ST segment resolution in ASSENT 3: insights into the role of three different treatment strategies for acute myocardial infarction.

AIMS ASSENT 3 (Assessment of the Safety and Efficacy of a New Thrombolytic) demonstrated that the bolus fibrinolytic tenecteplase (TNK), combined with enoxaparin (ENOX) or abciximab (ABCX), substantially reduced ischemic complications of acute myocardial infarction as compared with unfractionated heparin (UH). We compared ST resolution in each of the three treatment regimens in order to evaluate the speed, extent and stability of ST segment resolution and its relationship to the primary composite endpoint(s) of the trial. METHODS AND RESULTS We evaluated ST segment shift and its subsequent resolution i.e. complete (> or =70%), partial (<70-30%) and no resolution (<30%) in 4,304 patients 60 and 180 min after treatment. Sixty minutes after therapy there was a trend for both half-dose TNK/ABCX and TNK/UH to have more frequent complete ST resolution (P=0.072) than TNK/ENOX. Pair-wise comparison at 60 min revealed that patients receiving TNK/ABCX had significantly more complete ST resolution than TNK/ENOX (P=0.026). Further ST resolution had occurred 180 min after treatment: complete ST resolution was greater with TNK/ABCX (59.2%) than the TNK/heparin (50.8%) and TNK/enoxaparin (50.8%) (P<0.001). In the TNK/ENOX group achieving complete ST resolution by 180 min, in-hospital reinfarction was 1.9% vs 4.2% for TNK/UH (P=0.015) representing a 2.3% absolute and 55% relative reduction in reinfarction. Thirty day and one year mortality was greatest amongst those patients with <30% ST segment resolution in the TNK/ABCX group. CONCLUSIONS More rapid and complete ST resolution occurs with half-dose TNK/ABCX whereas less reinfarction occurs amongst those patients with > or =70% ST resolution receiving either TNK/ABCX or TNK/ENOX. These data highlight two potentially complementary mechanisms of clinical benefit associated with different pharmacologic regimens in acute myocardial infarction, i.e. more rapid versus more stable coronary patency.