Association of Autoantibodies against M2-Muscarinic Acetylcholine Receptor with Atrial Fibrosis in Atrial Fibrillation Patients

Abstract EN

Objectives.

To investigate the association of serum autoantibodies against M2-muscarinic acetylcholine receptor (anti-M2-R) with atrial fibrosis in long-standing persistent atrial fibrillation (AF) patients.

Methods.

Twenty-four long-standing persistent AF patients, scheduled to undergo hybrid ablation surgery, were enrolled in the study.

Twenty-six patients with sinus rhythm, scheduled to undergo coronary artery bypass grafting surgery, were enrolled into the non-AF group.

We detected serum anti-M2-R levels.

Left atrial appendages were subjected to histological and molecular biological assays.

Patients in the AF group received follow-up for two years.

Results.

The AF group showed significantly higher serum anti-M2-R levels compared to the non-AF group (496.2 ± 232.5 vs.

86.3 ± 25.7 pmol/L, p<0.001).

The AF group exhibited severe fibrosis in the left atrial appendages, as indicated by increased collagen volume fraction (45.2 ± 4.7% vs.

27.6 ± 8.3%, p<0.001), and higher levels of collagen I (0.52 ± 0.04 vs.

0.24 ± 0.06, p<0.001) and collagen III (0.51 ± 0.07 vs.

0.36 ± 0.09, p<0.001).

TGF-β1 and CTGF were also upregulated in the AF group.

A positive correlation between serum anti-M2-R levels and fibrosis of the left atrial appendage and fibrogenic indexes was observed.

Conclusions.

Serum anti-M2-R levels are higher in AF patients and are associated with the severity of atrial fibrosis.

In addition, serum anti-M2-R levels are positively correlated to TGF-β1 and CTGF expression in the left atrial appendage.