Left atrial remodeling and right ventricular-pulmonary arterial coupling after MitraClip implantation
Authors: Molnar A A , Pasztor D , Santa A , Hizoh I , Straub E , Nagy A , Nagy A I , Astrid A , Geller L , Merkely B 
Published: June 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Introduction
Transcatheter edge-to-edge mitral valve repair (TEER) with the MitraClip system has emerged as a therapeutic alternative to surgical solutions in high risk patients with severe mitral regurgitation (MR). MR is characterized by left ventricular volume overload, which leads to left ventricular dilatation. Furthermore, MR is a common cause of pulmonary hypertension. Right ventricular (RV) intrinsic contractility and its response to afterload is referred to as RV-pulmonary arterial (PA) coupling. Effect of TEER in patients with MR on left atrial (LA) function and RV-PA coupling is less investigated.

Purpose
The aim of our study was to assess clinical characteristics of patients undergoing MitraClip implantation including LA function and RV-PA coupling.

Methods
Eighty-eight consecutive patients with chronic severe MR were enrolled in the single-center observational study (mean age 71.5±7.9 years, male 54.5%, ischemic cardiomyopathy 54.5%). Primary MR (PMR) was present in 22.7%, secondary MR (SMR) in 73.9 % and mixed (MxMR) etiology in 3.4%. Conventional and advanced echocardiography examination was performed using speckle tracking echocardiography before TEER and at 6 month post-TEER follow-up. Left atrial maximal (LAV max) and minimal (LAV min) volumes were measured indexed for body surface area. Furthermore, we analysed left atrial functional parameters, such as reservoir strain, conduit strain and contraction strain.

Results
The technical success of MitraClip implantation was 95,5%. Mortality rate at 6 month follow-up time was 10.8% (1/88 PMR, 7/88 SMR, 1/88 MxMR). Severe residual MR developed during follow-up in 4.2% and New York Heart Association class III-IV functional status was concluded in 6.8% at 6 month post-TEER. Significant decrease in left ventricular end-diastolic median diameter (mm) was observed at follow-up compared to pre-TEER: 57.5 (IQR: 51.25 – 63.75) vs 60.5 (IQR: 52.5 – 66.75), respectively, p = 0.01. Similarly, the median value of pulmonary artery systolic pressure (PASP) substantially decreased (mmHg) after TEER: 42 (IQR: 32 – 52) vs 49.5 (IQR: 41 – 57), respectively, p = 0.003. Tricuspid annulus systolic excursion/PASP median value, representing RV-PA coupling, improved remarkably: 0.45 (IQR: 0.31 – 0.69) vs 0.38 (IQR: 0.29 – 0.52), respectively, p = 0.02. Compared to pre-TEER, median LA volumes and strain parameters did not change significantly at 6 month post-TEER: reservoir strain (%) 12.88 (IQR: 8.18–18.78) vs 11.74 (IQR: 7.48–20.36), p = 0.41; LAV max (ml) 48.70 (IQR: 39.81–62.29) vs 48.17 (IQR: 42.08–58.7), p = 0.31; LAV min (ml) 34.33 (IQR: 24.5–46.32) vs 33.89 (IQR: 26.02–44.53), p = 0.69.

Conclusions
The function of the enlarged LA was severely reduced, which did not change after MitraClip implantation in our population. However, positive left ventricular remodeling and improvement in RV-PA coupling was observed 6 month after MitraClip procedure.