Left Atrial Function Predicts Atrial Arrhythmia Recurrence Following Ablation of Long-Standing Persistent Atrial Fibrillation

Abstract

Background: Left atrial (LA) function following catheter or surgical ablation of de-novo long-standing persistent atrial fibrillation (AF) and its impact on AF recurrence was studied in patients participating in the CASA-AF trial (Catheter Ablation vs. Thoracoscopic Surgical Ablation in Long Standing Persistent Atrial Fibrillation).

Methods: All patients underwent echocardiography preablation, 3 and 12 months post-ablation. LA structure and function were assessed by 2-dimensional volume and speckle tracking strain measurements of LA reservoir, conduit, and contractile strain. Left ventricular diastolic function was measured using transmitral Doppler filling velocities and myocardial tissue Doppler velocities to derive the e', E/e', and E/A ratios. Continuous rhythm monitoring was achieved using an implantable loop recorder.

Results: Eighty-three patients had echocardiographic data suitable for analysis. Their mean age was 63.6±9.7 years, 73.5% were male, had AF for 22.8±11.6 months, and had a mean LA maximum volume of 48.8±13.8 mL/m². Thirty patients maintained sinus rhythm, and 53 developed AF recurrence. Ablation led to similar reductions in LA volumes at follow-up in both rhythm groups. However, higher LA emptying fraction (36.3±10.6% versus 27.9±9.9%; P<0.001), reservoir strain (22.6±8.5% versus 16.7±5.7%; P=0.001), and contractile strain (9.2±3.4% versus 5.6±2.5%; P<0.001) were noted in the sinus rhythm compared with AF recurrence group following ablation at 3 months. Diastolic function was better in the sinus rhythm compared with the AF recurrence group with an E/A ratio of 1.5±0.5 versus 2.2±1.2 (P<0.001) and left ventricular E/e' ratio of 8.0±2.1 versus 10.3±4.1 (P<0.001), respectively. LA contractile strain at 3 months was the only independent predictor of AF recurrence.

Conclusions: Following ablation for long-standing persistent AF, improvement in LA function was greater in those who maintained sinus rhythm. LA contractile strain at 3 months was the most important determinant of AF recurrence following ablation.

Registration: URL: https://www.

Clinicaltrials: gov; Unique identifier: NCT02755688.

Keywords: ablation; atrial fibrillation; left atrial function; left atrial strain; sinus rhythm.

Figure 1.

Left atrial (LA) volume measurement using the biplane area-length method. Zoomed view of the LA in the apical 4-chamber view is on the left and apical 2-chamber view on the right. A indicates area; and L, length.

Figure 2.

Two-dimensional left atrial strain data. The diagram shows reservoir, conduit, and contractile function measurements of left atrium (LA) in a patient in sinus rhythm. cd indicates conduit function; ct, contractile function; LAS, left atrial strain; and res, reservoir function.

Figure 3.

Changes in left atrial (LA) parameters in the total sample. A, Changes in LA maximum, minimum, and p wave volumes from baseline to 12 months in the total study population. B, Changes in LA ejection fraction (LAEF), sphericity index, and LA reverse remodelling (LA-RRM) from baseline to 12 months.

Figure 4.

Changes in left atrial reservoir (LASres), conduit (LAScd), and contractile (LASct) function from baseline to 12 months in the total study population.

Figure 5.

Receiver operating characteristic (ROC) curve of left atrial contractile strain at 3 months for predicting atrial fibrillation recurrence.

Figure 6.

Kaplan-Meier survival curves based on a left atrial strain contraction (LASct) cutoff value of 7.7% measured at 3-month follow-up. AF indicates atrial fibrillation; and HR, hazard ratio.