A novel index of myocardial viability derived from strain rate dobutamine echocardiography and rest-redistribution thallium-201 spect

Background. The purpose of the present study was to assess the quantitative segmental analysis by strain rate imaging (SRI) technique during dobutamine test for detecting myocardial viability in patients with chronic ischemic regional left ventricular (LV) dysfunction, to compare results with those of tissue Doppler imaging (TDI) as well as rest-4h-24h redistribution Thallium SPECT (Tl SPECT), and to establish the accuracy of dobutamine SRI, dobutamine TDI and Tl SPECT before and after revascularization. Methods. Thirty-two patients with chronic ischemic regional LV dysfunction (EF 29 +/- 8%) underwent dobutamine TDI/SRI and Tl SPECT on different days randomly within 15 days before myocardial revascularization. Velocity and strain traces from different wall segments were processed simultaneously in the same cineloop. Dobutamine was administered by infusion pump, at 3 min intervals up to a maximum of 20 mcg/Kg/min. Each patient was injected i.v. with 3.0 mCi of Tl in the rest state. Four hours and 24 hours after injection, delayed Tl SPECT acquisitions were performed using the same parameters. A 16-segment- 4-grade score model was used for analysis of both Dobutamine SR and Tl SPECT. Offline analysis of the myocardial velocity data sets was performed using dedicated software. Recovery of regional LV function was defined as wall motion score improvement > 1 grade in > 2 contiguous segments at resting follow-up echocardiogram in patients with angiographically controlled open target vessel. Results. Positive and negative predictive values were 81% and 78% for dobutamine TDI, 89% and 81% for dobutamine SRI, and 75% and 94% for Tl SPECT. The area under the ROC curve (AUC) which reflects the overall performance for the prediction of recovery was 0.79 for systolic-SRI, 0.81 for Tl SPECT, 0.83 for post-systolic strain and 0.87 for isovolumic-SRI. By obtaining an index that combines systolic and post-systolic SRI values with Tl SPECT, the AUC was improved to 0.93. Conclusion. Regional LV contractile reserve assessed by dobutamine SRI is more accurate than TDI in identifying hibernating myocardium. Systo-diastolic values obtained using dobutamine SRI echocardiography and values derived from nuclear perfusion techniques may be complementary in assessing myocardial viability