Reverse redistribution of technetium-99m-sestamibi following direct PTCA in acute myocardial infarction

A pattern of reverse redistribution (RR) has not been documented in myocardial 99mTc-sestamibi imaging. The purpose of the study was to clarify the time-related changes in myocardial distribution of 99mTc-sestamibi in patients with acute myocardial infarction.

Myocardial SPECT with 99mTc-sestamibi was performed in 27 patients with acute myocardial infarction within 1 wk after the onset. Twenty-three patients received direct percutaneous transluminal coronary angioplasty (PTCA) and 4 patients did not. Myocardial images were obtained 1 hr (early) and 3 hr (delayed) after the injection of 99mTc-sestamibi. Regional myocardial uptake of 99mTc-sestamibi was scored from 4 (normal) to 0 (no activity), and the RR pattern was defined as a decrease of more than 1 in the regional score at the 3-hr delayed images. Regional myocardial uptake and clearance of 99mTc-sestamibi was also assessed quantitatively. Coronary arteriography and left ventriculography were performed 1 mo later.

Out of 22 patients with successful PTCA, RR of 99mTc-sestamibi was observed in 15 patients (68%). Persistent defects (PD) were seen in 12 patients (7 patients with successful PTCA, 1 patient with unsuccessful PTCA, and 4 patients who did not receive angioplasty). In patients with RR, regional uptake of 99mTc-sestamibi in the area of myocardial infarction decreased from 54% +/- 10% in the early images to 43% +/- 8% in the delayed images (p < 0.01). Technetium-99m-sestamibi clearance from the myocardium was faster in the infarct area than in the normal area (26% +/- 7% versus 9% +/- 6%, p < 0.01). Coronary arteriography performed 1 mo later revealed that the patency of the infarct related artery was 100% (15/15) in patients with RR and 50% (6/12) in those with PD (p < 0.01). The extent and severity of a wall motion abnormality were less in patients with RR than in those with PD (extent: 24 +/- 10 versus 36 +/- 9 chord, p < 0.01; severity: -2.7 +/- 0.4 versus -3.4 +/- 0.6 s.d./chord, p < 0.01).

The RR of 99mTc-sestamibi was observed in 68% of patients after successful direct PTCA and was associated with the accelerated clearance of 99mTc-sestamibi from the myocardium. The presence of RR in 99mTc-sestamibi imaging indicates the patency of the infarct-related artery and predicts the preserved left ventricular function.