Familial hypercholesterolemia (FH) is a common inherited disorder with a frequency of 1 in 500 in the UK. Our aim is compare the carotid and coronary artery atherosclerosis in monogenic FH and polygenic hypercholesterolemia with means of a carotid ultrasound, a coronary CT angiogram and biochemical biomarkers.

Familial hypercholesterolemia (FH) is a common inherited disorder with a frequency of 1 in 500 in the UK. Previous Studies showed that risk of heart attack in these patients is at least 50% higher in men and 30% higher in women compared to the general population as they have high blood cholesterol since birth. We propose to develop a screening model based on non-invasive visualisation of the heart blood vessels (coronary arteries) by CT scan, ultrasound of the neck vessels (carotid arteries) and blood tests to access the extend of cholesterol deposit in the blood vessels in these patients. Participants with confirmed diagnosis of FH would be recruited from FH database registry at Royal Free Hospital. They would have a CT coronary angiogram, an ultrasound of carotid arteries and a blood test. The study is divided into overlapping stages of recruitment and data collection and data analysis. If CT scan shows more than 70% obstruction in their coronary arteries, they would be offered a coronary angiogram and an intracoronary Optical Coherence Tomography for assessment of their blood vessel blockage.

Inclusion Criteria:

• The subjects must give written informed consent to participate in the study, Male and female subjects ≥ 18 years old, documentation of clinical diagnosis of familial Hypercholesterolemia

Exclusion Criteria:

• Estimated GFR <45, pregnant women, Atrial fibrillation or unstable heart rate, Established ischemic heart disease, previous Percutaneous Coronary Investigations (PCI) or Coronary Artery Bypass Surgery (CABG), Known allergy to iodine contrast

50 monogenic FH and 50 polygenic hypercholesterolemia