Influence of diurnal variation in the size of acute myocardial infarction

Objective: To evaluate whether the size of acute myocardial infarction (AMI) shows circadian variability. Design: An observational, prospective study. Setting: A 12-bed coronary care unit. Patients: Consecutive patients diagnosed with ST-elevation myocardial infarction (STEM!) undergoing primary percutaneous coronary intervention. Interventions: The patients were divided into two groups according to the time of onset of AMI symptoms (Group A: 0-12 hours, Group B: 12-24 hours). Main variables of interest: Age, sex, cardiovascular risk factors, coronary anatomy, left ventricular ejection fraction, infarct location, time from onset of symptoms to reperfusion, presence of heart failure upon admission, and peak troponin I value. Results: A total of 108 patients with a diagnosis of STEM! were included. Patients in group A showed a higher troponin I concentration compared to group B (troponin I: 70.85+/-16.38 versus 60.90+/-22.92 ng / ml, p = 0.003). In the multivariate analysis the onset of AMI between 0-12 hours was identified as an independent predictor of infarct size (OR: 1.133, 95%CI 1.012-1.267, p = 0.01). Conclusions: An onset of AMI between 0-12 hours results in a significantly larger final size of necrosis compared with any other time of presentation. (C) 2011 Elsevier Espana, S.L. and SEMICYUC. All rights reserved.