The relationship between left ventricular ejection fraction and infarct size assessed by MRI

Objectives. We sought to study the relationship between left ventricular ejection fraction (LVEF) and infarct size in patients with ischemic heart disease (IHD) using magnetic resonance imaging (MRI), and to determine a dysfunction index based on the maximum possible LVEF in relation to infarct size. Design. In 149 patients with chronic IHD, LVEF and infarct size were quantified by MRI. Dysfunction index was defined as the maximum possible LVEF minus measured LVEF. Results. The maximum possible LVEF was found to be LVEF=72.2-[1.18*infarct size]. Dysfunction index for the study population was mean 20 (range -6 to 57), 74% of the study population had a dysfunction index 10 and 44% had a dysfunction index 20. Conclusions. The present study suggests that infarct size by MRI can be used to estimate a maximum possible LVEF and a dysfunction index. The distribution of dysfunction index in the population suggests a considerable prevalence of dysfunctional but viable myocardium. Future studies are needed to assess if the dysfunction index can be useful to assess the potential for improvement in LVEF following revascularization.