ST SEGMENT REELEVATION AFTER ACUTE MYOCARDIAL-INFARCTION - MARKED DIFFERENCES IN THE ELECTROCARDIOGRAPHIC PATTERN BETWEEN EARLY AND LATE EPISODES

This study assesses the electrocardiographic (EGG) morphologic differe nces between early (<24 h) and late (>24 h) episodes of ST segment ree levation after acute myocardial infarction. We studied the records of 101 consecutive patients with acute myocardial infarction whose admiss ion ECG demonstrated ST segment elevation with positive T waves, witho ut pathological Q waves in the relevant leads, and without signs of bu ndle branch block or left ventricular hypertrophy. Thirty-five patient s had 44 episodes of early ST segment reelevation, while 22 patients e xperienced 26 late episodes of ST segment reelevation. Seven patients experienced both early and late episodes. Early episodes of ST segment reelevation was seen more often after thrombolytic therapy: 43% (32 o f 74 patients) versus 11% (3 of 27 patients) (P < 0.006). No differenc es were found in the incidence of late episodes between those who unde rwent (23%) or did not undergo (19%) thrombolytic therapy. Two pattern s of ST segment elevation were distinguished. Pattern A with positive T waves, ST segment elevation (greater than or equal to 0.1 mV), but w ithout distortion of the terminal portion of the QRS complex. Pattern B characterized by positive T waves, ST segment elevation (greater tha n or equal to 0.1 mV) with distortion of the terminal portion of the Q RS complex. Each ECG was categorized according to these two patterns. The admission ECG pattern was A in 75 patients, and B in 26. No signif icant differences were found between patients with early, late, or no episodes of ST segment reelevation in the appearance of pattern A or B on admission. Pattern A was found in 32 episodes of ST reelevation, w hile pattern B was found in 38 episodes. Ten (23%) and 34 (77%) of the early episodes were of pattern A and B, respectively, while 22 (85%) and 4 (15%) of the late episodes were of pattern A and B, respectively (P < 0.000002). No relation was found between the ECG pattern on admi ssion and the pattern recorded during episodes of ST reelevation. The differences in the morphologic pattern of ST segment reelevation betwe en early and late episodes, shown in this study, may signify different pathophysiological mechanisms. There is a need to further characteriz e the different ECG patterns of ST reelevation after acute myocardial infarction, and to try to relate the differences to different pathophy siologic mechanisms of myocardial ischemia and injury.