Systemic inflammatory indices, cardiac conduction disorders, and atrial fibrillation: Phenotype-specific associations and incremental discrimination in the China National Health Survey (CNHS).

BACKGROUND

Systemic inflammation may influence cardiac electrophysiology, but evidence on phenotype-specific links with ECG-defined conduction disorders and atrial fibrillation (AF) in China is limited.

METHODS

We performed a cross-sectional analysis of 10,303 adults in the China National Health Survey. Nine inflammatory markers (neutrophils, lymphocytes, monocytes, platelets, hsCRP, NLR, SII, SIRI and PIV; log-transformed and standardized) were related to ECG-defined right bundle branch block (RBBB), intraventricular conduction delay (IVCD), left bundle branch block (LBBB), left anterior fascicular block (LAFB), atrioventricular block (AVB) and AF. Associations were estimated with Firth-penalised logistic regression with multivariable adjustment and false discovery rate control. Incremental discrimination beyond covariates was assessed by 10-fold cross-validated area under the curve (AUC).

RESULTS

LBBB showed the strongest pattern: lymphocytes were inversely associated (odds ratio [OR] 0.65, 95% CI 0.50-0.84), while neutrophils (OR 5.39, 4.05-7.29), SIRI (OR 4.24, 3.34-5.44), and SII (OR 6.93, 5.17-9.52) were positively associated. LAFB and AF displayed similar signals (LAFB: lymphocytes OR 0.68, 0.55-0.86; NLR OR 1.66, 1.34-2.05; AF: monocytes OR 2.30, 1.79-2.94; SIRI OR 2.42, 1.92-3.03). RBBB showed modest links (NLR OR 1.15, 1.03-1.27); IVCD and AVB were largely null. Composite indices improved discrimination beyond covariates: SIRI yielded ΔAUC +0.163 for LBBB (final AUC 0.923), +0.098 for AF, and +0.041 for LAFB; gains for RBBB/IVCD/AVB were negligible. Sex interactions were significant: neutrophil and SIRI effects were stronger in men with LBBB (P-interaction 0.032/0.038), while lymphocytes were more protective in women with AF (OR 0.51, 0.36-0.73; P-interaction 0.001).

CONCLUSIONS

Systemic inflammation showed phenotype-specific associations with ECG-defined conduction disorders and atrial fibrillation. Low-cost composite indices-especially SIRI-substantially improved discrimination of prevalent LBBB, LAFB, and AF beyond clinical covariates; prospective studies are needed to clarify temporality, validate thresholds, and assess clinical utility.