Correlation of left atrial reservoir function with diastolic filling and stroke volume of the left ventricle in patients with rheumatic mitral stenosis
Authors: Bouchahda N , Kallala Y , Ben Messaoud M , Boussaada M , Haj Amor H , Sassi G , Jarraya M , Dhouibi A , Memmi K , Mahjoub M , Hassine M , Gamra H 
Published: February 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.
Correlation of left atrial reservoir function with diastolic filling and stroke volume of the left ventricle in patients with rheumatic mitral stenosis

Introduction
It has been theoretically known that the left atrium (LA) plays a key role in compensating for the lack of diastolic left ventricular (LV) filling induced by mitral stenosis (MS). However, due to the lack of adequate tools to assess the LA function, proving this concept turned out to be difficult.
With the recent introduction of two-dimensional (2D) Speckle Tracking Echocardiography (STE) for exploring LA mechanics, this concept can be demonstrated.

Purpose
To assess correlation between LA reservoir function determined by 2D STE derived global strain and LV filling and stroke volumes.

Methods
We prospectively performed comprehensive trans thoracic echocardiography (TTE) in patients with rheumatic MS. Basic echocardiographic parameters were recorded, including indexed LA volume, mitral valve area (MVA) using planimetry and pressure half time (PHT), trans mitral mean gradient, maximal trans tricuspid velocity (MTTV), mitral inflow using continuity equation and LV stroke volume. Studied parameters represent the mean of at least three consecutive cardiac cycles.
LA global strain curve and peak reservoir strain data were obtained on a standard four-chamber view using STE technique.

Results
We enrolled a total of 186 patients with rheumatic MS between February 2018 and February 2021. The mean age of our cohort was 50.55 ± 12.07 yrs. A number of patients were thereafter excluded from the study due to impaired systolic LV function (n = 12), severe mitral or aortic regurgitation (n = 7, n = 1 respectively).
A total of 69.4% of our cohort were female (n = 129), 56.2% (n = 104) had history of percutaneous transvenous mitral commissurotomy (PTMC), 59.9% had permanent atrial fibrillation (n = 109) and 15,2% had history of ischemic stroke (n = 28).
The most prominent comorbidities were hypertension (16.3%, n = 30) and diabetes mellitus (15.8%, n= 29).
The mean 2D MVA was 1.40 ± 0.47 cm², mean PHT derived MVA was 1.47 ± 0.52 cm², mean gradient was 10.72 ± 5.82 mmHg, mean indexed LA volume was 80.70 ± 45.34 ml/m² and mean MTTV was (3.09 ± 0.62m/s).
The mean mitral inflow value was 85.80 ± 28.56 ml/beat and the mean stroke volume was 70.64 ± 25.51 ml/beat.
First, we found a statistically significant correlation between LV stroke volume and 2D mitral valve area (r = 0.284, p &lt; 0.001).
Interestingly, LA peak reservoir phase correlated positively with mitral inflow (r = 0.377, p &lt; 0.001) and LV stroke volume (r = 0.213, p = 0.008). It also correlated with MTTV (r= -0.234, p = 0.009).
However, we did not find any correlation between indexed LA volume and mitral inflow (r=-0.068, p = 0.359) and a weaker correlation with LV stroke volume was demonstrated (r=-0.184, p = 0.014).

Conclusion
LA reservoir function assessed by 2D STE is well correlated with diastolic mitral inflow and LV stroke volume in patients with rheumatic MS.