Electrocardiographic Dynamics of the St Segment and T Wave in Non–st-Segment Elevation Myocardial Infarction

To assess the characteristics and dynamics of ST-segment and T-wave changes in non–ST-segment elevation myocardial infarction, 200 patients were examined, including 164 men and 36 women; the mean age was 62.21±9.38 years. Based on coronary angiography findings, patients were divided into two groups: Group I included 94 patients with non–ST-segment elevation myocardial infarction and non-obstructive coronary artery lesions (stenosis <50 %); Group II included 106 patients with non–ST-segment elevation myocardial infarction and obstructive coronary artery lesions (stenosis≥50 %). In Group I, predominantly transient electrocardiographic changes were observed. During the acute phase, ST-segment depression in leads V4–V6 was most common (62.8 % of patients), and less frequent in leads II, III, and aVF (21.3 %). In Group II, ST-segment depression was deeper and more persistent; ST depression≥1 mm was recorded in 79.2 % of patients, predominantly in leads V4–V6 and II, III, aVF, which was significantly more frequent than in Group I (p=0.016). No significant intergroup differences were found for isolated T-wave inversion or for the combined ST↓+T pattern. ST-segment normalization on days 5–7 occurred significantly more often in Group I (p<0.001). Progression to transmural myocardial infarction (ST-segment elevation myocardial infarction) was observed only in Group II (p=0.019).