A Matter of Time

Aortic Stenosis (AS) is the most common type of cardiovascular valvular disease globally. Its risk of fatality escalates with its symptomatology and degree of severity. As many as 1.5 million people in the United States have AS — one-third of whom have severe aortic stenosis, or SAS.

Of the 500,000 people who have SAS, half are asymptomatic. Once AS progresses to severe, the race against the clock begins. The condition requires urgent intervention because up to half of patients with SAS die within one year of becoming symptomatic, according to research published in JAMA in 2019.

And previous data suggests that nearly all SAS patients die within five years
of developing symptoms, according to Mark Russo, M.D., chief of the division of cardiac surgery, director of structural heart disease and associate professor of surgery at Rutgers-Robert Wood John- son Medical School in New Brunswick, New Jersey.

“The biggest challenge in managing SAS patients is ensuring they receive timely treatment,” says Dr. Russo. “It is estimated that 30 to 50% of patients who have SAS do not undergo treatment.”

The condition, while rare during youth, rises in incidence with age. By the time
a person reaches the age of 80, they face a greater risk of developing the disease. Approximately 2% of people older than 65 years of age, 3% of those 75 and older and 4% of individuals older than 85 have AS — and Dr. Russo says these numbers are becoming higher in North America and Europe. The increased incidence of SAS in older people, combined with a growing number of elderly people, adds urgency to the quest to gain a better handle on the condition.

As if the impact of SAS on patient outcomes were not enough, the gravity associated with the upper end of SAS, known as “very severe aortic stenosis,”
is even worse — regardless of whether patients are symptomatic. Managing AS patients who fall into the upper echelon of severity often proves even more challenging, as the clinical presentation and echocardiographic features these patients carry are often nebulous.

SAS Intervention Plagued by Clinician and Patient Reticence, Controversy
SAS occurs when the aortic valve area falls below 1.0 cm2 with or without
the patient having a mean transaortic pressure gradient (MPG) >50 mm Hg with or without a peak aortic jet velocity (Vmax) > 4 m/s. Currently, pharmaco- logical intervention is only palliative in nature, as it can neither reverse nor prevent disease progression.

Instead, conventional treatment involves surgical aortic valve replacement (SAVR) — an invasive procedure touted for decades as the gold standard. The last 15 years have seen the emergence of the minimally invasive transcatheter aortic valve replacement (TAVR) as an option for certain SAS populations. Overall, Dr. Russo describes aortic valve replacement (AVR) procedures as being “safe and highly effective.”

However, SAS is not as simple as selecting the correct AVR procedure. Part of the question lies in whether to treat asymptomatic patients prophylactically, and the topic remains highly controversial in the medical community.

“Patients and physicians are sometimes reluctant to proceed with AVR until symptoms become quite severe, at which time the left ventricle and kidneys may be failing,” explains Brian Whisenant, M.D., medical director of heart valve and structural heart disease at Intermountain Healthcare in Salt Lake City. “This significantly increases the risks associated with AVR procedures.”

According to Dr. Russo, waiting until symptoms manifest in SAS endangers patients by putting them at risk for sudden cardiac death and increasing the potential that they may have suffered irreversible heart damage while waiting for symptoms to appear. He advocates for starting prompt treatment in symptomatic patients and employing echocardiography to provide objective measures of severity, including gradient and valve area.

The complexities do not end there. In addition to being under-treated, Dr. Whisenant said SAS is also moderately under-diagnosed or misdiagnosed.

“Echocardiograms may be misinterpreted as moderate SAS when aortic stenosis is, in fact, severe,” he notes.

Patient Education Key to Better Outcomes
The onus falls upon the healthcare team to teach patients to recognize when their AS turns symptomatic. Doing so also requires encouraging patients to seek medical attention as soon as their symptoms appear.

J. Bradley Oldemeyer, M.D., an interventional cardiologist at the University of Colorado Health in Fort Collins, says he cannot overstate the importance of physicians not ignoring when symptoms of AS progress in their patients. He advocates encouraging patients to engage in regular exercise so they can evaluate how they feel during physical activity, one of the easiest ways to spot a problem. Increased self-awareness through physical movement offers great benefits.

“The symptoms of aortic stenosis can be subtle in patients who do not exercise regularly or exert themselves,” he explained. “When routine exercise, such as walking briskly for 30 minutes daily, is done regularly, patients will know promptly if there has been a change in their usual exercise tolerance.”

Perhaps no teaching point is more important than educating patients on the symptoms of SAS. But doing so proves particularly challenging because of the insidious way SAS develops.

Also, because some SAS symptoms are nonspecific (i.e., fatigue), they may be erroneously dismissed and associated with the general aging process or heart failure (lower extremity edema, shortness of breath, etc.). While patients and physicians alike should suspect SAS when dyspnea presents in AS patients, Dr. Whisenant notes that dyspnea is sometimes mistaken for lung disease. Dr. Oldemeyer says patients should contact their physicians to reevaluate their SAS.