UNCLOGGING THE ISSUES IN THROMBOLYSIS

While there has been much study of current thrombolytic agents and their usefulness in post-myocardial infarction is clearly established, there are still some questions that need to be addressed, according to Marc Verstraete of the Katholieke Universiteit in Leuven, Belgium. He told those attending a cardiovascular colloquium sponsored by Bristol-Myers Squibb that these questions include which is the most suitable thrombolytic agent, which is the best dosing regimen, which drugs should be used in combination and which are the best adjuvant agents.

The GUSTO trial found that tissue plasminogen activator (Genentech's Activase) was superior to two streptokinase regimens (Marketletter November 28), and that if a double tPA bolus was given, better arterial patency results were obtained. However, the GUSTO trials also showed that even when adjuvant anti-thrombotic treatments were combined with tPA, there was still almost a 6% reocclusion rate. Aspirin is useful, but some of its activity can be counterproductive and does not favor anticoagulation, noted Dr Verstraete. "It's a good drug, but not good enough," he said, adding that heparin does not always prevent reocclusion and some patients do not respond to it.

The TIMI-5 study found that recombinant hirudin used with tPA is better than aspirin and tPA, and is better for patients who reoccluded too, he noted. The TIMI-9 trial, which assessed a combination of hirudin, heparin and tPA, has been halted temporarily because of a higher incidence of bleeding.