Myocardial viability assessment in patients with highly impaired left ventricular function: comparison of delayed enhancement, dobutamine stress MRI, end-diastolic wall thickness, and TI²⁰¹-SPECT with functional recovery after revascularization

This study compared different magnetic resonance imaging (MRI) methods with Tl²⁰¹ single photon emission computerized tomography (SPECT) and the “gold standard” for viability assessment, functional recovery after coronary artery bypass grafting (CABG). Twenty patients (64±7.3 years) with severely impaired left ventricular function (ejection fraction [EF] 28.6±8.7%) underwent MRI and SPECT before and 6 months after CABG. Wall-motion abnormalities were assessed by stress cine MRI using low-dose dobutamine. A segment with a nonreversible defect in Tl²⁰¹-SPECT and a delayed enhancement (DE) in an area >50% of the entire segment, as well as an end-diastolic wall thickness <6 mm, was defined as nonviable. The mean postoperative EF (n=20) improved slightly from 28.6±8.7% to 32.2±12.4% (not significant). Using the Tl²⁰¹-SPECT as the reference method, end-diastolic wall thickness, MRI-DE, and stress MRI showed high sensitivity of 94%, 93%, and 84%, respectively, but low specificities. Using the recovery of contractile function 6 months after CABG as the gold standard, MRI-DE showed an even higher sensitivity of 99%, end-diastolic wall thickness 96%, stress MRI 88%, and Tl²⁰¹-SPECT 86%. MRI-DE showed advantages compared with the widely used Tl²⁰¹-SPECT and all other MRI methods for predicting myocardial recovery after CABG.