Exploring the Operative Strategy for Secondary Mitral Regurgitation: A Systematic Review

Assessing emerging causes of mitral regurgitation: atrial functional mitral regurgitation

Functional or secondary mitral regurgitation is linked to increased cardiovascular morbidity and mortality. From a mechanical perspective, secondary mitral regurgitation occurs due to an imbalance between the forces that tether the mitral leaflets and those that close them. This results in incomplete coaptation. Most commonly, functional mitral regurgitation, which occurs in both ischaemic and non-ischaemic disease states, is usually caused by dysfunction and changes in the left ventricle. Atrial functional mitral regurgitation (AFMR) is a disease state that has been more recently recognized. It occurs when mitral annular enlargement is associated with left atrial dilatation, preserving left ventricular geometry and function. AFMR is typically seen in patients with chronic atrial fibrillation or heart failure who have a conserved ejection fraction. Published reports and ongoing investigations vary in how they define AFMR. This publication examines the pathophysiology of AFMR and highlights the importance of having a common working standard for the definition of AFMR to ensure consistency in the data reported and to drive forward the much needed research into the outcomes and treatment strategies in this area. Several studies have reported that restrictive annuloplasty and transcatheter edge-to-edge repair can reduce mitral regurgitation and improve symptoms. This narrative review will explore the pathophysiology, echocardiographic diagnosis and treatment of AFMR.

Prognosis for Mitral Valve Repair Surgery in Functional Mitral Regurgitation

Purpose: Our aim was to evaluate the development of new significant mitral regurgitation and long-term survival after mitral repair surgery in functional mitral regurgitation.

Methods: A retrospective observational analysis of the recurrence of functional mitral regurgitation (ischemic and nonischemic) and global mortality during follow-up of 176 patients who underwent mitral repair surgery between 1999 and 2018 in our center was conducted.

Results: The etiology of functional mitral regurgitation was ischemic in 55.7% of cases. After surgery, mitral regurgitation was 0-I in 92.3% of cases. We conducted a long-term clinical follow-up of a mean 42.2 months and an echocardiographic follow-up of a mean 41.8 months. We observed mitral regurgitation of at least grade II in 52 patients (36.9%). Survival at 1, 3, and 5 years was 78.8%, 66.7%, and 52.3%, respectively. Predictive factors for global mortality were age (hazard ratio = 1.038, p = 0.01) and a depressed preoperative ejection fraction. After a competing risk analysis, we found the only predictive factor for the recurrence of mitral regurgitation in our series to be age (sub-hazard ratio = 1.03, 95% confidence interval = 1.01–1.06, p = 0.016).

Conclusion: Repair surgery for functional mitral regurgitation shows age as the only independent predictor of recurrence. Age and depressed ejection fraction were predictors of mortality.

Surgical mitral valve repair technique considerations based on the available evidence

Mitral valve regurgitation is the second most common valve disease in the western world. Surgery is currently the best tool for generating a long-lasting elimination of mitral valve regurgitation. However, the mitral valve apparatus is a complex anatomical and functional structure, and repair results and durability show substantial heterogeneity. This is not only due to differences in the underlying mitral valve regurgitation pathophysiology but also due to differences in repair techniques. Repair philosophies differ substantially from one surgeon to the other, and consensus for the technically best repair strategy has not been reached yet. We had previously addressed this topic by suggesting that ring sizing is "voodoo". We now review the available evidence regarding the various repair techniques described for structural and functional mitral valve regurgitation. Herein, we illustrate that for structural mitral valve regurgitation, resuspension of prolapsing valve segments or torn chordae with polytetrafluoroethylene sutures and annuloplasty can generate the most durable results paired with the best achievable hemodynamics. For functional mitral valve regurgitation, the evidence suggests that annuloplasty alone is insufficient in most cases to generate durable results, and additional subvalvular strategies are associated with improved durability and possibly improved clinical outcomes. This review addresses current strategies but also implausibilities in mitral valve repair and informs the mitral valve surgeon about the current evidence. We believe that this information may help improve outcomes in mitral valve repair as the heterogeneity of mitral valve regurgitation pathophysiology does not allow a one-size-fits-all concept.