Bidirectional association between arterial and venous thrombosis

Abstract

Venous thromboembolism (VTE), a collective term for deep vein thrombosis (DVT) and pulmonary embolism (PE), has been considered a separate disease from arterial cardiovascular diseases (CVD, i.e. myocardial infarction (MI) and ischemic stroke). However, recent studies have proposed an association between VTE and arterial CVD. The aim of the thesis was to investigate this association in a general population. Papers I-III are prospective cohorts with participants from general populations (i.e. the Tromsø Study (papers I-III) and the Diet, Cancer and Health Study (paper II)). Paper IV is a matched cohort with participants attending ≥ 2 carotid ultrasounds in the Tromsø Study. Incident MI was associated with a transient increase in VTE risk, and a particularly high risk was found for PE during the first 6 months after MI. MI explained 6% of the PE events in the population. Incident VTE was associated with increased risk of future arterial CVD in all women and men < 65 years of age, and explained 1% of the arterial thrombotic events in the population. The risk of arterial CVD was particularly high the first year after a PE. Family history of MI (FHMI) was a risk factor for both MI and VTE. The association between FHMI and VTE applied to unprovoked DVT and was neither explained by atherosclerotic risk factors nor MI as an intermediate event. We found that incident VTE was associated with plaque progression in subjects with carotid plaques, but not with novel carotid plaque formation. The possible association between VTE and carotid plaque progression was not mediated by chronic inflammation secondary to the VTE. Based on our findings, there appears to be a bidirectional and transient association between VTE and arterial CVD. Family history of MI is a shared risk factor for VTE and MI, and atherosclerosis may partly mediate the association between VTE and future arterial CVD.