Insular abnormalities in F-fluorodeoxyglucose positron emission tomography and risk of fatal ventricular arrhythmic events in patients with cardiac sarcoidosis.

Introduction: A clinical significance of extra-cardiac uptake of F-fluorodeoxyglucose positron emission tomography (F-FDG-PET), particularly in the brain, is unclear in cardiac sarcoidosis (CS).

Methods And Results: We analysed data from 84 CS patients (mean age 58.3 years, 70.2 % woman) who underwent F-FDG-PET scans, including brain imaging, between May 2008 and December 2021, with follow-ups completed in July 2023. Brain F-FDG-PET images were processed using SPM12 software, with regional brain F-FDG uptake normalised to whole-brain uptake. Voxel-wise analysis identified the left insula, whose F-FDG uptake was lower in patients who experienced fatal ventricular arrhythmic events (FVAE) (N = 30) compared to those without FVAE (N = 54) (1.15 ± 0.06 vs. 1.20 ± 0.06, P < 0.001). Kaplan-Meier curve analysis showed that patients with lower left-insular F-FDG uptake (<1.18) had a higher FVAE incidence compared to those with higher uptake (≥1.18) (P = 0.003). Cox proportional hazard analysis demonstrated that the FVAE risk decreased with a hazard ratio of 0.538 (95 % confidence interval 0.359-0.808) for every 1 standard deviation increase in left-insular F-FDG uptake (P = 0.003). Combining both cardiac and brain F-FDG uptakes allowed a better discrimination of FVAE risk.

Conclusions: Brain F-FDG-PET, particularly evaluating the left insular cortex involved in parasympathetic regulation, may help to assess the FVAE risk in CS patients.