Right atrial endomysial fibrosis is associated with higher POAF-burden

Abstract Background Atrial endomysial fibrosis, rather than overall connective tissue content, determines the complexity of conduction in human atrial fibrillation (AF). Moreover, the AF-specific blood biomarker BMP10 is associated with atrial endomysial fibrosis, but not overall connective tissue content. It is unclear whether pre-operative atrial endomysial fibrosis predicts post-operative AF (POAF) incidence and burden. Objective To determine the predictive value of atrial fibrosis for early and late POAF burden. Methods Patients with and without AF history were included in the RACE V tissue bank study (n=134). Post-operative rhythm was monitored continuously for 2.5 years with implantable loop recorders. Late POAF-burden was investigated following a 90-day blanking period. Left (n=89) and/or right (n=92) atrial appendage biopsies (LAA/RAA) were snap-frozen and histologically investigated following WGA-staining. Results Logistic regression, corrected for age, sex and AF history, showed that left (st.β = 0.54 [0.23-0.85], p=0.001) and right (st.β=0.35 [0.07-0.64], p=0.017) atrial endomysial fibrosis were associated with early POAF burden in the blanking period. Only right atrial endomysial fibrosis, however, predicted late POAF-burden (st.β=0.44 [-], p=0.009). Adjusted Cox proportional hazards analyses indicated that patients in the highest tertile of right atrial endomysial fibrosis, in particular, are at risk for late POAF (HR T3 vs T1: 2.47 [1.18-5.17], p=0.016, Fig 1). Overall connective tissue content in both atria was not associated with POAF-burden. Conclusion Patients with higher levels of right atrial endomysial fibrosis are at risk for developing late POAF with a higher POAF-burden.Figure 1