What question did this study set out to answer?

To evaluate the relationship between atrial structural remodelling and atrial fibrillation across different types of mitral valvular diseases.

January 26, 2010EP Europace

Different structural remodelling in atrial fibrillation with different types of mitral valvular diseases

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To evaluate the relationship between atrial structural remodelling and atrial fibrillation across different types of mitral valvular diseases.
Obtained left atrial appendage tissue samples from 24 patients with mitral valvular disease undergoing mitral valve replacement surgery.
Assessed atrial fibrosis and ultrastructural alterations using Masson's trichrome staining, immunohistochemical staining, and electron microscopy.
Fibrosis significantly increased in patients with atrial fibrillation compared to those with sinus rhythm (P = 0.023).
Collagen volume fraction (P = 0.043) and Collagen Type I levels (P = 0.043) were significantly higher in mitral stenosis with atrial fibrillation than in mitral regurgitation with atrial fibrillation.
Matrix metalloproteinase-2 collagen volume fraction differed significantly between sinus rhythm and atrial fibrillation in mitral stenosis (P = 0.001), with fibrotic bands visibly separating cardiomyocytes under electron microscopy.

Structured PICO

Population

24 patients with mitral valvular diseases (MVDs) undergoing mitral valve replacement surgery

Comparator

Patients with sinus rhythm (SR) vs atrial fibrillation (AF); Mitral stenosis (MS) vs Mitral regurgitation (MR)

Outcome

Extent of fibrosis (collagen volume fraction, Collagen Type I levels, Matrix metalloproteinases-2) and ultrastructural changes in left atrial appendagessurrogate

Atrial structural remodelling and fibrosis severity differ significantly based on the type of mitral valvular disease and presence of atrial fibrillation.

Implication

Supports lesion-specific fibrosis assessment in mitral valve disease with AF; leaves open therapeutic targeting and clinical outcomes.

Abstract

AIMS: The aim of this study was to determine the relationship between atrial structural remodelling and atrial fibrillation (AF) for different types of mitral valvular diseases (MVDs). METHODS AND RESULTS: Left atrial appendages tissue samples were obtained from 24 patients with MVDs undergoing mitral valve replacement surgery. Masson's trichrome staining and immunohistochemical staining were performed to assess the extent of the fibrosis. Ultrastructural changes in left atrial appendages were examined by electron microscope. The degree of fibrosis showed significant increases in patients with AF compared with patients with sinus rhythm (SR) (P = 0.023). The collagen volume fraction (CVF) of fibrosis significantly increased in mitral stenosis and atrial fibrillation (MS-AF) compared with the mitral regurgitation and atrial fibrillation (MR-AF) group (P = 0.043). Collagen Type I levels were significantly increased in AF patients with mitral stenosis compared with AF patients with mitral regurgitation (P = 0.043). Different CVF of Matrix metalloproteinases-2 was present between the MS-SR group and the MS-AF group (P = 0.001). Electron microscopy revealed normally structured sarcomeres with a predominance of loosely packed cardiomyocytes in samples from patients with SR. Fibrotic bands, which tended to separate individual cardiomyocytes, were apparent in samples from patients with AF. CONCLUSION: Atrial structural remodelling is associated with AF patients with MVDs. Different heart rhythm statuses with different types of MVDs are associated with variable atrial structural remodelling. Different atrial structural remodelling is a mechanism that may contribute to the increased risk of AF with MVDs.