Valvar heart disease and prosthetic heart valves

Assessment

Risk factors that increase the incidence of systemic embolism must be considered when defining the need for starting antithrombotic therapy in patients with cardiac valvar disease and prosthetic heart valves. These factors include age, smoking, hypertension, diabetes, hyperlipidaemia, type and severity of valve lesion, presence of atrial fibrillation, heart failure or low cardiac output, size of the left atrium (over 50 mm on echocardiography), previous thromboembolism, and abnormalities of the coagulation system including hepatic failure.

Secondly, the type, number, and location of prostheses implanted must be considered. For example, mechanical prostheses are more thrombogenic than bioprostheses or homografts, and hence patients with mechanical valves require lifelong anticoagulant therapy. However, the intensity of treatment varies according to the type of mechanical prosthesis implanted. First generation mechanical valves, namely the Starr-Edwards caged ball valve and Bjork-Shiley standard valves, have a high thromboembolic risk; single tilting disc valves have an intermediate thromboembolic risk; and the newer (second and third generation) bileaflet valves have low thromboembolic risks.

In patients with a bioprosthesis in sinus rhythm, antithrombotic therapy with an …