Inflammation and day-to-day occurrence of atrial fibrillation

Inflammation is central in atrial fibrillation (AF) pathophysiology, but the temporal association between inflammatory activity and AF remains uncertain. This study investigated the day-to-day relationship between plasma C-reactive protein (CRP) levels and AF occurrence in continuously monitored individuals.

Post hoc analysis of the LOOP study randomizing participants with stroke risk factors to implantable loop recorder (ILR) screening (n = 1501) or usual care. ILR raw data were linked to blood samples collected within 1 day. The outcome was AF episodes lasting ≥60 min. Associations were examined using generalized and linear mixed models and as a self-controlled case series (SCCS). ILR and CRP data were available for 1065 participants combining >1.2 million days of heart rhythm monitoring (including ∼40 000 days with AF) with >7000 CRP measurements. CRP was higher during days with AF (geometric mean 8.37 [7.11–9.86] mg/L) vs. non-AF days (4.02 [3.71–4.35] mg/L). Each doubling of CRP was associated with 36% higher odds of AF (adjusted odds ratio [aOR] 1.36 [1.26–1.47]). Compared with CRP ≤3 mg/L, the odds of AF increased for CRP >10–50 and >50 mg/L (aOR 3.50 [2.18–5.60] and 5.75 [3.48–9.50], respectively). In SCCS analyses, CRP >10 mg/L was associated with higher incidence of AF compared to lower levels (incidence rate ratio 2.41 [1.53–3.80]).

This exploratory study found a temporal and dose–response relationship between CRP levels and AF occurrence, supporting inflammation as an acute trigger and underscoring the need to evaluate inflammatory markers as potential targets in AF management.

ClinicalTrials.gov, identifier: NCT02036450.