201- Thallium imaging as an indicator of graft patency after coronary artery bypass surgery

In a prospective study, forty one patients underwent myocardialimaging using 201 thallium (²⁰¹ Tl) scmtigraphy before and 6months after coronary artery bypass grafting (CABG). The resultswere compared with the findings at coronary arleriography performedat the same time. ²⁰¹ Tl was injected at peak exercise level performing an exercisescintigram. A thallium image equivalent to a redistributionscan was obtained at rest approximately 4 h after the injectionof²⁰¹ Tl. The overall angiographic patency rate was 0.77. Postoperativemyocardial perfusion was improved in 26 patients (88%) having72 of 83 grafts patent (patency rate 0.87). New perfusion defectsor unchanged ischaemic patterns were found in 5 patients, whohad 2 of 13 grafts patent (graft patency 0.15). Estimation ofthe graft status by ²⁰¹ Tl-scinligraphy showed a sensitivity,specificity, and predictive value of a positive and negativeresult of 0.71, 0.94, 0.79 and 0.91, respectively, using angiographicfindings as a reference. It is concluded, that comparison between preoperative and postoperative²⁰¹ Tl imaging of the myocardium at exercise and rest providesuseful information on graft patency after CABG. The procedureis superior to graft patency estimation based on resting orpostoperative scintigrams only.