Left atrial strain imaging and integrated backscatter: predictors of recurrence in patients with paroxysmal, persistent and long-standing persistent atrial fibrillation undergoing catheter ablation
Authors: Garcia Bras P , Silva Cunha P , Galrinho A , Portugal G , Valente B , Rio P , Timoteo A.T , Coutinho Cruz M , Paulo M , Delgado A.S , Bras M , Ferreira R , Moura Branco L , Oliveira M 
Published: October 2021

Abstract

Introduction
Left atrial (LA) strain imaging by echocardiography (TTE) is a promising tool in the evaluation of LA mechanical function. The aim of this study was to compare LA longitudinal strain and integrated backscatter (IBS) between paroxysmal (PAF), persistent (PersAF) and long-standing persistent AF (LsAF) and evaluate its association with AF recurrence post-index catheter ablation.

Methods
Analysis of consecutive patients (P) with symptomatic PAF and PersAF who underwent index AF catheter ablation and had performed TTE in our centre prior to AF ablation. LA reservoir phase longitudinal strain (LASr) and strain rate was assessed by 2D speckle-tracking at baseline. LA volume index (LAVi) and IBS were analysed. AF recurrence was documented with 12-lead ECG, 24h Holter monitoring, external loop recorder or pacemaker analysis in a 12-month follow-up period.

Results
78 P, 69% PAF vs 31% PersAF (46% LsAF), 65% male, 40% with structural heart disease, who underwent pulmonary vein isolation were studied (cryoballoon ablation in 53% and radiofrequency ablation in 47%). P with PersAF had a higher LAVi (46±15 mL/m2 vs 36±13 mL/m2 p=0.004), particularly LsAF P (55±17 mL/m2) and impaired LASr (9.2±4.9% vs 23.9±9.3%, p&lt;0.001) (especially LsAF 5.61±3.08% vs 12.20±4.04%, p&lt;0.001) as well as strain rate (0.58±0.25 s–1 vs 1.08±0.40 s–1, p&lt;0.001). There was no significant difference between groups regarding IBS (116.6±36.1 dB vs 106.6±21.5 dB, p=0.134), including LsAF (128.8±21.5 dB vs 102.1±45.1 dB, p=0.071). During follow-up there was a 28% (22P) AF recurrence rate, higher in PersAF (50% vs PAF 20%, adjusted HR 3.44 [95% CI 1.44–7.69], p=0.005), particularly in LsAF (72% vs 31%, adjusted HR 3.24 [95% CI 0.98–10.9], p=0.048). P with AF recurrence showed significantly impaired baseline LASr both in PersAF (6.44±3.26% vs 11.93±4.79%, p=0.003), as well as PAF (13.86±5.65% vs 26.29±8.47%, p&lt;0.001). LsAF P with AF recurrence demonstrated a considerably impaired LASr (4.99±2.93% vs 9.34±1.40%, p=0.006) vs PersAF. Multivariate analysis showed that impaired baseline LASr was an independent predictor of AF recurrence both in PersAF (adjusted HR 0.82 [95% CI 0.68–0.98], p=0.028) and PAF (adjusted HR 0.78 [95% CI 0.68–0.88], p&lt;0.001). Kaplan-Meier analysis (Fig. 1) showed that both PAF and PersAF P with baseline LASr below the 18% cut-off had a significantly higher rate of AF recurrence, with earlier recurrence in PersAF. PAF P with AF recurrence had a higher baseline IBS (109.3±22.1 dB vs 94.7±14 dB, p=0.016) vs non-recurring P, in contrast to PersAF P (117.8±31.1 dB vs 115.4±42.1 dB, p=0.876), however IBS was not a significant predictor of AF recurrence in PAF (HR 1.03 [95% CI 0.99–1.07], p=0.060) or PersAF.

Conclusion
P with PersAF (and particularly LsAF) showed significantly impaired LASr, and PAF P with AF recurrence had superior baseline IBS vs non-recurring P. Reduced baseline LASr was an independent predictor of AF recurrence both in PAF and in PersAF P.

Funding Acknowledgement
Type of funding sources: None. Figure 1