Ejection Fraction and Outcomes in Bicuspid Aortic Valve Disease
November 1, 2022
By Michael H. Crawford, MD, Editor
SYNOPSIS: A study of patients with bicuspid aortic valve and moderate or more aortic valve disease revealed the cutpoint for considering aortic valve replacement should be moved from < 50% to < 60% in the guidelines.
SOURCE: Hecht S, Butcher SC, Pio SM, et al. Impact of left ventricular ejection fraction on clinical outcomes in bicuspid aortic valve disease. J Am Coll Cardiol 2022;80:1071-1084.
Little is known about the prognostic value of left ventricular ejection fraction (LVEF) in patients with bicuspid aortic valves (BAV). Hecht et al interrogated an international BAV registry of 2,672 BAV patients with echocardiographic data. Those with other congenital heart disease, previous infective endocarditis, aortic valve surgery, or less than moderate aortic stenosis (AS) or regurgitation (AR) were excluded. This left 749 patients with AS, 554 with AR, and 190 with moderate or worse AS and AR (AS/AR).
The authors divided the study population into EF strata of > 70% (n = 269), 60-70% (n = 679); 50-59% (n = 316); 30-49% (n = 182), and < 30% (n = 47). The primary endpoint was all-cause mortality before or after AV replacement (AVR). The secondary endpoint was the composite of AVR and all-cause mortality. Indications for AVR followed contemporary guidelines. Among 1,493 patients, the median age was 51 years, and 70% were men.
Over a median follow-up of 56 months, 8.8% of patients died, and 51% reached the secondary endpoint. Both the primary and secondary endpoints were higher in those with EF < 50%. A spline curve analysis showed a higher risk of both endpoints occurring for EF < 60% patients. Using the 60-70% EF group as the reference, every EF stratum below 60% EF was associated with the two endpoints, but the > 70% strata was not. When examining those with isolated AS, the spline curve breakpoint was less than 55-60%. For isolated AR, it was less than 60%. For mixed AS/AR, it was < 55%. The authors concluded the risk of adverse clinical outcomes in BAV patients increases significantly when the LVEF is < 60%.
COMMENTARY
Criteria to replace the AV are particularly important in BAV patients without symptoms because it usually means surgery is needed — possibly with aortic root replacement. Also, BAV patients are younger, on average, so any valve replacement procedure must last longer. This decision is particularly important when the patient is asymptomatic.
Today, predominantly, clinicians use echocardiography to make clinical decisions. Since the EF lower limit is 55% by echocardiography, moving to this figure for AVR decisions perhaps is a no-brainer. The results of the Hecht et al study suggest moving the guidelines cutpoint to lower than 60% for BAV patients. Whether this more liberal cutpoint improves outcomes in these patients remains to be proven with future studies.
Also, before any changes occur, we must consider the limitations of this work. First, this was a retrospective, observational study, so biases can be operant, such as the decision for surgery. Second, there was no central echo lab to verify the measurements. Third, the diagnosis of BAV largely was made by using transthoracic echocardiography, which does not always accurately characterize the anatomy of the aortic valve. Using CT or MRI scans would have been more accurate. In addition, the authors did not use more sensitive echo measures of LV function, such as global longitudinal strain. Finally, symptoms were not considered in the analysis presented.
A study of patients with bicuspid aortic valve and moderate or more aortic valve disease revealed the cutpoint for considering aortic valve replacement should be moved from < 50% to < 60% in the guidelines.
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