Session S35.4

Infarct Size Measured by Cardiac Magnetic Resonance following Acute Myocardial Infarction Predicts Future Left Ventricular Function

R Goswami*, T Martin, M Ugander, GS Wagner

Duke University
Durham, NC, USA

Depressed ejection fraction following acute myocardial infarction (AMI) is a long-observed phenomenon. Qualities which predict the return of myocardial function following acute infarct are not well understood. Previous work has shown that in patients with chronic ischemic heart disease, cardiac magnetic resonance (CMR) can be used to predict a maximal left ventricular ejection fraction (LVEF) for a given patient by the equation: maximal LVEF = 73.1 – [(left ventricular infarct size) * 1.21]. This study was performed to test the hypothesis that this formula predicts chronic left ventricular function in patients following AMI.
Fifty patients with CMR diagnosed AMI at the Western Infirmary Glasgow were assessed by CMR for AMI size during their initial hospitalization and for LVEF approximately six months subsequently. A maximally attainable LVEF during the chronic phase, based on the above formula and the measured AMI size, was calculated for each patient for comparison with the MRI measured LVEF after 6 months.
The calculated maximal LVEFs attained a Pearson’s correlation of r = 0.67 (p < .01) when compared to the MRI measured six-month LVEFs.
Application of a formula relating infarct size to maximal predicted LVEF during the acute stage of a myocardial infarction predicts chronic post-infarct left ventricular function. There is an increase in LVEF following AMI presumably due to a combination of natural and therapeutic factors related to the size of the acute infarction.

(Abstract Control Number: 241)