NIH clinical study provides first rigorous comparison of these two surgical options for leaky mitral valves
Repair or replace? Consumers often ask this question when considering faulty cars, appliances, or other equipment. A new clinical study has now addressed this question for a serious medical decision: how to treat ischemic mitral regurgitation (IMR), a condition in which blood backflows into the heart because the mitral valve becomes leaky after a heart attack. The study compared the two surgical options –re-tightening the leaky mitral valve or replacing it with a prosthetic –and found no significant differences in patient outcomes after a year.
This was the first randomized clinical trial comparing these two approaches for IMR. It was carried out by the Cardiothoracic Surgical Trials Network (CTSN), a consortium supported by the National Heart, Lung, and Blood Institute (NHLBI) and the National Institute of Neurological Disorders and Stroke (NINDS) of the National Institute of Health, along with the Canadian Institutes of Health Research (CIHR).
“This study addressed an important question for a clinically vulnerable patient group,” said Michael Lauer, M.D., director of NHLBI’s Division of Cardiovascular Sciences. “People who have ischemic mitral regurgitation not only have bad valves, they have bad hearts. It’s critical we know the right procedure for these patients.”
Although the CTSN study did not find differences in health outcomes, the results still provide implications for surgeons, noted CTSN investigator Michael Acker, M.D., of the University of Pennsylvania Perelman School of Medicine, Philadelphia, who will present the results at the American Heart Association (AHA) Scientific Sessions in Dallas. “The medical community has recently gravitated towards valve repair as a preferred treatment option for IMR. The evidence this study presents does not suggest mitral valve repair is superior.”
The results of the Severe Mitral Regurgitation (SMR) trial will be published today in the New England Journal of Medicine to coincide with the AHA presentation.
IMR affects over 1 million people in the United States and can pose serious health consequences. The leaky valve, by forcing the heart to pump some blood backward, makes the heart work harder, which can eventually lead to heart failure, stroke, or sudden cardiac arrest. In severe cases, repairing or replacing the mitral valve is necessary. Both approaches offer benefits and risks, but as of yet no study has rigorously evaluated these approaches to see if the trade-offs result in significant differences in patient outcomes.
The SMR study enrolled 251 patients who had been diagnosed with severe IMR. These patients were then evenly randomized to receive surgical repair (a valve tightening procedure called an annuloplasty) or a prosthetic replacement mitral valve.
The participants were then monitored at one, six and 12 months after their procedure. The investigators examined how well the surgery worked by measuring the shrinkage of the heart’s left ventricle, which enlarges with chronic valve leakage. The study also measured various health outcomes as well as patient-assessed quality of life.
After a year of follow-up, there were almost no differences in ventricle shrinkage or health outcomes between the two treatments. The only significant change was a higher rate of recurrent regurgitation in the repair group (32.6 percent of repair patients versus 2.3 percent of replacement patients).
“The increased level of recurrent regurgitation falls in line with valve replacement offering more durable long-term protection,” noted Annetine Gelijns, Ph.D., CTSN investigator at the Icahn School of Medicine at Mount Sinai in New York City, and corresponding author of the study. “However, such regurgitation did not lead to any noticeable increases of health problems among patients in the repair group.”
Gelijns said the SMR study will continue to monitor the participants until they reach 24 months post-procedure, to see if long-term differences emerge, which may help identify patient groups better suited for repair or replacement.
The study was carried out at 22 participating CTSN centers across the United States and Canada. The International Center for Health Outcomes and Innovation Research, Icahn School of Medicine at Mount Sinai hospital in New York City, served as the coordinating c enter. To learn more about this study, visit http://clinicaltrials.gov/ct2/show/NCT00807040.
“The Canadian Institutes of Health Research are proud to support the CTSN and the Canadian researchers involved in this study,” said Dr. Jean Rouleau, scientific director of the CIHR Institute of Circulatory and Respiratory Health. “This cross-border collaborative research is helping both our countries to answer questions that directly impact treatment decisions our health care providers will make.”
To schedule an interview with an NHLBI spokesperson, contact the NHLBI Communications Office at 301-496-4236 or NHLBI_News@nhlbi.nih.gov.