Mitral valve surgery after failed MitraClip—Operation for the inoperable?

Percutaneous edge‐to‐edge mitral valve repair technique (MitraClip) is a widely used treatment for mitral regurgitation (MR) in patients assessed with high surgical risk or inoperability. Only limited experiences with this highest‐risk patient population exist. Procedural failure for MitraClip or recurrent MR is a strong predictor of 1‐year mortality. Open mitral valve surgery constitutes the last bailout for patients within this cohort.


| Characteristics of patients undergoing MitraClip
Baseline characteristics of patients (n = 17) before MitraClip (Table 1) were as follows: age = 76± 6 years, body mass index = 26 ± 5 kg/m 2 with 47% (n = 8) men. The patient population showed a typical cardio-vascular medical history. More than half (59%, n = 10) suffered from coronary artery disease and 24% (n = 4) underwent previous percutaneous coronary intervention. Forty-seven percent (n = 8) of this population had undergone previous heart surgery, and 29% (n = 5) of patients were operated on with a coronary artery bypass grafting. Ninety-four percent (n = 16) of patients showed at least a NYHA functional class Level III and 65% (n = 11) were decompensated preinterventional. A severe mitral insufficiency was reported in 82% (n = 14) and a severe tricuspid insufficiency in 35% (n = 6). The mean EuroSCORE II was 10 ± 2. The baseline characteristics reflect the typical MitraClip patient, which is now performed with a caseload of about 150 interventions per year at our institution.

| Peri-interventional characteristics of patients undergoing MitraClip
Underlying mitral valve disease was functional MR in 88% (n = 15) and degenerative MR in 18% (n = 3) of cases. The most common indication for surgery was persistent or recurrent MR (Grade > 2) in 88% of cases, whereas in 12% it was mitral stenosis. Etiologies associated with the second mechanism (leaflet perforation) include endocarditis (n = 2).
Abbreviation: NYHA, New York Heart Association.
T A B L E 4 Postoperative outcomes of patients after reoperation
The mean number of implanted MitraClips was 1.5 ± 0.9, of which 29%

| Postoperative outcomes after secondary mitral valve surgery
The 30-day all-cause mortality after secondary mitral valve surgery was 18% (n = 3), 12% (n = 2) of patients died in hospital. Valve related mortality was 6% (n = 1). A moderate to severe paravalvular leak was reported in 6% (n = 1 Further, randomized trials were performed, allowing a direct comparison between MitraClip and mitral valve surgery in different patient populations. 9 At this moment, mitral valve surgery is slightly superior to MitraClip therapy in terms of safety and efficacy, provided that the risk of cardiac surgery is acceptable. However, transcatheter mitral valve repair failure using a MitraClip device demonstrates a demanding condition with surgical strategies restricted by the high-risk profiles of the patients. 10 Nevertheless, in the hands of experienced surgeons, surgical treatment of the mitral valve disease after the MitraClip procedure is feasible and safe. 3 In the present study, in-hospital mortality was 12% (n = 2), in the range between 9% and 32% previously published by different authors. 2,[11][12][13] After 1 year, the mortality rate was significantly lower than the other studies published between 2016 and 2019. 11,12,14 When mortality is restricted to valvular causes, the result decreases from 18% to 6%. This trend continues throughout the entire observation period of the study, namely that 1/3 of the deaths occurring in this study did not have a cardiovascular cause.

The definition of treatment success for MitraClip therapy dates
back to the EVEREST-1 trial and includes implantation of at least one clip and achievement of a residual mitral insufficiency ≤2+. 15 In surgical therapy, on the other hand, treatment success is only considered to have been achieved when the residual mitral insufficiency does not exceed severity level 1+. 16 According to the study's data on which this paper is based, one of the patients had a mitral insufficiency severity ≥2+ postoperatively. These outcomes are slightly better in contrast to Mellilo et al. 2 Nevertheless, data from large registry studies showed that the treatment goal of residual mitral insufficiency ≤1+ can be achieved in most cases. 17 It is known from recent studies on mitral valve surgery that residual mitral insufficiency is an important negative prognostic factor. 18,19 This can also be assumed for patients after MitraClip procedures are supported by the previous study results. 20 However, even achieving a residual mitral insufficiency ≤1+ during MitraClip treatment is no guarantee that the treatment outcome will remain stable over time. Progress of the underlying disease or detachment of the clip from either sail may increase the severity of residual mitral insufficiency. 21 In this regard, the highest rate of progression is expected within the first 6 months. 9 The postsurgical outcome seems to show both good durability and improvement in clinical symptoms, according to available data. 2

| STUDY LIMITATIONS
Our study has several limitations beyond the retrospective and single-center design, reporting a relatively small cohort of patients.

ACKNOWLEDGMENTS
Open Access funding enabled and organized by Projekt DEAL.

CONFLICT OF INTEREST
None declared.