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Page 2 of 13 Echarte-Morales et al. Vessel Plus 2021;5:54 https://dx.doi.org/10.20517/2574-1209.2020.105

the etiology, it can be classified as primary (PMR) or secondary MR (SMR). In PMR, the valvular
incompetence is caused by organic disease of any of the mitral valve (MV) components, and myxomatous
[2]
degeneration is its most common cause . Conversely, SMR is characterized by normal MV leaflets and
tendinous cord structure, and MR results from annular dilatation and/or papillary muscle dysfunction due
to left ventricular (LV) and/or atrial disease . Conventional MV surgery (MVS) is currently the treatment
[3]
of choice for symptomatic patients with PMR while the indication for operation in SMR is now limited to
those patients undergoing simultaneous coronary artery bypass graft . Recurrence of significant MR after
[4]
MVS can be observed in up to 10%-30% of cases during follow-up, resulting in an increased morbidity and
mortality . Conservative management of these patients is related to adverse outcome, and reintervention is
[5]
infrequently performed given the high surgical risk. In this scenario, transcatheter techniques for MV repair
or replacement have become a reasonable alternative in patients at high surgical risk. The present review
discusses outcomes of MVS and percutaneous alternatives to approach MR recurrence after surgery.

MITRAL VALVE SURGERY FOR MITRAL REGURGITATION
Primary mitral regurgitation
Most recent guidelines for HVD recommend MVS in symptomatic patients with severe PMR and in those
who remain asymptomatic but show adverse LV remodeling (LV ejection fraction ≤ 60% or LV end-systolic
diameter ≥ 40 mm) . Intervention may be also considered in asymptomatic patients who develop atrial
[4]
[6]
fibrillation or moderate to severe pulmonary hypertension .
In patients with symptomatic PMR, surgical MV repair (MVr) has shown to improve expected prognosis of
untreated patients and is associated with better short- and long-term outcomes compared to surgical MV
replacement (MVR) . In a recent review of 12 different studies comparing both surgical approaches in
[7]
patients with PMV, short-term mortality ranged from 0% to 4% and from 2.1% to 13.9% after MVr and
[8]
MVR, respectively . Some of the predictors of likelihood of successful MVr are presented in Table 1 . The
[9]
ideal anatomy for MVr corresponds to cases of MR due to fibroelastic deficiency or focal myxomatous
prolapse. On the contrary, MVR should be considered in cases with low periprocedural risk and severe MV
disease with a non-favorable anatomy.

In highly experienced centers, most cases of PMR can undergo MVr with favorable outcomes and an
[10]
associated periprocedural mortality below 2% . Nevertheless, there are few centers worldwide that perform
enough procedures to achieve these outcomes. Despite MVr being the preferred surgical approach for PMR,
approximately 30% of patients receive a prosthetic valve because MVr is deemed not feasible, and this
occurs more frequently in low-volume centers .
[10]
Secondary mitral regurgitation
SMR is generally related to a LV disease, such as dilated cardiomyopathy or ischemic heart disease . For
[3]
this reason, optimal medical therapy for heart failure (HF) is the first line treatment for these patients,
leading in many cases to reverse LV remodeling and, consequently, a decrease in the severity of SMR. In
symptomatic subjects despite optimal medical therapy, including cardiac resynchronization if indicated,
[4]
percutaneous mitral valve repair (PMVR) can be considered in the absence of signs of end-stage HF . To
date, no clinical benefit in hard outcomes has been reported after MVS in patients with isolated SMR;
therefore, this approach is only suggested in patients undergoing concomitant surgical coronary
revascularization . In addition, MVr has not proven to be superior to MVR in this scenario.
[11]
[12]
Goldstein et al. compared both surgical approaches in a randomized controlled trial (RCT) that included
251 patients with ischemic SMR. After two years of follow up, there were no differences in mortality
between both groups, although there were more HF and cardiovascular readmissions in the MVr group,