A Case of Acute Myocardial Infarction after Thrombolytic Therapy for Mechanical Valve Dysfunction in the Late Postoperative Phase / 日本心臓血管外科学会雑誌

ABSTRACT

The patient was a 65-year-old man who had undergone AVR (SJM Regent 19 mm) for AR in June 2007. Since March 2008 there had been an increase in the pressure gradient between the aorta and the left ventricle on transthoracic echocardiography (peak PG 46 mmHg, mean PG 27 mm Hg). Plain x-ray films of the valve showed limited opening of the metallic valve. However, no symptoms of heart failure were observed on a physical examination. Blood tests performed in December 2007 showed a PT-INR value of 1.22. Since the effects of warfarin anticoagulant therapy were insufficient, its dose was adjusted on follow-up. An examination in June revealed further stenosis of the valve (peak PG 93 mmHg, mean PG 58 mmHg). Valve thrombosis was suspected because the condition was poorly controlled by warfarin. Thus, thrombolytic therapy using t-PA was performed (800,000 units). However, the patient complained of chest pain 1 h 30 min after initiation of thrombolytic therapy. Twelve-lead electrocardiography was performed, and ST-segment elevations were observed in the limb and chest leads. Acute myocardial infarction due to a free-floating thrombus was suspected, and emergency cardiac catheterization was performed. Segment 7 was totally occluded, and reperfusion was achieved by thrombus aspiration. Embolization of the coronary artery was speculated to have occurred because of the improved mobility of the metallic valve and dissolution of a thrombus adhering to the valve. A case of acute myocardial infarction as a complication of thrombolytic therapy for valve thrombosis is rare. This case reaffirms the necessity of careful monitoring during thrombolytic therapy.