Percutaneous Repair or Surgery for Mitral Regurgitation
How does implantation of the percutaneously delivered MitraClip (Abbott Vascular) compare to surgical mitral valve repair or replacement for the treatment of a population with mixed functional and degenerative mitral regurgitation (MR)?
A cohort of 279 patients with moderately severe (grade 3+) or severe (grade 4+) MR was randomly assigned in a 2:1 ratio to undergo either percutaneous placement of a MitraClip or conventional surgery for repair or replacement of the mitral valve in 1 of 37 centers in the United States or Canada. The primary composite endpoint for efficacy was freedom from death, from surgery for mitral valve dysfunction, or from grade 3+ or 4+ MR at 12 months. The primary safety endpoint was a composite of major adverse events within 30 days (death, myocardial infarction, reoperation for failed mitral valve surgery, nonelective cardiovascular surgery for adverse events, stroke, renal failure, deep wound infection, mechanical ventilation >48 hours, gastrointestinal complications requiring surgery, new-onset permanent atrial fibrillation, septicemia, or >2 U blood transfusion).
In the percutaneous and surgical groups, the respective etiologies of MR were functional (27% and 27%), posterior leaflet prolapse or flail (39% and 44%), anterior or bileaflet prolapse or flail (32% and 26%), or degenerative disease with no prolapse or flail (3% and 2%). Of 178 patients who underwent MitraClip implantation, 41 (23%) had ≥3+ MR after intervention, of whom 28 (16%) underwent cardiac surgery (15 [54%] mitral repair, 13 [46%] mitral replacement). The rate of mitral repair in the primary surgical group was 69 (86%) of 80 patients. At 12 months, the rates of the primary endpoint for efficacy were 55% in the percutaneous group and 73% in the surgery group (p = 0.007). The respective rates for the components of the primary endpoint were: death, 6% in each group; surgery for mitral valve dysfunction, 20% vs. 2%; and grade 3+ or 4+ MR, 21% vs. 20%. Major adverse events at 30 days occurred in 15% of patients who underwent the percutaneous procedure and 48% of patients who underwent surgery (p < 0.001). At 12 months, both groups had improved measures compared to baseline of left ventricular size, New York Heart Association functional classification, and quality of life.
The authors concluded that although percutaneous clipping of the mitral valve was less effective than surgery in reducing MR severity, the procedure was associated with fewer adverse events and similar improvement in clinical outcomes.
The MitraClip is an investigational device that is intended to percutaneously treat MR by approximating a portion of the commissural edges of the anterior and posterior mitral leaflets, in essence emulating the ‘bow-tie’ surgical stitch introduced by the Italian cardiac surgeon Ottavio Alfieri. On initial review, the conclusions of this trial look very attractive: percutaneous therapy associated with fewer adverse events; similar clinical outcomes; and if the percutaneous procedure does not work well, then just go on to cardiac surgery. However, some concerns are raised after more detailed review of the data.
1. Of patients who underwent initial surgery, 86% underwent mitral repair; only 54% of patients underwent repair after initial MitraClip therapy. Although selection bias could be responsible for this (more complex mitral valve disease underlying failed MitraClip treatment), this study leaves concern as to whether the placement of a MitraClip might adversely affect the ability to perform subsequent successful mitral repair.
2. The vast preponderance of adverse events in the surgical arm might not have been of substantial clinical importance. Specifically, of 55 total events occurring in 45 surgical patients, 46 events were either ventilation >48 hours or >2 U blood transfusion. Excluding these two events from both groups yielded 9 events among a total of 89 surgical patients compared to 13 events among a total of 181 MitraClip patients.
3. The finding of equal efficacy included equal rates of death at 12 months, an order of magnitude superiority of freedom from surgery among surgical patients, and equivalent (~20%) rates of 3+ or 4+ MR at 12 months. This is a surprisingly high rate of recurrent MR after surgical intervention, and hopefully is not representative of the best surgical centers.
It is likely that the MitraClip will find a niche for the treatment of MR in some patients who are not surgical candidates, or in patients with high predicted risks associated with surgery. Although encouraging, these data do not seem enough to support the use of this device to treat MR among patients who are reasonable candidates for surgical intervention.
Editorial note: The EVEREST II article reviewed in this Journal Scan gives the 1-year results. Dr. Feldman gave the 2-year results at his presentation at the ACC.11/i2 Summit (click on the link above under Related Resources).
Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Valvular Heart Disease, Cardiac Surgery and VHD, Interventions and Structural Heart Disease, Mitral Regurgitation
Keywords: Myocardial Infarction, Mitral Valve Insufficiency, Canada, Heart Valve Diseases, Cardiac Surgical Procedures, New York, United States
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