Significance of left circumflex artery-related acute myocardial infarction without ST-T changes

Abstract Introduction Left circumflex (LC)–related acute myocardial infarction (AMI) presenting without ST-T changes has been underdiagnosed in the emergency department. There is little information on its clinical features and significance. Aims The aims of the study were to investigate the clinical characteristics and outcomes of LC-related AMI without ST-T changes. Population and Methods Ninety-six patients were admitted for LC-related AMI. Comparisons between those with and without ST-T changes were analyzed. Results Twenty-two patients (23%) did not have ST-T changes, whereas 74 patients (77%) had them. Patients without ST-T changes had younger age (55.6 ± 16.8 vs 62.6 ± 12.0 years, P = .03), fewer presented as Killip III/IV (4.5% vs 27.4%, P = .02) and with lower creatine kinase (1647.3 ± 1602.2 vs 2778.2 ± 2343.3 IU/L, P = .037) and creatine kinase-MB (136.8 ± 130.3 vs 247.7 ± 200.0 IU/L, P = .017), and more were with concurrent culprit lesion in the middle or distal LC and right- or balanced-dominant coronary circulation (86.4% vs 44.6%, P < .001). During follow-up, the need for repeat percutaneous coronary intervention (48.6% vs 45.5%, P = .40) and recurrent infarction (13.5% vs 13.6%, P = .62) were similar between the 2 groups. The 30-day mortality (0% vs 5.4%, P = .35) and overall mortality rate (4.5% vs 12.2%, P = .28) between them were not different statistically. Conclusion The relatively lower prevalence of LC-related AMI without ST-T changes in the study might be underestimated. These patients have smaller infarct size than patients with ST-T changes without differences in the short- and long-term outcomes between them.