Association of left atrial strain by cardiovascular magnetic resonance with recurrence of atrial fibrillation following catheter ablation

Abstract

Background: Atrial fibrillation (AF) is a progressive condition, which is characterized by inflammation/fibrosis of left atrial (LA) wall, an increase in the LA size/volumes, and decrease in LA function. We sought to investigate the relationship of anatomical and functional parameters obtained by cardiovascular magnetic resonance (CMR), with AF recurrence in paroxysmal AF (pAF) patients after catheter ablation.

Methods: We studied 80 consecutive pAF patients referred for ablation, between January 2014 and December 2019, who underwent pre- and post-ablation CMR while in sinus rhythm. LA volumes were measured using the area-length method and included maximum, minimum, and pre-atrial-contraction volumes. CMR-derived LA reservoir strain (ℇR), conduit strain (ℇCD), and contractile strain (ℇCT) were measured by computer assisted manual planimetry. We used a multivariate logistical regression to estimate the independent predictors of AF recurrence after ablation.

Results: Mean age was 58.6 ± 9.4 years, 75% men, mean CHA₂DS₂-VASc score was 1.7, 36% had prior cardioversion and 51% were taking antiarrhythmic drugs. Patients were followed for a median of 4 years (Q1-Q3 = 2.5-6.2 years). Of the 80 patients, 21 (26.3%) patients had AF recurrence after ablation. There were no significant differences between AF recurrence vs. no recurrence groups in age, gender, CHA₂DS₂-VASc score, or baseline comorbidities. At baseline, patients with AF recurrence compared to without recurrence had lower LV end systolic volume index (32 ± 7 vs 37 ± 11 mL/m2; p = 0.045) and lower ℇCT (7.1 ± 4.6 vs 9.1 ± 3.7; p = 0.05). Post-ablation, patients with AF recurrence had higher LA minimum volume (68 ± 32 vs 55 ± 23; p = 0.05), right atrial volume index (62 ± 20 vs 52 ± 19 mL/m2; p = 0.04) and lower LA active ejection fraction (24 ± 8 vs 29 ± 11; p = 0.05), LA total ejection fraction (39 ± 14 vs 46 ± 12; p = 0.02), LA expansion index (73.6 ± 37.5 vs 94.7 ± 37.1; p = 0.03) and ℇCT (6.2 ± 2.9 vs 7.3 ± 1.7; p = 0.04). Adjusting for clinical variables in the multivariate logistic regression model, post-ablation minimum LA volume (OR 1.09; CI 1.02-1.16), LA expansion index (OR 0.98; CI 0.96-0.99), and baseline ℇR (OR 0.92; CI 0.85-0.99) were independently associated with AF recurrence.

Conclusion: Significant changes in LA volumes and strain parameters occur after AF ablation. CMR derived baseline ℇR, post-ablation minimum LAV, and expansion index are independently associated with AF recurrence.

Keywords: Atrial fibrillation; Cardiovascular magnetic resonance; Catheter ablation; Left atrial strain; Recurrence.

Fig. 1

Left: Example of left atrial (LA) tissue tracking in still frames of cine cardiovascular magnetic resonance (CMR) (balanced steady-state free precession imaging) four chamber (left top) and two chamber (left bottom) cine loops. Right: Longitudinal strain with two peaks representing reservoir (ℇR) and contractile (ℇCT) strain. The difference between the two measurements is conduit strain (ℇCD)

Fig. 2

Cox-proportional hazard model for survival free of atrial fibrillation by tertiles of baseline reservoir strain (ℇR), adjusted for age, gender, hypertension, and obstructive sleep apnea. Tertiles one, two, three corresponded to a baseline ℇR of < 21, 21–27 and > 27, respectively

Fig. 3

Cox-proportional hazard model for survival free of atrial fibrillation by tertiles of post-ablation contractile strain (ℇCT), adjusted for age, gender, hypertension, and obstructive sleep apnea. Tertiles one, two, three corresponded to a post-ablation ℇCT of < 5.3, 5.3–8 and > 8, respectively