Late dysfunction of a mechanical aortic valve after long-term low molecular weight heparin therapy: a case report

To date, vitamin K anticoagulants are the only recommended long-term therapy for mechanical heart valves. Bleeding episodes, thromboembolic events, and international normalized ratio monitoring are difficult and prevalent complications for these patients. This report reflects the late mechanical aortic valve dysfunction after long-term low molecular weight heparin therapy.

A 66-year-old male patient underwent mechanical aortic valve replacement in 2007. He was administered therapeutic doses of enoxaparin for nearly 12 years due to warfarin-related bleeding complications and labile international normalized ratios. However, he experienced multiple cardiovascular and cerebrovascular thromboembolic events, including an anterolateral ST-elevation myocardial infarction with left anterior descending artery thrombus, treated with thrombus aspiration and stenting. The patient was eventually admitted with symptoms and signs of acute heart failure, and echocardiography, fluoroscopy, and a cardiac computed tomography detected mechanical aortic valve prosthesis dysfunction, with an immobile leaflet and pannus. The patient demonstrated no improvement despite switching to unfractionated heparin, and he ultimately underwent redo aortic bioprosthetic valve surgery with a favourable outcome.

Low molecular weight heparin is prescribed for patients with aortic mechanical valves who are intolerant to vitamin K antagonists or as bridging in certain situations. Anti-Xa factor monitoring should be considered for long-term prescriptions.