New, Minimally Invasive Mitral Valve Repair System Treats Patients with Severe Mitral Regurgitation
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Patients with severe mitral regurgitation, a condition in which the heart's mitral valve does not close and seal properly, have a new, minimally invasive treatment option. The MitraClip system is a procedure that uses a small clip to repair the heart's mitral valve to treat mitral regurgitation. Massachusetts General Hospital in Boston is offering this MitraClip procedure for routine clinical use and is one of a few selected hospitals in the country to take part in a separate research study (COAPT trial) evaluating this treatment.
Understanding Mitral Regurgitation
The mitral valve separates the heart's left atrium (upper chamber) from the left ventricle (lower chamber), and has two leaflets that open and close like saloon doors. When the leaflets are open, blood flows from the upper into the lower chamber. When the heart contracts, the mitral valve closes. The leaflet edges meet and form a tight seal, a process called leaflet coaptation. Healthy, normal heart valves allow blood to flow only in one direction. This is important for the heart to effectively and efficiently pump oxygen-rich blood to all organs during rest and activity. When mitral valve closure is impaired and the leaflets do not seal properly, blood leaks and flows backwards into the upper chamber. This leakage is called mitral regurgitation, mitral insufficiency or mitral incompetence (see figure 1 panels a & b). If mitral regurgitation is significant, the heart will enlarge over time and its pump function will diminish (cardiomyopathy). Patients eventually develop heart failure symptoms like fatigue and weakness, shortness of breath, swollen feet or ankles, abdominal fullness or abnormal heart rhythms (predominantly atrial fibrillation). The lack of mitral leaflet coaptation can be due to mitral valve tissue abnormalities (primary, degenerative mitral regurgitation) or because of an enlarged and weakened heart (functional mitral regurgitation) (see figure 1 panels a & b). Current mitral regurgitation treatment options include medications to treat heart failure symptoms and open-heart surgery to directly repair or replace the leaking mitral valve. Patients with significant additional health problems are, however, often too high risk for open-heart surgery.
Minimally Invasive, Nonsurgical Mitral Valve Repair
The MitraClip system is a minimally invasive approach to nonsurgically repair the mitral valve and treat mitral regurgitation. It consists of a delivery catheter (thin plastic tube) with a small clip at the end that is inserted through a small skin incision into a leg vein in the groin. Using advanced cardiac imaging, the catheter and clip are advanced to the patient's heart and mitral valve. The clip is then permanently attached to both mitral leaflets exactly where the leak is most severe with the aim to minimize it (see figure 1 panels C-H). The MitraClip procedure is performed under general anesthesia, but there is no need for cardiopulmonary bypass or open-heart surgery (sternotomy). The MitraClip system is therefore a potential option for patients that are too high risk or have prohibitive risk for open-heart surgery. This MitraClip procedure has been performed in more than 10,000 patients worldwide since 2003.
Prior US and European studies have evaluated the MitraClip system in individuals with primary, degenerative mitral regurgitation and functional mitral regurgitation. For patients with:
- Primary, degenerative mitral regurgitation: The Food and Drug Administration (FDA) approved the MitraClip system in October 2013 for routine clinical use in the US for patients with significant symptomatic degenerative mitral regurgitation who are at prohibitive risk for mitral valve surgery.
- Functional mitral regurgitation: The MitraClip system is currently not approved for routine clinical use in patients with functional mitral regurgitation. Prior research in this patient population has shown, however, that the MitraClip procedure is very safe: One year after the device implantation, more than three-quarters of patients had significantly reduced mitral regurgitation and no, or only mild, heart failure symptoms. The heart regained a smaller size and shape and less than one in ten patients required additional open-heart surgery. A research study called the COAPT trial now aims to expand this knowledge. The COAPT trial evaluates the safety and effectiveness of the MitraClip system against optimal medical therapy in individuals with symptomatic, at least moderate-to-severe functional mitral regurgitation and who are extremely high risk for mitral valve surgery.
Multidisciplinary Heart Team and Heart Valve Program
Mass General Hospital is one of a few hospitals in the US to offer the MitraClip for routine clinical use and to be selected to participate in the COAPT study due to our extensive research, medical, interventional and surgical experience in treating mitral valve disease. In the Institute for Heart, Vascular and Stroke Care Corrigan Minehan Heart Center, a multidisciplinary heart valve team of heart failure specialists, interventional cardiologists, cardiac surgeons, and cardiac ultrasound experts evaluates patients with mitral regurgitation and, when it is appropriate for the patient, performs the MitraClip procedure in the cardiac catheterization lab. After MitraClip implantation, patients are initially monitored in the intensive care unit for one to two days and are usually released home from the hospital within five to six days of the procedure.