MitraClip for Treatment of Mitral Valve Regurgitation
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There is no question MitraClip is an incredibly effective option — more so than expected. Most patients experience a significant decrease in regurgitation, their ventricle shrinks, heart-failure symptoms resolve, medical management gets easier and hospital readmissions stop. Needless to say, patients are most grateful,” says Dr. Kapadia, who directs the catheterization laboratory. Much of the experience with MitraClip has been obtained in Europe, where the device has been used since 2008. A post-marketing study known as ACCESS-EU, published in June 2013, found low rates of adverse events at 30 days and 12 months. The mean age of enrolled patients was 74, with 45 percent being 75 or older. One year after implantation, 78.9 percent of patients had a mitral regurgitation (MR) severity score ≤ 2+, and 71.4 percent were New York Heart Association functional Class I (normal) or Class II (mild), as compared with 15 percent at baseline.
Minimally invasive option alleviates heart failure symptoms and improves quality of life in patients considered too high-risk for surgery MitraClip® (Abbott Vascular, Abbott Park, Ill.) is an emerging treatment option for patients with mitral regurgitation who are considered high-risk for surgery, as well as for patients with functional mitral regurgitation who exhibit heart failure symptoms. Interventional cardiologists Samir Kapadia, MD, Amar Krishnaswamy, MD, E. Murat Tuzcu, MD, and Patrick Whitlow, MD, who are intimately involved in clip implantation at Cleveland Clinic, say the minimally invasive, catheter-based treatment fills an unmet need.
Success in Reversing Heart Failure
Mitral regurgitation is a common cause of heart failure. Data from Cleveland Clinic’s patient registry have shown that patients with mitral regurgitation and heart failure have higher rates of hospitalization and mortality when treated medically compared with patients whose mitral regurgitation is treated surgically. Treatment of mitral regurgitation is directed at improving lives as well as saving them. Two different mechanisms can cause mitral regurgitation.
In some patients, the mitral valve itself can be damaged (degenerative mitral regurgitation). In other patients, annular dilatation or abnormal tension on the chordae supporting the valve leaflets due to left ventricular dysfunction adversely impacts mitral valve function (functional mitral regurgitation). “For patients with degenerative mitral regurgitation, surgical repair is an excellent option, with more than 99 percent operative success rate and more than 90 percent 10-year survival rates when performed in a Center of Excellence such as Cleveland Clinic, where more than 1,000 mitral valve repairs are done every year,” says Dr. Krishnaswamy. Despite the success of surgery, however, an estimated 10 percent of patients with degenerative mitral regurgitation are not healthy enough to undergo the operation safely. On the other hand, patients with functional mitral regurgitation have a less durable response to surgery, and its benefits remain questionable, particularly in patients who do not need coronary revascularization and have impaired left ventricular function.
“Retrospective, propensity-matched studies have shown no difference in mortality between medical management and valve repair in these patients. Therefore, surgery is not strongly recommended for this population,” says Dr. Tuzcu, Vice Chairman of Cardiovascular Medicine. About 50 percent of patients with heart failure and severe functional mitral regurgitation are managed medically. These patients have high rates of recurrent congestive heart failure, requiring hospital admissions, and mortality. MitraClip is most likely to benefit these patients, for whom no other effective treatment exists. Although a similar catheter-based device, the CARILLION® mitral contour system® (Cardiac Dimensions® Inc., Kirkland, Wash.), is being tried in Europe and as many as 15 other devices are in the pipeline, none are likely to be approved in the near future. “This is a reason for the FDA to be proactive with MitraClip,” says Dr. Kapadia.
Ameliorating FDA Concerns
In March 2013, an advisory panel of the FDA composed of cardiologists and cardiac surgeons recommended approval of MitraClip for patients with symptomatic regurgitation (MR ≥ 3+), who were deemed too high-risk for open surgery. There was no question about the safety of the device, but opinions about its efficacy were not unanimous: Five of the eight members felt the benefits of MitraClip exceeded the risks. Their cautious optimism was largely based on concerns that the clinical trials and registry data used to support the FDA application did not clearly define the patient population most likely to benefit from the device, or establish that patients at high surgical risk benefited above and beyond contemporary optimal medical management.
To clarify these issues, the FDA has requested a new study in which eligibility for valve repair surgery will be determined by a heart team that includes cardiac surgeons and cardiologists specializing in heart failure management and interventional cardiologists specializing in the MitraClip procedure. Dr. Kapadia serves on the steering committee for this 420-patient, open-label randomized trial known as COAPT (Clinical Outcomes Assessment of the MitraClip Percutaneous Therapy for High-Risk Surgical Patients). Enrollment began recently, but results are not expected for at least three years.
While refinement of the target patient population continues, Cleveland Clinic cardiologists are confident that they have a good understanding of how MitraClip fits into the spectrum of treatment options for patients with mitral valve disease. “We understand it is not the answer for all patients with mitral regurgitation. But there’s no question that it’s the right treatment for some,” says Dr. Krishnaswamy. Referrals of potential candidates for MitraClip are welcomed. The screening process involves an evaluation of cardiac anatomy, including the coronary arteries and valves, and a heart failure consultation. By the time the screening process has been completed, FDA approval of the MitraClip is likely for some patients; others may potentially qualify for the COAPT study.
Importantly, the heart team approach identifies other treatment options. “When a patient is better suited for surgery or other conventional therapy such as biventricular pacing, it can be performed immediately,” says Dr. Kapadia. “Awareness of evolving therapies for patients with heart failure and mitral regurgitation is critical and timely, because treatment options are rapidly evolving.”