PROSPECTIVE EVALUATION OF VIABLE MYOCARDIUM BY QUANTITATIVE DIPYRIDAMOLE-THALLIUM-201 SCINTIGRAPHY AND RADIONUCLIDE VENTRICULOGRAPHY

Improvement of myocardial function is a major goal of coronary revascu larization. Considerable interest remains in the preoperative identifi cation of viable myocardium. We examined 26 consecutive patients with left ventricular dysfunction undergoing coronary artery bypass graftin g. Serial dipyridamole-thallium imaging and radionuclide ventriculogra phy was performed preoperatively and postoperatively. The relationship between preoperative and postoperative thallium perfusion and segment al wall motion was analyzed. The mean preoperative ejection fraction w as 32 +/- 9 (21 to 51%) and increased to 41 +/- 12 (17 to 67%) postope ratively (p > 0.01). Seventy-seven percent of patients improved their global ejection fraction postoperatively by >5%. Thallium perfusion im proved postoperatively in 84% of reversible defects vs 63% of partiall y reversible defects and 35% of fixed defects. Segments with either re versible or partially reversible thallium defects showed an improved p ostoperative wall motion in 71% and 68%, respectively. Postoperative w all motion improved in 43% of fixed defects. Overall, 67% of hypokinet ic segments showed improved postoperative wall motion while only 29% o f akinetic or dyskinetic segments improved postoperatively. Preoperati ve thallium redistribution coupled with preserved wall motion was pred ictive of improvement in wall motion postoperatively and indirectly in dicates myocardial viability. However, 43% of fixed defects also showe d improved postoperative wall motion. A significant improvement in glo bal ejection fraction was found and could be predicted by a linear reg ression analysis utilizing clinical and thallium parameters.