Physical Activity Modifies the Risk of Incident Cardiac Conduction Disorders Upon Inflammation: A Population-Based...

Emerging evidence suggests a central role for inflammation in cardiac conduction disorder (CCD). It is unknown whether habitual physical activity could modulate the inflammation-associated risks of incident CCD in the general population.

This population-based cohort was derived from the China Kailuan study, including a total of 97 192 participants without prior CCD. The end points included incident CCD and its subcategories (atrioventricular block and bundle-branch block). Systemic inflammation was indicated by the monocyte-to-lymphocyte ratio (MLR). Over a median 10.91-year follow-up, 3747 cases of CCD occurred, with 1062 cases of atrioventricular block and 2697 cases of bundle-branch block. An overall linear dose-dependent relationship was observed between MLR and each study end point (all P-nonlinearity≥0.05). Both higher MLR and physical inactivity were significantly associated with higher risks of conduction block. The MLR-associated risks of developing study end points were higher in the physically inactive individuals than in those being physically active, with significant interactions between MLR levels and physical activity for developing CCD (P-interaction=0.07) and bundle-branch block (P-interaction<0.05) found. Compared with those in MLR quartile 2 and being physically active, those in the highest MLR quartile and being physically inactive had significantly higher risks for all study end points (1.42 [95% CI, 1.24-1.63], 1.62 [95% CI, 1.25-2.10], and 1.33 [95% CI, 1.13-1.56], respectively, for incident CCD, atrioventricular block, and bundle-branch block).

MLR should be a biomarker for the risk assessment of incident CCD. Adherence to habitual physical activity is favorable for reducing the MLR-associated risks of CCD.