Does dilated cardiomyopathy cause thromboembolism?

From the Guidelines

Dilated cardiomyopathy is a significant risk factor for thromboembolism, particularly in patients with severe left ventricular dysfunction, as evidenced by studies showing an inverse proportional relationship between ejection fraction (EF) and the incidence of stroke 1.

Pathophysiology and Risk Factors

In dilated cardiomyopathy, the weakened heart muscle and enlarged heart chambers create a condition of relative stasis, activating coagulation processes and increasing the risk of thromboembolic events. The cause of cardiomyopathy, whether ischemic or nonischemic, contributes to this risk. Key factors that increase the risk of thromboembolism in these patients include:

• Severe left ventricular dysfunction, with an EF below 35% 1
• Atrial fibrillation, although not directly mentioned in the context of dilated cardiomyopathy in the provided evidence, is a well-known risk factor for thromboembolism in other contexts
• Visible thrombi on cardiac imaging

Prevention and Management

The management of thromboembolism risk in patients with dilated cardiomyopathy involves anticoagulation therapy. However, the evidence regarding the efficacy of anticoagulation in preventing thromboembolic events in these patients is not conclusive. Studies such as the Warfarin/Aspirin Study in Heart Failure (WASH) and the Warfarin and Antiplatelet Therapy in Chronic Heart Failure Trial (WATCH) have shown mixed results 1.

• Warfarin has been associated with a reduced risk of stroke in some studies, particularly in patients with myocardial infarction 1
• Aspirin also reduces the stroke rate, although to a lesser extent than warfarin 1
• The decision to anticoagulate should be individualized, considering the patient's specific risk factors for thromboembolism and bleeding 1

Clinical Implications

Given the potential for dilated cardiomyopathy to cause thromboembolism, it is crucial to assess each patient's risk factors and consider anticoagulation therapy to prevent thrombus formation and subsequent embolism. This approach should be balanced against the risk of bleeding, and the choice of anticoagulant should be based on the patient's overall clinical profile. Regular monitoring and adjustment of anticoagulation therapy as needed are essential to minimize risks and maximize benefits.

From the Research

Relationship Between Dilated Cardiomyopathy and Thromboembolism

• Dilated cardiomyopathy is associated with a significant increase in the risk of thromboembolism, with an estimated incidence of 2.0-2.5 events per 100 patients per year 2.
• The prevalence of intracardiac thrombi in patients with dilated cardiomyopathy is high, with 20 to 25% for interatrial thrombi and 50% for intraventricular thrombi 3.
• Left atrial thrombosis or spontaneous contrast is more common in atrial fibrillation, when the LA diameter is increased with low velocity intra-left atrial blood flow on Doppler examination and when there are disturbances of haemorrheological factors (increased fibrinogen levels and plasma viscosity) 3.

Risk Factors for Thromboembolism in Dilated Cardiomyopathy

• Ventricular thrombi are more common when the fractional shortening is decreased (< 11% = 80% of thrombi) 3.
• Women with left ventricular ejection fraction < 25% are at higher risk of thromboembolism and anticoagulation is strongly indicated for them 2.
• Patients with intraventricular thrombi present a difficult therapeutic challenge, and anticoagulant treatment may not significantly decrease the risk of embolization, particularly in patients with flat thrombus 2.

Treatment and Prevention of Thromboembolism in Dilated Cardiomyopathy

• Anticoagulant treatment is mandatory for patients with heart failure and atrial fibrillation, with a target International Normalized Ratio between 2.0 and 3.0 2.
• Oral anticoagulant therapy may be safely given to subgroups of patients with dilated cardiomyopathy at risk of embolic episodes, following empirical guidelines, and with careful clinical and laboratory monitoring 4.
• Direct oral anticoagulants (DOACs) were comparable to warfarin in thrombus resolution and safety profile in patients with dilated cardiomyopathy and left ventricular thrombus 5.