Carotid atherosclerosis predicts future myocardial infarction but not venous thromboembolism: The Tromsø Study

Objective: Recent studies have suggested that arterial and venous thrombosis share common risk factors. Although carotid atherosclerosis is associated with arterial cardiovascular events, its role in venous thromboembolic disease is unclear. We wanted to investigate and compare the effect of carotid atherosclerosis on the risk of myocardial infarction (MI) and venous thromboembolism (VTE) in a general population, taking into account competing risks. Approach and Results: Mean intima-media thickness and total plaque area in the right carotid artery were measured with ultrasound in 6257 people aged 25 to 84 years who participated in a population-based health study, the Tromsø Study, from 1994 to 1995. Incident MI and VTE events were registered from date of enrollment to end of follow-up on December 31, 2010. Cox proportional hazards regression models using age as time scale were used to estimate cause-specific hazard ratios with 95% confidence intervals for MI and VTE by increasing levels of intima-media thickness and total plaque area. There were 894 incident MI cases and 256 VTE events during a median of 15.4 years of follow-up. The risk of MI increased significantly across quartiles of mean intima-media thickness (P for trend < 0.001) and with increasing total plaque area (P for trend < 0.001), but neither intima-media thickness (P for trend=0.94) nor total plaque area (P for trend=0.45) was associated with VTE risk in multivariable-adjusted analysis. Conclusions: In this study, carotid atherosclerosis was strongly associated with future MI but not with VTE. Our findings suggest that carotid atherosclerosis does not represent a link between arterial and venous thrombosis.