ST-segment analyses and residual thrombi in the infarct-related artery: a report from the ASSENT PLUS ST-monitoring substudy

Evolution of the ST segment during ST-elevation myocardial infarction (STEMI) has been shown to yield more information on prognosis than widely used invasive measurements. With continuous ST monitoring, even very occasional dynamic changes can be analyzed. We have recently suggested that ST variability during the reperfusion-phase is of prognostic importance. We wanted to further investigate this and relate it to angiographic findings. A total of 177 patients with STEMI were examined in the ST-monitoring substudy of the ASessment of the Safety and Efficacy of a New Thrombolytic (ASSENT) PLUS trial, comparing dalteparin with heparin as adjunctive therapy to t-PA. Patients underwent 24 hours of ST monitoring. These recordings were blindly analyzed by 2 independent observers. A coronary angiogram was performed on days 4 to 7, also blindly evaluated by 2 persons. Occurrence of ST re-elevations during and after the reperfusion-phase was significantly associated with residual thrombi and TIMI-flow in the infarct-related artery. Patients without any ST re-elevations showed a thrombus in only 5% of cases, as compared with 86% of patients with prolonged (lasting >30 minutes) ST re-elevations. In a multivariate comparison including baseline-data and treatment, most information on persistence of thrombi was contributed by the presence of any ST re-elevations (odds ratio, 5.8; 95% CI, 1.3–26). ST re-elevations during the first day of an acute myocardial infarction are associated with residual thrombi in the infarct-related artery even 4 to 7 days after the STEMI.