Thromboembolic risk is potentially reduced in mitral stenosis shortly after percutaneous mitral valvotomy
Authors: Sayed M , Salah Gaber H , Z Abd Elrhman M , A R Helmy H , Hasan-Ali H 
Published: October 2021

Abstract

Background
Rheumatic mitral stenosis (MS) is a problem in the developing countries. Left atrium (LA) and appendage (LAA) dysfunction are considered determinant factors for thrombus formation even in patients with sinus rhythm (SR). Percutaneous mitral valvotomy (PMV) is a well accepted therapeutic option. However, no available data considers patients with SR as a low risk group for the development of thrombus.

Purpose
Studying short term impact of PMV on P wave morphology, NT-pro BNP as well as LAA properties in patients with MS and SR.

Methods
A prospective study was conducted in a tertiary University hospital including 41 patients with symptomatic uncomplicated MS having favorable morphology with sinus Rhythm. P wave duration, amplitude and dispersion, NT-pro BNP, transthoracic and transesophageal echocardiography were carried out directly before and 1 month following PMV. Student t-test was used to compare the variables before and after PMV. Correlation was calculated using Pearson's correlation and multivariate regression analysis was used for prediction of unfavorable outcomes.

Results
After PMV, 36 (87.8%) patients had a favorable outcome manifested with improvement of NYHA class, valve area, estimated systolic pulmonary artery pressure (sPAP) as well as grade of spontaneous echo contrast (SEC). P wave duration, P wave amplitude and P wave dispersion decreased after PMV (14.97±2.65 vs. 13.21±2.36 ms, 4.01±1.01 vs. 2.51±0.71 ms and 4.01±1.01 vs. 2.51±0.71mv; P&lt;0.001 respectively). NT pro-BNP also reduced (2.90±2.19 vs. 2.01±1.31 Pg/L; P&lt;0.001). TEE PW of LAA showed increase of early (E LAA) and late (A LAA) emptying velocities after PMV (41.70±19.50 vs. 48.82±20.18 and 31.31±21.99 vs. 38.48±19.86 cm/s; P&lt;0.001 respectively). By TDI, late wall motion (LAA A) velocity increased (7.41±2.50 vs. 8.23±3.01 cm/s; P&lt;0.001) with an improvement of LAA ejection fraction post procedural (50.80±13.11 vs. 55.75±10.12%; P&lt;0.001). Negative correlation between LAA EF and P wave amplitude (r=−0.40; P&lt;0.001) as well as a correlation between reduction in NT pro-BNP and the improvement of both LAA A velocity and E LAA wave were noticed (r=0.55; P=0.02 and 0.01 respectively). The grade of SEC was negatively correlated with E LAA (r=−0.55, P=0.02). Only 5 patients (12.2%) had an unfavorable outcome. Four patients had severe mitral regurge (7.8%), only one patient (2.4%) was indicated for surgery. AF developed in one patient (2.4%). The grade of SEC remains the same in 3 patients (7.3%). Both baseline estimated sPAP and Wilkins score were predictors for unfavorable outcome; sPAP (odd's ratio= 4.08; 95% CI=1.01- 7.17; P=0.04); Wilkins score (odd's ratio= 1.59; 95% CI=1.22- 5.98; P=0.01).

Conclusion
PMV has a favorable rapid impact on LA and LAA properties in patients with MS and SR. Our data suggests that PMV could potentially contribute to lowering the risk of future thromboembolic events in those patients.

Funding Acknowledgement
Type of funding sources: Public Institution(s). Main funding source(s): Assiut University Hospital