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 = 23) and without (n = 7) mechanical dyssynchrony.Patients with mechanical dyssynchrony had significantly lower 18F-FDG SUVmean in the septum compared with the lateral wall (5.58 ± 2.65 vs 11.19 ± 4.10, p < 0.0001), while patients without mechanical dyssynchrony had a more homogeneous 18F-FDG distribution (7.33 ± 2.88 vs 8.31 ± 2.50, respectively, p = 0.30). Similarly, MBF was significantly different between the septal and lateral wall in the dyssynchrony group (0.57 ± 0.11 ml/g/min vs 0.92 ± 0.23 ml/g/min, respectively, p < 0.0001), whereas no difference was observed in the non-dyssynchrony group (0.61 ± 0.23 ml/g/min vs 0.77 ± 0.21 ml/g/min, respectively, p = 0.16). 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 = − 0.62, p = 0.001).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.

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“…This concept of detecting viable or scarred tissue with PET might be challenging in patients with ventricular conduction abnormalities. In previous work, we have demonstrated a heterogeneous regional distribution of absolute myocardial perfusion and glucose metabolism in nonischemic CRT candidates [4,5]. In particular, a low 13 N-NH 3 -derived absolute myocardial blood flow (MBF) and 18 F-FDG uptake in the septum were observed with high values in the lateral wall, most likely representing a physiological adaptation of the heart to the alterations in myocardial workload and energy demands [6].…”