Functional Mitral and Tricuspid Regurgitation by Kok Meng John Chan

Author:Kok Meng John Chan
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Principles of Treatment

Functional mitral regurgitation (FMR) is defined as mitral regurgitation (MR) in absence of any primary leaflet pathology. FMR occurs in the setting of an abnormal and dilated left ventricle and apically displaced papillary muscles, with leaflet malcoaptation occurring either as a result of annular dilation (type I dysfunction) or leaflet tethering (type IIIb dysfunction), or both. FMR can either be ischemic, where adverse LV remodeling is caused by coronary artery disease and myocardial infarction, or non-ischemic due to idiopathic or dilated cardiomyopathy. Thus, in FMR, mitral regurgitation is only one component of the disease pathophysiology, and the treatment of MR is not curative. The current mainstay of treatment of FMR is undersized ring annuloplasty that treats only the annular dilation but does little to improve leaflet tethering. As such, mitral valve repair for FMR is far less durable than repair of myxomatous mitral regurgitation and is associated with significant rate of recurrent MR [1, 2]. Presence of MR after myocardial infarction increases mortality risk in direct relation to the degree of MR [3]. Thus, in patients whom limited repair durability and FMR recurrence is expected, mitral valve replacement (MVR) with a prosthetic valve may be a better choice than MV repair.

Echocardiography remains the mainstay for assessment of FMR and is useful to establish MR etiology and assess global LV function. Quantification of FMR is more challenging than for MR due to leaflet prolapse because the regurgitant orifice and the resultant MR jet in FMR is often non-circular and asymmetric, and can be underestimated by standard flow convergence methods of grading MR severity. Recently, 3D- echocardiography has been utilized for characterizing regional patterns of leaflet tethering and direct assessment of severity of FMR [4–6]. Adjunct studies (nuclear stress test, PET scan, Cardiac MR, cardiac catheterization) may help assess myocardial viability and influence management of FMR.

Choice of valve intervention (repair vs. replacement) and prosthetic valve type (bioprosthetic vs. mechanical) should be a shared decision process between the surgeon and the patient with full disclosure of recurrence risk, risks of anticoagulant therapy and the potential need for reoperation, and must take into account the patient’s preference. A mechanical prosthesis is reasonable in patients <60 years of age who do not have a contraindication to anticoagulation. A bioprosthesis is recommended in patients of any age for whom anticoagulant therapy is contraindicated, or cannot be managed appropriately, or is not desired. A bioprosthesis is reasonable in patients >70 years of age. Either a bioprosthetic or mechanical valve is reasonable in patients between 60 and 70 years of age [7]. These recommendations are based on the risk of anticoagulation with mechanical prostheses and limited durability and need for redo replacement with bioprosthetic valves. However, recent studies have reported low operative mortality (~5 %) for redo-MVR and have suggested use of bioprosthetic valves even in younger patients [8, 9].

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