Circadian Effects on Coronary Flow and Left Ventricular Function in Patients with Acute St Elevation Myocardial Infarction (Stemi) Undergoing Primary Percutaneous Coronary Intervention

Adverse cardiovascular events demonstrate a time of day dependence with episodes of myocardial infarction, sudden cardiac death, and stent thrombosis peaking in the early morning hours. Aim: To test the hypothesis that patients presenting with acute ST-elevation myocardial infarction (STEMI) display circadian variation in coronary flow, microcirculation and left ventricular systolic function after primary percutaneous coronary intervention (PCI). Methods: A retrospective study of 604 patients with acute STEMI referred for primary PCI, 150 with anterior STEMI and acquisition of Doppler velocities in the left anterior descending coronary artery (LAD) were analyzed for circadian variation effects of chest pain onset. The time of symptom onset was categorized into four 6-hour intervals: midnight–6:00 A.M., 6:00 A.M.–noon, noon–6:00 P.M. and 6:00 PM.–midnight. Results: The 6:00-12:00 chest pain onset group was the largest (31.3%) while the 00-6:00 am group was the smallest (19.4%), p<0.05. Chest pain onset-PCI time intervals were similar between the groups. Patients with onset of chest pain between 12:00 and 18:00 had better coronary microcirculation function according to LAD velocity and diastolic deceleration times, less myocardial damage according to peak myocardial biomarker blood levels and 4-10 folds improvement in left ventricular systolic function by wall motion score index compared to the 18:00-mid night chest pain onset group, p<0.05. Conclusions: Despite similar time duration from pain to primary PCI, patients with onset of chest pain between 12:00-18:00 had better infarct related coronary artery microcirculation function, less myocardial damage and better recovery of left ventricular systolic function.