COMBINED THALLIUM-201 TECHNETIUM 99M-LABELED PYROPHOSPHATE TOMOGRAPHYFOR IDENTIFICATION OF THE CULPRIT VESSEL IN ACUTE MYOCARDIAL-INFARCTION

Background. Many previous investigations have used the presence of tra nsient ischemic (TI)-T-201 perfusion defect to localize coronary arter y stenosis. This study reports the results of (TI)-T-201 tomography al one and combined (TI)-T-201/Tc-90m-labeled pyrophosphate (Tc-90m PYP) tomography employed to identify the infarct-related vessel in patients with acute myocardial infarction (AMI).Methods and Results. All short -axis images were evaluated by dividing each left ventricular slice in to eight equal sectors. In addition, for combined (TI)-T-201/Tc-90m PY P tomography, two sectors were added to evaluate involvement of the ri ght ventricle. In a preevaluation phase of the study, the sectors were assigned to the supplying coronary arteries in 75 patients with singl e chronic myocardial infarction related to the left anterior descendin g coronary artery (LAD), left circumflex artery (LCX), or right corona ry artery (RCA). In this pilot phase, (TI)-T-201 tomograms were review ed in conjunction with the angiographic data. This assignment was then tested prospectively in 117 patients with AMI. As confirmed by angiog raphy, the AMI was related to the LAC, LCX, and RCA in 54, 17, and 46 patients, respectively. Sensitivity and specificity for Tc-90m PYP acc umulation on combined (TI)-T-201/Tc-90m PYP tomography were 98% a nd 1 00% for the LAD, 88% and 99% for the LCX, and 98% and 96% for the RCA, respectively. For (TI)-T-201 tomography, sensitivity and specificity for identification of the culprit vessel were 94% and 89% for the LAD, 82% and 91% for the LCX, and 72% and 96% for the RCA, respectively. C onclusion. This prospective study demonstrates that combined (TI)-T-20 1/Tc-90m PYP tomography is highly accurate for identification of the i nfarct-related artery in AMI, even in patients with multivessel diseas e. Positive contrast visualization of myocardial necrosis in both the left and right ventricle allows for reliable differentiation between A MI I elated to the LCX or RCA territory. In comparison, for (TI)-T-201 tomography the sensitivity to detect the culprit vessel, particularly the LCX and RCA, appears to be lower than fur (TI)-T-201/Tc-90m PYP i maging, particularly in patients with prior infarction or right domina nt coronary artery.