Venous thromboembolism and subsequent hospitalisation due to acute arterial cardiovascular events: a 20-year cohort study.

BACKGROUND In some studies, venous thromboembolism has been associated with atherosclerosis and with the risk of arterial cardiovascular events such as myocardial infarction and stroke. Other studies, however, do not show this association. To help clarify these discrepant findings, we aimed to investigate the risk of arterial cardiovascular events in patients who were diagnosed with venous thromboembolism. METHODS We undertook a 20-year population-based cohort study using data from nationwide Danish medical databases. After excluding those with known cardiovascular disease, we assessed the risk of myocardial infarction and stroke in 25,199 patients with deep venous thrombosis, 16,925 patients with pulmonary embolism, and 163,566 population controls. FINDINGS For patients with deep venous thrombosis, the relative risks varied from 1.60 for myocardial infarction (95% CI 1.35-1.91) to 2.19 (1.85-2.60) for stroke in the first year after the thrombotic event. For patients with pulmonary embolism, the relative risks in that year were 2.60 (2.14-3.14) for myocardial infarction and 2.93 (2.34-3.66) for stroke. The relative risks were also raised, though less markedly, during the subsequent 20 years of follow-up, with 20-40% increases in risk for arterial cardiovascular events. Relative risks were similar for those with provoked and unprovoked deep venous thrombosis and pulmonary embolism. INTERPRETATION Patients with venous thromboembolism have a substantially increased long-term risk of subsequent arterial cardiovascular events.