Quantification of atrial cardiomyopathy disease severity by electroanatomic voltage mapping and cardiac magnetic resonance imaging
Authors: Sim I , Razeghi O , Solis Lemus J A , Whitaker J , O'hare D , Harrison J , Gharaviri A , Kotadia I , Newby D E , Dweck M , Masci P G , Chiribiri A , Niederer S , O'neill M , Williams S E 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: Foundation. Main funding source(s): The authors acknowledge the support of the British Heart Foundation Centre for Research Excellence Award III (RE/18/5/34216). SEW is supported by the British Heart Foundation (FS/20/26/34952).

Background
Atrial late gadolinium enhancement (Atrial-LGE) and electroanatomic voltage mapping (Atrial-EAVM) quantify the anatomical and functional extent of atrial cardiomyopathy. Prior studies provide conflicting information relating to the level of agreement between these modalities for the assessment of atrial cardiomyopathy disease severity.

Purpose
We aimed to explore the relationships between, and outcomes from, these contrasting measures of atrial cardiomyopathy disease severity in patients with atrial fibrillation undergoing ablation.

Methods
Atrial-LGE and Atrial-EAVM was performed in patients undergoing first-time ablation for atrial fibrillation. Atrial cardiomyopathy disease severities were quantified using CEMRGApp and OpenEP[1] for Atrial-LGE and Atrial-EAVM, respectively. Correlations between modalities, their relationships with clinical features and their relationships with arrhythmia recurrence were assessed.

Results
Atrial-LGE and Atrial-EAVM quantification of atrial cardiomyopathy disease was performed In 123 atrial fibrillation patients (60±10 years, paroxysmal (n=58), persistent (n=65)) (Figure 1, panel A). Atrial-EAVM was moderately correlated with Atrial-LGE (r=0.41, P&lt;0.001), with a mean fibrosis burden of 32.4±21.8% (Figure 1, panel B). The strength of the correlation was dependent on the thresholds chosen to define abnormal atrial tissue. The thresholds yielding the strongest correlation were IIR &gt;0.97 (for Atrial-LGE) and voltage &lt;1.17 mV (for Atrial-EAVM).
Using these thresholds, agreement between modalities was strongest amongst patients in the highest tertile of fibrosis burden (mean of differences 5.9% (95% CI -30.4% to 42%)). Fibrosis burden was greater for Atrial-LGE than Atrial-EAVM (46.4±7.48% versus 13.7±7.13%, P&lt;0.005) for patients in the lowest tertile of fibrosis burden (Figure 1, panel C). These patients were younger, had smaller atria and a greater frequency of paroxysmal atrial fibrillation than patients in the higher tertiles of fibrosis burden (Figure 2).
Atrial cardiomyopathy disease severity was greater in patients with arrhythmia recurrence for both Atrial-EAVM (39.3±23.1% versus 28.5±20.2%, P=0.010) and Atrial-LGE (58.69±11.60 versus 53.33±9.63, P=0.011). In multivariable analysis, Atrial-LGE (OR 1.04 (95% CI 1.00-1.09), P=0.037) was independently associated with arrhythmia recurrence.

Conclusions
We demonstrate for the first time that the level of agreement between Atrial-EAVM and Atrial-LGE is dependent on the level of atrial cardiomyopathy disease severity. The functional consequences of atrial cardiomyopathy are most evident in patients with the highest anatomical extent of disease. This explains variations in prior studies and will inform future clinical applications of these techniques.