Basic components and patterns of acute ischemia recovery assessed from continuous ST monitoring in acute myocardial infarction treated by thrombolytic therapy

Abstract

Continuous ST monitoring of the lead showing the highest ST elevation on the admission 12-lead electrocardiogram was performed in patients with acute myocardial infarction of 6 hours or less enrolled in the OSIRIS and GUSTO trials. ST elevation measured at j + 50 ms was averaged from all normal beats every 20 seconds. ST trends were visually analyzed by two observers blinded from the thrombolytic treatment, its onset, and coronary angiograms performed 21 hours (median) after thrombolysis. Three basic and consecutive components were considered for analysis: the initial amplitude of ST elevation (A1), the maximal amplitude recovery (REC), and the minimal ST amplitude (A2). Prespecified patterns (PAT) were considered: PAT 1 integrated permanent A1 elevation followed by REC, PAT 2 intermittent A1 elevation, and REC. Prespecified pattern 3 was considered in absence of REC. Twenty-four-hour trends were recorded in 347 patients and judged adequate in 306 (88%) followed by angiography in 268 (77%). This group was not clinically different from the 79 patients without ST/angiography. Prespecified pattern 1 was identified in 81%, PAT 2 in 8%, and PAT 3 in 11% of the patients. The positive predictive value of PAT 1 + 2 for coronary patency was 94%, the negative predictive value 72%, sensitivity 96%, and specificity 60%. A salient feature was the occurrence of ST overshoot defined by a ≥1 mm increase above A1 within the first minutes of REC. Overshoot occurred in 35% of PAT 1 and predicted subsequent patency in all but two patients. Online display of the ST trend at the bedside contributes substantially to the immediate evaluation of thrombolytic efficacy. Finally, left ventricular ejection fraction correlated best with A2, which may significantly contribute to assessing the efficacy of myocardial reperfusion.