Increased Right Atrial FDG Uptake in Persistent Atrial Fibrillation: Insights Across Young vs. Old Age Groups

BACKGROUND AND OBJECTIVES: The atrial metabolic profile and underlying pathophysiology of young-onset atrial fibrillation (AF) may differ from those of old-onset AF, but age-related alterations in atrial metabolism remain poorly understood. We explored potential age-related atrial metabolic differences using ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging. METHODS: We prospectively performed FDG PET with myocardial suppression in 40 young-onset and 40 old-onset AF patients. FDG uptake of the right and left atrium (RA and LA) was assessed visually (grade 0-3) and quantitatively using target-to-background ratio (TBR). RESULTS: The mean age was 59.3±13.5 (young-onset, 47.0±5.2; old-onset, 71.6±5.5) years, with a median AF duration of 3.6 (0.8-6.8) years. Among 80 patients (41 paroxysmal, 39 persistent AF), the distribution of AF type was similar between age groups (p=0.121). A total of 51 patients (63.7%) showed atrial FDG uptake ≥mild (grade≥1). No significant age-related differences were observed in visual FDG uptake or TBR in either atrial wall or appendage. Current drinking and persistent AF type were independently associated with increased atrial FDG uptake, primarily in the RA. Persistent AF was consistently associated with elevated RA uptake across age groups (adjusted odds ratio, 10.2, 95% confidence interval, 1.9-55.3; p=0.007). Quantitative analysis revealed significantly higher RA-to-LA metabolic ratios in persistent AF, consistent across age groups. CONCLUSIONS: Atrial FDG uptake patterns did not differ by age in patients with AF. Increased RA FDG uptake in persistent AF was consistently observed, suggesting a shared metabolic alteration underlying AF progression transcending age-related pathological differences.