Fewer Than Half With Severe Aortic Stenosis Get New Valves

The chance that patients with severe aortic stenosis (AS) will receive aortic valve replacement (AVR) is worse than the flip of a coin, even a decade after the game-changing transcatheter option became available, a new study suggests.

Of the study’s 6150 patients with an indication or potential indication for AVR, 48% received the procedure at Massachusetts General Hospital and its partner institution Brigham and Women’s Hospital in Boston — both of which have active, high-volume transcatheter and surgical AVR (TAVR/SAVR) programs.

“Essentially, this is a best-case scenario. So, unfortunately, I think on the national level we are likely to see rates that are far worse than what we observed here,” senior author Sammy Elmariah, MD, PhD, Massachusetts General Hospital, told theheart.org | Medscape Cardiology.

The volume of AVR increased more than 10-fold over the 18-year study period (2000 to 2017), driven by the exponential growth of TAVR, he noted. However, the graying of America led to an even greater increase in the number of patients with severe AS and an indication for AVR.

The study, led by Shawn X. Li, MD, MBA, of Mass General, was published in the March 8 issue of the Journal of the American College of Cardiology.

Previous research has provided equally compelling data on the undertreatment of AS, including a 2021 study using natural language processing (NLP) that found AVR use was just 35.6% within 1 year of diagnosis and varied wildly among managing cardiologists.

The present study used NLP tools to identify symptoms consistent with severe AS in the medical record coupled with echocardiographic data from 10,795 patients with severe AS (valve area <1 cm2). Patients were divided into four AS subtypes and then classified as having a class 1 indication (high-gradient AS with symptoms or reduced ejection fraction [EF]) or a potential class 2a indication (low-gradient AS with symptoms) for AVR.

Among patients with high-gradient AS and class 1 indication for AVR, 1 in 3 did not receive AVR over the study period, including 30% with a normal EF and 47% with a low EF.

In those with low-gradient AS, 67% with a normal EF and 62% with a low EF did not receive AVR. The low-gradient groups were significantly less likely to receive AVR both in the entire study period and in the more contemporary period from 2014 to 2017, despite the valvular heart disease guideline 2014 update indicating AVR was “reasonable” in patients with low-gradient AS — a 2a recommendation upgraded to class 1 in the most recent 2020 update.

Better Survival

In patients with a class 1 or potential class 2a indication, AVR was associated with a significantly lower risk of mortality in all four AS subgroups:

  • High gradient/normal EF: 3% vs 15%; adjusted hazard ratio [aHR], 0.42

  • High-gradient/low EF: 16% vs 72%; aHR, 0.28

  • Low-gradient/normal EF: 5% vs 14%; aHR, 0.73

  • Low-gradient/low EF: 11% vs 34%; aHR, 0.48; P < .001 for all

“I think what we need to do is change the paradigm, such that patients with a valve area that is less than or equal to 1 [cm2] is severe aortic stenosis until proven otherwise and that essentially establishes a premise by which we default to treat these patients unless we can prove that it is in fact moderate,” Elmariah said.

Unfortunately, the opposite is currently true today, he said, and the default is not to treat and put patients through surgery or an invasive TAVR procedure unless physicians can definitively prove that it is severe AS. But they’re not always correct and don’t always have the ability to truly differentiate moderate from severe disease.

“The question, therefore, is ‘What do we do with those patients?’ ” Elmariah asked. “I think if a patient has symptoms, then we are obligated to intervene, given the stark difference in mortality that one sees when these patients go under treated.”

Sounding the Alarm

Robert Bonow, MD, a professor of cardiology at Northwestern University in Chicago and a writing committee member for the 2014 guideline update, said the study is a “big wake-up call” and “the take-home message is that we are missing some patients who have treatable aortic stenosis.”

The sheer magnitude of the problem, however, can be difficult to fully ascertain from administrative data like this, he said. Notably, patients who did not receive AVR were significantly older, with 37% aged 81-90 years and 12% over age 90, and had a lower hematocrit and lower estimated glomerular filtration rate. But it’s not clear how many had cancer, end-stage renal disease, or severe lung disease, which could have factored into the decision to undergo AVR.

“What’s also an issue is that over 50% of patients had low gradient disease, which is very problematic and takes careful assessment in an individual patient,” said Bonow, who is also editor-in-chief of JAMA Cardiology. “That’s all being generated by a low valve area of less than 1 cm2  from echo reports, so that’s not necessarily a careful prospective echo assessment…so some of the patients with low-gradient disease may not have true severe aortic stenosis.”

Elmariah agreed that echocardiogram reports are not always clear cut and pointed out that referral to a valve specialist was highly predictive of whether or not a patient underwent AVR, supporting the class 1 guideline recommendation.

He also noted that Mass General is launching the DETECT-AS trial to determine whether electronic physician notifications highlighting clinical practice guideline recommendations will improve AVR utilization over standard care in 940 patients with severe AS on echocardiogram, defined by a valve area less than 1 cm2.

Reached for comment, Catherine Otto, MD, director of the Heart Valve Clinic at the University of Washington in Seattle and a fellow member of the 2014 guideline writing committee, said “this adds to the data [that] we’re undertreating severe aortic stenosis and it continues to be surprising given the availability of transcatheter options.”

The biggest challenge is trying to find out why it persists, which is difficult to determine from these data, she said. Whether that’s because the diagnosis is being missed or whether there are barriers to access because cardiologists aren’t understanding the indications or patients aren’t understanding what’s being offered, isn’t clear.

“The other [issue], of course is, are there inappropriate inequities in care? Is it fewer women, age-related, ethnic/racial-related; is it financial? Do people have coverage to get the treatment they need in our country?” Otto said. “All of those issues are areas that need to be addressed and I think that is a concern we all have.”

An accompanying editorial points out that the “key lever” in combating undertreatment of AS is getting patients seen by a multidisciplinary heart team and details other possible solutions, such as adding process metrics regarding evaluation and treatment of AS to hospital performance.

“We track quality when AVR is performed (desirable), but how a hospital system performs in getting individuals treated who would benefit from AVR remains a complete blind spot,” write Brian Lindman, MD, MSc, and Angela Lowenstern, MD, MHS, both of Vanderbilt University Medical Center, Nashville, Tennessee.

“Is it appropriate to consider the hospital ‘high performing’ when data from Li et al show a 2-year absolute mortality difference from 9% to 56% based on treatment vs nontreatment with AVR for various AS patient subgroups?” they add.

Lindman and Lowenstern observe that having a 50% utilization rate for an effective therapy for a deadly cancer or stenting of ST-segment elevation myocardial infarction (STEMI) would generate negative headlines and a collective commitment to swift action by multiple stakeholders to address what would be “incontrovertibly unacceptable.”

“In one of America’s leading health care systems, there was evidence of an overwhelming reduction in the risk of death with AVR in all AS subgroups examined, but <50% of patients with AS with an indication or potential indication for AVR were treated with an AVR. Let that set in; hear and internalize the alarm. The status quo is unacceptable. What will you do? What will we do?” they conclude.

The study was funded by Edwards Lifesciences. Elmariah has received research grants from the American Heart Association, National Institutes of Health, Edwards Lifesciences, Svelte Medical, Abbott Vascular, and Medtronic; and has received consulting fees from Edwards Lifesciences.  Bonow and Otto have disclosed no relevant financial relationships. Lindman has received investigator-initiated research grants from Edwards. Lowenstern has received consulting fees from Edwards.

J Am Coll Cardiol. Published online February 28, 2022. Abstract, Editorial

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