Revascularization of Infarcted Myocardium: Effect on Myocardial Perfusion Assessed with Quantified T1–201 SPECT Technique

Abstract

Myocardial perfusion was studied in 21 patients before and after revascularization of all graftable stenotic vessels following post-infarction anteroapical akinesia and minor dyskinesia. At preoperative and late postoperative evaluation, perfusion abnormalities in identified sectors were quantified with two methods, one (Q1) assessing the extent and the other (Q3) the severity of abnormal perfusion. The preoperative scores with both methods indicated permanent myocardial perfusion defects in all 21 patients and reversible defects, indicating myocardial ischemia, in 16 with Q1 and 14 with Q3. After bypass grafting there was overall reduction of myocardial perfusion defect and of abnormality scores: Notably, 13/21 patients (62%) had decreased permanent myocardial defect score, reflecting reactivation of ‘hibernating myocardium’. The findings indicated that obstructed but graftable vessels supplying myocardium with loss of contractile function should be bypassed, since flow contribution to distant, viable myocardium is probable via preserved collateral circulation. This should be particularly relevant for the LAD, because of that artery's septal branches.

Key Words:

• myocardial infarction
• myocardial perfusion
• myocardial revascularization
• SPECT technique