The Cutting Edge of Medical Technology Content, Community & Collaboration
The mitral valve separates the heart’s left atrium from the left ventricle. When the ventricle contracts to send blood to the aorta and out to the body, the mitral valve closes to prevent blood rushing backward into the atrium and back to the lungs. The mitral valve can become stiff and tight, called stenosis or it can become unable to close tightly, called regurgitation. Once the regurgitation becomes sufficiently severe to cause heart failure, the death rate reaches about 5% per year. Most such individuals are referred for cardiac surgery to either try to repair the valve, replace the valve or do a procedure that in effect lessens the amount of regurgitation without actually replacing the valve. The latter procedure, although not curative, can be quite successful and alleviate the heart failure and the symptoms leading to a longer and better quality life.
A new procedure has now been reported in the New England Journal of Medicine, April 14, 2011 that does not use open surgery to repair the mitral valve leak. The process is to insert a catheter via the large femoral vein in the groin and pass it up to the heart. From the right atrium it crosses over to the left atrium and then is positioned at the opening of the mitral valve. This mechanical device, manufactured by Abbott Vascular, is able to grasp the two sides of the mitral valve and clip the two leaflets together. It does not create a tight seal but in most cases can markedly reduce the amount of regurgitant flow back into the atrium.
The study randomly allocated patients with grade 3+ or 4+ (i.e., serious) mitral valve dysfunction to either the customary open repair or replacement (the specific procedure at the surgeon’s discretion based on the valve status) or to have a percutaneous repair done with the new device. The study endpoints were freedom from death, freedom from surgery for mitral valve dysfunction and freedom from grade 3+ or 4+ regurgitation at the end of 12 months. The primary safety end point was freedom from major complications during the 30 days post procedure.
The study ws performed at 37 institutions in the United States and Canada. 279 patients were randomized with a 2:1 ratio of percutaneous vs. open procedures. 21 patients withdrew consent before the procedure was done, leaving 258 treated patients.
After the procedure, 41 of 178 (23%) patients who had the percutaneous procedure still had grade 3+ or 4+ regurgitation and were therefore referred for open surgery. Among those 80 patients who initially had open surgery, all had less that 3+ regurgitation after the procedure. By the 12 month end of study time, the composite of freedom from death, from surgery or from grade 3+ or 4+ valve dysfunction for all randomized patients were 55% vs. 73%. If one looks only at those who actually were treated per the protocol (i.e., did not exclude themselves, etc) then the rates were 72% vs. 88%. As to safety, the rates of major adverse events (most often the need for transfusion) as of 30 days were 15% vs. 48%. Quality of life improved in both groups of patients over the 12 months although there was a decrease at 30 days for the open surgery patients.
What these results suggest is that open surgery is more likely to greatly relieve the mitral regurgitation than will the percutaneous catheter procedure. However, the percutaneous procedure is safer, requires less time in the hospital, and is associated with improved quality of life and improved ventricular function from baseline. Many patients might therefore decide to choose the percutaneous catheter-based procedure on the grounds that it greatly relieves the problem in almost three quarters of the patients, is less invasive and is safer than surgery. Then if that individual patient was not among the success stories, he or she can choose to have the follow-up open surgery.
Further, although not mentioned in this article, there are patients who simply cannot tolerate open surgery for any number of reasons who might still be able to undergo the catheter-based procedure. This might then open up an option for repair not otherwise available today with open surgery. Not discussed in the article was cost. This might become a deciding factor as well once the procedure is on the market.
In an accompanying editorial, Otto and Verrier suggest that the decision on surgery (and which surgical procedure) or one of a number of catheter-based procedures (assuming logically that others will undoubtedly arrive soon) should rest on the advice of not one physician but the joint opinion of a multi-disciplinary team of, at least, a nonprocedural valve-disease specialist, and interventionalist cardiologist and a cardiac surgeon, each with substantial expertise in mitral valve disease. To this team I would add the patient’s primary care physician and principal cardiologist – both of whom will have known the patient and his or her overall health and family situation over the years. The other addition to the team is the patient --whose opinions should be incorporated from the beginning of the evaluation and advice process.