Left atrial thrombosis following mitral valve repair and maze procedure: case report

The case is described of a 71-year-old woman with left atrial thrombosis after successful mitral valve repair and a Kosakai-maze procedure. At three months after surgery, electrocardiography showed a normal sinus rhythm, but echocardiography revealed a mural thrombus on the posterior wall of the left atrium. During those three months, the anticoagulation level (thrombotest index range: 29-41%) was lower than target level. Anticoagulant therapy with heparin plus warfarin failed to reduce the thrombus size. Anticardiolipin antibodies were positive, and lupus anticoagulants negative. A Doppler study of the mitral valve indicated peak velocity 1.48 m/s, mean pressure gradient 4.5 mmHg, and valve area 2.1 cm2. During reoperation, an old spherical thrombus (weight 38 g) which was firmly adhered to the posterior wall and included an incision line of the Kosakai-maze procedure, was identified and totally removed. After reoperation, the patient received warfarin and an antiplatelet agent to maintain the INR at 2.5-3.5. Echocardiography performed at 11 months postoperatively revealed no thrombus formation on the left atrium.