Abstract 10875: Circadian Dependence of Infarct Size and Left-Ventricular Function Following ST-Elevation Myocardial Infarction
Circadian rhythms profoundly influence cardiovascular physiology. In rodents, infarct size following ischemia/reperfusion (I/R) is dependent on the time of coronary occlusion with the largest infarct size occurring when the occlusion is applied at the sleep to wake transition. It is not known if a similar circadian dependence of infarct size occurs in humans. We performed an analysis of 1025 consecutive patients presenting with ST-elevation myocardial infarction (STEMI) to our institution who had ischemic times between 1 and 6 hours. All patients underwent successful primary PCI of the infarct vessel. Important exclusion criteria included patients with TIMI flow > 0 or significant collaterals (n=556), pre-infarction angina (n=94), previous CABG or MI in same vascular distribution (n=74) or cardiac arrest (n=70) leaving a total of 166 patients who underwent circadian analysis. Peak CK was used as a surrogate of infarct size and was validated in a subgroup of patients that underwent cardiac MRI. Left ventricular ejection fraction (LVEF) was measured in 141 patients within 48 hours of PCI. We performed a periodic sinusoidal regression analysis to determine if infarct size is dependent on the onset of infarction. We observed that the extent of infarct size was significantly associated with time of day onset of infarction (p<0.0002). Similarly, left-ventricular ejection fraction (LVEF) measured within 2 days of infarction was also dependent on time of onset of STEMI with the absolute LVEF at peak more than 8% higher than at trough (42% vs. 51%), (p< 0.002) with the peak LVEF shifted by nearly 12 hours from the peak infarct size. We conclude that myocardial infarct size and LVEF show profound time of day dependence in patients with STEMI.
- © 2011 by American Heart Association, Inc.