Risk Of Heart Attack And Stroke Much Higher For Patients With Venous Thromboembolism

Main Category: Cardiovascular / Cardiology
Also Included In: Vascular;  Stroke
Article Date: 24 Nov 2007 - 0:00 PST

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Patients with venous thromboembolism (VTE) have a substantially increased long-term risk of subsequent arterial cardiovascular events, such as heart attack and stroke. These are the conclusions of authors of an Article published in this week's edition of The Lancet.

Professor Henrik Sørensen, Department of Clinical Epidemiology, Aarhus University Hospital, Denmark, and colleagues did a 20-year population-based cohort study using data from nationwide Danish medical databases. After excluding patients with known cardiovascular disease, the researchers assessed the risk of heart attack and stroke in 25 199 patients with deep venous thrombosis, 16 925 patients with pulmonary embolism, and 163 566 population controls.

They found that for patients with deep vein thrombosis, the relative risk of heart attack was 60% higher than controls in the first year after the thrombotic event, and that of stroke was 119% higher than controls. For patients with pulmonary embolism, the relative risk of heart attack was over two-and-a-half times higher than controls, and for stroke was nearly three times higher than controls in the first year after the thrombotic event. Further, over the 20-years of complete follow-up, the combined increased risk for arterial cardiovascular events was between 20% and 40% higher, with these risks similar for those with both provoked* and unprovoked* deep venous thrombosis and pulmonary embolism.

The authors say the study shows that the increased relative risk of cardiovascular disease in patients with VTE is comparable to that of other conventional risk factors for arterial cardiovascular events, such as diabetes and smoking - at least during the first year of follow-up. However, they add the value of preventive measures against heart attack and stroke in VTE patients is uncertain, and that trials are ongoing to establish this, for example the effect of aspirin on long-term treatment of VTE.

They conclude: "We find strong evidence that venous thromboembolism is associated with an increased long-term risk of arterial cardiovascular events, irrespective of the presence or absence of classic risk factors for venous thromboembolism. Common risk factors or pathways are most likely responsible for this association. Future studies are needed to further clarify the association, and to evaluate its implications for clinical practice."

In an accompanying Comment, Professor Gordon Lowe, University of Glasgow, Royal Infirmary, Glasgow, UK, says: "Further epidemiological studies (especially prospective studies) and systematic reviews are needed to establish the magnitude, duration, and possible causes of increased risk of myocardial infarction and stroke after diagnosis of venous thromboembolism. Meanwhile, what are the implications for management? An assessment of absolute risk of myocardial infarction or stroke should be done, as has been recommended for all people aged 40 years and older (most patients with an episode of venous thromboembolism are older than 40 years), followed by appropriate lifestyle advice and consideration of drugs that lower cardiovascular risk."

*Provoked VTE cases are those with an obvious risk factor, eg. pregnancy, surgery, other predisposing conditions, whereas unprovoked VTE cases do not have an obvious risk factor associated with them.

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