Degree of Fibrosis in Human Atrial Tissue Is Not the Hallmark Driving AF.

BACKGROUND: The current paradigm is that fibrosis promotes electrophysiological disorders and drives atrial fibrillation (AF). In this current study, we investigated the relation between the degree of fibrosis in human atrial tissue samples of controls and patients in various stages of AF and the degree of electrophysiological abnormalities. METHODS: The degree of fibrosis was measured in the atrial tissue and serum of patients in various stages of AF and the controls. Hereto, picrosirius and H&E staining were performed to quantify degree of total, endo-perimysial fibrosis, and cardiomyocyte diameter. Western blot quantified fibrosis markers: neural cell adhesion molecule, tissue inhibitor of metalloproteinase, lysyl oxidase, and α-smooth muscle actin. In serum, the ratio carboxyl-terminal telopeptide of collagen/matrix-metalloproteinase1 was determined. High-resolution epicardial mapping evaluated low-voltage areas and conduction abnormalities. RESULTS: No significant differences were observed in the degree of fibrosis between the groups. Finally, no significant correlation-absolute nor spatial-was observed between all electrophysiological parameters and histological fibrosis markers. CONCLUSIONS: No differences in the degree of fibrosis were observed in patients from various stages of AF compared to the controls. Moreover, electrophysiological abnormalities did not correlate with any of the fibrosis markers. The findings indicate that fibrosis is not the hallmark of structural remodeling in AF.

Blood-based 8-hydroxy-2'-deoxyguanosine level: A potential diagnostic biomarker for atrial fibrillation.

BACKGROUND: Recent research findings have revealed a key role of oxidative DNA damage in the pathogenesis of atrial fibrillation (AF). Therefore, the circulating oxidative DNA damage marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) may represent a biomarker for staging AF and identifying patients at risk for AF recurrence and postoperative atrial fibrillation (POAF) after treatment. OBJECTIVE: The purpose of this study was to investigate whether serum levels of 8-OHdG correlate with the stage of AF, recurrence after AF treatment, and onset of POAF after cardiac surgery. METHODS: In this prospective observational study, 8-OHdG levels were detected by enzyme-linked immunosorbent assay in human serum samples. Blood samples were collected from control patients without AF history; patients with paroxysmal AF and persistent AF undergoing electrical cardioversion or pulmonary vein isolation (PVI); and patients with sinus rhythm (SR) undergoing cardiac surgery. AF recurrence was determined during 12-month follow-up. Univariate and multivariate analyses were used to identify changes in 8-OHdG levels between the groups. RESULTS: Compared to the control group, 8-OHdG levels in the patient groups gradually and significantly increased during arrhythmia progression. 8-OHdG levels in AF patients showing AF recurrence after PVI treatment were significantly increased compared to patients without AF recurrence. Moreover, in SR patients undergoing cardiac surgery, 8-OHdG levels were significantly elevated in those showing POAF compared to patients without POAF. CONCLUSION: 8-OHdG level may represent a potential diagnostic biomarker for AF staging as well as for predicting AF recurrence and POAF after treatment.