Abstract
Objective: To evaluate the electrocardiographic characteristics in patients diagnosed with acute myocardial infarction (AMI) accompanied by complete left bundle branch block (LBBB). Subjects and research methods: A retrospective case-control and prospective cross-sectional study. Results: The mean age in the study group was 68.12 ± 12.33. The age in the group with AMI was higher than in the group without AMI, p<0.05. The rate of ST segment elevation in at least 1 lead in the AMI group was 73.17%, with a mean ST segment elevation value of 0.82 ± 0.03 mm. The rate of ST segment elevation ≥1mm concordant with QRS was 4.86% in the AMI group, mainly in leads D2, D3, aVF and leads D1, aVL, V5, V6. The Sgarbossa criteria had high diagnostic specificity. Among the criteria used, the Smith II criteria (Sgarbossa ≥ 2 points) had the highest positive likelihood ratio (18.44). Combining the Sgarbossa or Smith criteria with the Chapman sign helped improve diagnostic sensitivity, but reduced specificity and positive likelihood ratio. Conclusion: The electrocardiograms of patients with myocardial infarction accompanied by left bundle branch block have a relatively high rate of signs such as Q waves, ST segment elevation or depression. Using criteria such as Sgarbossa, Smith or Chapman improves the ability to diagnose myocardial infarction in patients with left bundle branch block, however the sensitivity of these criteria is still limited. Combining these criteria with echocardiographic findings and blood tests helps increase the ability to definitively diagnose acute MI as well as diagnose the affected myocardial region.