Transcatheter Mitral Valve Repair (MitraClip) for Treating Functional Mitral Regurgitation in Patients at High/Prohibitive Surgical Risk
July 15, 2016 | Emerging Technology Reports
This report focuses on transcatheter mitral valve repair (TMVR) using MitraClip for treating functional mitral regurgitation (MR) in patients who are at high/prohibitive surgical risk. Please also see the companion Emerging Technology Evidence Reporton TMVR for treating degenerative MR in patients who are at high/prohibitive surgical risk.
Proprietary names: MitraClip Clip Delivery System
Generic names: catheter-based mitral valve repair, edge-to-edge mitral valve repair, leaflet plication device, percutaneous mitral valve repair, sutureless mitral valve repair
MR, broadly defined as a backward flow of blood from the heart's left ventricle into the left atrium and the lungs during contraction, can be divided into two major categories: degenerative (i.e., primary) and functional (i.e., secondary).4 Functional mitral regurgitation (FMR) occurs when the mitral valve leaflets are structurally intact but the mitral valve apparatus is geometrically distorted due to ventricular remodeling. This involves annular distortion, tethering of the leaflets, and reduction in closing forces. In FMR, the regurgitation stems from conditions that affect the left ventricle and atrium, including coronary artery disease, dilated cardiomyopathy, hypertrophic cardiomyopathy, and left atrial dilation.5,6 Degenerative mitral regurgitation (DMR) occurs when valve disease arises from incompetence of the mitral valve leaflets and their immediate supporting apparatus (e.g., chordae, annulus). Conditions that lead to DMR include myxomatous degeneration, endocarditis, chordae tendineae rupture, rheumatic heart disease, and papillary muscle rupture.5
MR usually develops slowly, and patients may remain asymptomatic for years. Signs and symptoms that develop as the disease progresses include heart murmur, shortness of breath, fatigue, reduced exercise capacity, lightheadedness, cough, heart palpitations, and swollen feet or ankles.7 Left untreated, severe, symptomatic MR can lead to congestive heart failure, serious cardiac arrhythmias, and death.7
As part of diagnosis and screening, clinicians use the New York Heart Association (NYHA) classification system (Class I–IV) to classify heart failure according to symptoms related to functional status (i.e., shortness of breath, fatigue, palpitations).8
Patients with heart failure who develop FMR have a poor prognosis.9,10 Goals of therapy are to improve symptoms and quality of life (QOL), reduce heart failure hospitalizations, and potentially improve survival. Management of FMR is controversial, with debate over the optimal approach, indications, intervention timing, and intervention effectiveness.4,11 According to American Heart Association (AHA) guidelines, "patients with chronic FMR and heart failure with reduced left ventricular ejection fraction should receive standard guidance-directed medical therapy for heart failure including angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, beta blockers, and/or aldosterone antagonists as indicated."12 AHA guidelines further recommend cardiac resynchronization therapy with biventricular pacing for select symptomatic patients with chronic severe FMR who have left ventricular dyssynchrony. Although surgery is the standard of care for patients with DMR, "the role of surgery in patients with severe FMR who are not candidates for coronary artery bypass surgery is not well-established."13 Mitral valve repair or replacement may be considered for patients with chronic severe FMR who have persistent severe symptoms despite optimal medical therapy; however, only sparce evidence suggests that correcting FMR may prolong life or improve symptoms, and the benefits of performing mitral valve repair over mitral valve replacement are unclear in this patient population.12 Furthermore, a large percentage of patients with severe, symptomatic FMR are not candidates for open mitral valve surgery due to impaired cardiac function, advanced age, and comorbid disease.14
Clinicians often assess presurgical risk using the Logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE)15 and the Society of Thoracic Surgeons (STS) Predicted Risk of Mortality Score.16 Risk score cutoffs are the same as those used to treat high-risk patients with aortic stenosis and are based on those data. The EuroSCORE uses 17 risk factors to predict postoperative mortality and has been shown to overestimate surgical risk.17,18 The STS score predicts 30-day mortality risk in patients who undergo surgery16,19 A EuroSCORE ≥15% to 20% or an STS score ≥10% indicates high surgical risk.20-22 Clinical factors (e.g., porcelain aorta, severe frailty, liver disease, chest wall deformities) may also confer high surgical risk and not be captured by these scoring systems. Because patients with these clinical factors may have relatively low risk scores, risk assessment by a multidisciplinary heart team of heart failure specialists, interventional cardiologists, cardiac surgeons, and imaging experts is essential to direct appropriate treatment allocation for high-risk patients with FMR.
Clinicians and patients have considerable interest in less-invasive approaches to mitral valve repair and replacement.23 This reports focuses on a TMVR procedure that interventional cardiologists have performed in Europe for several years. In the United States, TMVR is under study as a possible treatment option for carefully selected patients with severe FMR who are at high risk for complications from open surgical repair.
Moderate or severe MR is the most common type of heart valve insufficiency in the United States.24 According to a population-based study, significant MR occurs in about 2% of the U.S. population (about 6.4 million people).25 Each year, moderate to severe MR is diagnosed in more than 250,000 new patients,26 and about 50,000 U.S. patients undergo open-heart surgery for mitral valve repair or replacement each year.27 MR predominantly affects patients ≥65 years of age, affecting 5% to 7% of people aged 65 to 74 years, and 8% to 10% of people aged 75 years or older.24 The prevalence and incidence are increasing as the aging population grows.24 In the United States, FMR is the most common cause of MR.10 Our searches did not identify FMR-specific epidemiology data.
Our searches did not identify worldwide epidemiology data on MR.
TMVR using the MitraClip Clip Delivery System (Abbott Vascular, Abbott Park, IL, USA) is intended to percutaneously replicate the functional effects of the Alfieri edge-to-edge double-orifice open surgical repair technique used for treating MR.28 In the Alfieri procedure, a surgeon sutures together the edges of the two opposing mitral valve leaflets at the center of the valve opening, leaving two smaller openings on either side that close more completely than a single large opening.29 TMVR using the MitraClip Clip Delivery system mimics this procedure by "clipping together" the mitral valve leaflets rather than using sutures.30
The MitraClip Clip Delivery System has three major components: a steerable guide catheter, a clip delivery system, and a metal clip covered with polyester fabric.31 System accessories (i.e., stabilizer, lift, support plate, silicone pad,...