Relationship of Familial Hypercholesterolemia and High LDL Cholesterol to Ischemic Stroke: The Copenhagen General Population Study
Background—Familial hypercholesterolemia(FH) is a condition with very high concentrations of low-density lipoprotein(LDL) cholesterol and high risk of ischemic heart disease including myocardial infarction. However, there is limited and contradictory information on whether FH and high LDL cholesterol per se confer high risk of ischemic stroke. We tested the hypotheses that individuals in the general population with FH and/or high LDL cholesterol have higher risk of ischemic stroke.
Methods—The associations of FH and high LDL cholesterol with ischemic stroke risk were tested in both causal, genetic and observational analyses using 106,412 individuals from the Copenhagen General Population Study(CGPS; 2823 ischemic strokes and 3,792 myocardial infarctions) and/or 10,372 individuals from the Copenhagen City heart Study(CCHS; 945 ischemic strokes and 1,142 myocardial infarctions). FH causative mutations were LDLR W23X(rs267607213), W66G(rs121908025), and W556S, and APOB R3500Q(rs5742904). A Mendelian randomization design tested whether high LDL cholesterol per se has a causal effect on ischemic stroke risk, using a combination of the FH causative mutations and common genetic variants associated with high LDL cholesterol.
Results—The cumulative incidences in individuals in the CGPS with and without FH causative mutations were similar for ischemic stroke(P=0.50) but not for myocardial infarction(P<0.001): at age 80, 4% and 7% of these individuals developed ischemic stroke and 20% and 8% myocardial infarction, with similar results in the CCHS. There was no association between clinical FH and ischemic stroke, except if personal premature ischemic heart disease was included in the clinical FH criteria. Ischemic heart disease at baseline was associated with higher ischemic stroke risk, explaining the higher ischemic stroke risk in those with high LDL cholesterol. For a 1mmol/L higher LDL cholesterol the genetic causal risk ratio was 1.11(0.62-2.02) for ischemic stroke and 1.45(1.08-1.93) for myocardial infarction.
Conclusions—FH and high LDL cholesterol did not confer an increased risk of ischemic stroke. A positive association with ischemic stroke observed for some clinical FH criteria and high LDL cholesterol appears to be due by previous ischemic heart disease, rather than by high LDL cholesterol per se.
- low-density lipoprotein
- familial hypercholesterolemia
- Cardiovascular Disease
- Lipids and Cholesterol
- Received January 3, 2018.
- Revision received February 17, 2018.
- Accepted March 14, 2018.