DETECTION OF MYOCARDIAL VIABILITY IN THE PREDICTION OF IMPROVEMENT INLEFT-VENTRICULAR FUNCTION AFTER SUCCESSFUL CORONARY REVASCULARIZATIONBY USING THE DOBUTAMINE STRESS ECHOCARDIOGRAPHY AND QUANTITATIVE SPECT REST-REDISTRIBUTION-REINJECTION TL-201 IMAGING AFTER DIPYRIDAMOLE INFUSION

The aim of this study was to assess the feasibility, safety, and respe ctive diagnostic accuracy of low-dose dobutamine infusion and rest-red istribution-reinjection thallium 201 single photon emission computed t omography (SPECT) after dipyridamole infusion (Th-DIP), in the predict ion of functional improvement of asynergic infarcted zones, after succ essful revascularization in patients with chronic ischemic heart disea se. Thirty-one patients with a previous myocardial infarction and left ventricular dysfunction (mean ejection fraction: 41 +/-5.8%) were stu died. The regional wall motion of the left ventricle was evaluated by basic echocardiography before and 14 +/-1.7 weeks after successful rev ascularization (19 by percutaneous transluminal coronary angioplasty a nd 12 by coronary artery bypass grafting). Dobutamine stress echocardi ography (DSE) was performed in all patients with dobutamine infusion o f 5 and 10 mu g/kg/minute over five minutes. Within three days after D SE and prior to revascularization, all patients underwent Th-DIP for m yocardial viability assessment. A 16-ventricular-segment model was use d for basic, DSE, and Th-DIP images. Viability was assessed by applyin g the standard criteria for each technique. In the 31 patients, 496 se gments were analyzed. By basic echocardiography, 164 (33%) of them wer e classified as asynergic. The DSE detected viable tissue in 69/496 (1 4%) segments, whereas Th-DIP identified viability in 95/496 (19%) segm ents. When the postrevascularization basic echocardiographic study was used as the gold standard in identifying myocardial viability, the se nsitivity and specificity for the DSE and Th-DIP were 86.5%, 94.4% and 90.5%, 69%, respectively. No major side effects were observed with bo th techniques. In conclusion, DSE seems to be an accurate method for i dentifying viable but asynergic myocardium in patients with chronic is chemic heart disease, whereas Th-DIP overestimates the postrevasculari zation recovery. Detection of hibernating myocardium can be obtained b y these two noninvasive methods. However, DSE seems to be more useful in determining the prospective selection of patients who are going to benefit from revascularization.