Increased myocardial uptake of 18F-fluorodeoxyglucose (FDG) in regions with perfusion defects (perfusion-FDG mismatch) has been shown to predict functional recovery after revascularization; conversely, a concordant decrease in perfusion and FDG uptake (perfusion-FDG match) represents scar tissue (varying from subendocardial to transmural scar) that will not improve in contractile function after revascularization. Several recent studies have used a mild reduction in perfusion or FDG uptake (or both) as an indicator of viable tissue. To our knowledge, this criterion has not been validated against functional outcome after revascularization. This study aimed to compare the predictive value for functional recovery of these different perfusion-metabolism criteria.
Methods: Forty-two patients referred for revascularization were studied with early resting 201Tl SPECT (to evaluate perfusion) and FDG SPECT. Contractile function was evaluated before and 3-4 mo after revascularization using two-dimensional echocardiography. Angiography was not repeated.
Results: Two hundred six dysfunctional segments were identified; functional recovery occurred in 71 segments. The 206 dysfunctional segments were divided into five groups: group I, segments (n = 37) with normal perfusion; group II, segments (n = 69) with a mild reduction in perfusion (> or =60% of normal 201Tl uptake) without increased FDG uptake (mild match); group III, segments (n = 29) with a mild reduction in perfusion and increased FDG uptake (mild mismatch); group IV, segments (n = 46) with a more severe reduction in perfusion (<60% of normal 201Tl uptake) without increased FDG uptake (severe match); and group V, segments (n = 25) with a 201Tl activity < 60% and increased FDG uptake (severe mismatch). The mean wall motion score improved significantly in groups I, III and V but not in groups II and IV. Improvement of function was observed in 76% of group I segments, in 69% of group III segments and in 68% of group V segments. In contrast, only 13% of group II segments and 7% of group IV segments improved after revascularization.
Conclusion: The results indicate that normal perfusion and mismatch patterns (either mild or severe) are predictive of functional recovery, whereas match patterns (either mild or severe) are predictive of absence of recovery. Match patterns are likely to represent different degrees of scar tissue, ranging from subendocardial to transmural scars. To identify segments with a high likelihood of improvement of function after revascularization, integration of information on perfusion and FDG uptake appears mandatory.