The optimal dosage and duration of administration of clot-dissolving medications for the treatment of patients with mechanical heart valves with clots is not known. We hypothesized that a large dose of the clot-dissolving medicine given initially (akin to the dose given in the treatment of heart attacks), might speed up the dissolution of the clot and rapidly restore the functioning of the mechanical heart valve.

The optimal fibrinolytic strategy for left sided prosthetic valve thrombosis (PVT) is not known. A large initial bolus dose of streptokinase (SK) might accelerate fibrinolysis and restore valve function more rapidly.

This is a prospective, randomized trial comparing 2 fibrinolytic protocols in a first episode of PVT. In the rapid fibrinolytic protocol (RFP) 1.5 MU of SK is given over 1 hour, followed if required by a 0.1 MU/h infusion. In the standard protocol (SP) 0.25 MU is given over 30 minutes, followed by an infusion of 0.1 MU/h. Serial echocardiography and fluoroscopy will be done to monitor therapy. The primary end point is the occurrence of a complete clinical response (CCR, complete hemodynamic response without any major complication). 58 patients are required in each arm for detecting a 30% difference with 80% power at α=0.05.

Inclusion Criteria:

• First episode of left sided prosthetic valve thrombosis

Exclusion Criteria:

• Contraindication to thrombolysis
• Refusal to give informed consent
• Pregnant women
• age less than 12 years or more than 70 years
• previous treatment for prosthetic valve thrombosis