Mechanical cardiac valve thrombosis. Is fibrinolysis justified?

Thrombosis is a serious complication of heart valve replacement, and management is often difficult. In recent years, thrombolytic therapy has been used as the primary technique by some investigators.

Sixty-four consecutive patients presenting with 75 instances of prosthetic heart valve thrombosis (41 mitral, 33 aortic, one tricuspid) were treated with fibrinolytic agents. Obstructed prosthetic valves comprised 39 tilting disc and 36 bileaflet valves. The time interval between valve replacement and obstruction ranged from 15 days to 192 months (mean, 38 months). Fibrinolytic agents used were streptokinase (42 patients), urokinase (27 patients), or recombinant tissue-type plasminogen activator (six patients). Immediate results of fibrinolytic treatment were 1) full success after one or several consecutive fibrinolytic regimens in 55 cases (73%), 2) incomplete improvement in two cases, and 3) failure in 18 cases, leading to an emergency surgery in nine cases. Nine patients died (four strokes, four cardiac arrests, one hemorrhage). Only one severe hemorrhagic complication was observed, but 11 cases of embolism occurred during fibrinolytic treatment (14.6%) (four major cerebral embolisms with death). The immediate efficacy was better for thrombosed aortic prosthesis than with the mitral prosthesis (85% versus 63%).

Fibrinolytic treatment appears to be an attractive nonsurgical alternative for prosthetic heart valve thrombosis, but because of the risk of cerebral embolism, its use should be reserved for tricuspid valve thrombosis or critically ill patients with mitral or aortic valve thrombosis. The use of a fibrinolytic agent in cases of small, nonobstructive paravalvular thrombosis demonstrated with transesophageal echocardiography needs further studies.