Insights on Distinct Left Atrial Remodeling Between Atrial Fibrillation and Heart Failure With Preserved Ejection Fraction

Abstract

Background: Heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF) commonly coexist with overlapping pathophysiology like left atrial (LA) remodeling, which might differ given different underlying mechanisms.

Objectives: We sought to investigate the different patterns of LA wall remodeling in AF vs. HFpEF.

Methods: We compared LA wall characteristics including wall volume (LAWV), wall thickness (LAWT), and wall thickness heterogeneity (LAWT[SD]) and LA structure, function among the controls (without AF or HFpEF, n = 115), HFpEF alone (n = 59), AF alone (n = 37), and HFpEF+AF (n = 38) groups using multi-detector computed tomography and echocardiography.

Results: LA wall remodeling was most predominant and peak atrial longitudinal strain (PALS) was worst in HFpEF+AF patients as compared to the rest. Despite lower E/e' (9.8 ± 3.8 vs. 13.4 ± 6.4) yet comparable LA volume, LAWT and PALS in AF alone vs. HFpEF alone, LAWV [12.6 (11.6-15.3) vs. 12.0 (10.2-13.7); p = 0.01] and LAWT(SD) [0.68 (0.61-0.71) vs. 0.60 (0.56-0.65); p < 0.001] were significantly greater in AF alone vs. HFpEF alone even after multi-variate adjustment and propensity matching. After excluding the HFpEF+AF group, both LAWV and LAWT [SD] provided incremental values when added to PALS or LAVi (all p for net reclassification improvement <0.05) in discriminating AF alone, with LAWT[SD] yielding the largest C-statistic (0.78, 95% CI: 0.70-0.86) among all LA wall indices.

Conclusions: Despite a similar extent of LA enlargement and dysfunction in HFpEF vs. AF alone, larger LAWV and LAWT [SD] can distinguish AF from HFpEF alone, suggesting the distinct underlying pathophysiological mechanism of LA remodeling in AF vs. HFpEF.

Keywords: atrial fibrillation; heart failure with preserved ejection fraction; left atrial remodeling; left atrial wall; multi-detector computed tomography; strain.

Figure 1

Five major steps in the LA mapping workflow for LA wall indices in the current study: (1) LA delineation, (2) inner boundary segmentation, (3) outer boundary segmentation, (4) wall mass calculation, (5) three-dimensional (3D) projection map, and display of the LAWT (SD). The LAWT in each dataset was expressed by different colors as a visual projection map together with four PVs orifices. Nos. 1, 2, 3, and 4 represent the right superior, right inferior, left superior, and left inferior PVs, respectively (A). Cardiac CT images from 3 representative individuals from the Control, HFpEF, and AF groups (B). LA, left atrial; LAWT, left atrial wall thickness; LAWT (SD), left atrial wall thickness heterogeneity; PV, pulmonary vein; MDCT, multi-detector computed tomography; HFpEF, heart failure with preserved ejection fraction; AF, atrial fibrillation.

Figure 2

ROC among all LA wall indices in discriminating isolated AF from control and HFpEF after excluding patients with both HFpEF and AF (final n = 211) (A). Fitting curves showing inverse associations between a greater unfavorable remodeling of the various MDCT LA wall indices and PALS (B). ROC, receiver operating characteristic curve; PALS, Peak atrial longitudinal strain; other abbreviations as Figure 1.

Figure 3

Comparisons of LA wall indices in isolated HFpEF and AF in smaller and larger indexed LA volume after excluding patients with both HFpEF and AF (total n = 211).

Figure 4

Hypothetical distinctive pathological mechanisms of LA remodeling in AF and HFpEF.