Early prediction of regional functional recovery in reperfused myocardium using single-injection resting quantitative electrocardiographic gated SPET.

Abstract

By evaluating concordant or discordant perfusion and systolic wall thickening patterns, resting quantitative electrocardiographic (ECG) gated single-photon emission tomography (SPET) can identify various myocardial pathological conditions with different functional recovery after revascularisation therapy. However, no data are available on the ability of this methodology to predict regional functional recovery after primary percutaneous transluminal coronary angioplasty (PTCA). This study evaluated whether single-injection ECG gated SPET imaging performed at rest with 99mTc-tetrofosmin early after successful PTCA can predict recovery of regional wall motion. ECG gated SPET was performed 3 days and 3 weeks after successful PTCA in 26 patients. Regional functional parameters were automatically calculated with a 20-segment model on the day 3 image, and segments with perfusion/thickening mismatch were defined as showing preserved perfusion (>55% uptake on the end-diastolic image: mean-standard deviation of the normal value) without systolic wall thickening (mean-standard deviation of the normal value). On the third day, the regional wall motion score of 37 mismatched segments (3.8+/-2.1) was significantly lower than that of 41 matched normal segments (6.0+/-2.9), but was significantly higher than that of 108 matched abnormal segments (1.4+/-1.9, both P<0.01). At 3 weeks after acute MI, the regional wall motion score of mismatched segments (6.4+/-3.9) improved to the level of matched normal segments (7.1+/-3.0) and was significantly higher than that of matched abnormal segments (2.5+/-3.0, P<0.01). Absolute change in the regional wall motion score (3 days to 3 weeks) of mismatched segments (2.6+/-3.5) was significantly greater than that in the regional wall motion score of matched normal segments and matched abnormal segments (1.1+/-1.3 and 1.2+/-2.6, respectively, both P<0.05). Twenty-seven of 37 segments (73%) with perfusion/thickening mismatch showed significant improvement in regional wall motion, whereas improvement in regional wall motion was observed in 22 of 108 segments (20%) with matched abnormal segments and 6 of 41 segments (15%) with matched normal segments. Segments with perfusion/thickening mismatch had a significantly higher incidence of regional functional improvement than did matched abnormal or matched normal segments (chi2=42.3, P<0.01). Thus, by estimating both perfusion and wall thickening, single-injection resting ECG gated SPET imaging with 99mTc-tetrofosmin early after primary PTCA can predict recovery of regional wall motion after successful reperfusion.