Incidence of arterial cardiovascular events in patients with idiopathic venous thromboembolism. A retrospective cohort study.

Recent data have shown a higher incidence of arterial events in patients with venous thromboembolism (VTE) of unknown origin than in those with the secondary form of disease. Whether patients with idiopathic VTE have a higher risk of subsequent arterial events than the general population is unknown. The aim was to evaluate the rates of subsequent arterial events in patients with idiopathic VTE and control subjects. In a retrospective cohort study we compared the rates of subsequent arterial events (i.e. acute myocardial infarction, ischemic stroke and peripheral arterial disease) in 151 consecutive patients with objectively confirmed spontaneous VTE and 151 control subjects randomly selected from the database of two family physicians. We collected information about cardiovascular risk-factors (hypertension, hypercholesterolemia, diabetes, obesity and smoke) at the time of VTE episode, or corresponding date for the controls, and considered the follow-up from this time. Patients and controls who had suffered from arterial events before the index date were excluded. During a mean follow-up of 43.1 (+/- 21.7) months there were 16 arterial events in the VTE patients and six in the control group (HR, 2.84;95% CI,1.11 to 7.27; p = 0.03). The difference remained significant after adjusting for age and other cardiovascular risk factors (HR 2.86;95% CI,1.07 to 7.62). Overall mortality was also higher in the VTE patients (12 vs.4 deaths). In conclusion, arterial events are more common in patients with previous idiopathic VTE than in the general population. These findings may have practical implications.