Th1/Th17-Treg Imbalance in Asian Atrial Fibrillation: Subtype and Demographic Heterogeneity

Atrial fibrillation (AF) involves adaptive immune imbalance, particularly within T-cell subsets, yet systematic profiles in Asian cohorts remain limited.

The authors aimed to characterize peripheral adaptive immune dysregulation in Asian patients with AF and to examine heterogeneity across AF subtypes and demographics.

In this case-control study of 173 AF patients and 87 controls, cases were adults with electrocardiogram-confirmed AF recruited from the hospital; controls were participants undergoing routine examinations who were in sinus rhythm and had no structural heart disease. T-cell subsets were quantified by flow cytometry and serum cytokines by enzyme-linked immunosorbent assay. Multivariable logistic models, adjusted for left atrial diameter, left ventricular ejection fraction, and neutrophil-to-lymphocyte ratio, assessed associations of immune indices with AF.

AF was characterized by higher T helper (Th)1 and Th17 cell counts and percentages, with no significant difference in T regulatory cells (Tregs); accordingly, Th1/Treg and Th17/Treg ratios were higher (all P < 0.05). Systemic inflammatory markers (high-sensitivity C-reactive protein, interleukin-6) and effector cytokines (interferon-γ, interleukin-17A) were elevated in AF. In multivariable models, higher Th17 count (OR: 3.30; 95% CI: 1.27-8.53; P = 0.014) and Th1/Treg (OR: 4.20; 95% CI: 1.72-10.24; P = 0.002) were associated with AF. Immune alterations appeared broader in paroxysmal AF, whereas persistent AF showed a more selective Th1/Treg imbalance. Patterns were generally consistent across age, sex, and body mass index strata in exploratory analyses.

In this Asian cohort, AF was associated with an adaptive immune shift toward Th1/Th17 relative to Treg, with subtype-specific patterns. These associations are hypothesis-generating and warrant prospective, tissue-level studies to clarify mechanisms and clinical relevance.