Electrocardiographic Findings and Prognosis of Acute Myocardial Infarction Due to Left Main Trunk Occlusion

Abstract

Purpose: Patients with left main trunk (LMT) infarction include many cases who develop cardiopulmonary arrest (CPA) before arriving at a hospital and those who have already gone into shock before reaching the hospital. Relationships between electrocardiographic (ECG) findings and prognosis have not been elucidated. Thus, the purpose of this study was to analyze acute-phase ECG findings in LMT infarction patients and to clarify the prognosis of this disease. Methods: Of 414 patients with acute myocardial infarction (AMI), including patients with prehospital cardiac arrest who underwent emergency coronary angiography (CAG), 10 who had completely occluded LMT were enrolled in the study. An assessment was made of the relationships between ECG findings on admission (or at the resumption of heart beat) and prognosis. Results: The death rate of the 10 patients was 70% (7/10), and the cause of death was low output syndrome (LOS) in 6 patients and cardiac rupture in 1. The assessment of the relationships between ECG findings on admission (or at heart beat resumption) and prognosis showed that 75% (3/4) of the narrow QRS wave form survived, whereas all patients with wide QRS (6/6) died. V1 conduction with this wide QRS was of the rR' type in 4 patients and of R type in 2. Conclusion: The ECG characteristics of LMT infarction, from the aspect of the QRS wave form, have been reported. Hence, the relationships between ECG findings and prognosis in LMT infarction were assessed. It was demonstrated that patients with the most severe AMI suffered LMT infarction showing a wide QRS. All of these subjects died. This QRS wave form was characterized by V1 conduction exhibiting a pattern of right bundle branch block of the rR' or R type. On the other hand, LMT infarction patients with a narrow QRS had a relatively good prognosis when treatment, such as reperfusion, was effective.