Cardiac Fibrosis in Patients With Atrial Fibrillation

Abstract

Atrial fibrillation (AF) is associated with structural, electrical, and contractile remodeling of the atria. Development and progression of atrial fibrosis is the hallmark of structural remodeling in AF and is considered the substrate for AF perpetuation. In contrast, experimental and clinical data on the effect of ventricular fibrotic processes in the pathogenesis of AF and its complications are controversial. Ventricular fibrosis seems to contribute to abnormalities in cardiac relaxation and contractility and to the development of heart failure, a common finding in AF. Given that AF and heart failure frequently coexist and that both conditions affect patient prognosis, a better understanding of the mutual effect of fibrosis in AF and heart failure is of particular interest. In this review paper, we provide an overview of the general mechanisms of cardiac fibrosis in AF, differences between fibrotic processes in atria and ventricles, and the clinical and prognostic significance of cardiac fibrosis in AF.

High‐Normal Thyroid‐Stimulating Hormone Shows a Potential Causal Association With Arrhythmia Recurrence After Catheter Ablation of Atrial Fibrillation

“…In other words, substrate modifications were done in a few patients. Thus, what made the difference in the long‐term outcome between patients of TSH quartile 1 to 3 and quartile 4 may have been the extent of the arrhythmia substrate, which is closely related to atrial fibrosis 14. Among analyzed subjects, the lowest prevalence of long‐term arrhythmia recurrence after the last session was observed in quartile 1 to 3 patients with paroxysmal AF.…”

“…Also, previous studies have provided no clear evidence that additional thyroid hormone therapy in subjects with milder forms of subclinical hypothyroidism could improve lipid status and other cardiovascular risk factors,18 as well as symptoms associated with hypothyroidism 19. Alternatively, because hypothyroidism enhances atrial fibrosis, leading to increased AF substrate,6 adjunctive ablation strategies, such as ablation targeting low‐voltage areas,14, 20 may improve the atrial tachyarrhythmia–free survival in this subset of the patients.…”

“…In addition, they found that the hypothyroid rats showed a significantly longer atrial effective refractory period and increased LA interstitial fibrosis than euthyroid rats. Atrial fibrosis can lead to slow conduction and increased conduction heterogeneity, thus favoring reentry formation and increasing AF vulnerability 14. The development of atrial fibrosis is a hallmark of structural remodeling in AF and is considered a substrate for AF perpetuation.…”

“…The development of atrial fibrosis is a hallmark of structural remodeling in AF and is considered a substrate for AF perpetuation. In fact, several studies have linked more extensive atrial interstitial fibrosis to lower effectiveness of AF catheter ablation 14. Thus, it may be reasonable to assume that the high incidence of arrhythmia recurrence observed in the highest TSH euthyroid quartile is at least partly attributable to increased atrial fibrosis.…”

Activin Receptor‐Like Kinase 4 Haplodeficiency Mitigates Arrhythmogenic Atrial Remodeling and Vulnerability to Atrial Fibrillation in Cardiac Pathological Hypertrophy

“…AF is associated with structural and electrical remodeling, including atrial fibrosis, atrial dilatation, cellular hypertrophy, variation in ion channel expression, and inflammation. Among these, structural remodeling characterized by atrial fibrosis and dilatation enhances the AF vulnerability by reentry activity 2. Electrical remodeling is another essential pathomechanism of AF.…”