Heart valve reconstruction operation
ANN ARBOR—Heart failure patients once thought too sick for most surgery—and facing an 80 percent chance of dying within a year if they don’t receive a heart transplant—may now have a chance to have their ailing hearts repaired, in the first clinical trial of a promising surgical procedure developed at the University of Michigan Health System.
The surgery repairs the valve that controls the flow of blood between two of the damaged heart’s chambers. Its pioneer, Steven F. Bolling, M.D., professor in the Cardiac Surgery Section of the U-M Surgery Department, and his colleagues have reported dramatic survival improvements in 118 pilot patients operated on during the past four years.
Over 80 percent survived the first year, and 70 percent were still alive after two years, compared with a 20 percent one-year survival for similar patients on medication alone.
Called mitral valve reconstruction, the operation is similar to a kind of surgery that is routinely performed on heart patients with less serious conditions. But for patients with the two most severe forms of heart failure—an estimated 30 percent of the 4.6 million Americans with all forms of heart failure—the surgery may make a heart transplant unnecessary.
The only other surgical option for such patients, which removes a portion of the heart muscle, results in the operating-room deaths of 60 percent of patients who undergo it. Only one heart failure patient at U-M has died during the mitral valve reconstruction procedure. Initial results have been published in the Journal of Thoracic and Cardiovascular Surgery and presented at the American Heart Association’s annual meeting.
Surgeons at U-M and nationwide will now test the surgery combined with conventional medical treatment against medical treatment alone in a multi-center trial named PREMIUM, short for Prospective Randomized Evaluation of Mitral Intervention started at the U-M.
The study is supported by Baxter Healthcare Corp., Medtronic and St. Jude Medical, three manufacturers of the flexible annuloplasty rings used to reinforce the two muscular flaps of the mitral valve. Prospective patients “It is crucial to give heart failure patients more and better options, especially in light of the current shortage of transplant organs,” says Bolling. “We have been very encouraged by our results to date, but only a randomized clinical trial will show how well our approach does relative to medication, and whether it stops these patients’ downward spiral.”
Says U-M Executive Vice President for Medical Affairs Gilbert Omenn, M.D., Ph.D., “This surgical procedure appears to significantly improve the care of patients with severe congestive heart failure, a condition rising in incidence in the United States. The randomized clinical trial will establish how well this approach does at giving even the most advanced patients longer and better lives, and reducing their reliance on heart transplants.”
Heart failure most often arises as a result of other common diseases, including heart attack, narrowing of the arteries, high blood pressure and infection of heart muscle or valves. The weakened heart muscle deteriorates and cannot pump blood as efficiently, causing patients to feel tired and short of breath. Eventually, the heart fails. Heart transplant is often the only option.
The PREMIUM trial will focus on those whose condition is most advanced. It will enroll 180 patients between the ages of 18 and 80 who have been diagnosed with Class III or Class IV congestive heart failure. Even patients who are not candidates for heart transplant, either because of age, diabetic condition, or Class III status, are eligible.
Patients must have moderate or severe mitral valve problems that cause blood to leak, or regurgitate, backward from the left ventricle and collect in the left atrium. Such problems with the valve force the left ventricle to work even harder to pump blood into the body, causing it to eject less blood than normal with each beat—a measure known as ejection fraction.
Participants in the trial will have ejection fractions less than 30 percent, as compared with a normal 70 percent. Such low ejection rates can cause further heart deterioration, clots in the left atrium that can travel to the brain and set off strokes, and other serious problems.
The mitral valve reconstruction surgery aims to “overcorrect” for the leaky gateway, using a smaller-than-usual ring to reinforce the flaps. This overcorrection, Bolling feels, enhances the effect of stopping backward flow and helps the left ventricle pump better. It may also help weakened heart muscle heal. But, he emphasizes, the surgery makes patients better, not cured. They must continue on medication and controlled diets and exercise regimes after surgery.
The trial will compare surgery with the current optimal medical therapy, which includes drugs called ACE inhibitors and beta-blockers as well as digoxin and a diuretic. All patients will take such medications, and half of the patients will be selected at random to undergo surgery.
The trial will feature strict observation to assess the effect of the two options over a long period. At the start of the trial, and at regular intervals until one or two years afterward, doctors will assess patients’ ability to exercise; their heart pressure, volume, flow and regurgitation rates; their quality of life; the number of times they are hospitalized; and the cost of all their treatments.
Bolling says he hopes the trial will increase understanding of the mitral valve’s importance to the entire heart’s function, and to the overall failure of the heart. “The mitral valve is not just a door, it’s an active mechanism that determines the power of the heart,” he says. “It is integrated with the rest of the heart, and must work in concert with other components.”
EDITORS: Dr. Bolling acts as a consultant to all three companies sponsoring the trial.
Health SystemSteven F. BollingJournal of Thoracic and Cardiovascular SurgeryBaxter Healthcare CorpGilbert Omenn