Objective- The diagnosis of perioperative myocardial infarction (PMI) after coronary artery bypass graft surgery (CABG) is difficult because there is no consensus on the criteria, and silent ischemia may be difficult to detect. The purpose of the SCENARIO study was to evaluate the use of 99mTechnetium-tetrofosmin myocardial perfusion tomography (SPECT) at rest in the diagnosis of PMI and reversible ischemia after CABG.
Design- We did a prospective trial of 102 patients undergoing elective CABG surgery. The patients were randomized into two groups. 48 patients underwent traditional management with serial ECG recordings and measurements of CK-MB, CK and Troponin Tpostoperatively. 54 patients were additionally examined with myocardial scintigraphy preoperatively, and 2-4 days and 6 weeks postoperatively.
Results and discussion- Based on different ECG and biochemical marker criteria, we found an incidence of PMI between 2,9-6,9%. In addition, 5 other patients had scintigraphic findings of PMI, as measured by the hypoperfusion index (HPI).This may represent subendocardial infarctions, without significant changes in ECG. Overall the study group showed a highly significant improvement in myocardial perfusion after CABG. No significant change in HPI was observed from 2-4 days to 6 weeks postoperatively. 15 patients had a gradual reduction in HPI that may be due to stunning or hibernating myocardium.
Conclusion- Our results show that SPECT can detect more cases of reversible and irreversible ischemia after CABG, than ECG and biochemical markers. However, further data processing is needed to draw final conclusions in the SCENARIO study.