To quantify regional ejection fraction (EF) in patients with myocardial infarction (MI) by using merged late gadolinium enhancement (LGE) and cine magnetic resonance (MR) imaging, and compare this method with the standardized 17-segment American Heart Association approach.
After institutional review board approval and informed consent, 15 MI patients (14 men, one woman; mean age, 63 years +/- 10 [standard deviation]) were studied at 1 week and at 4 months after MI. Short-axis LGE MR information was used to quantify infarct size, and to divide the left ventricle (LV) on short-axis cine MR images in infarct, periinfarct, and remote regions by using a fixed-center method, yielding information on regional volumes, regional EFs, systolic wall thickening (SWT), and systolic wall motion (SWM). This approach was compared with a floating-center approach and the 17-segment approach.
Mean infarct size (normalized to LV mass) was 25% +/- 14 at 1 week and 16% +/- 8 at 4 months (P < .001). At 4 months, LV EF significantly improved (mean, 47.9% +/- 5.9 vs 50.9% +/- 6.6, P = .031), matching an improvement of regional EF (mean, 17.1% +/- 11.5 vs 24.6% +/- 13.1, P = .005) and SWM (mean, 3.2 mm +/- 1.7 vs 3.9 mm +/- 2.1, P = .027) in the infarcted myocardium. No significant changes in regional EF, SWT, or SWM occurred in the remote myocardium. Regional EF estimates correlated well with SWT and SWM (both r = 0.92, P < .001). The floating-center method invariably underestimated regional EF (mean, -20.8% +/- 7.6; 95% confidence interval: -23.7%, -17.9%), especially with increasing infarct size. By using the 17-segment approach, no functional improvement was shown in the infarcted myocardium.
Assessment of regional ventricular performance (regional EF) in well-defined areas (eg, infarcted and remote myocardium) is feasible by using merged LGE and cine MR imaging.