Clinical characteristics of ventricular fibrillation occurrence in the early phase of acute myocardial infarction between patients with and without early repolarization

Abstract

Background: We recently showed that the presence of early repolarization (ER) increases the risk of ventricular fibrillation (VF) occurrences in the early phase of acute myocardial infarction (AMI). However, clinical characteristics of VF occurrence in the early phase of AMI between patients with and without ER were still unknown. Methods: This study included 220 consecutive patients with AMI (69±11 years; 57 females) in whom 12-lead ECGs before the AMI onset could be evaluated. The patients were classified based on the VF occurrence 0.1 mV from baseline in at least 2 inferior or lateral leads, manifested as QRS slurring or notching. Results: Twenty-one patients experienced an episode of VF <48 hours after AMI onset and ER was present in 34 patients. Among 34 patients who had ER, ER was present at inferior leads in 26 patients, at lateral leads in 5, at both inferior and lateral leads in the remaining 3 patients. The prevalence of a match between the location of ER and infarction area did not differ in patients with and without VF occurrence among 34 patients with ER (40% versus 38%; p=1.0). Among 186 patients without ER, peak creatine kinase level (4000±3200 U/L versus 2100±1900 U/L; p<0.05), number of diseased coronary arteries (2.4±0.8 versus 1.7±0.8; p<0.01), and the prevalence of male gender (100% versus 71%; p<0.05) and right coronary culprit artery (63% versus 31%; p<0.05) was higher in the patients with VF occurrence than in those without. On the other hand, among 34 patients with ER, there was no significant difference in peak creatine kinase level (2400±1900 U/L versus 2800±2300 U/L; p=ns), number of diseased coronary arteries (1.7±0.7 versus 1.6±0.8; p=ns), and the prevalence of male gender (90% versus 79%; n=ns) and right coronary culprit artery (30% versus 21%; n=ns) between patients with and without VF occurrence. Killip class on admission was higher in patients with VF occurrence than in those without among patients both with and without ER. Duration from AMI onset to admission in emergency room was earlier in patients with VF occurrence than in those without among patients with ER (146±251 minutes versus 418±384 minutes; p<0.01) but not among patients without ER (240±223 minutes versus 404±410 minutes; p=ns). Conclusion: There were significant differences in clinical characteristics of VF occurrence in the early phase of AMI between patients with and without ER. These findings may indicate the mechanism that ER provokes VF in the early phase of AMI.