The endothelium and thrombotic risk in heart failure

Thromb Haemost 2009; 102: 185–187 Chronic heart failure (HF) is increasingly recognised as a syndrome which confers a considerable prothrombotic risk. Whilst the annual incidence of venous thromboembolism is about 0.1% in general population, prospective observational studies have shown that thromboembolic events would occur in 1.7–2.7% of patients with HF each year (1). Indeed, a retrospective analysis of the Studies of Left Ventricular Dysfunction (SOLVD) trials reported that the annual incidence of thrombotic events (including strokes, pulmonary emboli and peripheral emboli) in patients with ventricular dysfunction and sinus rhythm was 1.8% in men and 2.4% in women (2). Furthermore, patients with HF generally suffer more severe strokes that are associated with high mortality rate (3). However, even this high prevalence of thromboembolic events may just represent the tip of the iceberg. Indeed, more than 30% of patients with HF, irrespective of its aetiology, may experience ‘silent’ asymptomatic thromboembolic strokes detected by brain magnetic resonance imaging (4). In addition to the risk of venous thromboembolism, patients with HF also have a high (and often underestimated) risk of arterial thrombosis. The risk of sudden cardiac death, often attributable to acute arterial thrombosis, is 6– to 9-fold higher in those with HF compared to the general population (5). In the Assessment of Treatment with Lisinopril and Survival (ATLAS) study, fresh coronary thrombus was found in more than 30% of such sudden death cases (6). Both acute myocardial infarction and unstable angina are independent risk factors for death in patients with congestive HF (7). Why does HF confer a prothrombotic state? HF is associated with abnormalities of flow (low cardiac output, impairment of intracardiac haemodynamics, dilated cardiac chambers, stasis of blood in peripheral vascular beds, etc), vessel wall (endothelial damage/ dysfunction), and abnormalities of blood constituents (abnormalities of platelets and haemorrheology). Thus HF fulfils all of Virchow's triad of characteristics of a prothrombotic state, which promote the risk of thrombosis and unsurprisingly, the risk of thromboembolic complications rises accordingly the degree of left ventricular contractility impairment (2). Given that endothelial dysfunction is commonly seen in HF pathophysiology, the contribution of the endothelium to thrombosis may be especially important in patients with HF. Endothelium and thrombogenic alterations in heart failure