Use of phase analysis of gated SPECT perfusion imaging to quantify dyssynchrony in patients with mild-to-moderate left ventricular dysfunction.

BACKGROUND: CRT has been shown to be beneficial in the majority of patients with NYHA class III-IV symptoms, prolonged QRS duration, and an EF < or =35%. The use of imaging modalities to quantify dyssynchrony may help identify patients who may benefit from CRT, but do not meet current selection criteria. We hypothesize that patients with mild-to-moderate LV dysfunction have significant degrees of mechanical dyssynchrony. METHODS: We compared phase analysis measures of mechanical dyssynchrony from gated SPECT imaging in patients with mild-to-moderate LV dysfunction (EF 35-50%, n = 93), with patients with severe LV dysfunction (EF < or = 35%, n = 167), and with normal controls (EF > or = 55%, n = 75). Furthermore, we evaluated the relationships between QRS duration and dyssynchrony and determined the prevalence of dyssynchrony in patients with mild-moderate LV dysfunction. RESULTS: Patients with mild-moderate LV dysfunction have more dyssynchrony than normal controls (phase SD 37.7 degrees vs 8.8 degrees , P < .001 and bandwidth 113.5 degrees vs 28.7 degrees , P < .001), but less dyssynchrony than patients with severe LV dysfunction (phase SD 37.7 degrees vs 52.0 degrees , P < .001 and bandwidth 113.5 degrees vs 158.2 degrees , P < .001). In the cohort of patients with LV EF 35-50%, there were only weak correlations between QRS duration and dyssynchrony (phase SD, r = 0.28 and bandwidth, r = 0.20). There were 73 patients with LVEF 35-50% and QRS duration <120 milliseconds of which 21 (28.8%) had mechanical dyssynchrony. Overall, 37% of patients with mild-to-moderate LV dysfunction had significant degrees of mechanical dyssynchrony. CONCLUSIONS: This is the largest reported study evaluating mechanical dyssynchrony in patients with mild-moderate LV dysfunction using phase analysis of gated SPECT imaging. In this study, approximately one-third of patients with mild-to-moderate LV dysfunction had significant LV mechanical dyssynchrony. With further study, phase analysis of gated SPECT imaging may help improve patient selection for CRT.

Duke Scholars

Author Zainab Samad Medicine, Cardiology

Author Salvador Borges-Neto Radiology, Nuclear Medicine