Elevated Lipoprotein(a) and Risk of Ischemic Stroke

This large Copenhagen study extended lipoprotein(a)’s causal reach to ischemic stroke, using both observational data and Mendelian randomization to test whether elevated Lp(a) drives cerebrovascular as well as coronary events.

In nearly 50,000 participants, those with Lp(a) above the 96th percentile had 60 percent higher ischemic stroke risk compared to those with the lowest levels (HR 1.60, 95% CI 1.24–2.05). The observational estimate was concordant with genetic estimates from two Mendelian randomization instruments — the usual signature of causation. Cumulative stroke incidence by age 80 reached 14 percent in those with very high Lp(a) versus 8.6 percent in those with low levels.

The magnitude of the stroke association, however, was notably smaller than Lp(a)’s effect on myocardial infarction or aortic stenosis. Ischemic stroke is mechanistically heterogeneous — embolic, lacunar, and large-vessel subtypes differ substantially in their lipid sensitivity — and this heterogeneity may dilute the overall Lp(a) signal when all stroke subtypes are pooled together.

We rate the evidence strong. A large, well-conducted study adding ischemic stroke to Lp(a)’s expanding list of causal cardiovascular targets, though with a more modest effect size than the better-established coronary and valvular associations.