Prediction of functional recovery after revascularization in patients with chronic ischemic myocardial dysfunction: perfusable tissue index by positron emission tomography and contrast-enhanced MRI comparison study.

Objectives: In patients with chronic ischemic myocardial dysfunction, perfusable tissue index (PTI) obtained with positron emission tomography using oxygen-15-labeled water and carbon monoxide as tracers is inversely related to the extent of myocardial scar (nonperfusable tissue). Delayed contrast-enhanced (DCE) magnetic resonance imaging (MRI) accurately depicts the regional extent of myocardial fibrosis and predicts functional recovery after revascularization in patients with ischemic cardiomyopathy. Our aim was to compare PTI as a viability marker with DCE MRI.
Methods: Fourteen patients with ischemic left ventricular dysfunction were studied with positron emission tomography, using oxygen-15-labeled water and carbon monoxide as tracers, and with contrast-enhanced MRI.
Results: Functional improvement occurred in 38 of initially dysfunctional, revascularized segments (56%). Mean PTI was 1.04 ± 0.20 in the improved segments versus 0.85 ± 0.21 in the group without functional improvement (P<0.001). The areas under the receiver operator characteristics curves of PTI and DCE MRI were 0.7 and 0.74, respectively (P=not significant). Cutoff value of 25% DCE allowed correct identification of 82% segments with reversible dysfunction and 64% segments without reversible dysfunction. A threshold of 0.89 for PTI yielded the best diagnostic accuracy with sensitivity and specificity values of 76 and 54%, respectively.
Conclusion: PTI can identify viable myocardium and predict improvement in regional function after revascularization in patients with chronic ischemic left ventricular dysfunction. Its diagnostic accuracy is comparable with that of DCE MRI.