Robotic mitral valve repair: how to select the ideal candidate?

Context and challenges of robotic mitral surgery

Although sternotomy remains the gold standard in the United States, robotic mitral surgery is experiencing a rapid rise, representing 15% of repairs in 2021, a 50% growth since 2015. This technological transition raises a major clinical challenge: adopting a minimally invasive approach without sacrificing standards of excellence, namely a maximal repair rate and minimal morbi-mortality. For the surgeon, the challenge is to ensure that the benefit of the reduced incision is not achieved at the expense of the quality of the repair or intraoperative safety.

The objective of this review is to evaluate the safety and efficacy of the robot compared to traditional sternotomy, while structuring the critical steps for implementing a robotic program. The authors detail the essential preoperative investigation protocols and define the selection criteria for the "ideal patient" to secure the teams' learning curve, estimated at approximately 50 procedures.

The study is based on the hypothesis that the robotic approach can match the effectiveness of sternotomy while offering tangible clinical benefits: decreased blood transfusion requirements, reduced incidence of postoperative atrial fibrillation, and accelerated functional recovery. However, these benefits depend on rigorous management of prolonged clamping times and strict anatomical selection of candidates during the learning curve phase.

Methodological approach and registry data analysis

This clinical review synthesizes data from the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database for the 2015-2021 period, during which 103 hospitals performed robotic mitral repairs. The authors analyze practice trends (50% increase in robotic volume since 2015) and integrate results from the UK Mini-Mitral controlled trial comparing right minithoracotomy to sternotomy.

The protocol for selecting the ideal patient is based on specific quantitative and clinical parameters detailed in the review:

• Biometric and anatomical criteria: BMI between 20 and 25 kg/m², femoral artery diameter ≥ 7 mm validated by CT scan (thorax, abdomen, pelvis), and absence of thoracic deformity (pectus excavatum).
• Cardiovascular assessment: Normal ventricular functions (LV/RV), absence of aorto-iliac atherosclerosis and aortic insufficiency (confirmed by TTE and angiography).
• Surgical complexity: Focus on P2 prolapse with peripheral healthy tissue for initial phases.

The authors also report the evaluation of the technical learning curve, setting a methodological milestone at 50 cases for the acquisition of team skills. The efficacy analysis compares the valve repair rate, mortality, and major morbidity between the robotic approach and conventional sternotomy.

Growth and Performance of the Robotic Approach

Data from The Society of Thoracic Surgeons Adult Cardiac Surgery database reveal a growing adoption of robotics: in 2021, approximately 15% of mitral valve repairs were performed robotically in the United States, representing a 50% increase compared to 2015. This activity is distributed across 103 hospital centers.

The synthesis of monocentric studies and national registries (including Japanese and American data) confirms that the robotic approach offers very high repair rates with extremely low morbidity and mortality, comparable to sternotomy. The UK Mini-Mitral trial, comparing right minithoracotomy to sternotomy, showed no significant difference in terms of major morbidity, mortality, or physical function at 12 weeks (primary endpoint).

Selection Criteria and Learning Curve

Analysis of the results highlights the importance of patient selection to optimize safety, particularly during the initial phase. The data indicate that:

• Learning curve: A structured team generally reaches key performance milestones after 50 cases.
• Anatomical parameters: A femoral artery diameter ≥ 7 mm is required for safe direct cannulation. Significant aorto-iliac atherosclerosis (plaque occupying more than 50% of the circumference) contraindicates femoral perfusion due to the risk of stroke.
• Morphology: The ideal body mass index (BMI) is between 20 and 25 kg/m². Extremes (obesity or very narrow thorax) increase technical complexity.

From a qualitative perspective, preoperative CT imaging (thorax, abdomen, pelvis) is considered crucial for identifying anatomical variants impacting the strategy, such as a discontinuous inferior vena cava or a retroesophageal right subclavian artery.

Clinical analysis: the balance between innovation and safety

The data compiled in this review highlight a profound shift in practices: 15% of mitral repairs in the United States are now performed robotically, representing a 50% growth between 2015 and 2021. This transition does not appear to sacrifice safety. Similar to the results of the UK Mini-Mitral trial on minithoracotomy, the authors report that the robotic approach maintains high repair rates and morbi-mortality comparable to sternotomy. The clinical benefits are tangible: reduced need for transfusions, lower incidence of postoperative atrial fibrillation, and a faster return to professional activity.

Identified technical limits and challenges

The lack of specific randomized controlled trials for the robot still limits the level of formal evidence, with data relying largely on national registries (STS) or single-center studies. On a technical level, robotic surgery requires longer cardiopulmonary bypass and aortic clamping times. The learning curve is a critical factor: the authors estimate that approximately 50 cases are necessary for a team to stabilize its results and master the nuances of myocardial protection in a closed-chest approach.

Implications for patient selection

The success of the procedure depends on a rigorous preoperative assessment. The thoraco-abdominal-pelvic CT scan is presented as the key examination for evaluating femoral access — a minimum diameter of 7 mm being required — and for excluding aorto-iliac atherosclerosis which would contraindicate retrograde perfusion. For the practitioner, targeting the "ideal" patient (BMI 20-25, isolated P2 prolapse, absence of aortic insufficiency) allows for the secure implementation of the program before expanding indications to more complex pathologies such as Barlow's disease.

Summary of results

Health data show that robotic surgery accounts for 15% of mitral repairs in the United States (+50% since 2015), with safety and success rates equivalent to sternotomy. This approach allows for a significant reduction in transfusions, the incidence of postoperative atrial fibrillation, and the length of hospital stay, while accelerating the return to work.

In concrete terms, for the practitioner:

• Strategic selection: Identify the ideal candidate (BMI 20-25, P2 prolapse, normal ventricular function) to secure the team's learning curve, estimated at 50 initial procedures.
• Mandatory vascular assessment: Systematically use CT scan to validate a femoral artery diameter ≥ 7 mm and exclude any aorto-iliac atherosclerosis, ensuring peripheral perfusion without embolic risk.
• Clinical arbitration: Prioritize the robotic approach to optimize functional recovery and aesthetics, provided that the valvular complexity and the patient's anatomy allow for maintaining the excellence of the repair rate.

Technical lexicon of the study

P2 Prolapse: Prolapse of the middle segment of the posterior mitral valve. This study defines it as the ideal pathology to start robotic activity, allowing management by triangular resection and annuloplasty.

Barlow's disease (Barlow's valve): Complex degenerative mitral pathology involving excess tissue and multi-segmental prolapse. The study confirms that these valves can be treated robotically in expert centers without compromising outcomes.

Cardioplegia (antegrade and retrograde): Myocardial protection methods. While the antegrade route is standard in robotics, the study recommends the use of the retrograde route (via the coronary sinus) to compensate for even mild aortic insufficiency and avoid ventricular damage.

Aorto-iliac atherosclerosis: Presence of atheromatous plaques in the aorta or iliac arteries. The study specifies that a plaque occupying more than 50% of the arterial circumference contraindicates femoral perfusion due to the increased risk of stroke.

Pectus excavatum: Funnel chest deformity. The study identifies it as a relative contraindication that may require concomitant correction or conversion to a sternotomy depending on the severity.

Fibroelastic deficiency: Structural alteration of the valvular tissue. The study mentions this condition in contrast to healthy tissues to highlight the selection criteria for the ideal patient during the initial phase of the learning curve.

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