Reteplase Thrombolysis for Treatment of Mechanical Valve Thrombosis

Thrombolytic therapy and surgery are 2 approaches to the treatment of mechanical valve thrombosis (MVT). Because surgery is an invasive and very costly procedure, noninvasive thrombolytic therapy may be a practical and effective treatment option for MVT.1 We report the case of a 46-year-old woman who developed thrombosis of a 33 mm Carbomedics mechanical mitral valve prosthesis (Sulzer Carbomedics, Austin, Texas) implanted because of severe mitral insufficiency secondary to mitral valve prolapse. She had been prescribed warfarin for long-term anticoagulation. Fifteen months post-operatively, the patient presented with increasing dyspnea. A chest x-ray revealed pulmonary edema consistent with congestive heart failure. Upon admission, sinus bradycardia with a first-degree atrioventricular block was present; acute myocardial infarction was excluded. An echocardiogram revealed severe mitral regurgitation with a dilated left atrium; the left ventricular ejection fraction was moderately reduced at 35%. The international normalized ratio (INR) was 1.7. Warfarin was discontinued and heparin was administered. Cardiac catheterization demonstrated a frozen posterior mechanical leaflet with slightly reduced excursion of the anterior leaflet (Fig. 1). MVT due to subtherapeutic anticoagulation was considered the likely cause of the valvular dysfunction. Because the patient was clinically stable, we elected to treat with thrombolytic therapy using 10 units of reteplase intravenously over 2 minutes with a repeat dose of 10 units administered 30 minutes later. Reteplase was considered a rational therapeutic option because of its rapid thrombolytic activity, convenience of bolus dosing requiring no adjustment for body weight, efficacy in acute myocardial infarction, and good overall safety profile.2 Following administration of reteplase, the auscultatory findings improved within 12 hours. Follow-up cinefluoroscopy 6 days after admission demonstrated normal function of the prosthetic valve, with both leaflets having free excursion (Fig. 2). The patient was gradually converted to anticoagulation with warfarin, and was discharged 15 days after admission with an INR of 3.1, receiving 10 mg of warfarin and 325 mg of aspirin once daily. Reteplase and other thrombolytic agents are not currently approved for the treatment of MVT. However, in selected patients with a clearly defined episode of subtherapeutic anticoagulation, treatment of MVT with reteplase may be effective and safe.

1. Silber H, Khan SS, Matloff JM, et al. The St. Jude valve. Thrombolysis as the first line of therapy for cardiac valve thrombosis. Circulation 1993;87:30–37. 2. Smalling RW, Bode C, Kalbfleisch J, et al. More rapid, complete and stable coronary thrombolysis with bolus administration of reteplase compared with alteplase infusion in acute myocardial infarction. RAPID Investigators. Circulation 1995;91:2725–2732.