This article by Kuhl et al in European Heart Journal, is one that drives the cause of contrast-enhanced CMR in viability imaging. In this article, CE-CMR is compared with PET and SPECT.
"Sensitivity and specificity for the prediction of functional recovery at follow-up was 97 and 68% for ce-CMR and 87 and 76% for PET/SPECT. The positive predictive value was identical for both techniques (73%). However, ce-CMR achieved a higher negative predictive value (93 vs. 77%, respectively), indicating that ce-CMR may be superior to PET/SPECT for the identification of segments unlikely to recover function after revascularization. Both methods had a similar yield in the prediction of global functional improvement."
Their conclusion therefore was, "ce-CMR is comparable with a PET/SPECT imaging protocol for the prediction of regional and global functional improvement after revascularization. However, ce-CMR may be superior to nuclear imaging for the identification of segments that are unlikely to recover function at follow-up."
This essentially means that when CMR says categorically that the myocardium is non-viable, the predictive value is around 93%, whereas when it says that the myocardium is viable, the predictive value is 73%. This can be illustrated with these two examples.
The first is a patient with an inferior wall infarct with full thickness infarction (Fig. 1) as seen on CMR, with akinesia (video file) with a 99% RCA stenotic lesion. This is non-viable myocardium and revascularization will not help. On the other hand, is this patient with an LAD territory infarct (Fig. 2), where the infarct involves around 50-70% of the thickness of the myocardium, which shows severe hypokinesia (video file). Here the chance of improvement after revascularization is around 25% or so and so the predictive value becomes low. In such a situation, a more specific test such as dobutamine stress echo or CMR may help.
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