Revascularization of viable myocardial segments has been shown to improve left ventricular (LV) function and long-term prognosis; however, the surgical risk is comparatively higher in patients with a low ejection fraction (EF). We compared contrast-enhanced MRI with (18)F-FDG PET/(201)Tl SPECT for myocardial viability and prediction of early functional outcome in patients with chronic coronary artery disease (CAD).
Methods: Forty-one patients with chronic CAD and LV dysfunction (mean age +/- SD, 66 +/- 10 y; 32 men; mean EF +/- SD, 38% +/- 13%) referred for (18)F-FDG PET, (201)Tl-SPECT and MRI within 2 wk were included. Twenty-nine subjects underwent coronary artery bypass grafting (CABG), and LV function was reassessed by MRI before discharge (17 +/- 7 d after surgery). Two were excluded from outcome analysis (1 death due to sepsis; 1 perioperative myocardial infarction). The extent of viable myocardium by (18)F-FDG PET/(201)Tl SPECT was defined by the metabolism-perfusion mismatch or ischemia, in comparison with the extent of delayed enhancement (DE) on MRI in a 17-segment model. Segmental functional recovery was defined as improvement in the wall motion score of > or =1 on a 4-point scale. EF and LV volume change were used as global functional outcome.
Results: Three hundred ninety-four dysfunctional segments were compared, and the extent of DE on MRI correlated negatively with the viability on (18)F-FDG PET. Of 252 dysfunctional segments that were successfully revascularized, the sensitivity, specificity, positive predictive value, and negative predictive value of PET/SPECT were 60.2%, 98.7%, 76.6%, and 96.7% and of MRI were 92.2%, 44.9%, 72.4%, and 78.6% using the cutoff value of 50% DE on MRI, without significant differences in overall accuracies. In 18 subjects who underwent isolated CABG, improvement of EF (> or =5%) and reverse LV remodeling (> or =10% LV size reduction) was best predicted by the no DE on MRI, and patients with substantial nonviable myocardium on (18)F-FDG/SPECT predicted a poor early functional outcome (all P < 0.001).
Conclusion: Accurate prediction of early functional outcome by PET/SPECT and contrast-enhanced MRI is possible.