Reintervention after percutaneous mitral balloon commissurotomy in patients with rheumatic heart disease: feasibility of surgical mitral valve repair

Introduction

In patients with rheumatic heart disease (RHD) who have undergone percutaneous mitral balloon commissurotomy (PMBC), there are substantial cases that might suffer symptomatic disease progression, such as restenosis, regurgitation, or mixed lesions (1). According to current European and American guidelines for the management of valvular heart disease, mitral valve replacement is the preferred treatment option in these patient populations (2,3). Only a small portion of patients can perform repeated PMBC if they have favorable valve anatomy and the predominant mechanism is commissural fusion (4).

Up to now, the safety and effectiveness of mitral valve repair for the treatment of rheumatic mitral valve disease has been confirmed (5-10). However, for patients with a history of PMBC, it remains unclear whether mitral valve repair is still feasible. Therefore, in this study, we aimed to investigate the feasibility of mitral valve repair in such patients and report its therapeutic outcomes compared to mitral valve replacement. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1485/rc).

Methods

Patients

The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the Ethics Committee of Beijing Anzhen Hospital, Capital Medical University (approval No. KS2022064) and individual consent for this retrospective analysis was waived.

A flowchart of this study is shown in Figure 1. Between January 2011 and August 2023, patients with a history of PMBC who underwent mitral valve surgery due to disease progression were included in this study. Patients who underwent concomitant cardiac procedures consisting of aortic valve surgery, coronary artery bypass grafting, tricuspid annuloplasty (TAP), atrial fibrillation (AF) ablation, and left atrial thrombectomy were included. According to the type of surgery, all patients were divided into two groups: the repair group and the replacement group.

Figure 1 Flow chart of this study. PMBC, percutaneous mitral balloon commissurotomy; SIPTW, stabilized inverse probability of treatment weighting.

Perioperative echocardiographic assessment

All patients underwent preoperative transthoracic echocardiographic (TTE) test routinely to evaluate the valve morphology, hemodynamic severity, ventricular function and chamber size. Transesophageal echocardiography (TEE) was performed if the TTE image was not clear or there was a suspected thrombus in the left atrium. During repair surgery, the ultrasound probe was placed inside the esophagus after general anesthesia. After the repair process finished, the TEE examination was carried out to evaluate the results when the patient’s heart-beat recovered to normal rhythm. Before discharge, all the operated patients reconfirmed the function of repaired valve or prosthesis by postoperative TTE test. The severity of mitral regurgitation (MR) and tricuspid regurgitation was graded as follows: none or trivial (0), mild (1+), moderate (2+), moderate-to-severe (3+), or severe (4+).

Surgical procedures

All procedures were performed by experienced surgeons at our center. The approach was through anterior chest skin incision, then followed by median sternotomy. After acquiring satisfied cardioplegia, a right sided left atrial incision was carried out to expose the mitral valve. The valve lesions and extent of sub-valvular involvement were evaluated again through intraoperative direct vision. Whether to perform repair was at the discretion of surgeons. For repair, the Score procedure was used, as described by Luo et al. (11,12) in detail. Briefly, the Score procedure comprised four steps (shaving, checking, commissurotomy, and releasing), in which commissurotomy was the main operative technique. Following the aforementioned steps, the saline injection test was performed to assess the repaired valve competence. Finally, an annuloplasty ring was implanted to shrink the mitral annulus to reduce the risk of future annulus dilation. The process of mitral valve repair in a patient with a history of PMBC is shown in Video 1. For replacement, the anterior leaflet was completely removed from the mitral annulus, and whether preserving the posterior leaflet was based on intraoperative observation. Subsequently, a suitable bioprosthetic or mechanic valve was implanted according to the measurement of the mitral annulus. The choice of prosthesis type adhered to the patient’s selection after fully preoperative informing.

Postoperative management

At discharge, all patients were instructed to attend regular outpatient visits, and the time interval was according to the standard institutional practices. Patients who underwent mechanical valve replacement or had persistent AF were prescribed warfarin for long-term use, with a target international normalized ratio of 2.0 to 3.0.

Data collection and outcomes

The hospital’s electronic medical records system was used to collect demographic information, echocardiographic parameters, surgical details, and perioperative clinical outcomes for all enrolled patients. Follow-up data was obtained through direct telephone interviews with the patients or their relatives, or by examining visit records from the hospital’s outpatient information system. Survival status was censored at the last available contact, if the patients were lost to follow-up. The follow-up of this study was concluded on November 12, 2023. Clinical outcomes of interest included freedom from mitral valve reoperation and overall survival.

Statistical analysis

Continuous variables were expressed as mean ± standard deviation (SD) or median with interquartile range (IQR), and group differences are compared using Student’s t-test or Mann-Whitney U test. Categorical variables were reported as numbers and percentages (%), and the differences between groups were compared with Pearson’s Chi-squared test or Fisher’s exact test, as appropriate. Kaplan-Meier (K-M) method was used to plot the survival curves, and the differences between groups were compared by the Log-rank test. The median follow-up time was evaluated using reverse K-M method.

To make the baseline characteristics of the two groups comparable, we applied stabilized inverse probability of treatment weighting (SIPTW) to balance intergroup differences. First, we constructed a multivariable logistic regression model to estimate the probability of each patient receiving “treatment”, known as the propensity score (PS). In the PS model, the dependent variable was replacement, while covariates included age, sex, AF, MR ≥2+, left atrial anteroposterior diameter (LAAPD), mitral valve orifice area (MVOA), fraction shorting, left ventricular ejection fraction, and left ventricular end diastolic diameter. We then used the PS to calculate individual weights: the replacement group weight was calculated using the formula Pt/PS, and the repair group weight was calculated using the formula (1 − Pt)/(1 − PS), where Pt represents the proportion of patients in the replacement group relative to the total sample size. Finally, we conducted weighted analysis on the outcome variables using the calculated weights. The balance between groups after SIPTW is assessed using the standardized mean difference (SMD). However, there is no consensus on a specific threshold for the SMD that would indicate good balance between groups. In this study, we consider an SMD value of less than 0.2 to be acceptable.

All data analyses were conducted by means of IBM SPSS version 22.0 (IBM Corp., Armonk, NY, USA) and R version 4.4.0 (http://www.R-project.org, The R Foundation). All reported P values were 2-sided, and P values <0.05 were considered statistically significant.

Results

Baseline characteristics

A total of 215 patients with a history of PMBC who underwent mitral valve surgery at our center were reviewed. Among them, 5 patients were excluded due to missing data. Ultimately, 210 patients were included in this study, of whom 32 underwent valve repair and 178 underwent valve replacement. Regarding mitral valve lesions, the distribution of different severities of mitral stenosis (MS) relative to various grades of MR is shown in Figure 2A, with MS-dominant lesions being the most common type (Figure 2B).

Figure 2 Summary of the distribution of mitral stenosis and mitral regurgitation (A), as well as the proportion of different types of mitral valve lesions (B). MR, mitral regurgitation; MS, mitral stenosis; MVOA, mitral valve orifice area.

A comparison of baseline characteristics between the two groups is presented in Table 1. Prior to SIPTW, patients in the repair group were younger (53.1±9.5 vs. 57.2±10.0 years, P=0.03), had a greater MVOA (1.2±0.3 vs. 1.0±0.3 cm², P<0.001), but were associated with a lower LAAPD (48.2±7.0 vs. 52.9±9.7 mm, P=0.008), as compared with those in the replacement group. With regard to other baseline characteristics, no statistically significant differences were observed between the two groups. After SIPTW, all baseline characteristics were well balanced between the two groups (Table 1). The changes in each baseline characteristic variable before and after SIPTW are shown in Figure 3.

Figure 3 Balance assessment of baseline characteristics. SIPTW, stabilized inverse probability of treatment weighting; SMD, standardized mean difference; MVOA, mitral valve orifice area; LAAPD, left atrial anteroposterior diameter; LAT, left atrial thrombus; TR, tricuspid regurgitation; LVESD, left ventricular end systolic diameter; LVEDD, left ventricular end diastolic diameter; FS, fraction shorting; LVEF, left ventricular ejection fraction; NYHA, New York Heart Association; CI, cerebral infarction; MS, mitral stenosis; MR, mitral regurgitation.

Operative details and early outcomes

Operative data are listed in Table 2. Compared with the replacement group, patients in the repair group underwent more concomitant TAP procedures (96.1% vs. 67.4%, P<0.001), but fewer aortic valve surgeries (3.0% vs. 25.2%, P<0.001). Among all concomitant TAP procedures, the use of annuloplasty rings was significantly higher in the repair group than in the replacement group (90.3% vs. 64.0%, P=0.01). For other surgical details, there were no significant differences between the two groups. The types of mitral and TAP rings used during surgery are shown in Figure S1.

Postoperative outcomes during hospitalization are shown in Table 3. The results for the repair group appeared to be better than those for the replacement group; however, none of the differences reached statistical significance, except for the duration of mechanical ventilation [15.0 (11.2–19.0) vs. 19.0 (15.0–37.0) h, P=0.001] and the length of stay in the intensive care unit [18.8 (16.1–22.0) vs. 21.0 (17.0–35.9) h, P=0.01]. The TTE results before discharge are presented in Table S1.

Follow-up outcomes

Follow-up was completed for 187 (89.0%) patients. The median follow-up time for the entire cohort was 75.6 months. There were no significant differences in baseline characteristics between patients with and without loss to follow-up (Table S2). The K-M analysis after SIPTW adjustment showed no statistically significant differences between the two groups in terms of freedom from mitral valve reoperation (Log-rank P=0.07) and overall survival (Log-rank P=0.36). The adjusted survival curves are shown in Figure 4, while the unadjusted curves are presented in Figure S2.

Figure 4 The adjusted Kaplan-Meier curves showing freedom from mitral valve reoperation (A) and overall survival (B). The P value derived from the Log-rank comparison.

Discussion

In this study, we reported the feasibility of mitral valve repair in patients with a history of PMBC and compared its therapeutic outcomes with those of mitral valve replacement. The major finding of this study was that if patients suffer disease progression after PMBC, repair was also a feasible and effective treatment option for suitable cases. Compared to mitral valve replacement, its early postoperative outcomes seem to be better, and the long-term durability is also satisfactory.

Many studies have documented the excellent immediate and good long-term outcomes after PMBC. However, owing to the progression of RHD, a considerable number of patients require reintervention within 10 years after PMBC (13-15). Especially in low-income and developing countries, where limited technology and equipment may contribute to a higher reintervention rate (16-18). While repeated PMBC is considered the ideal treatment option, the worsening of valve morphology after the initial procedure greatly limits its feasibility. Bouleti et al. (4) reported that even in experienced European centers, only one out of four patients were eligible for a repeated PMBC. Therefore, mitral valve surgery remains the primary treatment choice in clinical practice.

In terms of surgical approaches, replacement surgery remains the most common choice for many teams. However, patients who undergo mitral valve replacement face numerous challenges, such as progressive heart failure, anticoagulation-related complications, and a heightened risk of prosthetic valve infective endocarditis, all of which significantly impact long-term survival and quality of life (19-21). In cases of degenerative valvular disease, it is widely recognized that repair surgery offers various survival advantages over replacement. The efficacy and safety of rheumatic mitral valve repair are increasingly being validated, and we believe that many surgeons are actively attempting to repair the mitral valve after PMBC. However, published literature on this topic remains scarce.

Certainly, the repair of rheumatic mitral valve disease is challenging and complex, often requiring the integration of multiple techniques. Our study suggests that, for appropriately selected patients with a history of PMBC, the repair is also a viable option. In this patient population, repair surgery does not significantly increase the cardiopulmonary bypass time or aortic cross-clamp time compared to valve replacement. In addition, early clinical outcomes in the repair group seem to be superior to those in the replacement group, such as shorter mechanical ventilation times and reduced lengths of stay in the intensive care unit, indicating that repair may offer a quicker recovery and fewer postoperative complications.

The durability of rheumatic mitral valve repair is a major concern for surgeons. Previous studies have shown that, with good repair, its durability can be comparable to that of degenerative lesions (22,23). In this study, the adjusted K-M analysis revealed that the risk of mitral valve reoperation in the repair group did not significantly increase compared to the replacement group. This indicates that even when the original valve anatomy has been compromised by PMBC, careful repair still ensures reliable durability. Furthermore, no significant statistical differences were observed between the two groups in terms of overall survival rates. These results provide valuable insights for surgical decision-making, supporting repair as a reliable option for suitable RHD patients with a history of PMBC.

Currently, several studies report varying results regarding rheumatic mitral valve repair (24-26). We believe that, in addition to the use of different repair techniques, the repairability of rheumatic mitral valves is a critical factor. The current Wilkins score primarily assesses the feasibility of PMBC, but according to our experience, it is not suitable for repair surgery. Although, Coutinho et al. (27) proposed an intraoperative morphological scoring system based on the analysis of 2,334 cases of rheumatic mitral valve surgery, this system closely resembles the Wilkins score and lacks refinement. Moreover, this scoring system does not account for commissural lesions. In this context, our team has developed a preoperative predictive model for the repairability of rheumatic mitral valve disease based on computed tomography (CT) imaging findings (28). This model has demonstrated good predictive performance.

Our study had the following limitations. First, it was a retrospective study conducted at a single center, which might introduce biases such as selection bias and information bias. Second, the sample size in our study was small, particularly for patients undergoing repair, which limited the statistical efficiency. Third, we did not collect echocardiographic data for discharged patients who underwent repair, thereby preventing us from evaluating long-term valvular conditions like restenosis and regurgitation. Fourth, 11.0% of patients were lost to follow-up, potentially leading to an underestimation of the cumulative incidence of clinical events. However, this proportion of patients was small and their baseline characteristics were comparable to those with follow-up. Finally, the follow-up time was not sufficiently long, warranting the need for long-term follow-up.

Conclusions

In summary, repair surgery offers significant advantages in terms of preserving heart function, reducing complications, and improving quality of life, as compared to replacement surgery. Based on our findings, although patients with RHD have previously undergone PMBC, it is still possible to perform mitral valve repair in suitable patients. However, a careful systematic assessment of the patient should be conducted preoperatively to determine the reparability of the mitral valve.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1485/rc

Data Sharing Statement: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1485/dss

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1485/prf

Funding: This study was supported by Major Scientific and Technological Innovation Research and Development Project of Beijing Anzhen Hospital affiliated to Capital Medical University and High-end Foreign Expert Introduction Plan (grant No. G2022001039L).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1485/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the Ethics Committee of Beijing Anzhen Hospital, Capital Medical University (approval No. KS2022064) and individual consent for this retrospective analysis was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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