European Journal of Cardiovascular Medicine

The left atrium (LA) plays a crucial role in cardiac hemodynamics, functioning as a reservoir, conduit, and booster pump during the cardiac cycle. Left atrial dysfunction is associated with a wide range of cardiovascular diseases, including atrial fibrillation, heart failure, and valvular heart disease, and serves as an important predictor of adverse cardiovascular outcomes. Traditional echocardiographic parameters such as LA volume and diameter provide structural information but may not adequately reflect functional changes. Advances in speckle-tracking echocardiography (STE) have introduced Peak Atrial Longitudinal Strain (PALS) as a sensitive and reproducible marker of LA function, offering insights into atrial mechanics beyond conventional measures [1].

PALS, measured during ventricular systole, represents the reservoir function of the LA and is influenced by left ventricular compliance, LA stiffness, and atrial myocardial properties. Reduced PALS has been associated with increased atrial fibrosis, elevated filling pressures, and a higher risk of arrhythmias and heart failure [2]. Given its prognostic value, PALS is increasingly being used for risk stratification in various cardiovascular conditions, including mitral valve disease, hypertensive heart disease, and cardiomyopathies.

Mitral stenosis (MS) remains a significant cause of cardiovascular morbidity, particularly in developing countries where rheumatic heart disease (RHD) remains prevalent despite advances in healthcare. Percutaneous Balloon Mitral Valvuloplasty (PBMV) has emerged as the preferred intervention for symptomatic moderate-to-severe MS, offering a less invasive alternative to surgical commissurotomy with excellent short- and long-term outcomes. However, the impact of PBMV on left atrial (LA) function, particularly the reservoir function and volume, has garnered increasing interest due to its prognostic implications [3].

The left atrium plays a critical role in cardiac hemodynamics, serving as a reservoir during ventricular systole, a conduit during early diastole, and a booster pump during late diastole. Chronic pressure overload in MS leads to LA remodeling, dilation, and fibrosis, contributing to reduced atrial compliance and an increased risk of atrial fibrillation. Left atrial reservoir function, assessed using peak atrial longitudinal strain (PALS) via speckle-tracking echocardiography (STE), has emerged as a sensitive marker of LA function, providing insights into atrial mechanics beyond conventional volume-based indices [4].

This study aims to evaluate changes in LA reservoir function and volume following PBMV, using PALS as a key echocardiographic parameter. Understanding these changes could improve the assessment of post-procedural hemodynamic improvements and long-term atrial function, ultimately aiding in risk stratification and management of patients undergoing PBMV.

Study Design: Prospective cohort study

Study Time: one year

Sample size: 36

Inclusion Criteria:

1. Adults aged 18–80 years.
2. Symptomatic moderate to severe mitral stenosis (mitral valve area ≤ 1.5 cm²).
3. Indication for percutaneous balloon mitral valvuloplasty (PBMV).
4. Feasible 2D echocardiography and speckle-tracking imaging for PALS assessment.
5. Written informed consent.

Exclusion Criteria:

1. Severe mitral regurgitation (grade ≥ 3).
2. Left ventricular ejection fraction (LVEF) < 40%.
3. Severe coronary artery disease requiring intervention.
4. Anatomical contraindications to PBMV (e.g., calcified valve, thrombus).
5. Pulmonary artery pressure > 60 mmHg.

Statistical Analysis

Data were entered into Excel and analysed using SPSS and GraphPad Prism. Numerical variables were summarized using means and standard deviations, while categorical variables were described with counts and percentages. Two-sample t-tests were used to compare independent groups, while paired t-tests accounted for correlations in paired data. Chi-square tests (including Fisher’s exact test for small sample sizes) were used for categorical data comparisons. P-values ≤ 0.05 were considered statistically significant.

Table 1: Clinical characteristics of the study population

Table 2:  Echocardiographic characteristics of the study population.

Table 3: Segmental peak systolic strain of the different left atrial walls evaluated by color Doppler myocardial imaging (CDMI) study in the mitral stenosis and mitral regurgitation patients compared with the healthy subjects

The study compared baseline characteristics among patients with mitral stenosis (MS, n = 17), mitral regurgitation (MR, n = 19), and healthy individuals (n = 16). The mean body surface area (BSA) was similar across groups (MS: 1.6 ± 0.1 m², MR: 1.7 ± 0.1 m², Healthy: 1.7 ± 0.1 m²). Patients with MR were slightly older (49 ± 13 years) compared to those with MS (42 ± 12 years) and healthy controls (41 ± 13 years). Heart rate was highest in the healthy group (83.8 ± 11.8 beats/min), followed by MS (79.8 ± 13.5 beats/min) and MR (77.1 ± 15.4 beats/min). Systolic blood pressure (SBP) was lowest in the MS group (120.4 ± 15.7 mmHg) and highest in the healthy group (131.1 ± 19.0 mmHg), while diastolic blood pressure (DBP) was highest in the MR group (89.3 ± 27.3 mmHg) and lowest in the healthy group (78.9 ± 14.1 mmHg). Despite some variations, no statistically significant differences were observed among the groups.

The study evaluated left atrial (LA) and left ventricular (LV) parameters among patients with mitral stenosis (MS, n = 17), mitral regurgitation (MR, n = 19), and healthy individuals (n = 16). LA volume was significantly larger in MS (105.7 ± 28.4 ml) and MR (111.1 ± 34.0 ml) compared to healthy controls (45.0 ± 7.7 ml, p < 0.001). Similarly, the LA volume index was elevated in both MS (63.4 ± 18.8 ml/m²) and MR (60.9 ± 20.9 ml/m²) compared to the healthy group (25.5 ± 4.1 ml/m², p = 0.001). Left ventricular end-diastolic diameter (LVEDD) was significantly higher in MR (5.7 ± 0.1 cm) compared to MS (4.6 ± 0.1 cm) and healthy individuals (4.6 ± 0.1 cm, p = 0.049), with a similar trend seen in the LVEDD index (p = 0.05). No significant differences were observed in left ventricular end-systolic diameter (LVESD) or LVESD index among the groups (p = NS). Left ventricular ejection fraction (LVEF) was significantly higher in MR (69.0 ± 3.0) compared to MS (58.4 ± 3.1%) and healthy individuals (59.3 ± 2.9, p < 0.001). The mitral valve area in MS patients was 0.8 ± 0.2 cm². These findings highlight significant structural and functional differences in LA and LV remodeling between MS and MR patients compared to healthy individuals.

The study assessed strain parameters in different atrial wall regions among healthy individuals (n = 16), patients with mitral stenosis (MS, n = 17), and mitral regurgitation (MR, n = 19). In the interatrial septum (IAS), strain at the annulus was lowest in MS (19.5 ± 20.3) compared to MR (25.7 ± 9.6) and healthy controls (32.2 ± 24.8, p = 0.176), while strain at the roof was significantly reduced in MS (48.7 ± 37.3) compared to healthy (133.4 ± 102.4) and MR (105.1 ± 55.1, p = 0.005), with a similar trend in the mean IAS strain (p = 0.01). In the lateral wall, annular strain was lowest in MS (21.1 ± 9.6) compared to MR (25.5 ± 21.6) and controls (42.5 ± 25.3, p = 0.007), while mean lateral wall strain was also significantly lower in MS (28.2 ± 19.8) than in MR (40.3 ± 30.6) and healthy subjects (53.3 ± 43.0, p = 0.009). Anterior wall strain followed a similar pattern, with significantly reduced annular strain in MS (16.5 ± 8.5) versus MR (17.3 ± 9.0) and healthy individuals (26.6 ± 12.3, p = 0.009), and mean anterior wall strain was also lowest in MS (18.2 ± 8.8) compared to MR (36.8 ± 28.4) and controls (36.7 ± 24.1, p = 0.001). Inferior wall strain showed significantly lower annular and roof values in MS (19.7 ± 15.8 and 23.0 ± 10.7) compared to healthy controls (44.8 ± 21.3 and 44.1 ± 25.9) and MR (35.6 ± 18.5 and 65.9 ± 37.8, p < 0.001). Mean annular strain was significantly lower in MS (19.3 ± 14.2) compared to MR (26.0 ± 16.6) and healthy controls (36.6 ± 22.5, p < 0.001), while mean roof strain was also lowest in MS (32.4 ± 25.2) compared to MR (70.5 ± 43.7) and controls (74.0 ± 71.0, p < 0.001). These results indicate significantly impaired atrial strain in MS patients, particularly in the roof and annular regions, compared to MR and healthy individuals.

In the current study, we investigated difference in the LA physiol-ogy in LA pressure and volume overload. Advanced echocardio-graphic technology has now made it possible to assess regional atrial function with new noninvasive and objective measures, in particular by tissue Doppler-derived velocity and strain/SR imaging. [5] In a study, Sirbu et al. [6] assessed the feasibility of measuring regional longitudinal strain/SR profiles in the LA wall and validated these measurements by correlating them with the standard indicators for LA function derived from volumetric mea-suements in healthy young subjects. They concluded that strain and SR imaging could be considered a robust technique for the noninvasive assessment of LA deformation and the understand-ing of LA pathophysiology. The three components of atrial func-tion are reservoir function, conduit function, and booster pump function. According to the previous studies on the deformational properties of the LA, systolic strain and SR represent atrial reser-yoir function and early and late diastolic SRs show conduit and booster functions, respectively.

In the present study, we aimed to compare LA reservoir func- tion by strain imaging study in MS and MR as LA pressure and volume overload, respectively. According to previous stud- ies, strain and SR can predict symptoms in MS patients[7] and they are relatively independent of preload and afterload as well as translational motion. Moreover, among the other parameters for the evaluation of LA physiology such as E/A ratio, LA fractional area change, and LAEF, these parameters are more sensitive.

Comparison of the annular and roof segments of the different LA walls and their mean in our healthy subjects showed that longi- tudinal systolic velocity was larger in the annular segments than in the roof segments. This means that there was velocity gradient and inhomogeneity in velocity from annulus to roof in the nor- mal, MR, and MS groups. Our results showed that, although there was a larger decline in velocity in the MS patients, the percentage of changes in velocity gradient was the same in the three groups (about 47%). In the healthy subjects, the LA inferior wall and the IAS had lower systolic velocity. In the MS and MR patients, the inferior wall had the lowest systolic velocity. This fact is perhaps due to the insertion of four pulmonary veins to the inferior wall, which causes limited motion, as was described in a previous study.[8]

Assessment of the correlation in the healthy subjects showed a significant correlation between systolic velocity and maximal LA volume in both roof and annular segments in the anterior wall, but only in the roof segments in the IAS and the lateral and inferior walls. There was a different result in the MS group insofar as there was a correlation in the roof segments. Whereas this correlation was positive in the MS group, the correlation was negative in the healthy group: this may show the signifi- cance of the assessment of the roof segments in comparison with the annular segments, which are influenced more by tethering.[9] There was no significant correlation in the MR group.

Comparison of the annular and roof segments of the different LA walls in our healthy subjects showed that longitudinal sys-tolic strain and SR were larger in the roof segments than in the annular ones. These data show that myocardial motion does not follow the same pattern as does myocardial deformation.  This means that, similar to systolic velocity, there is gradient and inhomogeneity in strain and SR values from annulus to roof, but in a reverse direction. This gradient was noted in our MS and MR patients as well. In the MS patients, besides the decline in strain and SR, strain gradient (40% in the MS group vs. 63% in the control group). In the MR patients, there was no significant decline in strain and SR value and strain gradient. The strain and  Sk of the LAS was the largest between the four LA walls in the patient groups and the healthy subjects This may be due to the fact that the septum lies between the LA and the right atim and its deformation is, thus, influenced by both atria. Another fact that should be noted is that with respect to the results mentioned in Tables III–V, in most of the comparisons, there were significant differences between the annular and roof segments. Calculation of the mean of these values in the LA walls may be problematic inasmuch as in some of the mean val- ues, there is a considerable standard deviation. However, it is noteworthy that these mean values were calculated in the same situation in the three groups in the present study.

Our findings demonstrated a significant decrease in LA deforma- tional indices in the MS patients by comparison with the MR patients and normal subjects. This reduction in LA strain and SR in our MS patients signifies that pressure overload could have more severe deleterious effects on the LA than could MR despite similar LA volume indices, which could be secondary to hemo-dynamic load and higher LA pressure in MS or the direct involve-ment of the LA myocardial fibers by pathological changes related to the rheumatic process. According to previous studies, as the atrium fills during the reservoir phase, the atrial myocardium (like the ventricle) stores elastic energy, which is released when the mitral valve opens to aid early ventricular filling. Hoit et al. [10] examined LA mechanics during LV dysfunction and compared the compensatory response with a normal atrium versus a failing atrium (induced with rapid atrial pacing). With a normal atrium, reservoir function increased by 19% and booster pump func-tion (atrial contraction) nearly doubled to maintain cardiac output despite a fall in LVEF from 57% to 32%. In contrast, with a failing atrum, reservoir fintion feil by 30%, conduit function increased. by 33%, and atrial kick disappeared Our results showed that conditions with the same LA sias the reservou function of the LA could be diminished more significantly in pressure overload than volume overload, which means that pressure overload may have more pathologic effects on the atrial wall and its function as assessed by strain imaging. The other components of atrial func-tion (conduit and booster) and their changes following pressure or volume overload were not assessed in the present study and should be addressed in another research.

We concluded that, percutaneous balloon mitral valvuloplasty (PBMV) significantly improves left atrial (LA) reservoir function and reduces LA volume in patients with mitral stenosis. Assessment using peak atrial longitudinal strain (PALS) demonstrates enhanced LA compliance and function post-procedure. Following PBMV, increased PALS values indicate improved LA deformation and reservoir capacity, while decreased LA volume reflects reduced pressure overload. These findings highlight the beneficial effects of PBMV on LA remodeling, contributing to better hemodynamics and atrial function. PALS serves as a valuable echocardiographic parameter for evaluating LA recovery and predicting long-term outcomes after PBMV in patients with rheumatic mitral stenosis.

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