Pediatric mitral valve repair: the value of global strain for follow-up

The challenge of pediatric mitral surgery

Mitral valve pathology remains rare in children, but its management requires critical surgical arbitration. While prosthetic replacement is an option, it exposes the young patient to severe complications: prosthetic mismatch related to growth, the need for lifelong anticoagulation, and risks of conduction disorders. In this context, mitral repair emerges as the strategy of choice to preserve the functional future of these patients.

Objectives and focus of the SCTIMST study

This retroprospective study, conducted in a tertiary care center, analyzes the clinical outcomes and survival of a cohort of 49 children (aged 0 to 18 years) who underwent mitral repair between January 2011 and December 2019. The central objective is to evaluate the safety of the procedure and the long-term durability of the results in a predominantly non-rheumatic population (81.6%).

The study specifically tests the hypothesis that annuloplasty, ideally using a ring, is essential to ensure long-term valvular competence. Furthermore, the authors evaluate the relevance of left ventricular global longitudinal strain (GLS) as a marker for detecting occult myocardial dysfunction during postoperative follow-up.

Study methodology

This retro-prospective observational study was conducted in a tertiary care center (SCTIMST). It included all pediatric patients, aged 0 to 18 years, who underwent mitral valve repair between January 1, 2011, and December 31, 2019.

The protocol and the sample are based on the following criteria:

• Population: 49 children in total (28 boys and 21 girls) undergoing elective surgery.
• Etiologies: 9 patients presented with rheumatic heart disease (18.4%) compared to 40 patients (81.6%) with non-rheumatic pathology.
• Clinical profile: Severe mitral regurgitation was documented in 31 patients (63.3%). The dominant lesion morphology was type 2 according to the Carpentier classification (71.4%).
• Associated anomalies: Presence of atrial septal defects (ASD, n=18), ventricular septal defects (VSD, n=11), as well as isolated cases of Shone's complex, pulmonary atresia with intact ventricular septum, and patent ductus arteriosus.

The evaluation of postoperative outcomes combined a retrospective review of medical records and prospective follow-up via transthoracic echocardiography (TTE) and telephone interviews. Imaging analysis specifically integrated the measurement of left ventricular global longitudinal strain (GLS), with a reference threshold set at > -19.9% to identify occult dysfunctions.

Cohort profile and etiologies

The study included 49 children (28 boys and 21 girls) who underwent elective mitral repair. The etiological distribution shows a clear predominance of non-rheumatic pathologies compared to classic rheumatic involvement.

Associated cardiac anomalies

The majority of patients presented with concomitant congenital anomalies, requiring comprehensive management during the mitral intervention:

• Atrial septal defect (ASD): 18 patients (36.7 %).
• Ventricular septal defect (VSD): 11 patients (22.4%).
• Isolated cases: Shone's complex, pulmonary atresia with intact ventricular septum (IVS) and patent ductus arteriosus (PDA).

Postoperative follow-up and complications

The surgical reintervention rate was 18.4% (9 patients). Furthermore, 5 patients (10.2%) progressed towards a univentricular correction pathway. Regarding infection, although two cases of infective endocarditis were recorded (4.08%), no deaths were attributed to this complication.

Functional imaging evaluation

Postoperative myocardial function evaluation integrated the measurement of the left ventricular Global Longitudinal Strain (GLS). The results show:

• Left ventricular GLS > -19.9% in 80.9% of evaluated patients.
• This data highlights the value of GLS in detecting subclinical ventricular dysfunctions that conventional echocardiography might overlook.

Note: Source data do not mention specific p-values for comparisons between rheumatic and non-rheumatic subgroups.

Analysis of results and clinical relevance

This retroprospective study, conducted on 49 pediatric patients at SCTIMST, confirms that mitral repair is a safe and effective alternative to valve replacement, thus avoiding prosthesis-related complications (growth mismatch, anticoagulation). The data show a marked predominance of non-rheumatic pathologies (81.6%) and Carpentier type 2 lesions (71.4%). Clinically, the long-term maintenance of valvular competence appears closely linked to the performance of an annuloplasty, with the authors highlighting the superiority of ring annuloplasty when anatomy and growth permit.

The emerging role of Global Longitudinal Strain (GLS)

A major contribution of this work concerns postoperative evaluation. The observation of a left ventricular GLS greater than -19.9% in 80.9% of patients suggests that this ultrasound tool is more sensitive than simple ejection fraction for detecting subclinical myocardial dysfunction. For the practitioner, the systematic integration of GLS could refine follow-up and guide early interventions before the onset of irreversible ventricular failure.

Limits and implications for practice

Although the results are encouraging, the study reports a significant reoperation rate of 18.4% and a progression toward a univentricular pathway for 10.2% of subjects, illustrating the complexity of associated congenital heart diseases (ASD in 36.7% of cases, VSD in 22.4%). The main limitation lies in the single-center nature and the relatively modest sample size (n=49). Nevertheless, the absence of mortality related to infective endocarditis, despite an incidence of 4.08%, reinforces the superiority of the conservative strategy over prosthetic replacement in this young population.

Summary of results

This study conducted on 49 pediatric patients (81.6% non-rheumatic etiologies) reports a reoperation rate of 18.4% with excellent procedural safety. Global longitudinal strain (GLS) was found to be greater than -19.9% in 80.9% of subjects, confirming the preservation of ventricular function after repair.

In concrete terms, for the practitioner:

• Prioritize repair: this approach avoids the prosthetic mismatch associated with the child's growth and eliminates the need for long-term anticoagulation.
• Optimize annuloplasty: prioritize the use of a ring as soon as the anatomy allows to ensure long-term stability and valvular competence.
• Adopt GLS monitoring: integrate this measure into postoperative echocardiography to detect occult ventricular dysfunctions that conventional ejection fraction cannot identify.

Technical lexicon of the study

Carpentier classification: Nomenclature system used to describe the mechanism of mitral regurgitation based on the mobility of the valve leaflets. In this study, type 2 (leaflet hypermobility) was the most frequent lesion (71.4%).

Global Longitudinal Strain (GLS): Advanced echocardiography parameter measuring the longitudinal deformation of the left ventricle. The study highlights its role in detecting postoperative occult dysfunctions, with a value > -19.9% observed in 80.9% of the evaluated patients.

Annuloplasty: Surgical procedure consisting of remodeling, stabilizing or reducing the mitral ring. The authors consider it essential for the durability of the repair, favoring ring annuloplasty when pediatric anatomy permits.

Shone's complex: A rare congenital heart malformation involving several levels of left heart obstruction (often four). This complex has been identified as an associated anomaly in some patients of the cohort.

Prosthesis-patient mismatch: A complication specific to the pediatric population where an artificial valve becomes too narrow relative to the child's somatic growth. Repair is preferred in this study precisely to avoid this phenomenon.

Univentricular pathway: Surgical palliation strategy for hearts with only one functional ventricle. In this series, 10.2% of patients progressed towards this clinical pathway.

Rheumatic heart disease: Valvular damage following acute rheumatic fever. Although representing a minority in this sample (18.4%), it is one of the two main etiologies of treated mitral valve disease.

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