EDITORIAL Thrombolysis, clot selectivity, and kinetics

WHEN the editorial offices of Circulation moved to St. Louis, a series of "Perspectives " was initiated. The first, published in August 1983, dealt with coro-nary thrombolysis. It presaged the publication in Cir-culation of 11 manuscripts concerning thrombolysis within the next 12 months.-, An additional 13 are presently in review. One focus of consideration has been the potential importance of "clot selectivity " of activators of fibrinolysis such as tissue-type plasmino-gen activator (t-PA). Advantages of clot selectivity. Clot selectivity appears to render t-PA useful for coronary thrombolysis in part because: (1) Clot lysis can be accomplished with t-PA in doses that do not induce a systemic lytic state character-ized by consumption of c,-antiplasmin, depletion of plasminogen, fibrinogenolysis, increased circu-lating fibrinogen degradation products (FDPs), and predisposition to systemic bleeding;3. 14 (2) Definitive surgical treatment of high-grade residu-al coronary stenosis can be initiated promptly after successful thrombolysis with t-PA in contrast to conventional activators because of its short bio-logical half-life (approximately 5 min) and its lack of induction of a systemic lytic state; (3) Bleeding from arteriotomy sites may be less fre-quent after lysis induced with t-PA compared with streptokinase and other non-clot selective activa-tors, perhaps because of the conspicuous, antico-agulant effects of elevated FDPs and prolonged depletion of fibrinogen; (4) Early treatment of suspected infarction offering the greatest opportunity for myocardial salvage may be more justifiable with a clot-selective acti-vator than with streptokinase or urokinase because risks associated with a systemic lytic state can be avoided; and (5) Systemic administration of large doses may be more practical with t-PA compared with strepto