BENEFICIAL-EFFECTS OF RHEOTHRX INJECTION IN PATIENTS RECEIVING THROMBOLYTIC THERAPY FOR ACUTE MYOCARDIAL-INFARCTION - RESULTS OF A RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED TRIAL

Background RheothRx (poloxamer 188) is a surfactant with hemorheologic al and antithrombotic properties that reduces myocardial reperfusion i njury in animal models of myocardial infarction. The purpose of the pr esent study was to evaluate the safety and efficacy of adjunctive ther apy with poloxamer 188 in patients receiving thrombolytic therapy for acute myocardial infarction. Methods and Results In this multicenter t rial, we randomized 114 patients to a 48-hour infusion of poloxamer 18 8 or vehicle placebo beginning immediately after the initiation of thr ombolytic therapy. Tomographic imaging with Tc-99m sestamibi before re perfusion and again 5 to 7 days after the infarction was used to deter mine myocardium at risk for infarction, infarct size, and myocardial s alvage. Radionuclide angiography at 5 to 7 days after infarction was u sed to measure left ventricular ejection fraction. The treated and con trol groups had comparable baseline characteristics, time to thromboly tic administration, and time to treatment with poloxamer 188 or placeb o. Poloxamer 188-treated patients demonstrated a 38% reduction in medi an myocardial infarct size (25th and 75th percentile) compared with pl acebo (16% [7, 30] versus 26% [9, 43]; P=.031), greater median myocard ial salvage (13% [7, 20] versus 4% [1, 15]; P=.033), and a 13% relativ e improvement in median ejection fraction (52% [43, 60] versus 46% [35 , 60]; P=.020). Poloxamer 188 treatment also resulted in a reduced inc idence of reinfarction (1% versus 13%; P=.016). Poloxamer 188 was well tolerated without adverse hemodynamic effects or significant organ to xicity. Conclusions Adjunctive therapy with poloxamer 188 resulted in substantial benefit in this randomized trial, including significantly smaller infarcts, greater myocardial salvage, better left ventricular function, and a lower incidence of in-hospital reinfarction. Although the mechanisms are unproven, poloxamer 188 treatment may accelerate th rombolysis, reduce reocclusion, and ameliorate reperfusion injury.