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4.23.2014

Research Finds Link Between Aortic Valve Replacement and Atrial Fibrillation

A team of Miller School researchers has found a strong correlation between the type of aortic valve replacement procedure a patient undergoes and the development of post-operative atrial fibrillation. Their findings are reported in an article, “New-Onset Atrial Fibrillation After Aortic Valve Replacement,” that appears in the April 22 issue of the Journal of the American College of Cardiology.

Approximately 85,000 aortic valve replacement procedures are performed in the U.S. each year. The most common cause is aortic stenosis, an acquired condition usually found in elderly patients in which scarring or calcium buildup narrows the valve and restricts blood flow from the heart to the aorta, and from there to the rest of the body. An estimated 1.5 million Americans suffer from aortic stenosis; 500,000 (half of whom are undiagnosed) have a severe form that has a high risk of death within two years without valve replacement.

“Historically, the only way to perform a valve replacement was using open-heart surgery,” said Robert J. Myerburg, M.D., professor of medicine and physiology, and the American Heart Association Chair in Cardiovascular Research, who mentored Tanyanan Tanawuttiwat, M.D., a cardiology trainee who was the lead author of the article. “Then a number of less-invasive, catheter-based procedures were developed. Some of the patients included in the study were enrolled in a research protocol, but the majority underwent the non-surgical procedures for specific approved clinical indications.”

The researchers evaluated the outcomes for 123 patients who had procedures through the University of Miami’s aortic valve replacement program between March 2010 and September 2012. Of that total, 35 had conventional surgical aortic valve replacement (SAVR). The remaining 88 received one of three alternative procedures: transapical transcatheter aortic valve replacement (TA-TAVR), 36; transaortic transcatheter aortic valve replacement (TAo-TAVR), 24; or transfemoral transcatheter aortic valve replacement (TF-TAVR), 28.

New-onset atrial fibrillation (an irregular heartbeat) occurred in nearly half (42.3 percent) of the patients overall, but the differences among the procedures were dramatic — SAVR, 60 percent; TA-TAVR, 53 percent; TAo-TAVR, 33 percent; TF-TAVR, 14 percent. The two techniques that required a pericardiotomy (opening the pericardium, the membranous sac that encloses the heart) — conventional surgery and the transapical procedure — had a five-fold increase in risk of developing atrial fibrillation, compared to those techniques that did not involve entering the pericardium.

“Developing atrial fibrillation, which can be treated with medication, is a relatively common phenomenon following open heart surgery, including conventional aortic valve replacement surgery,” said Myerburg. “It does tend to prolong hospitalizations, but it is not a major problem in terms of mortality.”

Still, will these findings spark greater adoption of transcatheter procedures by cardiac interventionalists and surgeons? “That would be the preferred approach if you can perform the procedure with just as much efficacy and safety,” said Myerburg, “but we’re not going to be making decisions on which procedure to use based on risk of atrial fibrillation. We can, however, consider it when we have a patient in whom we have procedure options.”

“The study numbers were small, but given the number of procedures we perform, we were far ahead of most institutions at the time,” Myerburg said. “Relative to what is available in the literature, these were pretty big numbers.”

Myerburg refers to the study as a collaborative effort among several medical disciplines. “Our interventional cardiologists, electrophysiologists, and cardiovascular surgeons, along with cardiology trainees and some students, all collaborated in this area of common interest,” he said.

Other authors of the study included Mauricio G. Cohen, M.D., associate professor of medicine and Director of the Cardiac Catheterization Laboratory at UM Hospital; Alan W. Heldman, M.D., professor of medicine, Cardiovascular Division; Claudia A. Martinez, M.D., assistant professor of medicine; Carlos E. Alfonso, M.D., assistant professor of medicine and Cardiology Fellowship Program Director; and Raul D. Mitrani, M.D., associate professor of internal medicine. Another former fellow in cardiology, Dr. Brian O’Neill, M.D., and a former faculty member, William O’Neill, M.D., also participated in the study.

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