Medical Device Daily

Information concerning the complexities of the heart – and the concomitant complexities of heart disease – keeps growing, driven by increasingly sophisticated imaging and assessment systems.

That is a truism most recently underlined by last week's joint rollout by the American College of Cardiology (ACC; Bethesda, Maryland) and the American Heart Association (AHA; Dallas) of updated guidelines concerning the diagnosis and treatment of patients with diseased heart valves at the ACC's Heart Valve Summit in Chicago.

Additionally, the guidelines, by focusing on more sophisticated systems to identify the earliest indicators of valve disease as it develops, are likely to drive uptake of valve repair vs. replacement, but also replacement using both tissue and mechanical valves.

The guidelines discuss evaluating patients with heart murmurs, preventing and treating endocarditis, managing valve disease in pregnancy and treating patients with concomitant coronary artery disease, as well as more specialized issues regarding specific valve lesions, all determined by the more precise information gathered concerning valve activity and heart function in general.

The guidelines – which update valve disease guidelines previously released in 1998 – “highlight major advances in noninvasive testing and surgery for patients with valvular heart disease,” said Robert Bonow, MD, chief of cardiology at Northwestern Memorial Hospital (Chicago), Goldberg distinguished professor of cardiology at Northwestern University's Feinberg School of Medicine and lead author of the joint statement. “There have always been areas of uncertainty and differences of opinion on how to diagnose and treat patients with valvular heart disease. Today we have much more solid data to draw on.”

The guidelines refer to the use of a variety of echocardiography systems – 2-D and Doppler echocardiography, dobutamine stress echocardiography, transesophageal echocardiography (TEE), exercise Doppler echocardiography – as well as radionuclide angiography, MRI and computed tomography, to evaluate valve function and the determination of early problems and the more exact treatment of clearly symptomatic problems.

Also among the new recommendations is the use of TEE in the operating room to guide surgery. TEE involves passing a probe into the esophagus and using sound waves to create real-time pictures of the heart.

Among the key changes in the 2006 document is a focus on the proper timing of valve surgery.

These timing guidelines are based on more precise and quantitative definitions of mild, moderate and severe valvular disease, derived from the patient's symptoms and the results of exercise testing, echocardiography and the other testing modalities referred to in the document, according to ACC/AHA.

This change, the organizations said, “may prompt earlier referral of some patients for surgery, even before they develop noticeable symptoms.”

“The guidelines encourage physicians to look behind the scenes, rather than waiting for symptoms to develop,” said Patrick O'Gara, MD, director of clinical cardiology at Brigham & Women's Hospital and an associate professor of medicine at Harvard Medical School (both Boston). “For example, an abnormal response to exercise could help identify patients with aortic stenosis who may be candidates for surgery sooner rather than later.”

Other highlights of the guidelines include:

  • Surgical advances that increasingly permit repair, rather than replacement, of heart valves in many patients. These are important for some patients with leaky mitral valves and are increasingly used in selected patients with aortic valve regurgitation, according to the document.
  • Further clarification of the use of blood thinners in patients who have undergone heart valve surgery.
  • An update on preventive medical treatment for some heart valve conditions.

The guidelines also acknowledge the complexity of managing many patients with valvular heart disease, including the selection of replacement heart valves.

For example, a young woman who has surgery to replace a diseased heart valve with a mechanical heart valve would need blood-thinning medications to prevent blood clotting and stroke. If she became pregnant, blood thinners would pose a toxic risk to the fetus. Implanting a biological heart valve would eliminate the need for blood thinners, but it would be unlikely to last a lifetime, necessitating another open-chest surgery in the future, according to the ACC/AHA statement accompanying release of the guidelines.

“It is important for patients to understand that we have much better data today, but we still don't have all the answers,” Bonow said.

Applauding and giving its support to the new guidelines was heart valve technology specialist Edwards Lifesciences (Irvine, California), focused on the development of tissue valves.

“Under the new guidelines,” Edwards said, “more emphasis is put on patient preference than strict age requirements for the choice of a tissue valve over a mechanical valve. Additionally, the recommended age for tissue valve replacement in the mitral position has been lowered from 70 to 65,” the company said in a statement. “These modifications reflect continuous improvements in tissue valve performance and cardiac surgery outcomes in general, as well as consideration of patient lifestyle decisions.”

“Fundamentally, the new guidelines open up the use of tissue valves to patients of all ages, assuming careful discussion of benefits with their doctor,” said Anita Bessler, vice president of global franchise management for Edwards. “Also, we are very pleased to see that the new guidelines acknowledge the advancements in tissue valve design technology, especially the long-term hemodynamic benefits of stented pericardial tissue valves in the aortic position.”

Each year, more than 300,000 people worldwide undergo open-heart surgery to treat their malfunctioning or diseased heart valves. These are primarily patients that exhibit clear symptoms of valve disease. However, the new ACC/AHA guidelines also suggest more aggressive treatment of certain patients with asymptomatic aortic stenosis.

Valvular heart disease resulted in about 20,000 deaths in 2003. The total mentioned mortality (that is, underlying or contributing number of deaths) is about 42,500. An estimated 95,000 inpatient valve procedures were performed in the U.S. in 2003.

The full text of the guidelines will be published online at www.acc.org and www.americanheart.org.

No Comments