Asymptomatic Intracranial Artery Stenosis/Occlusion in Heterozygous Familial Hypercholesterolemia: Its Frequency and Implications for Cerebrovascular and Cardiovascular Events.

Background: The atherogenic characteristics of heterozygous familial hypercholesterolemia (HeFH) increase the risk of premature atherosclerotic cardiovascular disease including not only coronary artery disease but ischemic stroke. Asymptomatic intracranial artery stenosis/occlusion (IASO) is a major cause of ischemic stroke, but it has not yet been fully characterized in patients with HeFH.

Methods And Results: This study analyzed 147 clinically diagnosed subjects with HeFH who underwent magnetic resonance imaging/magnetic resonance angiography imaging for evaluation of IASO (≥50% diameter stenosis). Major adverse cerebrovascular and cardiovascular events (cardiac death, ischemic stroke, and acute coronary syndrome) were compared in patients with HeFH with and without asymptomatic IASO. Asymptomatic IASO was observed in 13.6% of patients with HeFH. The untreated low-density lipoprotein cholesterol level (240±95 versus 244±75 mg/dL; =0.67) did not differ between the 2 groups. Despite the use of lipid-lowering therapies (statin, =0.71; high-intensity statin, =0.81; ezetimibe, =0.33; proprotein convertase subxilisin/kexin type 9 inhibitor, =0.39; low-density lipoprotein apheresis, =0.14), on-treatment low-density lipoprotein cholesterol level in patients with both HeFH and IASO was still suboptimally controlled (97±62 versus 105±50 mg/dL; =0.17), accompanied by a higher triglyceride level (median, 109 versus 79 mg/dL; =0.001). During the 12.4-year observational period (interquartile range, 6.2-24.6 years), asymptomatic IASO exhibited a 4.04-fold greater likelihood of experiencing a major adverse cardiovascular event (95% CI, 1.71-9.55; =0.001) in patients with HeFH. This increased risk of a major adverse cardiovascular event was consistently observed in a multivariate Cox proportional hazards model adjusting clinical characteristics (hazard ratio, 4.32 [95% CI, 1.71-10.9]; =0.002).

Conclusions: A total of 13.6% of Japanese subjects with HeFH presented with asymptomatic IASO. Despite lipid-lowering therapies, patients with both HeFH and IASO more likely had elevated risk of cerebrovascular and cardiovascular events. Our findings highlight asymptomatic IASO as a phenotypic feature of HeFH-related atherosclerosis, which ultimately affects future outcomes.