[Indication of aorto-coronary bypass surgery for the infarcted myocardium: assessment using exercise T1-201 myocardial imagings].

Using exercise thallium-201 myocardial imagings, 23 patients with previous myocardial infarction were evaluated before and after aorto-coronary bypass graft (ACBG) surgery to assess the indication of the operation for the infarcted myocardium. The patients were categorized as group I with regional hypoperfusion and redistribution in the infarcted site (11 patients), and group II with regional hypoperfusion without redistribution (12 patients). Changes in the exercise tolerance before and after ACBG: By the criteria of Canadian Cardiovascular Society, clinical symptoms improved in nine of 11 patients (82%) in group I, and eight of 12 patients (67%) in group II. Pressure rate product improved significantly in group I (201 +/- 28% to 219 +/- 21% p less than 0.05), whereas it showed no significant change in group II (200 +/- 44% to 203 +/- 35%). Changes in the global left ventricular ejection fraction before and after ACBG: There was a significant increase in group I (63 +/- 11% to 68 +/- 9% p less than 0.02), whereas no significant change in group II (53 +/- 16% to 54 +/- 14%). Changes in myocardial perfusion in the infarcted segment before and after ACBG: Group I showed an increase in myocardial perfusion in all of the 11 (82%) except two patients with the occluded graft, and group II showed an increase in only two of the 12 patients (17%). Changes in wall motion abnormality in the infarcted segment before and after ACBG: Improvement of the wall motion abnormality was observed in eight of the 11 patients (73%) in group I, whereas only one of the 12 patients (8%) in group II. It is suggested that preoperative redistribution of the infarcted site in the delayed image suggests myocardial viability, and allows us to expect the postoperative improvement of myocardial hypoperfusion and wall motion abnormality.