Abstract and Introduction
Background MitraClip implantation has emerged as a viable option in high surgical risk patients with severe mitral regurgitation (MR). We performed the present systematic review to assess the safety and efficacy of the MitraClip system for high surgical risk candidates with severe organic and/or functional MR.
Methods Six electronic databases were searched for original published studies from January 2000 to March 2013. Two reviewers independently appraised studies, using a standard form, and extracted data on methodology, quality criteria, and outcome measures. All data were extracted and tabulated from the relevant articles' texts, tables, and figures and checked by another reviewer.
Results Overall 111 publications were identified. After applying selection criteria and removing serial publications with accumulating number of patients or increased length of follow-up, 12 publications with the most complete dataset were included for quality appraisal and data extraction. All 12 studies were prospective observational studies. Immediate procedural success ranged from 72–100%; 30 day mortality ranged from 0–7.8%. There was a significant improvement in haemodynamic profile and functional status after implantation. One year survival ranged from 75–90%. No long term outcomes have been reported for high surgical risk patients.
Conclusions MitraClip implantation is an option in managing selected high surgical risk patients with severe MR. The current evidence suggests that MitraClip can be implanted with reproducible safety and feasibility profile in this subgroup of patients. Further prospective trials with mid- to long-term follow-up are required.
Mitral regurgitation (MR) is the second most common valvular heart disease after aortic stenosis. Without surgical intervention, prognosis is poor in patients with severe symptomatic MR. Although mitral valve (MV) surgery is recommended for symptomatic severe MR or asymptomatic severe MR complicated by left ventricular (LV) dysfunction or dilation, as many as 49% of patients in need of MR repair or replacement are considered high risk for surgical intervention, and therefore do not qualify for surgery. Various technologies of percutaneous MV repair, at different stages of investigation, have been introduced to minimise surgical trauma, with significant potential to become the intervention of choice for high surgical risk patients.
Edge-to-edge repair, an original MV repair technique developed by Alfieri et al, involves suturing of the middle scallops of the anterior and posterior MV leaflets, which results in a double-orifice valve. Long term results have shown durability in selected patients, although the technique is commonly combined with an annuloplasty ring. The surgical edge-to-edge technique has been adapted to be performed percutaneously, with the development of a mechanical implant that serves as an alternative to cardiac surgery in selected patients (MitraClip System, Abbott Vascular, Menlo Park, California, USA). The MitraClip enables permanent leaflet approximation of the anterior and posterior MV leaflets, and creates a double-orifice valve during diastole and maintains closer apposition of the leaflets during systole, thereby reducing the amount of regurgitation.
The EVEREST (Endovascular Valve Edge-to-Edge Repair Study) I trial, first conducted in 2004, demonstrated the safety, feasibility and significant hemodynamic improvement of the MitraClip. Following the success of EVEREST I, EVEREST II, a randomised controlled trial (RCT) of 279 surgical candidates with grade 3+ or 4+ MR, randomised in a 2:1 design to the MitraClip system (n=184) or MV surgery (n=95), was conducted. The 12 month per protocol success rate was 72% in the device group and 88% in the surgery group, and New York Heart Association (NYHA) functional class I and II were seen in 98% of the device group and 87% of the surgical group. Although major adverse events were significantly lower in the device group (15% vs 48%), this difference was almost entirely attributable to the inclusion of transfusion ≥2 units of blood as an adverse event. The efficacy of MitraClip and surgery was similar, with 21% of MitraClip patients and 20% of surgery patients still suffering from grade 3+ or 4+ MR at 12 months. However, there was a significant difference in the rate of MV surgery/reoperation in favour of the surgical group (2% vs 20%).
At present, the evidence does not support the superiority of MitraClip implantation over surgical MV repair or replacement in terms of efficacy, especially in patients with low surgical risk. However, MitraClip implantation can be seen as a viable option in high surgical risk patients. We performed the present systematic review to assess the safety, success rate, clinical efficacy, and survival outcomes of MitraClip implantation in managing MR patients with a high surgical risk.