Mediating effect of subclinical inflammation on the process of morning hypertension leading to atrial fibrillation in community-based older adults

Background The impacts and mechanisms of morning hypertension (MHT) on the risk of new-onset atrial fibrillation (AF) in the elderly have not been clarified. We aimed to investigate an association between MHT and new-onset AF and explore a mediating effect of subclinical inflammation on this association. Methods From 2008 to 2010, 1789 older adults aged ≥60 years were recruited in Shandong area, China. Morning blood pressure (BP) was assessed using 24-hour ambulatory BP monitoring. MHT was defined as BP ≥ 135/85 mm Hg during the period from wake time to 0900 a.m. Subclinical inflammation was assessed by hypersensitive C-reactive protein (hsCRP), tumor necrosis factor-alpha (TNF-α), systemic immune-inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and galectin-3. New-onset AF was rated during the follow-up period. Results Over an average 129.0 [standard deviation (SD): 21.58] months of follow-up, the hazard ratio of new-onset AF in MHT patients was 1.39 (95% confidence interval: 1.01 to 1.91) compared with non-MHT participants (Padjusted = 0.027). The risk of new-onset AF was 1.17-fold with one-SD increment of morning systolic BP. Subclinical inflammation was significantly associated with new-onset AF. The hazard ratios of new-onset AF were 2.29, 2.04, 2.08, 2.08, 2.03, and 3.25 for one-SD increment in hsCRP, TNF-α, SII, NLR, PLR, and galectin-3, respectively (Padjusted < 0.001). The analysis showed that hsCRP, TNF-α, SII, NLR, PLR, and galectin-3 separately mediated the process of MHT inducing new-onset AF (Padjusted < 0.05). Conclusions MHT is associated with an increased risk of new-onset AF. The subclinical inflammation might play a mediating role in this association.