Visualization of intensive atrial inflammation and fibrosis after cryoballoon ablation: PET/MRI and LGE‐MRI analysis

BACKGROUND: Atrial inflammation plays an important role in initiating atrial fibrosis, which could perpetuate atrial fibrillation (AF). However, the method of visualization of atrial inflammation has not been established. We sought to investigate whether the intensive atrial inflammation caused by cryoballoon ablation (CBA) could be detected by positron emission tomography/ magnetic resonance imaging (PET/MRI) and whether the atrial inflammation could be associated with consequent fibrosis. METHODS: A total of 10 paroxysmal atrial fibrillation patients after CBA were enrolled. To detect and quantify intensive atrial inflammation, PET/MRI was performed to assess regional (18)F‐fluorodeoxyglucose ((18)F‐FDG) uptake one day after the CBA, and the standardized uptake values (SUV) max were compared between the pulmonary vein (PV) antrum where CBA could be applied and the healthy left atrial (LA) wall where CBA could not be applied. Furthermore, the atrial inflammation one day after the procedure and atrial fibrosis areas one month after the procedure were three‐dimensionally quantified by PET/MRI and late‐gadolinium enhancement magnetic resonance imaging (LGE‐MRI), respectively. RESULTS: The mean SUV max at the PV antrum was significantly higher than that on the healthy LA wall (2.12 ± 0.35 vs 1.73 ± 0.30, P = .00021). The volume of the atrial inflammation strongly correlated with that of the atrial fibrosis (r = .94 [.76‐.99], P = .00006). CONCLUSIONS: The atrial inflammation after CBA could be detected by PET/MRI. CBA‐induced atrial inflammation was strongly associated with consequent lesion maturation.