Systemic Inflammation and Recurrence After Atrial Fibrillation-Related Stroke: An Individual Participant Data...

The residual recurrence risk after atrial fibrillation (AF)-related stroke is high despite anticoagulation, thereby necessitating new therapies. The importance of inflammation in AF is increasingly recognized. However, patients with AF-related stroke were excluded from recent trials of anti-inflammatory therapies. It is uncertain whether associations between IL-6/high-sensitivity C-reactive protein (hsCRP) and poststroke recurrence are modified by AF status. In this study, we aimed to analyze the association between IL-6/hsCRP and recurrence according to AF history.

We leveraged individual participant data from studies identified by systematic review. We analyzed associations between IL-6/hsCRP and recurrent stroke/major adverse cardiovascular events (MACEs) (defined as fatal or nonfatal recurrent stroke or major coronary events) using multivariable Cox regression analyses (conditional logistic regression for 1 study) adjusted for age, sex, index event, cardiovascular risk factors, and medication use, stratified by AF status.

Data from 11 prospective studies with 10,080 patients (2,134 with AF, mean age 70 years, 59.3% male) were included. During 21,080 person-years of follow-up, 1,677 patients had MACEs and 1,342 had recurrent stroke. Inflammatory markers were higher in patients with AF, irrespective of stroke severity and timing of measurement, with elevated levels persisting well beyond the acute phase. hsCRP was associated with recurrent MACEs in patients with AF (adjusted risk ratio [aRR] 1.14, 95% CI 1.04-1.25, per log_e-unit increase) and without AF (aRR 1.08, 1.03-1.13) (P_interaction 0.30). There were similar associations on per-quarter analysis in patients with AF (aRR 1.51, 1.04-2.18) and without AF (aRR 1.32, 1.10-1.59) (Q4 vs Q1). No association was observed between hsCRP and recurrent stroke in either group. For IL-6, there was no evidence of interaction according to AF status for MACEs (P_interaction 0.57) or recurrent stroke (P_interaction 0.82). The aRR per log_e unit for MACE was 1.17 (1.07-1.27) in patients without AF and 1.10 (0.91-1.34) in those with AF. The corresponding aRR for recurrent stroke was 1.15 (1.05-1.25) and 1.12 (0.91-1.37) in patients without and with AF, respectively.

These data highlight the importance of inflammatory mechanisms in vascular recurrence irrespective of AF, provide rationale for the inclusion of patients with AF in trials of anti-inflammatory therapy, and support a selection approach in future trials based on elevated inflammatory marker levels, rather than stroke etiology alone.