Transcatheter Mitral Valve Repair (MitraClip) for Treating Degenerative Mitral Regurgitation in Patients at High/Prohibitive Surgical Risk
July 20, 2016 | Emerging Technology Reports
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
Mitral regurgitation (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 categorized as degenerative (i.e., primary) or functional (i.e., secondary).1 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.2 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.2,3
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, lightheadedness, cough, heart palpitations, and swollen feet or ankles.4 Left untreated, severe, symptomatic MR can lead to congestive heart failure, serious cardiac arrhythmias, and death.4
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., dyspnea, fatigue, palpitations).5
Treatment for MR depends on the NYHA classification, MR disease severity measured using echocardiography and graded on a scale (mild 1+, moderate 2+, moderately severe 3+, and severe 4+), life expectancy, and the presence of underlying medical conditions (e.g., renal disease, atrial fibrillation, chronic obstructive pulmonary disease). According to American Heart Association guidelines, the standard of care for symptomatic patients with severe DMR consists of open surgical mitral valve repair or mitral valve replacement.6 Mitral valve repair is preferred over mitral valve replacement because it is associated with a lower mortality rate.6 However, up to half of patients with severe, symptomatic MR are not candidates for open surgical mitral valve repair because of impaired cardiac function, advanced age, and comorbid disease.7
Clinicians often assess presurgical risk using the Logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE)8 and the Society of Thoracic Surgeons (STS) Predicted Risk of Mortality Score.9 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.10,11 The STS score predicts 30-day mortality risk in patients who undergo surgery.9,12 A EuroSCORE ≥15% to 20% or a STS score ≥10% indicates high surgical risk.13-15 Clinical factors (e.g., porcelain aorta, severe frailty, liver disease, chest wall deformities) might also confer high surgical risk and might 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 is essential to direct appropriate treatment allocation for high-risk patients.
Clinicians and patients have considerable interest in less-invasive approaches to mitral valve disease. Transcatheter mitral valve repair (TMVR) is intended to simulate the functional effects achieved by standard open-surgery repair and may offer a treatment option for some patients 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.16 According to 1 population-based study, significant MR occurs in about 2% of the U.S. population (about 6.4 million people).17 Each year, moderate to severe MR is diagnosed in more than 250,000 new patients18 and about 50,000 U.S. patients undergo open-heart surgery for mitral valve repair or replacement.19 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.16 The prevalence and incidence are increasing as the aging population grows.16
Our searches did not identify specific epidemiology data by MR type. However, according to a report from a U.S. consulting firm, about 20,000 to...