Prevalence of DNA-confirmed familial hypercholesterolaemia in young patients with myocardial infarction ★

• DNA testing service shows that 1.3% of young heart attack patients have FH.
• 77 patients aged 50 or less with a heart attack need testing to identify one new case of FH.
• 2/3 of patients aged 50 or less with heart attack are smokers or diabetics.
• More action is needed to control endemic risk factors in the young.

PurposeTo report the prevalence of DNA-confirmed Familial Hypercholesterolaemia (FH) in young patients with acute myocardial infarction, the relative contribution of smoking and diabetes and to compare these rates with those in the general population.MethodsA pilot clinical service was established to diagnose FH in young patients (≤ 50 years) with myocardial infarction at a London hospital. Over 23 months, 231 such patients, underwent testing for 48 common FH-mutations and whole exon LDLR gene deletions and duplications. Patients with total cholesterol levels ≥ 7.0 mmol/L, additionally, underwent full sequencing of the LDLR gene. Smoking and diabetes history were recorded. The prevalence of FH, smoking and diabetes were determined and compared with the prevalence in age and sex matched controls from published surveys.ResultsThe prevalence of DNA-confirmed FH was 1.3% (95% confidence interval 0.3%–3.8%) compared with 0.2% (0.17%–0.23%) in the general population (p = 0.012). Observed prevalence rates for smoking and diabetes were 57% (50.3%–63.6%) and 13.4% (9.2%–18.6%) respectively in patients, compared with expected rates of 25% (23.9%–26.2%) and 4.6% (4.1%–5.2%) in the general population (p < 0.001 for both comparisons).ConclusionFH is an important cause of premature myocardial infarction but it accounts for only a small proportion of all such events. The endemic risk factors, smoking and diabetes, far exceed FH in patients with acute myocardial infarction aged 50 or less. Consideration should be given to extending the use of statins and blood pressure drugs to a younger group of smokers and diabetics, who are excluded from treatment by conventional prevention strategies.