Thallium 201 at rest and 24 hours redistribution identifies different patterns of myocardial viability in patients with unstable angina. Preoperative and postoperative study

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Abstract

To test the hypothesis that akinetic or hipokinetic myocardial segments with radionuclide pattern of hibernating or stunned will improve wall motion and/or perfusion after coronary artery revascularization whereas those with necrotic pattern will not, we studied 36 patients with unstable angina who were to undergo coronary by pass surgery. They had no chest pain 48 hours prior to the study. Rest and 24 hours redistribu- tion planar thallium 201 images and radionuclide angiography were obtained before and after (mean 14 days) surgery. Fifteen segments/patient were analized qualitatively. Postoperative studies were completed in 20 patients. Akinetic or hipokinetic segments were defined necrotic when had fixed Tl-201 defects, stunned they had normal perfusion images and hibernating when initial perfusion defects had partial or complete redistribution at 24 hours images. Segments with normal wall motion and perfusion were devined as normal. Results: 1) preoperative pattern: 17 % segments showed necrotic pattern, 14 % stunned, 14 % hibernating and 55 % normal (this distribution was similar in 16 patients that did not complete postoperative studies); 2) postoperative changes: 20 % of necrotic segments improved motility and perfusion; 60 % stunned segments improved motility and 40 % remained with the same pattern, 85 % hibernating segments improved motility and/or perfusion and 15 % developed necrotic pattern. Conclusions: 1) necrotic pattern under estimated myocardial viability; 2) preoperative hibernating pattern disappeared post- operatively either developing perioperative infarction or improving; 3) stunned pattern had only moderate capacity to predict viability. This may be explained by insufficient time up to the postoperative study or preoperative non transmural necrosis.