Mitral stenosis (MS) is a prevalent outcome of rheumatic heart disease (RHD), which remains a significant health challenge, particularly in developing countries [1]. This condition affects a large portion of the population, causing MS and consequently reducing quality of life while increasing the risk of severe cardiovascular complications, including heart failure, stroke, and arrhythmia [2, 3]. Percutaneous balloon mitral valvuloplasty (PBMV) stands out as an effective treatment for MS, offering a less invasive approach with shorter procedure times and greater cost-effectiveness compared to surgical commissurotomy [4]. First introduced in 1984, PBMV gained widespread adoption after four decades of practice, achieving procedural success rates exceeding 90% and consistently increasing the mitral valve area (MVA) to more than 2.0 cm² [5, 6]. However, the radiation-dependent guiding approach poses extra risks for vulnerable populations, such as pregnant patients, individuals with iodinated contrast allergies, or those with chronic kidney disease, thereby limiting procedural safety and accessibility.

Echocardiography is a crucial part of cardiac interventional procedures, utilized for both intraoperative adjustments and postoperative assessments. Our prior studies have established the safety and efficacy of performing various cardiac interventions solely under echocardiographic guidance [7]. Thus, to extend and ensure the safety of the PBMV procedure, we have endeavored to conduct PBMV using echocardiographic guidance exclusively, thereby mitigating the risks of radiation exposure for both medical staff and patients. Despite this, limited evidence exists on the safety and efficacy of PBMV when conducted under echocardiographic guidance alone. This study aimed to evaluate the mid- to long-term effectiveness and safety of PBMV using different guidance methods, providing evidence-based recommendations for optimizing patient selection and procedural safety.

A total of 429 patients who underwent PBMV from January 2016 to December 2022 were included in this study, comprising 71 patients in the echocardiography-guided group and 358 patients in the fluoroscopy-guided group. All 429 patients survived the interventions, with an overall PBMV success rate of 98.8%. Each group had one patient who required surgical intervention due to valvuloplasty failure; the success rate was 98.6% in the echocardiography-guided group and 98.9% in the fluoroscopy-guided group (p = 0.84).

3.2 Procedural Outcomes

After propensity score matching, the echocardiography-guided group had one patient (1.6%) who required surgical intervention, while the fluoroscopy-guided group had one patient (0.8%) with severe mitral regurgitation (MR) intra-operatively. Postoperative echocardiography data are summarized in Table 2. MVA was significantly larger in the echocardiography-guided group compared with the fluoroscopy-guided group (1.68 $\pm$ 0.27 vs. 1.56 $\pm$ 0.28 cm²; p = 0.005) (Fig. 2), and the Emax was improved more in the echocardiography-guided group (1.72 $\pm$ 0.34 vs. 1.84 $\pm$ 0.34 m/s; p = 0.014). Additionally, MTG was significantly decreased in the echocardiography-guided group (5.04 $\pm$ 2.21 vs. 6.13 $\pm$ 2.43 m/s; p = 0.003).

Table 2. Postoperative outcomes of study patients.

Outcomes	Pre-PSM		p-value	Post-PSM		p-value
	Echo (n = 71)	Ra (n = 358)		Echo (n = 64)	Ra (n = 126)
LAD, mm	45.1 (7.21)	45.3 (6.95)	0.81	45.3 (7.54)	45.4 (8.08)	0.93
LVEDD, mm	45.8 (3.93)	45.5 (4.12)	0.53	45.8 (4.09)	45.3 (4.04)	0.40
EF, %	64.6 (5.20)	64.7 (4.71)	0.94	64.2 (5.10)	64.0 (4.65)	0.84
MVA, cm2	1.70 (0.28)	1.60 (0.27)	0.003	1.68 (0.27)	1.56 (0.28)	0.005
Emax, m/s	1.70 (0.33)	1.81 (0.32)	0.012	1.72 (0.34)	1.84 (0.34)	0.014
MTG, mmHg	5.18 (2.19)	6.09 (2.38)	0.003	5.04 (2.21)	6.13 (2.43)	0.003
Severe TR	5 (7.0)	8 (2.2)	0.047	5 (7.8)	6 (4.8)	0.51

Data are presented as the mean (SD) or n (%). PSM, propensity score matching; Echo, echocardiography-guided; Ra, radiation-guided; LAD, left atrial diameter; LVEDD, left ventricular end-diastolic diameter; LVEF, left ventricular ejection fraction; MVA, mitral valve area; Emax, transmitral E peak velocity; MTG, mean transmitral gradient; TR, tricuspid regurgitation.

Fig. 2.

Flow of study population. MS, mitral stenosis; PBMV, percutaneous balloon mitral valvuloplasty; MR, mitral regurgitation; PSM, propensity score matching.

3.3 Follow-up Outcomes

The median follow-up period was 50.6 months, ranging from 3.6 to 84.5 months. During the follow-up, surgery was performed on nine patients (14.3%) in the echocardiography-guided group and 13 patients (10.4%) in the traditional group due to re-stenosis. One patient (1.6%) in the echocardiography-guided group died from heart failure, while six patients (4.8%) in the traditional group died, including two (1.6%) from stroke and four (3.2%) due to heart failure. The related data from these patients were excluded during analysis. Follow-up echocardiographic data are summarized in Table 3. There was a larger MVA in the echocardiography-guided group compared with the fluoroscopy-guided group (1.73 $\pm$ 0.41 vs. 1.49 $\pm$ 0.27 cm²; p 0.001; Fig. 3). Kaplan–Meier survival curve analysis showed no significant differences in re-intervention rates (Fig. 4) or survival between the groups at 7 years (Fig. 5).

Table 3. Follow-up outcomes of study patients.

Outcomes	Pre-PSM		p-value	Post-PSM		p-value
	Echo (n = 71)	Ra (n = 358)		Echo (n = 54)	Ra (n = 126)
LAD, mm	43.9 (6.89)	44.9 (6.97)	0.29	44.3 (7.04)	45.0 (7.23)	0.49
LVEDD, mm	45.0 (4.82)	45.6 (3.34)	0.19	45.0 (4.80)	45.5 (3.50)	0.39
EF, %	63.4 (4.67)	63.7 (5.01)	0.71	63.4 (4.62)	63.0 (5.00)	0.59
MVA, cm2	1.70 (0.43)	1.50 (0.27)	0.001	1.73 (0.41)	1.49 (0.27)	0.001
Emax, m/s	1.89 (0.28)	1.86 (0.26)	0.35	1.87 (0.26)	1.85 (0.17)	0.68
MTG, mmHg	6.20 (2.31)	6.39 (2.55)	0.55	6.10 (2.03)	6.62 (2.68)	0.17
Severe TR	1 (1.4)	4 (1.1)	1.00	1 (1.6)	1 (0.8)	1.00

Data are presented as the mean (SD) or n (%). PSM, propensity score matching; Echo, echocardiography-guided; Ra, radiation-guided; LAD, left atrial diameter; LVEDD, left ventricular end-diastolic diameter; LVEF, left ventricular ejection fraction; MVA, mitral valve area; Emax, transmitral E peak velocity; MTG, mean transmitral gradient; TR, tricuspid regurgitation.

Fig. 3.

Preoperative, postoperative, and follow-up changes in MVA of the two groups. MVA improved significantly in both groups, with more pronounced enhancement noted in the echocardiography-guided group.

Fig. 4.

Freedom from re-intervention in the two groups. No significant difference was observed between groups (p = 0.33).

Fig. 5.

Survival in the two groups. No significant difference was observed between groups (p = 0.23).

Echocardiography has emerged as an indispensable imaging modality in cardiac interventional procedures, offering distinct advantages in real-time visualization of three-dimensional cardiac anatomy while minimizing the requirement for specialized catheterization laboratory equipment. These inherent benefits establish echocardiography-guided interventions as a clinically valuable strategy [11]. Building on the well-documented efficacy of echocardiographic guidance and considering the specific requirements of the patient population, we implemented an echocardiography-only-guided approach for PBMV, aiming to optimize its clinical utility. This study found no significant difference in procedural success for the mid- to long-term outcomes between the two groups, providing valuable evidence to support the adoption of this innovative method.

Additionally, this study observed a statistically significant difference in postoperative and follow-up MVA between the two groups (Fig. 3). This phenomenon may be attributed to several key factors: (1) Enhanced balloon positioning: Real-time echocardiographic guidance allows for more precise balloon placement and optimal commissural splitting, minimizing the risk of suboptimal dilation. (2) Avoidance of overstretching: Direct visualization of the valve structure helps prevent excessive balloon inflation, reducing the likelihood of leaflet damage or excessive commissural tearing, which may contribute to mitral regurgitation. (3) Individualized dilation strategy: Echocardiography provides immediate feedback on valve morphology and leaflet mobility, enabling tailored balloon sizing and pressure adjustments to achieve an optimal balance between effective dilation and structural integrity. Although the difference between the two groups was small, this difference could suggest that echocardiography guidance may have a more favorable long-term effect in the interventional treatment of MS, highlighting the advantages of echocardiography in procedural aspects of intervention. However, further studies with longer follow-up periods and larger sample sizes are needed to investigate and validate this conclusion. Furthermore, this study demonstrated that the echocardiography-guided group can effectively manage surgical treatment for patients in more compromised conditions. In the echocardiography-guided group, a higher proportion of patients were classified as NYHA functional classes III or IV, indicating a potential advantage of echocardiographic guidance in managing critically ill patients. Nonetheless, this observation is based on a limited sample size, and further studies with larger cohorts are necessary to confirm these findings.

Since the inception of PBMV in 1991, this treatment has evolved into the gold-standard Class I recommendation for symptomatic rheumatic MS in anatomically suitable patients, as endorsed by the American College of Cardiology/American Heart Association (ACC/AHA) guidelines [12]. Radiation exposure presents significant risks, particularly to fetuses, and should not be underestimated, as it can lead to fetal deformities and tumor development [13]. Protective measures, such as using lead aprons to shield the abdomen and reducing radiation exposure time, are insufficient to fully mitigate the adverse effects of radiation on pregnant women and their fetuses. Furthermore, contrast agents can induce allergies and renal failure [14]. Hence, replacing radiation with echocardiography for interventional procedures provides a safer alternative for patients with these conditions, safeguarding both medical staff and patients. In this study, three pregnant patients and two patients with renal insufficiency who underwent PBMV under echocardiographic guidance showed marked improvements in hemodynamics and clinical symptoms, further validating the applicability of the technology in special patient populations.

Notably, operators primarily rely on specific anatomical landmarks for positioning and execution in traditional interventional procedures. However, echocardiography offers enhanced visualization, significantly improving procedural accuracy. Moreover, echocardiography enables precise identification of the optimal puncture site during interatrial septal puncture. In both the apical four-chamber and parasternal short-axis views, the characteristic “tent-like” deformation of the interatrial septum revealed the puncture needle tip, allowing real-time adjustments. This facilitates optimization of the distance between the puncture site and the mitral valve orifice based on left atrial size, ensuring the smooth passage of the balloon. More importantly, echocardiography provides a clear delineation of the mitral valve annular plane, ensuring precise balloon positioning at the annular level. This accuracy minimizes the risk of balloon misplacement in the left ventricle or left atrium, a potential limitation of fluoroscopic guidance [15, 16]. Moreover, RHD remains highly prevalent in developing nations and low- to middle-income countries [17], where the economic feasibility of ultrasound machines offers a significant advantage over catheterization laboratories. Echocardiography-guided PBMV can enhance accessibility and utilization in these resource-limited settings, potentially improving procedural efficacy and expanding the reach of life-saving interventions.

In this study, one patient in the echocardiography-guided group developed mitral valve rupture due to severe leaflet fibrosis, thickening, and adhesion, resulting in chordal rupture at the P2 segment and subsequent severe MR, which required surgical intervention on the third postoperative day. This case underscores the importance of a thorough preoperative assessment, particularly for patients with severe valvular calcification, to minimize the risk of surgical intervention. Echocardiography, which visualizes structures based on their reflective surfaces, may not delineate the catheter and guidewire tip, presenting a significant learning curve due to the differences between echocardiographic and radiation guidance. Therefore, selecting a guidewire detectable by echocardiography is crucial. Indeed, a guidewire with a spindle-shaped tip is more visible under echocardiography [18], facilitating the deployment of the wire and catheter (Fig. 1A,B).

In our study, the absence of systematically collected patient-reported outcomes represents a key study limitation. While echocardiographic and clinical endpoints provide objective measures of efficacy, these endpoints cannot fully capture the impact of the treatment on symptom burden, functional status, or health-related quality of life, particularly in this young patient population. Future studies should integrate validated tools, such as the MLHFQ and KCCQ, administered at standardized intervals, to contribute to an improved comprehensive comparison of the effectiveness of different percutaneous balloon mitral valvuloplasty guidance methods, especially with regard to their impact on patient well-being.

For patients with rheumatic MS, our study demonstrates that clinical outcomes, including postoperative, mid-term, and long-term mortality and complications, are comparable between PBMV performed under echocardiography guidance and traditional guidance. This approach preserves the minimally invasive and safety profiles of traditional percutaneous interventional treatments while avoiding the risks associated with radiation and contrast agents.

The data sets generated and analyzed during the current study are not publicly available due to regulation of Ethics Committee, but are available from the corresponding authors on reasonable request.

YAZ, YMY, WBOY and XBP designed the research study. YAZ, YMY, WCL and ZPL performed the research. YAZ, YMY, HL, and JNC collected the data. JKC, FWZ and FF collected and analyzed echocardiographic data. YAZ and YMY completed statistical analysis of data. XBP, WBOY and QL helped perform the analysis with constructive discussions. YAZ and YMY drafted the manuscript. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript. All authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.

The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the ethics committee of Fuwai Hospital (approval numbers: 2023-2221). Informed consent for the operation and clinical record review was signed by patients and legal guardians.

This work was supported by National High Level Hospital Clinical Research Funding (2023-GSP-RC-04), Development Project of National Major Scientific Research Instrument (82327801) and National Key Research and Development Program of China (2022YFC2503400).

The authors declare no conflict of interest.

Supplementary material associated with this article can be found, in the online version, at https://doi.org/10.31083/RCM46811.