either allele * undergoing LDL-apheresis or plasma apheresis * unsuitable plaque or artery morphology * use of certain drugs, foods, or other agents known to alter cholesterol levels or to cause pharmacokinetic interactions with either ezetimibe or simvastatin