Regional left atrial interstitial remodeling in patients with chronic atrial fibrillation undergoing mitral-valve surgery

Abstract

Ablation of the left atrial free wall around the pulmonary vein ostia (LAFW) may be effective in the treatment of chronic atrial fibrillation associated with mitral disease (CAF-MVD). Using light and conventional electron microscopy analyses, we wanted to evaluate, in CAF-MVD, the interstitial remodeling in the LAFW as well as in a more remote region, such as the left atrial appendage (LAA). LAFW and LAA samples were obtained from 33 CAF-MVD patients during combined mitral surgery and radiofrequency ablation and from 16 autoptic controls. Interstitial fibrosis (IF) and perivascular fibrosis (PF), capillary densities and the maximal oxygen diffusion distance were morphometrically determined. In CAF-MVD patients, the LAFW, compared with the LAA, showed a higher percentage of IF (7.16+/-3.23% versus 2.51+/-1.40%, respectively), a lower myocardial capillary density per mm(2) (830+/-106 versus 989+/-173) and an increased oxygen maximal diffusion distance (19.70+/-1.27 microm versus 18.13+/-1.58 microm). All these values were also significantly different than controls. No differences were found in evaluating PF. At variance with the LAA, in CAF-MVD patients, the LAFW around the pulmonary vein ostia is a region characterized by a marked interstitial remodeling such that it may be morphologically indicated as an appropriate target for ablation treatment aimed at sinus rhythm restoration.

Myocardial sleeves of pulmonary veins and atrial fibrillation: a postmortem histopathological study of 100 subjects

“…Patients with chronic AF, compared with those in sinus rhythm, showed more fibrosis of the atrial myocardium [3,6,21,25,48], often associated with atrial dilatation, so-called atrial structural remodelling [10,32]. Other authors, however, failed to find this correlation [34,43].…”

Histopathological Features of the Resected Left Atrial Appendage as Predictors of Recurrence After Surgery for Atrial Fibrillation in Valvular Heart Disease

“…They showed that interstitial fibrosis was more extensive in the myocardium of the left atrium than in the LAA; however, they also found a significant correlation between the morphometric percentage of interstitial fibrosis in the left atrial free wall and that in the LAA. 24 Therefore, we believe that the histopathological alterations observed in the LAA reflect those of other parts of the left atrial free wall.…”

Sinus Rhythm Restoration and Treatment Success: Insight From Recent Clinical Trials

“…11 Fibrotic changes in peripulmonary vein tissue have been observed in patients with AF who undergo mitral valve surgery. 14 Although the causes of these structural changes are not completely understood, they may include AF-induced changes in the expression of collagen and matrix metalloproteinase. 15 -17 Atrial stretch and compensatory elevations of catecholamine and angiotensin II concentrations, triggered by the loss of atrial systole and suboptimal ventricular filling, also may play a role.…”