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Transient ischemic dilation (TID) ratio of the left ventricle following stress, when accompanied by abnormal perfusion, is associated with severe coronary artery disease (CAD). The aim of this study is to assess the hypothesis that TID ratio is useful in screening patients who may be optimal coronary artery bypass surgery candidates in the contemporary intervention era.
Medical records of all patients undergoing gated single photon emission computed tomography (G-SPECT) myocardial perfusion imaging (MPI) at our institution between September 2010 and December 2013 were reviewed. Patients with no history of revascularization who underwent coronary angiography within 3 months of G-SPECT MPI were included in this study. Obstructive CAD was defined as a ≧ 50% LMT lesion or a ≧ 70% major epicardial coronary artery. The operator scoring TID ratio was blind to the CAD status of the patients. Receiver operating characteristic (ROC) curve analysis was performed to derive the optimal cutoff of TID ratio.
A total of 256 out of the 4004 patients who underwent MPI during the study period were included (54% male; mean age 66±14 yrs). Of the 256 patients, 78 patients were found to have obstructive CAD (Table 1). ROC analysis indicates a cutoff value of 1.15 confers 80% sensitivity and 77% specificity for LMT disease + three vessel CAD (group 1), 100% sensitivity and 39% specificity for three-vessel CAD with diabetes (group 2), respectively. Area under the curve was 0.802 (95%CI 0.666-0.937) and 0.709 (95% CI 0.567-0.852) for group 1 and group 2, respectively.
In conclusion, TID ratio obtained through G-SPECT is useful in identifying patients with high-risk CAD who may be optimal coronary artery bypass surgery candidates.