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Penn researchers find one-third of patients with low flow aortic stenosis do not improve with transcatheter aortic valve replacement

June 15, 2016

PHILADELPHIA - Aortic stenosis (AS), the narrowing of the aortic valve in the heart which causes restricted blood flow, is one of the most common and serious valve disease problems. For patients with one type of AS - low flow - transcatheter aortic valve replacement (TAVR), a minimally invasive procedure which corrects the damaged aortic valve, is often the best option for restoring the heart's normal pumping function. However, approximately one-third of low flow AS patients treated with TAVR continue to suffer persistent low flow AS even after the procedure, ultimately increasing their risk of death. Now, researchers from the Perelman School of Medicine at the University of Pennsylvania have examined this high-risk patient population to determine the cause of this persistent low flow AS and to evaluate their risk of dying during the year following the procedure. Their findings are detailed in a paper published in the Journal of the American Medical Association - Cardiology.

"There has been a lot of interest in these patients with low flow AS, as their surgical mortality is higher than other patients. TAVR is often a good option, but not all of them will be able to normalize flow following the procedure and these persistently low flow patients have a 60 percent higher rate of mortality at one year," said Howard C. Herrmann, MD, FACC, MSCAI, John W. Bryfogle Professor of Cardiovascular Medicine and Surgery, and director of Penn Medicine's Interventional Cardiology Program. "Low flow before TAVR is one of the most important predictors of mortality following TAVR, but it is one of the harder qualities to measure. This presents a challenge to properly treating patients with low flow AS, and can leave some patients at higher risk."

To better understand the potential benefits of TAVR for low flow AS, researchers conducted an analysis of 984 patients with low flow AS from the PARTNER trial and continued access registry from April 2014 through January 2016. A baseline and follow-up echocardiogram, evaluation of post-TAVR hemodynamics - blood flow - and one year outcomes were assessed.

Through this analysis, researchers identified the large subgroup of patients who, following TAVR, failed to regain normal flow despite a successful procedure. In the first six months following TAVR, flow improved in roughly 66 percent of the patients evaluated. However, those with severe low flow AS had the highest mortality rate - 26 percent - at one year, as compared to approximately 20 percent for those with moderate low flow and even less for those with normal flow.

"Unfortunately, many centers do not routinely measure flow, but rather focus more on a patient's pressure gradient or valve area when evaluating aortic stenosis pre-and post-TAVR," said Herrmann. "While low flow is more challenging to monitor, this measurement can better inform the patient's risk of mortality, and in turn lead to better treatment."

The researchers noted that the identification of remedial, or treatable, causes of persistent low flow following TAVR, such as severe mitral regurgitation and atrial fibrillation, may represent an opportunity to improve the outcomes of these patients.
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Additional Penn authors on this study include Venkatesh Y. Anjan, MD, an Interventional Cardiology Fellow at the Hospital of the University of Pennsylvania. Funding for the PARTNER trial was provided by Edwards Lifesciences, and the protocol was designed collaboratively by the sponsor and the trial executive committee.

Editor's Note: Herrmann has received speaking honoraria and research funding from Edwards Lifesciences.

Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System, which together form a $5.3 billion enterprise.

The Perelman School of Medicine has been ranked among the top five medical schools in the United States for the past 18 years, according to U.S. News & World Report's survey of research-oriented medical schools. The School is consistently among the nation's top recipients of funding from the National Institutes of Health, with $373 million awarded in the 2015 fiscal year.

The University of Pennsylvania Health System's patient care facilities include: The Hospital of the University of Pennsylvania and Penn Presbyterian Medical Center -- which are recognized as one of the nation's top "Honor Roll" hospitals by U.S. News & World Report -- Chester County Hospital; Lancaster General Health; Penn Wissahickon Hospice; and Pennsylvania Hospital -- the nation's first hospital, founded in 1751. Additional affiliated inpatient care facilities and services throughout the Philadelphia region include Chestnut Hill Hospital and Good Shepherd Penn Partners, a partnership between Good Shepherd Rehabilitation Network and Penn Medicine.

Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2015, Penn Medicine provided $253.3 million to benefit our community.

University of Pennsylvania School of Medicine

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