Percutaneous Mitral Valve Repair
Percutaneous mitral valve repair using the MitraClip (Abbott Laboratories, Menlo Park, California, USA) has been approved in 2008 in Europe and 2013 in the United States. Is one of the most common procedures performed today for patients with primary severe mitral regurgitation (MR) who are deemed unfit for surgery. This is usually the case for older patients with multiple co-morbidities.7, 27-31
The MitraClip device has 2 essential components: the clip delivery system and a guide catheter.30 It enters the circulation through the femoral vein and is directed towards the heart. Transseptal puncture allows the advancement of the MitraClip to the left atrium. Moving through the mitral valve (MV), the apparatus reaches the left ventricle. The clip will grasp the leaflets, bringing them together, connecting the middle segment of the anterior leaflet to the one of the posterior leaflet. The MitraClip technology is based on Alfieri’s surgical technique, thus creating a ‘double orifice’ MV. Before releasing the clip, assessment of the procedure via transesophageal echocardiogram (TEE) is required, as the MitraClip can be reopened and repositioned. This step also allows re-evaluation of mitral valve defect (if still present) and re-grading.27,30-32
After the operation, patients receive clopidogrel for 30 days and aspirin for the next 6 to12 months.27 Procedural success is highly dependent on patient factors. TEE along with transthoracic echocardiography is used for patient screening and ensures that anatomic requirements are met for a feasible MitraClip repair. Calcification of more than 80% of leaflet area, short leaflets, and low baseline MV area are common disqualifiers from the procedure, while orifice area greater than 70.8 mm2 or mitral valve area less than 3 cm2 were indicators of clip failure.33
Although considered safer than surgical treatment for severe primary MR, percutaneous repair still has its risks. Common postoperative complications include atrial fibrillation and acute kidney injury, as well as partial detachment of the clip. Mitral stenosis or full displacement of the clip have occurred in less than 5% of cases. The EVEREST II trial, which proved the efficacy of MitraClip in 2010 and gained its approval in the US, also highlighted that nearly 20% of patients needed another operation within a year.27,32
Since 2019, the MitraClip has been approved in the USA for secondary functional MR as well.27  Ongoing clinical trials in Europe (RESHAPE-HF2) and Canada  (EVOLVE-MR) are considering the effectiveness of promoting this treatment for functional MR, after another two anticipated clinical trials, COAPT and MITRA-FR, had conflicting results (mainly due to different selection criteria).34-36 Cardioband (Edwards Lifesciences, Irvine, California) percutaneous annuloplasty procedure is currently used in Europe for the treatment of this condition.33
Nevertheless, the first line of management of secondary MR remains pharmacological therapy: angiotensin-converting enzyme inhibitors, beta-blockers, and diuretics, providing symptom relief.37 Tsang et al. paper on recent advances in the management of mitral valve disease argued that doctors are more reticent in offering interventional therapy such as mitral valve repair or replacement, in the absence of clear guidelines (in the US, replacement is still favored, sparing the sub-valvular apparatus, while in Europe repair is considered first). This could adversely affect outcomes for patients.13 Case studies are expected to be published in the coming years (especially from the USA) and careful documentation of medical decisions and considerations would be advisable. Over time, the conduction of longitudinal studies should also shed some light on the issue.
PASCAL Transcatheter mitral valve repair system is a newer device that is used for percutaneous repair of MR. It hopes to fill in the gap left by the MitraClip and help patients who do not meet the anatomic criteria for the procedure. PASCAL is still developing, although an initial clinical trial including 23 patients has yielded favourable results. The CLASP study was shortly commenced, which gained CE marking approval after 98% out of the 62 patients had an MR grade of two or under at 6 months follow-up. More randomized controlled trials are needed before the procedure becomes widely available.13,38,39