Relationship Between Morphology of the Valve and Left Ventricular Systolic Function in Patients With Aortic Valve Stenosis

Aortic valve stenosis accounts for about 5% of all forms of congenital heart disease, with higher prevalence in males.¹ First described by Lababidi in 1983,² balloon aortic valvuloplasty emerged as an alternative to open surgical valvotomy with acceptable mid-term to long-term results.^3,4 However, outcomes remain suboptimal in neonates, in patients with higher postvalvuloplasty residual gradient, and in patients with poor left ventricular systolic function.^5-7 Patients with poor left ventricular systolic function tend to have higher rates of reintervention, higher rates of development of aortic valve insufficiency, higher rates of aortic valve replacement, and even higher mortality. The complex relationship between the morphology of the aortic valve (which is a strong predictor of interventional success) and left ventricular systolic function has not been well studied. 

We have come to know that valve morphology influences the outcome of aortic balloon valvuloplasty. Patients with bicuspid aortic valve do better than those with a unicuspid valve; also, leaflet thickness and fusion pattern predict procedural success. Furthermore, left ventricular systolic function also influences outcomes after aortic balloon valvuloplasty, where patients with better preintervention systolic ventricular function do better compared to those with poor systolic function.

However, one thing we still do not have full understanding of is the relationship between morphology and function. The severity of aortic stenosis has been shown to have significant detrimental effects on left ventricular function in the adult population. In fact, one of the criteria for valve intervention in the adult patient with aortic stenosis is the deterioration of left ventricular function. However, in adults, several other variables have to be factored into the possible etiology of depressed ventricular function in patients with aortic valve stenosis (ie, hypertension, coronary artery disease, etc). While valve morphology (or “pathology/type”) may influence severity of stenosis, the association is demonstrated between stenosis severity (using gradient or valve area) and ventricular function. The other issue relates to procedural outcomes; in particular, are there quantitative valve variables that we can use in addition to systolic ventricular function that may predict the outcome of the procedure?

In this issue of the Journal of Invasive Cardiology, Gao and colleagues tried to answer this complex question in a retrospective study of 89 patients who underwent balloon aortic valvuloplasty at two medical centers⁸ looking at aortic valve morphology and ventricular function. Interestingly, the authors mention “that aortic valve morphology can be described through quantitative variables such as degree of aortic valve stenosis,” which may be confusing for the reader in differentiating severity of aortic valve stenosis and the type/pathology of the valve.

The authors found that the severity of the aortic stenosis (by gradient and aortic valve area) as well as valve morphology (or “pathology/type” unicuspid vs bicuspid) correlated with poor left ventricular function. Furthermore, they showed that the severity of the stenosis and the valve morphology, rather than the age of patient, determine outcomes of the valvuloplasty procedure. 

Specifically, patients with functionally bicuspid valves were more likely to have normal left ventricular systolic function compared with patients with unicuspid valves. While this correlation was shown, this may simply indicate that unicuspid valves are more stenotic than bicuspid valves, and in turn are associated with poor ventricular function.  Furthermore, the authors have demonstrated that the severity of aortic valve stenosis most strongly correlated with intermediate outcomes and left ventricular systolic function. In this article, they demonstrated worse intermediate outcomes in those patients with small orifice area and higher gradient, suggesting that perhaps the severity of aortic valve stenosis may be a stronger predictor than the type of valve (bicuspid vs unicuspid) in determining the outcome of the procedure.

One thing that remains unclear (unanswered) from this study is which is more crucial, and is a more definitive predictor of outcomes in these patients: systolic left ventricle function, valve type, or the severity of stenosis?

Common practice has always been to rely on both the gradient across the aortic valve as well as the ventricular function for clinical decision making. Certainly, in the neonatal period, for aortic valve stenosis in the presence of normal left ventricular systolic function, the gradient is the main one to use. However, if the ventricular function is abnormal, the valve area, degree of opening, and type of valve are used for determining the need for intervention. In the postneonatal period, assuming normal ventricular function, the severity of stenosis (by gradient) is primarily used.

What this study adds to our knowledge is that along with the severity of the aortic stenosis, and the ventricular function, we need to have comprehensive morphologic characterization of the valve (valve type, aortic valve opening area, thickened leaflets, raphae length, annulus diameter), which in turn may be useful in defining functional valve characteristics and predicting procedural success and clinical outcomes.

References

1.    Lababidi Z. Aortic balloon valvuloplasty. Am Heart J. 1983;106:751-752.

2.     Samanek M, Slavik Z, Zborilova B, et al. Prevalence, treatment and outcome of heart disease in liveborn children: a prospective analysis of 91,823 liveborn children. Pediatr Cardiol. 1989;10:205-211.

3.     Fratz S, Gildein HP, Balling G, et al. Aortic valvuloplasty in pediatric patients substantially postpones the need for aortic valve surgery: a single-center experience of 188 patients after up to 17.5 years of follow-up. Circulation. 2008;117:1201-1206. Epub 2008 Feb 19.

4.     Brown DW, Dipilato AE, Chong, et al. Aortic valve reinterventions after balloon aortic valvuloplasty for congenital aortic stenosis. Intermediate and late follow-up. J Am Coll Cardiol. 2010;56:1740-1749.

5.     Maskatia SA, Ing FF, Justino H, et al. Twenty-five year experience with balloon aortic valvuloplasty for congenital aortic stenosis. Am J Cardiol. 2011;108:1024-1028. Epub 2011 Jul 24.

6.     Petit CJ, Ing FF, Mattamal R, et al. Diminished left ventricular function is associated with poor mid-term outcomes in neonates after balloon aortic valvuloplasty. Catheter Cardiovasc Interv. 2012;80:1190-1199. Epub 2012 Apr 17.

7.     Reich O, Tax P, Marek J, et al. Long-term results of percutaneous balloon valvoplasty of congenital aortic stenosis: independent predictors of outcome. Heart. 2004;90:70-66.

8.     Gao K, Sachdeva R, Goldstein BH, et al. Aortic valve morphology correlates with left ventricular systolic function and outcome in children with congenital aortic stenosis prior to balloon aortic valvuloplasty. J Invasive Cardiol. 2016;28:381-388.

From the ¹Sidra Cardiac Program, Sidra Medical & Research Center, Doha, Qatar; and ²St. Louis University School of Medicine, St. Louis, Missouri.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Address for correspondence: Ziyad M. Hijazi, MD, Chair, Department of Pediatrics, Sidra Medical & Research Center, P.O. Box 26900, Doha, Qatar. Email: zhijazi@sidra.org