# Pathogenesis of Oxidative Stress Biomarkers in Atrial Fibrillation: A Narrative Review

## TL;DR

This paper reviews how oxidative stress contributes to atrial fibrillation and highlights specific biomarkers that may help understand and manage the condition.

## Contribution

The paper provides a comprehensive review of oxidative stress biomarkers and their roles in atrial fibrillation pathogenesis.

## Key findings

- Plasma 8-OHdG levels increase with atrial fibrosis severity, linking oxidative DNA damage to AF progression.
- Reduced GPx activity is associated with arrhythmogenic disturbances and oxidative lipid damage.
- Elevated 8-isoprostane levels are linked to thromboembolic events in AF patients on anticoagulants.

## Abstract

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia. Although its pathogenesis remains incompletely elucidated, accumulating evidence implicates oxidative stress (OS) as a key contributor to the development of the arrhythmogenic substrate. OS may facilitate atrial remodeling through modulation of calcium-handling proteins and ion channel function, potentially promoting the initiation and maintenance of AF. This article summarizes the role of OS biomarkers such as 8-hydroxydeoxyguanosine (8-OHdG), glutathione peroxidase (GPx), advanced glycation end-products (AGEs), superoxide dismutase (SOD), malondialdehyde (MDA), isoprostanes (IsoPs), derivatives of reactive oxidative metabolites that oxidize reduced glutathione (Eh GSH) and cysteine, and advanced oxidation protein products (AOPPs) in the pathogenesis of AF. Plasma 8-OHdG levels progressively increase with advancing low-voltage area stages, indicating a strong association between oxidative DNA damage and the severity of atrial fibrosis. Also, the reduction in GPx activity appears to contribute to arrhythmogenic electrochemical disturbances and oxidative lipid damage, independent of dyslipidemia. The receptor for the AGE axis plays a part in arrhythmogenic structural atrial remodeling. Patients who develop post-surgical AF demonstrate paradoxically elevated SOD activity, possibly reflecting a compensatory antioxidant response to heightened OS. As serum MDA levels were not linked to the development of postoperative AF (POAF), it is possible that lipid peroxidation is not the primary cause of POAF pathogenesis. Even when AF patients are receiving anticoagulant medication, elevated 8-isoprostane levels are linked to thromboembolic events, in part because of changes in the fibrin clot structure. Each 10% increase in Eh GSH was associated with a 40% increase in the risk of incident AF. Future research is required on AOPPs in AF pathogenesis. Future investigations should aim to identify and characterize novel OS markers and evaluate their potential therapeutic relevance in the prevention and management of AF.