Left atrial remodeling after mitral valve repair for primary mitral regurgitation: evolution over time and prognostic significance
Authors: Stassen J , Van Wijngaarden A L , Palmen M , Tomsic A , Bax J J , Delgado V , Marsan N A 
Published: October 2021

Abstract

Background
Although preoperative left atrial (LA) dilation is a well-known predictor of adverse cardiovascular events in patients with severe, primary mitral regurgitation (MR), little is known about LA reverse remodeling after mitral valve (MV) surgery and its prognostic value.

Purpose
This study sought to systematically investigate the changes in LA volume in patients undergoing MV repair for severe, primary MR and the association between LA volume after surgery and long-term outcome.

Methods
In patients undergoing MV repair for severe, primary MR, echocardiography was evaluated at three different time points: pre-operatively, immediate postoperatively (5 [4–6] days) and within 1–3 years (19 [14–24] months) follow-up. Outcome was all-cause mortality happening after the third echocardiographic evaluation.

Results
A total of 226 patients (mean age 62±13 years, 66% male) were included. Mean pre-operative LA volume index (LAVi) was 56±28 ml/m2 and significantly decreased immediately after surgery (to 38±21 ml/m2; p&lt;0.001) as well as at long-term follow-up (to 32±17 ml/m2; p&lt;0.001). Significant correlations were found between reduction in LAVi at long-term follow-up and age (R=−0.139; p=0.037), pre-operative left ventricular end-diastolic volume index (R=0.199; p=0.003), preoperative LAVi (R=0.498; p&lt;0.001), preoperative effective regurgitant orifice area (R=0.205; p=0.004), preoperative regurgitant volume (R=0.222; p=0.002) and postoperative transmitral mean pressure gradient at long-term follow-up (R=−0.150; p=0.026). Patients were subsequently divided into 3 groups: patients with a preoperative LAVi &lt;42 ml/m2 (n=68), based on the definition of moderately dilated LA; patients with a LAVi 42–59 ml/m2 (n=88) and patients with a LAVi ≥60 ml/m2 (n=70), based on the current class IIaC indication for intervention in primary MR. Although patients with a LAVi ≥60 ml/m2 at baseline showed the most pronounced reduction in LAVi, their values of LAVi at long-term follow-up remained above the range of normality (figure 1). During a median follow-up of 72 (40–114) months, 43 (19.0%) patients died. Patients who had a LAVi ≥42 ml/m2 at long-term follow-up (3rd echocardiographic evaluation) showed significantly higher mortality rates as compared to patients with a LAVi &lt;42 ml/m2 (p&lt;0.001) (figure 2). Multivariable Cox regression analysis showed that, after adjusting for age, sex and coronary artery disease, postoperative LAVi ≥42ml/m2 at long-term follow-up remained independently associated with all-cause mortality (HR 2.494; CI 1.292 to 4.815; p=0.006).

Conclusions
In patients with severe primary MR, LA reverse remodeling occurs immediately after MV repair, with a further reduction in LAVi during follow-up. Patients in whom LAVi does not remodel to normal values present worse long-term prognosis as compared to patients who achieve normal LAVi values.

Funding Acknowledgement
Type of funding sources: Other. Main funding source(s): ESC Training Grant (Appehab724.011664741). Changes in LA volume over timeKM curve for all-cause mortality