The impact of mitral regurgitation grade on exercise capacity following cardiac rehabilitation program after transcatheter aortic valve implantation
Authors: Ribeiro Da Silva M , Vilela E , Mosalina Manuel A , Barbosa A , Almeida J , Guerreiro C , Ribeiro Queiros P , Tavares A , Dias A , Caeiro D , Sousa O , Braga P , Rodrigues A , Teixeira M , Fontes-Carvalho R 
Published: October 2021

Abstract

Introduction
Severe aortic stenosis (AS) and mitral regurgitation (MR) often coexist. Transcatheter aortic valve implantation (TAVI) is becoming widely used for the treatment of patients (pts) with symptomatic severe AS. However, conflicting data reside concerning the impact of MR on outcomes after TAVI. Also, very few data exist regarding the benefits of a cardiac rehabilitation program (CRP) following TAVI in pts with MR.

Purpose
To evaluate the effect of a CRP in functional parameters after TAVI, particularly in pts with MR grade ≥ II.

Methods
Retrospective study which included all pts submitted to TAVI between 2014 and 2020 that completed a CRP following the procedure. Cardiopulmonary exercise tests (CPET) were performed after TAVI at baseline (pre-CRP) and post-CRP. We evaluated pre- and post-CRP peak oxygen consumption (pVO2), pVO2 at the anaerobic threshold (AT), respiratory exchange ratio (RER), VE/VCO2 and CPET duration. The exercise protocol included low/medium intensity exercises and consisted of sessions 3 times per week carried over 3 months. MR grading severity was assessed with transthoracic echocardiography performed after TAVI and was divided into 2 groups (grade &lt; II vs grade ≥ II).

Results
Fifty-two pts were included, 59,6% were male, mean age of 78,6±8,6 years-old. Mean Society of Thoracic Surgery (STS) risk score was 4,9. Mean pre-TAVI aortic valve area was 0,68 cm2, with a mean gradient of 45,5 mmHg and a mean ejection fraction (EF) of 51%. The majority of pts implanted a self-expandable prosthesis (55,8%).
Twenty-seven (51,9%) pts had MR grade ≥ II. Baseline characteristics were similar between pts with MR grade &lt; II vs MR grade ≥ II, with the exception of the prevalence of coronary artery disease which was higher in MR grade ≥ II (p=0,036). Patients with MR grade &lt; II had higher maximum and median aortic gradients before TAVI (p&lt;0,05 for all). The mean number of cardiac rehabilitation sessions was 21±7, without differences between both groups. In pts with MR grade ≥ II, there was an improvement in CPET duration after CRP (HF protocol from 03:57 min to 05:02 min; p=0,017 and modified Bruce protocol from 06:03 min to 06:41 min; p=0,049) but without significant changes in pVO2 (14,7 mL/kg/min to 14,9 mL/kg/min; p=0,990), RER or VEVCO2/VO2 ratio. Patients with MR grade &lt; II significantly improved pVO2 (13,8 mL/kg/min to 14,7 mL/kg/min; p=0,015), and CPET duration with HF protocol from 05:04 min to 06:23 min; p=0,006 after CRP. There was also an improvement in VEVCO2/VO2 ratio, although not statically significant.

Conclusions
Patients with MR grade &lt; II after TAVI who underwent a CRP significantly improved pVO2 and CPET duration. Although pts with MR grade ≥ II did not improved pVO2 after a CRP, an improvement in CPET duration may translate into a clinical benefit in these pts. These results highlight the importance of further research and personalization among this potentially higher risk subset of pts.

Funding Acknowledgement
Type of funding sources: None.