Assessment of myocardial viability by tissue Doppler and strain rate dobutamine echocardiography: comparison with rest-distribution thallium-201 spect.

Background. The introduction of Doppler measurement of myocardial wall velocities (tissue Doppler imaging, TDI) and the recently developed strain rate (SR) imaging technique have made possible a more adequate assessment of global and regional systolic and diastolic myocardial function. However, no study has so far tested the diagnostic accuracy of SR during dobutamine testing for detecting myocardial viability and predicting recovery of chronic ischemic LV dysfunction. Our purpose was: 1) to establish the accuracy of quantitative segmental analysis by SR during dobutamine testing for detecting myocardial viability in patients with chronic ischemic regional LV dysfunction; 2) to compare results of dobutamine SR with those of rest-4h-24h redistribution Thallium SPECT (T1 SPECT), a well validated method for assessing hibernating myocardium. Methods. Twenty-seven patients (age 5313 years) with chronic ischemic regional LV dysfunction (EF 2811%) underwent dobutamine SR and T1 SPECT on different days and in random order, within 15 days before myocardial revascularization (PTCA in 15 and CABG in 12). Functional recovery was identified at 9619 days after coronary revascularization by means of resting 2D echocardiography. Offline analysis of the myocardial velocity data sets was performed using dedicated software (Aplio, Toshiba Corp.). 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. Results. Of 163 segments with baseline WMA, 56 (34%) segments showed viability on Dobutamine SR, and 67 (41%) on Tl SPECT. Positive and negative predictive values were 87% and 60% for Dobutamine SR and 78% and 63% for Tl SPECT (p=NS). The sensitivity, specificity and accuracy of SR dobutamine echocardiography were 75%, 84%, and 82%, respectively; those of thallium tomography were 80%, 66%, and 71%, respectively. Conclusion. Segmental analysis of SR images during dobutamine infusion appears to be as feasible as visual diagnosis of regional wall motion changes but with the advantage of being automated and quantitative. Regional LV contractile reserve assessed by dobutamine SR is highly concordant with Tl SPECT in identifying hibernating myocardium.