Severe MS causes many functional and morphological changes in the left atrium due to chronic resistance to active and passive emptying and a chronic increase in left-atrium pressure. Left-atrial structural and functional remodeling is expected to occur after the relief of mitral obstruction by balloon valvuloplasty [9]. Many studies have investigated the changes after BMV, but most have focused on the immediate or short-term effects using standard 2D Echocardiography, and there is not much data on long-term effects or speckle-tracking measures. This study evaluated the outcomes of BMV either immediately after the procedure and at different time points using 2D speckle-tracking Echocardiography. The results demonstrated that LA GLS, sPAP, MVA, and the LAV index were significantly lower in patients with severe MS compared to the control group. However, all of these parameters improved immediately after BMV and at 6 and 12 months (p < 0.01).

This study was extended to compare various distinctive parameters before and after BMV, as detailed in Tables 7, 8, 9. Table 7 presents the BMV and the immediate LA GLS relationship in two patient groups categorized by the MVA's severity. The results indicate that the severity of MVA impacts the immediate LA GLS following BMV. The severe group consists of 44 patients with severe MVA but not as severe as the second group. The more severe group includes 51 patients with an even more severe condition characterized by a smaller MVA. Patients with more severe MVA (MVA less than 1.0 cm2) tend to have a lower immediate LA GLS than those with severe MVA (MVA less than 1.5 cm2). The value of 0.03* suggests a statistically significant difference in immediate LA GLS between these groups.

Table 8 examines the potential relationship between gender and immediate LA GLS. The results suggest that the Improvement of LA GLS was higher in females. However, the data indicates that gender does not appear to significantly explain variations in immediate LA GLS values in this study.

Table 9 investigates the relationship between MR severity and the immediate LA GLS. Mild MR cases had a significantly higher immediate LA GLS, followed by moderate MR cases, then severe MR cases. The severity of MR is strongly associated with the immediate LA GLS values. Patients with more severe MR tend to have lower immediate LA GLS values, indicating impaired left atrial function. The statistical significance reinforces the validity of these findings.

Our results are consistent with those of Reddy et al. [5], who performed strain imaging to evaluate the early effects of PBMV on the mechanics of the left atrium for 29 patients with MS. They compared the results with those of 30 age- and sex-matched healthy control subjects. The MS cases showed a significant increase in the mean left atrial diameter and left atrial area compared to the control group. Also, the MS cases had significantly lower left atrial strain at baseline compared to the control group. Similar to our results, they observed that patients with severe MS exhibited impaired LA GLS, which improved within 24–48 h after BMV (p < 0.001). Furthermore, they found a significant decrease in the mean mitral gradient (MMG) and sPAP (both p < 0.001) and A significant rise IN MVA (p < 0.001) after BMV.

Ansari et al. [12] investigated the immediate and late outcomes of BMV in the left atrium and left atrial appendage (LAA) in patients who had severe MS with sinus rhythm. They found no considerable improvement in the fractional LAA area change (LAAAC) directly after percutaneous transvenous mitral commissurotomy (PTMC), but significant improvement was observed by 6 months after PTMC. Also, a considerable increase was observed in LAA PW Doppler velocities (LAALDE, LAAEDE, and LAAF velocity) directly after PTMC, which improved significantly within 6 months of follow-up.

Additionally, a considerable rise in LAA DTI velocities was noted (ALAA, ELAA, and SLAA velocity) directly after PTMC, leading to significant improvement within 6 months of follow-up. The MVA increased significantly after PTMC (p < 0.001). In contrast, both left atrial volume indexes and PASP decreased significantly after PTMC (p < 0.001). However, that study focused on the appendage function, not the LA GLS, and there was no healthy control group, unlike our study.

Our results agree well with a recent study by Samart et al. [13], who observed significant improvement in the MVA after BMV (p < 0.001). Also, a significant improvement (24% compared to baseline) was achieved in peak atrial longitudinal strain immediately after the procedure (p < 0.001), and the improvement continued as of 3 months after BMV (74% compared to baseline; p < 0.001). The left atrial volume index significantly decreased immediately after the procedure (p = 0.003) and at the 3-month follow-up (p = 0.002). The left atrium volume and left atrium volume index were notably reduced at 24 h after the procedure and during follow-up. Although their results were similar to our study, the follow-up was only for 3 months, and there was no control group.

Rohani et al. [14] reported an improvement in the peak systolic LA GLS after MVR (p = 0.012) and after PTMC (p < 0.001). Also, the results showed a significant reduction in the estimated PASP after MVR (p = 0.006) and BMV (p < 0.001). In addition, MS patients' mean MVA was significantly increased after BMV (p < 0.001). Despite having similar results regarding BVM, there was no significant difference in PALS after PTMC and MVR (p = 0.60). The results were also a combination of the outcomes of both PTMC and MVR with no assessment of the short and long-term outcomes of only BMV.

In the present study, a significant positive correlation was found between immediate LA GLS and the achieved MVA (0.64, p < 0.01), and the function class was improved significantly after valvuloplasty (p < 0.01). This correlation was unique to our study and reflected the efficiency and success of BVM in enhancing both the left atrial volume and function. Ahmed [15] found a significant positive correlation between the left atrial longitudinal strain improvement and drop in the mean trans-mitral pressure gradient, as well as left atrial volume reductions at 12 months after BMV. Rohani et al. [14] reported a significant correlation between the drop in mean transmitral pressure gradient and left atrial global longitudinal strain (r = 0.60, p < 0.01) after PTMC. However, a non-significant correlation was observed between the PALS and the MVA (r = 0.03). Many studies have also demonstrated the improvement of function class after a successful BMV [6, 13, 15].

This study had some limitations, such as a lack of investigation of BMV's effects on the right and left ventricular strain. Another limitation of this study is that we focused on the reservoir function only, although it contributes 70% of the left atrial function. The reason was that the equipment used at the time of the study was limited to only determining the reservoir function, so further studies are needed to include all functions of the left atrium. However, the study had some strengths, such as a relatively large sample size of case and control groups and a relatively long-term follow-up compared to previous studies.