Inclusion Criteria:
* Must be willing to participate in the study and provide written informed consent;
* Male and female adults ≥18 years of age;
* Female participants of child bearing potential with negative serum pregnancy (beta human chorionic gonadotropin) test who are not breastfeeding, do not plan to become pregnant during the study, and agree to use effective birth control per locally agreed requirements; male participants who have sexual intercourse with a female partner of child bearing potential from the first dose of study drug until 1 month after study completion must either be surgically sterile (confirmed by documented azoospermia \>90 days after the procedure) or agree to use a condom with spermicide. All male participants must agree not to donate sperm from the first dose of study drug until 1 month after study completion;
* Must have a diagnosis of HeFH by genetic testing or by having met the diagnostic criteria for definite familial hypercholesterolemia outlined by the Simon Broome Register Group or World Health Organization/Dutch Lipid Network (score \>8);
* Must have had a fasting LDL-C (low density lipoprotein cholesterol) ≥2.6 mmol/L (100 mg/dL); and
* Must be on a stable or maximally tolerated dose (≥4 weeks prior to screening) of an approved statin (rosuvastatin ≤40 mg daily, atorvastatin ≤80 mg daily), with or without ezetimibe. Patients intolerant to statins were allowed.
Exclusion Criteria:
* Homozygous familial hypercholesterolemia
* LDL or plasma apheresis within 2 months prior to randomization;
* New York Heart Association class III or IV heart failure, or known left ventricular ejection fraction \<30%;
* Uncontrolled cardiac arrhythmia, including confirmed QT interval corrected using Fridericia's formula \>450 msec for males and \>470 msec for females at the screening electrocardiogram assessment;
* Myocardial infarction, unstable angina, percutaneous coronary intervention, coronary artery bypass graft, or stroke within 3 months prior to randomization;
* Type 1 diabetes, or newly diagnosed or uncontrolled type 2 diabetes (hemoglobin A1c \>8%);
* History of significant alcohol consumption for a period of more than 3 consecutive months within 1 year prior to screening; Note: Significant alcohol consumption is defined as average of \>20 g/day in female participants and \>30 g/day in male participants;
* Hyperthyroidism;
* Thyroid replacement therapy;
* Hypothyroidism;
* Evidence of chronic liver disease;
* Hepatitis B, as defined by the presence of hepatitis B surface antigen;
* Hepatitis C, as defined by the presence of hepatitis C virus (HCV) antibody (anti-HCV) and HCV ribonucleic acid (RNA). Participants with positive anti-HCV who test negative for HCV RNA at screening will be allowed to participate in the study;
* Serum alanine aminotransferase \>1.5 x upper limit of normal (ULN) (one repeat allowed);
* Estimated glomerular filtration rate \<60 mL/min;
* Creatine kinase \>3 x ULN (one repeat allowed);
* History of biliary diversion;
* Positive for human immunodeficiency virus infection;
* History of malignant hypertension;
* Systolic blood pressure \>160 mmHg or diastolic blood pressure \>100 mmHg at screening or randomization and confirmed at an unscheduled visit;
* Triglycerides \>5.7 mmol/L (500 mg/dL) at screening and confirmed by repeat assessment;
* Active, serious medical disease with likely life expectancy \<2 years;
* Active substance abuse, including inhaled or injection drugs within the year prior to screening;
* Participation in an investigational new drug trial within the 30 days prior to randomization; or
* Any other condition which, in the opinion of the Investigator, would impede compliance, hinder completion of the study, or compromise the well-being of the participants.
