Direct imaging of viable myocardium by gated SPECT in patients with ischaemic left ventricular dysfunction

The aim of the study was to evaluate a novel polar map of myocardial viability obtained by gated SPECT imaging to predict functional recovery after revascularization in patients with ischaemic left ventricular (LV) dysfunction. The study group comprised 17 patients (15 men, mean age 58 +/- 9 years) with ischaemic LV dysfunction (ejection fraction <or=40%) who underwent nitrate-enhanced gated SPECT before and 6 months after coronary revascularization. A parametric image of viable myocardium (VIA) was obtained using a semiautomated method to subtract the point-to-point motion polar map from the perfusion polar map. A parametric image of segments with functional recovery (REC) was obtained by subtracting the baseline motion polar map from the motion polar map after revascularization. Of the total 340 segments, 248 (73%) were considered viable on the basis of the VIA map. After revascularization, of 248 dysfunctional viable segments 186 (75%) showed an improvement in LV function. An increase in LV ejection fraction (from 30 +/- 10% to 42 +/- 11%, p < 0.01) and a decrease in end-diastolic volume (from 207 +/- 74 ml to 174 +/- 74 ml, p < 0.01) were observed after revascularization. Overall concordance between the VIA map and the REC map was 85%, with a k value of 0.63. Sensitivity, specificity, and positive and negative predictive values of the VIA map for predicting functional recovery were 89%, 75%, 91% and 71%, respectively. The proposed polar map of myocardial viability obtained by gated SPECT imaging accurately predicts functional recovery after coronary revascularization. Thus, a direct quantitative image of viability obtained from perfusion/function matching may be helpful for clinical decision-making in patients with ischaemic LV dysfunction.