Dobutamine stress MRI as a pre operative predictor of myocardial viability in areas of regional wall motion abnormality

We have examined dobutamine stress MRI as a predictor of functional recovery after coronary artery bypass grafting (CABG) in subjects with areas of akinetic or severely hypokinetic myocardium. Seventeen patients with multivessel coronary disease and at least one substantial wall motion abnormality demonstrated at ventriculography were studied before, and 3-6 months after revascularisation. Rest and dobutamine stress MRI were performed using a 26 segment model. The mean dobutamine dosage used was 15μg.kg.min^-1, with a mean heart rate achieved of 95 bpm. Radial wall thickening (RWT) analysis was performed in comparison to our normal reference range (n=31), and semi-subjective regional wall motion (RWM) observer analysis was scored on a 0 to 3 scale. Reduced RWT was taken as >1 SD below normal, and reduced RWM as a score of ≤2. At rest, 147 segments had reduced RWT and 97 reduced RWM. 55/147 segments had improved RWT with stress, and 20/97 an improved RWM. Post operative improvement in RWT and RWM was seen in 33 and 57 segments respectively, with a maximal predictive sensitivity and specificity of 52% and 88%. Conclusion: Dobutamine stress MRI is highly specific, though at best moderately sensitive as a predictor of functional recovery after CABG in akinetic or severely hypokinetic myocardium.