Aortic Valve Replacement Substantially Underutilized for Severe Aortic Stenosis

Encouraging data suggest treatment of aortic stenosis (AS) with aortic valve replacement (AVR) is increasing, mainly because of the broad adoption of transcatheter AVR (TAVR) across the spectrum of risk.

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On the other hand, studies suggest a rapidly growing prevalence of AS, driven partly by the aging population but also by improved identification of symptomatic AS, greater disease awareness, and wider recognition of low-gradient severe AS.

Shawn X. Li, MD, MBA, an internal medicine resident at Massachusetts General Hospital, Sammy Elmariah, MD, MPH, director of the Interventional Cardiology Research Program, and colleagues have determined the use of AVR is not keeping pace with the growing AS population. In the Journal of the American College of Cardiology, they call attention to the need for proper treatment of symptomatic severe AS.

Methods

The researchers identified a multicenter cohort of 10,795 patients in the Mass General Brigham system who had a transthoracic echocardiogram (TTE) showing severe AS (aortic valve area <1 cm²) between 2000 and 2017. The patients fell into four groups:

• 4,009 had a high mean aortic valve gradient (≥40 mm Hg) with normal left ventricular ejection fraction (LVEF) (≥50%) (HG-NEF), of whom 57% were symptomatic
• 549 had a high gradient with low LVEF (>50%) (HG-LEF)
• 4,694 had a low gradient (<40 mm Hg) with normal LVEF (LG-NEF), of whom 58% were symptomatic
• 1,543 had a low gradient with low LVEF (LG-LEF), of whom 40% were symptomatic

All patients with HG-LEF and those with symptomatic HG-NEF had a class I indication for AVR pursuant to the 2014 American Heart Association/American College of Cardiology guidelines for the management of valvular heart disease. Patients with low-gradient AS and symptoms consistent with severe AS were considered to have a potential class IIa indication.

Frequency of AVR

The primary endpoint of this study was the performance of surgical AVR or TAVR within two years of the index TTE. Of the 6,150 patients with a class I or potential class IIa indication for AVR, only 48% underwent the procedure. AVR was performed in only:

• 70% of the HG-NEF group
• 53% of the HG-LEF group
• 33% of the LG-NEF group
• 38% of the LG-LEF group

The difference between the high- and low-gradient groups in frequency of AVR was statistically significant both over the total study period and the contemporary period (2014–2017).

Temporal Trends

AVR volumes grew over the 18-year study period but were paralleled by comparable growth in the number of patients with an indication for AVR:

• Number of patients with an indication for AVR—Compounded annual growth rates were 14%, 3%, 17%, and 21% for HG-NEF, HG-LEF, LG-NEF and LG-LEF, respectively
• Number of AVRs performed—14%, 6%, 15%, and 22%

Survival Analysis

Among patients who had an indication for AVR and underwent the procedure, a survival advantage was noted in all AS subgroups (P<0.001 for all):

• HG-NEF—3% mortality with AVR vs. 15% without (adjusted HR [aHR], 0.42)
• HG-LEF—16% vs. 72% (aHR, 0.28)
• LG-NEF—5% vs. 14% (aHR, 0.73)
• LG-LEF—11% vs. 34% (aHR, 0.48)

Opportunities to Improve Care

These findings highlight significant underutilization of AVR for severe AS, especially among patients with low-gradient severe AS. Given the dismal outcomes when symptomatic severe AS is left untreated, urgent efforts are needed to maximize guideline-directed use of AVR.

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