Clinical value of gated MPI phase histogram in patients with chronic total occlusive coronary artery disease

Objective: To evaluate the clinical value of phase diagrams in G-MPI for patients with chronic total occlusive coronary artery disease (CTO). Methods: Twenty-one CTO patients (all males, average age: 56.6 years, age range: 37-77 years) from CTO Club of China in 2012 were retrospectively analyzed. ⁹⁹Tc^m-MIBI myocardial perfusion and ¹⁸F-FDG myocardial metabolic imaging were performed. Patients were divided into normal group with LVEF > 60% (n = 11) and abnormal group with LVEF ≤ 60% (n = 10). Differences of LVEF, perfusion/metabolic deficit and synchrony were compared by two-sample t test or Wilcoxon rank sum test. Correlations between LVEF and synchrony were analyzed by linear correlation analysis in all CTO patients. The synchrony parameters included peak phase, phase standard deviation (SD), phase histogram bandwidth, skewness and kurtosis. Results: The history of occlusion for the 21 patients ranged from 3 to 60 months. In all CTO patients, the phase SD and bandwidth were higher than the healthy reference values: ((30.8 ± 28.3)° vs (14.2 ± 5.1)°, t = 3.09; (58.1 ± 39.4)° vs (38.7 ± 11.8)°, t = 2.61, both P < 0.05). LVEF was negatively correlated with the phase SD and bandwidth (r = -0.785, -0.883, both P < 0.01) but positively correlated with phase histogram skewness and kurtosis (r = 0.755, 0.666, both P < 0.01). Higher LVEF value was shown in normal group than that in group((69.3 ± 4.7)% vs (44.7 ± 13.0)%, t = -5.65, P < 0.01). The perfusion deficit in normal group (4.0%) was lower than that in abnormal group (16.0%) (Z = -2.23, P < 0.05) while the metabolic deficit of the two groups was similar (Z = -1.82, P > 0.05). The phase SD and bandwidth were lower in normal group than those in abnormal group ((18.7 ± 19.0)° vs (44.2 ± 31.6)°, t = 2.21; (36.4 ± 12.7)° (82.1 ± 45.4)°, t = 3.08, both P < 0.05) and skewness and kurosis were higher in normal group than those in abnormal group (5.11 ± 0.75 vs 3.55 ± 1.05, t = -3.89; 30.77 ± 10.49 vs 15.66 ± 10.12, t = -3.35, both P < 0.01). Conclusions: The left ventricle synchrony was significantly worse in patients with CTO than that in normal individuals. The phase histogram could be used to estimate the the contractile function of left ventricle in the patients with CTO. (authors)