[Clinical significance of ST segment shifts during chest pain in predicting the pathogenesis of impending myocardial infarction].

To know whether the pathogenesis of impending myocardial infarction(IMI) could be predicted by the direction of ST segment shifts during an ischemic chest pain, we studied 62 patients with IMI and undergoing emergent coronary angiography(CAG). They were selected from a consecutive number of 474 patients with unstable angina. IMI was defined when patients had more than 2 episodes of chest pain at rest under intensive pharmacological interventions after their CCU admission, and at least one of those was not relieved by nitroglycerin given intravenously. They were divided into 2 groups according to ST segment shifts during chest pain; 35 patients with ST elevation (G-1) and 27 patients with ST depression (G-2). The time of CAG was individually determined in each patient according to the severity of illness. Those with acute MI within 3 months before the study and 24 hours following the chest pain just before CAG were excluded from the study. New onset angina accounted for 49% in G-1 and 4% in G-2(p less than 0.01). Average history length of IMI, frequency of symptoms after CCU admission, and interval from the last symptom to CAG were similar in each groups. Single vessel disease was more predominant in G-1 than in G-2 (54% vs 11% p less than 0.01). Intracoronary thrombus(IT) in an ischemia related artery(IRA) was found in 97% of G-1 and 22% of G-2(p less than 0.001), while complex lesions(CL) proposed by Ambrose as another genesis of IMI were in 26% of G-1 and 74% of G-2(p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)