Rest-redistribution Thallium-201 Imaging in Predicting Improvement in Left Ventricular Function After Coronary Bypass Surgery

This study was performed to test the hypothesis that TI-201 uptake on resting scintigraphy would identify viability in noncontracting myocardial regions and predict improved systolic function after revascularization. Fifteen of 19 consecutive patients referred for coronary artery bypass surgery (CABS) comprised the study group. Baseline studies obtained before CABS included coronary angiography and left ventriculography, planar rest-redistribution TI-201 imaging and radionuclide ventriculography. Postoperative studies obtained 10 weeks after CABS included repeat rest-redistribution TI-201 imaging and radionuclide ventriculography. Segments were classified as showing, mildly reduced or severely reduced viability on the basis of quantitative analysis ofg detect severity and redistribution on planar resting TI-201 imaging. Postoperative increase in segment TI-201 uptake of one or more grade from the viability class were considered as improved and these segments were accepted as adequately revascularized. By TI-201 criteria 93% of severely hypokinetic segments and 78% of akinetic or dyskinetic segments had normal or mildly reduced viability. Sixtyone percent of asynergic segments with normal or mildly reduced viability improved function after surgery, while only 36% with severely reduced viability improved funtion (p<0.035). When only adequately revascularized segments were considered, the improvement was found to be 94%. The greatest improvement in global left ventricular function after surgery occurred in patients with greatest number of viable and adequately revascularized segments. In conclusion, preoperative rest-redistribution quantitative TI-201 imaging identifies viability in many asynergic segments in patients with coronary artery disease and depressed left ventricular function and helps the clinician for the selection of patients who will benefit from CABS.