It is well-recognized that patients with
congestive heart failure are at an increased risk of
stroke and
venous thromboembolism. Nevertheless,
stroke,
thromboembolism and
myocardial infarction have generally been regarded to be end points of secondary importance in large
heart failure trials, when compared with mortality or
hospital readmissions. It may well have been that the incidence of thrombotic events are underestimated. The problem of
thrombus formation (thrombogenesis) in
heart failure may therefore be a much more significant problem than is currently recognized. The pathophysiology of thrombogenesis in
heart failure could well be explained in the context of Virchow's original triad. In addition to "abnormal flow" through
low cardiac output, dilated cardiac chambers and poor contractility, patients with
heart failure also demonstrate abnormalities of hemostasis and platelets (that is "abnormal blood constituents") and endothelial dysfunction ("vessel wall abnormalities"). These abnormalities contribute to a prothrombotic or hypercoagulable state, which increases the risk of
thrombosis in
heart failure and impaired left ventricular systolic function. Some observational data are available on the role of
anticoagulants in
heart failure, and there is sound evidence to support the use of antithrombotic
therapy in patients with
heart failure and
atrial fibrillation. However, there are no large-scale prospective randomized controlled trials of antithrombotic
therapy in patients with
heart failure who remain in sinus rhythm, although important studies are in progress. Although the results of these studies are awaited, measurement of suitable markers of thrombogenesis might prove to be valuable in identifying "high risk" patients and in determining the nature, duration and intensity of such treatment. Further information is also needed on the predictive value of various markers of
hypercoagulability in patients with
heart failure, the association between
hemostatic variables and the severity of
heart failure, and the effects of different treatments.