Abstract 10647: Common Familial Effects on Ischemic Stroke and Myocardial Infarction: A Swedish National Cohort Study

Abstract

Introduction: Recent genome-wide association analyses suggest some overlap of genetic determinants of ischemic stroke (IS) and myocardial infarction (MI). This study aimed to assess shared familial risk between IS and MI in a large population-wide cohort study.

Methods: Study participants free of IS and MI were identified through linkage with their affected siblings extracted from the Swedish Hospital Discharge and Cause of Death Registers between 1987 and 2007, forming an exposed sib-pair. The Swedish Multi-Generation Register was used to match each exposed sib-pair, by birth year of both siblings and calendar period, to up to five unexposed sib-pair. Stratified Cox regression analyses were used to assess familial risk of incident MI and IS in those exposed to having a sibling with IS and MI, respectively, compared to unexposed.

Results: A total of 31,659 exposed and 143,728 unexposed to siblings with IS, and a total of 62,766 exposed and 265,974 unexposed to siblings with MI were included in the analyses. The overall risk of incident MI when exposed to having a sibling with IS was significantly increased (RR, 1.44; 95% CI, 1.34-1.55, p<0.001) to a similar extent to risk of incident IS when exposed to having a sibling with MI (RR, 1.41; 95% CI, 1.32-1.50, p<0.001). The familial risks were higher among full siblings in both groups (RR for MI, 1.46; 95% CI, 1.35-1.58, p<0.001; and RR for IS, 1.40; 95% CI, 1.30-1.40, p<0.001) compared to half siblings (RR for MI, 1.29; 95% CI, 1.05-1.59, p<0.001; and RR for IS, 1.38; 95% CI, 1.16-1.65, p<0.001).

Conclusion: Our large, population-wide study indicates that there is a considerable overlap of familial risk between ischemic stroke and myocardial infarction. The sources of this overlap should be evaluated using other study designs.