Gated SPECT Phase Analysis of Abnormal Left Ventricular Wall Motion Polar Maps in Patients With Normal Perfusion, Normal Global Function, and Low Pretest Probability of Ischemic Heart Disease

Background: One of the probable reasons for wall motion polar map abnormalities is left ventricular (LV) dyssynchrony. The objective of this study was to evaluate LV dyssynchrony via the phase analysis on myocardial perfusion imaging (MPI) in patients with a low pretest probability of ischemic heart disease (IHD) and normal electrocardiography (ECG)-gated MPI as the possible contributor to LV regional wall motion polar map abnormalities. Methods: A total of 181 patients with a low likelihood of IHD, normal MPI, a normal global function, and a normal global ejection fraction were divided into 2 groups: Group A: 81 patients with abnormal regional wall motion and Group B: 100 patients with normal wall motion polar maps. Dyssynchrony in the LV wall was assessed in terms of the phase analysis indices of entropy, the phase histogram bandwidth, and the phase standard deviation quantified by quantitative gated SPECT software, and the results for both groups were compared. Results: The mean entropy values in the LV anterior, lateral, inferior, and particularly septal walls (P < 0.0001), as well as the mean entropy value in the LV apical wall (P = 0.030), in Group A were significantly higher than those in Group B. Moreover, the phase histogram bandwidth and the phase standard deviation were considerably higher in Group A than in Group B in all LV walls (P < 0.0001), except the LV apical wall (P = 0.063 and P = 0.036) respectively. Conclusions: Assessment of the phase analysis indices for LV dyssynchrony could be used in patients with a low probability of IHD, a normal LV perfusion, and abnormal wall motion polar maps as a complementary tool for the interpreting physician.