Predictors of left atrial fibrosis in patients with atrial fibrillation referred for catheter ablation

Abstract

Background: Left atrial (LA) fibrosis in patients with atrial fibrillation (AF) is associated with an increased risk of AF recurrence after catheter ablation. Therefore, we searched for clinical risk factors that confer an increased risk of LA fibrosis, which can influence the treatment strategy.

Methods: We included 94 patients undergoing 3-dimensional electroanatomical voltage mapping-guided catheter ablation of AF. LA low-voltage areas during sinus rhythm as a surrogate parameter of fibrosis were measured with the CARTO3 mapping system and adjusted for LA volumes obtained by computed tomography. Blood tests including N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) and echocardiographic parameters of left ventricular function were also analyzed.

Results: Patients were 62.5 ± 11.4 years old, and 29% were female. LA fibrosis was present in 65%, with 50% having a fibrotic area > 5% (≥ Utah-Stage 1). Mean left ventricular ejection fraction (LVEF) was 53.9 ± 10.5%. Patients with LA fibrosis had higher NT-proBNP levels (869 ± 1056 vs. 552 ± 859 ng/L, p = 0.001) and larger LA volumes (body surface area-corrected 63.3 ± 19.3 vs. 80 ± 27.1 mL/m2, p = 0.003). In univariable analyses, LA fibrosis was significantly associated with female gender, older age, increased LA volumes, hypertension, statin therapy, higher NT-proBNP values, and echocardiographic E/e'. In bivariable analyses, higher NT-proBNP, echocardiographic parameters of diastolic dysfunction, female gender, older age, and higher DR-FLASH scores remained as independent predictors of LA fibrosis.

Conclusions: In this single-center longitudinal study, surrogate parameters of elevated left-sided cardiac filling pressures such as higher NT-proBNP levels and higher echocardiographic E/e' values as well as female gender independently predicted the prevalence of LA fibrosis in patients referred for catheter ablation of AF.

Keywords: atrial fibrillation; atrial fibrosis; diastolic dysfunction; gender medicine; heart failure with preserved ejection fraction.

Figure 1

Left atrium divided into four segments in the CARTO3 software. Left upper (anterior-posterior view): anterior segment; right upper (posterior-anterior view): posterior segment; left bottom (right anterior oblique view): septal segment; right bottom (left anterior oblique): lateral segment. The pulmonary veins are not shown in this illustration

Figure 2

A. Mean distribution of left atrial fibrosis in subjects with > 5% fibrosis divided for male (blue) and female (red). B. Three-dimensional reconstruction of the left atrium and aortic position by voltage mapping and corresponding computed tomography-scan.

Figure 3

A. Receiver operating charasteristic curves for serum N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) levels as a predictor of left atrial (LA) fibrosis (cut-off: ≥ 5%); area under the curve (AUC) 70%, p = 0.001, NT-proBNP cut-off 400 ng/L: sensitivity 55%, specificity 73%; B. Receiver operating characteristic curves for serum NT-proBNP levels as a predictor of relevant LA fibrosis (cut-off: ≥ 20%); AUC 70%, p = 0.005, NT-proBNP cut-off 400 ng/L: sensitivity 59%, specificity 65%.