Early myocardial infarction and familial hypercholesterolemia

1. In this retrospective cohort study of adults under age 50 with myocardial infarction, 9% met criteria for definite or probable familial hypercholesterolemia, which is roughly 20x the prevalence in the general American population.

2. Only about two-thirds of patients with familial hypercholesterolemia and myocardial infarction were discharged on high intensity statin therapy.

Evidence Rating Level: 2 (Good)

Study Rundown: Familial Hypercholesterolemia (FH) is an inherited condition that leads to elevated cholesterol levels and premature cardiovascular disease. The existing literature suggests poor rates of statin use for young patients with FH. In this retrospective cohort study of adults under or at age 50 admitted with type-1 myocardial infarction (MI), 9% met criteria for probable/definite FH, which is about 20x the prevalence of the general American population. Less than half of them were on statin therapy prior to MI, and only 2/3 were discharged on high intensity statin therapy as per accepted guidelines. All-cause mortality was 11.4% over median follow up of 11.2 years with no significant difference between FH and non-FH patients. FH patients had higher levels of LDL-C reduction at one year however they still had higher absolute LDL-C levels compared with non-FH patients.

Strengths of this study include the large cohort size, and broad availability of clinical and demographic information. Weaknesses of the study include the retrospective design, and lack of genetic testing information available as part of FH diagnosis.

Click to read the study published in JACC

Relevant Reading: LDL-cholesterol goal achievement, cardiovascular disease, and attributed risk of Lp(a) in a large cohort of predominantly genetically verified familial hypercholesterolemia

In-Depth [retrospective cohort]: This was a retrospective cohort study from two large academic centers in the United States. Inclusion criteria were admission for myocardial infarction (MI) at or before age 50 between 2000 and 2016. Exclusion criteria included any MI not classified as type 1, missing LDL-C, or history of prior coronary arteria disease (prior MI or revascularization). Dutch Lipid Clinic Network Criteria were used to identify patients with probable/definite Familial Hypercholesterolemia (FH). Total sample was 1996 patients. Median follow up was 11.2 years. Outcomes of interest included proportion of patients with probable/definite FH, proportion of patients discharged on any statin or on high-intensity statin therapy, reduction in LDL-C after one year, and survival free from all-cause death and cardiovascular death. Of the cohort, 19.1% of patients were women and 54.2% had an ST-Elevation myocardial infarction. There were 128 patients who met criteria for probable FH (6.4%) and 52 patients for definite FH (2.6%). Seventy-seven of the total 180 patients (42.8%) with probable/definite FH were not on statin therapy prior to their MI. Of the 1,966 patients who survived to discharge, 1,768 (89.9%) were prescribed statins, 978 of whom were on high-intensity statins (55.3%). Ninety percent of patients with FH were discharged on some form of statin therapy, and 63.3% on high-intensity statin therapy. Despite higher rates of statin prescription, patients with FH had higher rates of elevated LDL after 1 year. There were 228 deaths that occurred over the study period (11.4%), of which 104 were from cardiovascular cause (45.6%). There was no difference in all-cause mortality or cardiovascular death between patients with or without FH.

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