Low septal to lateral wall 18F-FDG ratio is highly associated with mechanical dyssynchrony in non-ischemic CRT candidates

Abstract

BackgroundIn order to better understand the concept of mechanical dyssynchrony, a promising hallmark of cardiac resynchronization therapy (CRT) response, we investigated its effect on regional myocardial metabolism and myocardial blood flow (MBF) in non-ischemic CRT candidates.ResultsThirty consecutive non-ischemic CRT eligible patients underwent static 18F-FDG and resting dynamic 13N-NH3 PET/CT. 18F-FDG uptake and MBF for septal and lateral wall were analysed and septal-to-lateral wall ratios (SLR) were calculated. Based on the presence of mechanical dyssynchrony (septal flash and/or apical rocking) on echocardiography, patients were divided into 2 groups, with (n\u2009=\u200923) and without (n\u2009=\u20097) mechanical dyssynchrony.Patients with mechanical dyssynchrony had significantly lower 18F-FDG SUVmean in the septum compared with the lateral wall (5.58\u2009±\u20092.65 vs 11.19\u2009±\u20094.10, p\u2009<\u20090.0001), while patients without mechanical dyssynchrony had a more homogeneous 18F-FDG distribution (7.33\u2009±\u20092.88 vs 8.31\u2009±\u20092.50, respectively, p\u2009=\u20090.30). Similarly, MBF was significantly different between the septal and lateral wall in the dyssynchrony group (0.57\u2009±\u20090.11\u2009ml/g/min vs 0.92\u2009±\u20090.23\u2009ml/g/min, respectively, p\u2009<\u20090.0001), whereas no difference was observed in the non-dyssynchrony group (0.61\u2009±\u20090.23\u2009ml/g/min vs 0.77\u2009±\u20090.21\u2009ml/g/min, respectively, p\u2009=\u20090.16). 18F-FDG SLR, but not MBF SLR, was associated with the presence of mechanical dyssynchrony and showed a significant inverse correlation with volumetric reverse remodeling after CRT (r\u2009=\u2009−\u20090.62, p\u2009=\u20090.001).ConclusionsNon-ischemic heart failure patients with mechanical dyssynchrony demonstrate heterogeneous regional metabolism and MBF compared with patients without dyssynchrony. However, only 18F-FDG SLR appeared to be highly associated with the presence of mechanical dyssynchrony.Trial registrationClinicaltrials, NCT02537782. Registered 2 September 2015.