Blood coagulation in patients with chronic heart failure - Evidence for hypercoagulable state and potential for pharmacological intervention

Incidence data on thromboembolism in patients with heart failure (which may include stroke, peripheral embolism, pulmonary embolism) are limited but provide a general population range from 1-5 cases per 1000 each year, increasing with age to more than 30 cases per 1000 each year among people aged 75 years or older. However, the incidence of thromboembolism varied depending very much on what was being investigated in each of these studies. Data from subgroup analysis of the larger heart failure trials would seem to support this incidence data, although there is very little true epidemiological data and no randomised, controlled trial has been designed to specifically investigate thromboembolism in patients with heart failure. The pathophysiology of heart failure is complex. There are many well recognised factors which are associated with thrombosis in heart failure patients, such as vascular abnormalities, increased coagulability and impaired blood flow. In the past 50 years many studies have been performed to investigate if oral anticoagulation is of benefit for the prevention of thromboembolism in patients with heart failure. The use of warfarin therapy for heart failure patients has been a controversial subject. Warfarin does have a role to play in patients with myocardial infarction and those with atrial fibrillation. Furthermore, in patients with congestive heart failure secondary to coronary artery disease, warfarin reduces the occurrence of nonfatal myocardial infarction and, therefore, may reduce the chances of progression to heart failure. It has also been shown that warfarin reduces the risk of thromboembolic strokes in patients recovering from myocardial infarction. At present, there is a lack of randomised data, and the incidence of bleeding complications in patients with heart failure has caused a decrease in the use of oral anticoagulants for the prevention of thrombosis. This review summarises the incidence, potential mechanism and therapeutic approaches for management of thromboembolism in heart failure.