Abstract 5702: Oxidative Stress in Patients with Lone Atrial Fibrillation
Background: Lone atrial fibrillation (LAF) is a common arrhythmia, but its mechanism and the aggravated factor of arrhythmia are poorly understood. Oxidative stress has been implicated in the pathogenesis of heart failure. We have previously demonstrated that the amount of 4-hydroxy-2-nonenal (HNE) modified protein, which is a major lipid peroxidation product and a cytotoxic aldehyde, causes intracellular Ca2+ overload via reactive oxygen species (ROS) formation in cardiomyocytes and leads to develop arrhythmia. Accordingly we examined the levels of HNE and major histocompatibility complex (MHC) with the disease severity in LAF patients.
Method: Atrial and ventricular myocardial samples were obtained from twelve patients (11 men and 1 woman, mean 48±14 years old) by endomyocardial biopsy in 10, autopsy sample in 1 and surgical resection sample in 1. Histological assessments and immunohistochemical analysis for HNE modified protein, MHC class-I and -II antigens (grade 0 to 3) were performed and compared with LAF severity.
Results: Histological assessment showed that increased number of interstitial cells (mainly activated T cells) was observed only in the atrium but not in the ventricle. Moderate to severe expression of MHC antigens (grade 2 or 3) was more observed in the atrium than the ventricle (MHC-I: seven in atrium and three in ventricle; MHC-II: ten in atrium and four in ventricle). Atrial myocarditis was detected in 6 out of 11 samples. HNE modified protein was also more observed in the atrium than that in the ventricle. In addition, more severe expression of HNE staining was observed in the samples from persistent/chronic LAF than that in paroxysmal LAF.
Conclusion: These data indicates that oxidative stress plays an important role as an aggravating factor in LAF patients.