Functional bicuspid aortic valves associated with improved outcomes compared with other morphology types

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Shiraz Maskatia, Texas Children’s Hospital, Houston, USA, and others report, in a study published ahead of print in Catheterization and Cardiovascular Interventions, that a patient with a functional bicuspid valve is less likely to require repeat valvuloplasty, aortic valve replacement, death, or a heart transplant than a patient with other types of valve morphology.

Maskatia et al wrote that studies have shown that valve morphology can significantly affect early outcomes following balloon aortic valvuloplasty (BAV) for congenital aortic stenosis but they added: “Few reports have analysed valve morphology and its association with long-term outcomes; those reports have low agreement on the associations between morphologic type and outcomes”. Therefore, the aim of their study was to evaluate the incidence of various morphological types of congenital aortic stenosis and the association between valve morphology and long-term outcomes.

Of 210 patients who underwent BAV between 1992 and 2009 at the authors’ institution (Texas Children’s Hospital), 147 had detailed data available for their pre-BAV aortic valve morphology. Maskatia et al reported that the most common morphology was functionally bicuspid (92 patients; 63%), followed by functionally unicuspid (20; 14%), dysplastic (16; 11%), true bicuspid (13; 9%), and true unicuspid (6; 4%). They added that neonatal patients, compared with the rest of the patient cohort, were less likely to have functional bicuspid valves (p=0.02) and more likely to have functional unicuspid valves (p=0.02).

The authors commented that “the primary endpoint (repeat valvuloplasty, aortic valve replacement, heart transplant, or death) was less likely to occur in patients with functionally bicuspid valves (p<0.01) and patients with true bicuspid valves (p=0.03), whereas it was more likely to occur in patients with functionally unicuspid valves (p=0.02) and patients with true unicuspid valves (p=0.05).” In a univariate analysis, patients with functionally unicuspid valves were more likely to undergo repeat valvuloplasty (p<0.01) and aortic valve replacement (p=0.04), patients with true bicuspid valves were more likely to undergo aortic valve replacement (p<0.01), patients with true unicuspid valves were more likely to die or have a heart transplant (p<0.01), and patients with dysplastic valves with more likely to undergo repeat valvuloplasty (p=0.04). However, patients with functionally bicuspid valves were less likely to undergo repeat valvuloplasty, aortic valve replacement, or experience death/transplant than patients with other morphology types (P<0.01).

Maskatia et al concluded: “Our findings suggest that long-term outcomes following BAV indeed reflect the underlying valve substrate.” They added that other long-term studies have found that residual aortic stenosis is associated with worse outcomes following BAV and that, in their series, the degree of residual aortic stenosis was not found to be associated with balloon annulus, diameter ratio, or number of balloon inflations. The authors wrote: “That is, the patients who were left with significant gradients (>20mmHg) following BAV were no less aggressively dilated compared with those patients with a post-BAV gradient <20mmhg. This suggests that residual aortic stenosis is more likely due to underlying valve substrate than to operator preference.”

Maskatia told Cardiovascular News: “Our goal for this study was to refine the way in which we risk stratify patients undergoing balloon valvuloplasty for aortic stenosis. Based on recent studies published by our group and studies published by other centres, factors associated with a suboptimal outcome include the need for valvuloplasty as a neonate, higher residual gradient after valvuloplasty, and worse pre-valvuloplasty systolic function. In this study, we linked valve morphology to other poor predictors and also to poor outcomes. If the substrate you start with is a difficult valve, the child is more likely to present early and need future interventions. We hope that this finding serves to enhance the care of children with aortic stenosis and counseling of their parents.”

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