SNOWMASS, COLO. – The 2014 American Heart Association/American College of Cardiology guidelines for the management of valvular heart disease break new ground in numerous ways, Dr. Rick A. Nishimura said at the Annual Cardiovascular Conference at Snowmass.
“We needed to do things differently. These guidelines were created in a different format from prior valvular heart disease guidelines. We wanted these guidelines to promote access to concise, relevant bytes of information at the point of care,” explained Dr. Nishimura, professor of medicine at the Mayo Clinic in Rochester, Minn., and cochair of the guidelines writing committee.
These guidelines – the first major revision in 8 years – introduce a new taxonomy and the first staging system for valvular heart disease. The guidelines also lower the threshold for intervention in asymptomatic patients, recommending surgical or catheter-based treatment at an earlier point in the disease process than ever before. And the guidelines introduce the concept of heart valve centers of excellence, offering a strong recommendation that patients be referred to those centers for procedures to be performed in the asymptomatic phase of disease (J. Am. Coll. Cardiol. 2014;63:2438-88).
These valvular heart disease guidelines place greater emphasis than before on the quality of the scientific evidence underlying recommendations. Since valvular heart disease is a field with a paucity of randomized trials, that meant cutting back.
“Our goal was, if there’s little evidence, don’t write a recommendation. So the number of recommendations went down, but at least the ones that were made were based on evidence,” the cardiologist noted.
Indeed, in the 2006 guidelines, more than 70% of the recommendations were Level of Evidence C and based solely upon expert opinion; in the new guidelines, that’s true for less than 50%. And the proportion of recommendations that are Level of Evidence B increased from 30% to 45%.
The 2014 update was prompted by huge changes in the field of valvular heart disease since 2006. For example, better data became available on the natural history of valvular heart disease. The old concept was not to operate on the asymptomatic patient with severe aortic stenosis and normal left ventricular function, but more recent natural history studies have shown that, left untreated, 72% of such patients will die or develop symptoms within 5 years.
So there has been a push to intervene earlier. Fortunately, that became doable, as recent years also brought improved noninvasive imaging, new catheter-based interventions, and refined surgical methods, enabling operators to safely lower the threshold for intervention in asymptomatic patients while at the same time extending procedural therapies to older, sicker populations.
Dr. Nishimura predicted that cardiologists and surgeons will find the new staging system clinically useful. The four stages, A-D, define the categories “at risk,” “progressive,” “asymptomatic severe,” and “symptomatic severe,” respectively. These categories are particularly helpful in determining how often to schedule patient follow-up and when to time intervention.
The guidelines recommend observation for patients who are Stage A or B and intervention when reasonable in patients who are Stage C2 or D. What bumps a patient with hemodynamically severe yet asymptomatic mitral regurgitation from Stage C1 to C2 is an left ventricular ejection fraction below 60% or a left ventricular end systolic dimension of 40 mm or more. In the setting of asymptomatic aortic stenosis, it’s a peak aortic valve velocity of 4.0 m/sec on Doppler echocardiography plus an LVEF of less than 50%.
The latest guidelines introduced the concept of heart valve centers of excellence in response to evidence of large variability across the country in terms of experience with valve operations. For example, the majority of centers perform fewer than 40 mitral valve repairs per year, and surgeons who perform mitral operations do a median of just five per year. The guideline committee, which included general and interventional cardiologists, surgeons, anesthesiologists, and imaging experts, was persuaded that those numbers are not sufficient to achieve optimal results in complex valve operations for asymptomatic patients.
The criteria for qualifying as a heart valve center of excellence, as defined in the guidelines, include having a multidisciplinary heart valve team, high patient volume, high-level surgical experience and expertise in complex valve procedures, and active participation in multicenter data registries and continuous quality improvement processes.
“The most important thing is you have to be very transparent with your data,” according to the cardiologist.
Ultimately, the most far-reaching change introduced in the current valvular heart disease guidelines is the switch from textbook format to what Dr. Nishimura calls structured data knowledge management.
“The AHA/ACC clinical practice guidelines are generally recognized as the flagship of U.S. cardiovascular medicine, but they’re like a library of old books. Clinically valuable knowledge is buried within documents that can be 200 pages long. What we need at the point of care is the gist: concise, relevant bytes of information that answer a specific clinical question, synthesized by experts,” Dr. Nishimura said.