The Surge

The top challenges and their impact on treatment choices 

When determining the best intervention for patients with mitral regurgitation (MR), many factors need to be considered, from the individual patient’s pathology and risk factors to the available treatment options and the surgeon’s experience with them. The key is to determine the relative risk of the various procedures and decide on the one that gives the patient the best survival probability and functional outcome.

Mitral valve disease presents as a continuum.^1-3 Mitral valve surgery is particularly challenging due to the complexity and interdependent nature of the various pathologies and surgical options.¹ In this article I’ll discuss some of the top challenges facing cardiac surgeons and their implications.

Challenge 1: Accurate assessment of the mitral valve 

Accurate assessment of mitral valve pathology is a fundamental driver of surgical decisions, but can be difficult to achieve due to its complex and varied nature as well as the hemodynamics of the individual patient’s mitral valve.² Because the arrested heart and volume-loaded heart differ, the reality that the surgeon encounters may not align with the assessment when the heart resumes beating and normal circulation is restored. 

In the preoperative phase, the heart team must determine whether the valve is repairable or must be replaced and what type of technique to use based on the pathology causing MR.^1-3 Further, the cause of MR needs be determined: degenerative MR or functional MR secondary to ventricular dysfunction.² A full understanding of the pathology is essential in the choice of repair or replacement technique: certain pathologies may respond well to leaflet repair with artificial chords, others may require resection of leaflet tissue, while some may require full valve replacement. 

The preoperative assessment may be found to be inaccurate once the surgeon actually begins the procedure.^1-4 During the operation with the patient under anesthesia and prior to chest incision, the hemodynamics are changing due to lower blood pressure and volume shifts. The mitral regurgitation and annulus size may change as a result, requiring the surgeon to stimulate the heart to see if the preoperative findings can be replicated, or if the actual pathology is different. The surgeon may need to make a quick decision, opting for a different course of action.^{1, 5-8} 

Accurate post-operative assessment is also necessary to determine if the residual regurgitation shows improvement or not.^1,4 Re-operation may not be a viable option due to risk factors in some high-risk patients so making the right decision regarding repair or replacement prior to or during surgery is critical.¹ 

Challenge 2: Surgical access and approach 

Unlike the aortic valve, the mitral position is both difficult to visualize and difficult to access. To get access to the left atrium, the surgeon needs to go down from the sternotomy or skin incision, lift the roof of the left atrium up and move horizontally roughly two inches.^1,4  

The surgeon needs to be able to see the valve in all areas both to make the intra-operative assessment and to repair or replace the valve. Lighting is an issue and good visibility is hard to achieve. 

Access is critical. Conventional sternotomies provide different access compared to minimally invasive approaches such as port access or robotic assistance, with the latter requiring a steep learning curve and extensive surgeon experience.⁹ Factors such as the surgical approach used and surgeon expertise and comfort level will determine which options for repair or replacement are available.^1,2 

Challenge 3: Risk and durability 

In general, if a valve is repairable surgeons are expected to do so due to the higher mortality associated with replacement.^1,2 

The surgeon has several available repair options¹:  

• Respect - preserving leaflet tissue with placement of artificial chords 
• Resect - removal of excessive leaflet tissue  
• Addition of an annuloplasty ring – either a complete ring or a band  

Durability of the repair is an important consideration.^{2,3, 10} Should the repair need to be redone one or more times due to failure or a less-than-optimal outcome, the prognosis for some patients may not be favorable, and as a result, the surgeon may choose to replace the valve to begin with rather than attempt a repair. 

Surgeon experience also comes into play. Posterior leaflet repair is different from anterior repair, for example, and pathologies such as commissural prolapse require an entirely different skillset from repair of the leaflet tissue itself. The surgeon may not be fully comfortable with attempting the procedure required to achieve the needed repair, making replacement the safer and simpler option.² 

In addition, the best therapy for chronic secondary MR is not clear, because MR is only one component of the disease. For example, the current guidance states that mitral valve surgery (repair or replacement) or transcatheter edge-to-edge repair (TEER) may be considered for severe secondary MR.² 

Risk takes on increased importance when there are multiple concurrent pathologies. For example, the patient may also require coronary bypass surgery in addition to the mitral procedure. Adding additional layers of complexity (and time) to the overall surgery can play into the surgeon’s decision to replace instead of repair.²  

Challenge 4: Choosing the right valve 

Ongoing developments in mitral valves are changing the repair vs. replace calculation. All valves have pros and cons, so it is important to consider the implications of valve design and materials for the patient and also the procedure itself. 

Because of the limited access associated with the mitral position, ease of sizing and implantation is extremely important. Valve designs and materials vary, so how well the valve works in the mitral position should be fully understood. Related products such as annuloplasty rings should also be looked at since the surgeon may need to change strategies during surgery; a consistent platform can simplify the procedure. 

There’s also the shared decision with the patient of whether to opt for a tissue or mechanical valve. This decision is driven by safety and efficacy data, expected valve durability, the use of anticoagulants and anti-thrombotic agents, patient lifestyle and prognosis. Quality of life and the potential for re-operation are important considerations as are the age and risk profile of the individual patient.²  

Expand your options 

The evolution of mitral valve surgery is ongoing, and more patients are being referred for surgery as advances are made. For this reason, I believe it is important for cardiologists and surgeons to stay abreast of current clinical trial data and surgical product developments. Doing so may open up new treatment options and go a long way towards ensuring the best outcomes for patients.