A novel software to quantify LV dyssynchrony in ECG-gated myocardial perfusion SPECT for the management of cardiac resynchronization therapy

Objectives Assessment of LV dyssynchrony has a pivotal role in predicting the positive response to cardiac resynchronization therapy (CRT) as revealed by echocardiographic studies. We developed a new software to quantify LV dyssynchrony in ECG-gated myocardial perfusion SPECT (GMPS) and evaluated its utility for the management of CRT.

Methods Thirty-one patients with chronic heart failure underwent GMPS with 16 frames per cardiac cycle before and 6-month after CRT. LVESV and LVEF were calculated by QGS software. We generated regional myocardial time-activity curves per cardiac cycle reflecting the serial changes in wall thickness for 20 myocardial segments, and measured the time from R-wave to the maximum-count point (time to end-systole; TES) in each segment. We used the maximum difference in TES among 20 segments corrected for R-R time as dyssynchrony index (DI) and calculated coefficient variation (CV) of TES of 20 segments.

Results The patients were divided into 2 groups, CRT responders (Gp-A; 16 cases) with EF increase≥10% or ESV decrease≥10% and CRT non-responders (Gp-B; 15 cases). Pre-CRT DI was significantly higher in Gp-A than in Gp-B (65.7±25.9 vs. 46.9±18.5, P<0.05), and pre-CRT CV of TES was also significantly higher in Gp-A than Gp-B (0.40±0.19 vs. 0.24±0.12, P<0.05). After CRT therapy, CRT responders showed improvement of DI and CV in association with LV functional improvement.

Conclusions Our newly developed software which allows the quantification of LV dyssynchrony in GMPS is helpful for the decision-making and effect-evaluation of CRT.