Mitral regurgitation decreases over time after successful thoracoscopic ablation, a subanalysis of a prospective cohort study
Authors: Zappala P , De Vries T A C , De Bruin-Bon H A C , Al-Shama R F , Keshtkar S K , Meulendijks E R , De Jong J S S G , Van Boven W J , Driessen A H , De Groot J R 
Published: November 2023

Abstract

Background
Patients with atrial fibrillation (AF) often present with mitral regurgitation (MR) without significant changes in the morphology of the valve leaflets. Even though these patients are at increased risk of developing and maintaining AF, concomitant mitral valve surgery still exclusively occurs in the setting of severe MR. The interplay between AF and MR is incompletely understood, particularly it has not been established how ablation of AF affects the grade of MR. We hypothesized that successful TA decreases the grade of MR.

Purpose
We aimed to to explore the course of MR severity after TA in patients with AF.

Methods
We performed a subanalysis of the MARK-AF registry, a single-arm single-center prospective cohort study on patients with paroxysmal and persistent AF undergoing thoracoscopic pulmonary vein isolation. Those with persistent AF were also treated with a roof and trigone line. All patients within this cohort without a history of morphological MR, prior mitral valve prosthesis and left ventricular ejection fraction (LVEF) &lt;30% who underwent TA between January 2016-January 2022 were included. Transthoracic echocardiography (TTE) was performed 1 month preoperatively and at 6-9 months post-operatively. MR was graded ordinally 1-4 (1:None/Trivial, 2:Mild, 3:Moderate, 4:Severe). Successful TA was defined as absence of ≥1 episodes of AF, atrial flutter or atrial tachycardia lasting &gt;30s on electrocardiogram or 24-hour Holter monitoring after a blanking period of 90 days, which were performed at 3, 6, and 12 months post-operatively.

Results
Of the 283 patients, 31 were excluded. The remaining 252 patients were on average 64 years old (IQR 49-71), 25% were women, and 75% had persistent AF. The median duration between AF diagnosis and TA was 4 years (IQR 2.2-8.0) and the median left atrial volume index (LAVI) 42.5 ml/m2 (IQR 35.1-50.7). Between baseline and follow-up, the median LAVI decreased from 43.5 (IQR 35-50) to 38.7(IQR 32-47) p&lt;0.001, MR grade improved in 33% of patients by at least one grade, and worsened in 17%. In total, 70% of patients had no AF recurrences during follow-up of 12 months. 34% of patients with a successful TA improved in MR grade during follow-up, versus 26% after a failed TA. Mean MR grade improved after successful TA (2.22 ±1.01 versus 1.60± 1.4 p&lt;0.001). MR improved less in patients with AF recurrence (2.13± 1.1 versus 1.80± 1.38 P=0.016). 40% of the patients with MR worsening had AF recurrence versus 23% in whom MR improved. In multivariable ordinal regression analysis, age &lt;65 years and AF recurrence were negative predictors of MR grade at follow-up (OR 4.45: 95%CI 3.432–5.468 p=0.003and 3.83: 95%CI: 2.750–5.090 p=0.040, respectively).

Conclusion
Successful TA is associated with more MR grade improvement. More AF recurrence is observed in patients whose MR grade aggravates. Whether MR improvement relates to restoration of sinus rhythm or to a smaller left atrium, remains to be investigated.