Atrial fibrosis in non–atrial fibrillation individuals and prediction of atrial fibrillation by use of late gadolinium enhancement magnetic resonance imaging

Abstract

Introduction Besides the traditional concept of atrial fibrillation (AF) perpetuating atrial structural remodeling, there is increasing evidence that atrial fibrosis might precede AF, highlighting the need for better characterization of the fibrotic substrate. We aimed to assess atrial fibrosis by use of late gadolinium enhancement magnetic resonance imaging (LGE‐MRI) in non‐AF individuals and to identify predisposing risk factors. A second aim was to establish a risk score for the prevalence of AF using atrial fibrosis in addition to established clinical variables. Methods and Results Non‐AF individuals without structural heart disease (n = 91) and matched AF controls (n = 91) underwent MRI for assessment of LGE. According to the established UTAH classification, atrial LGE ≥20% was considered extensive. Mean left atrial (LA) fibrosis in non‐AF and AF individuals were 8.8 ± 6.5% and 12.5 ± 5.8%, respectively. Body mass index (BMI) >30 kg/m 2 and LA volume were predictors of atrial fibrosis. Diastolic function was not significantly different with respect to atrial fibrosis. A novel scoring system for the prevalence of AF (2 points for arterial hypertension and/or left ventricular ejection fraction <55%; 3 points for atrial fibrosis >6%) was derived demonstrating that patients in the intermediate/high‐risk group had a significantly increased risk of AF. Conclusion This study reports unexpectedly high atrial fibrosis in non‐AF patients without apparent heart disease, highlighting the concept that structural fibrotic alterations may precede AF onset in a significant proportion of individuals. BMI as a predictor of atrial fibrosis suggests that lifestyle and drug intervention, that is, weight reduction, could positively influence fibrosis development. The derived risk score for AF prevalence provides the basis for prospective studies on AF incidence.

Do most patients with obesity or type 2 diabetes, and atrial fibrillation, also have undiagnosed heart failure? A critical conceptual framework for understanding mechanisms and improving diagnosis and treatment

“…Cardiac magnetic resonance imaging (MRI) reveals meaningful myocardial fibrosis (in the LA and LV) in both patients with HFpEF and those with AF . Fibrosis is indicative of an underlying atrial and ventricular myopathy and may precede the clinical identification of AF or HFpEF …”

“…There is little controlled clinical trial evidence of the effects of catheter ablation in patients with obesity or type 2 diabetes and HFpEF. Nevertheless, it is known that the LA and LV in patients with these two metabolic disorders are typically affected by extensive fibrosis; this fibrosis also represents a cardinal feature of both HFpEF and longstanding AF . Unfortunately, patients with AF who have myocardial fibrosis are unlikely to maintain sinus rhythm following an ablation procedure; this is likely to explain the high rate of AF recurrence following catheter ablation in patients with obesity or type 2 diabetes …”

“…37,38 Fibrosis is indicative of an underlying atrial and ventricular myopathy and may precede the clinical identification of AF or HFpEF. 32,39,40…”

“…Nevertheless, it is known that the LA and LV in patients with these two metabolic disorders are typically affected by extensive fibrosis; 225,226 this fibrosis also represents a cardinal feature of both HFpEF and longstanding AF. 34,39 Unfortunately, patients with AF who have myocardial fibrosis are unlikely to maintain sinus rhythm following an ablation procedure; 227,228 this is likely to explain the high rate of AF recurrence following catheter ablation in patients with obesity or type 2 diabetes. [229][230][231][232][233][234] Among patients with AF who undergo ablation, those who have increased LA dimensions, pressures or fibrosis, or LV fibrosis or abnormal diastolic filling parameters are at increased risk for AF recurrence and often require repeated ablation procedures; 227,228,[232][233][234][235][236][237][238][239][240] in patients without a prior myocardial infarction (i.e.…”

Left Atrial Structural Remodelling in Non-Valvular Atrial Fibrillation: What Have We Learnt from CMR?

“…Although there is an agreement on the importance of LA remodelling in AF pathophysiology and patients' management [51], there is a lack of consensus regarding the remodelling of LA appendage (LAA). The lack of this agreement is even more striking since almost 90% of the AF thrombi occur at this level [52,53].…”