Accuracy of technetium-99m tetrofosmin myocardial perfusion imaging in thedetection of spontaneous recanalization in patients with acute anterior myocardial infarction

To avoid the haemorrhagic risk of unnecessary thrombolysis in acute myocard ial infarction (MI), early and precise diagnosis of spontaneous recanalizat ion (SR) of the infarct-related artery is required. To clarify the accuracy of technetium-99m tetrofosmin myocardial single-photon emission tomography (SPET) in the detection of SR in patients with acute anterior MI, electroc ardiography (ECG), echocardiography and Tc-99m-tetrofosmin SPET imaging wer e performed in 49 patients with acute anterior MI before emergency coronary angiography. Defect score was calculated as the sum of the perfusion defec ts of each segment: from 3 (complete defect) to 0 (normal perfusion). Echoc ardiographic asynergic score (the sum of asynergic grades) and the greatest ST elevation of the 12-lead ECG on admission were also measured. SR was de fined as Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow on emerg ency coronary angiography, Defect score in 11 patients with SR (9.2 +/-3.7) was significantly lower than that in 38 patients without SR (18.5 +/-5.0) (P<0.001), whereas there were no significant differences in asynergic score and ST elevation between the two groups. From the receiver operating chara cteristic curves, the optimal cut-off points of defect score, asynergic sco re and ST elevation for the detection of SR were calculated to be 12, 13 an d 3.5, respectively. The sensitivity and specificity of the scintigraphic d efect score (91% and 89%) were significantly higher than those of the asyne rgic score (64% and 68%) and ST elevation (73% and 71%). Thus, Tc-99m-tetro fosmin SPET imaging on admission is a very accurate method for the detectio n of SR in patients with acute anterior MI.