Expert Review: Valve Disease

Dilatation of the Remaining Aorta After Aortic Valve or Aortic Root Replacement in Patients With Bicuspid Aortic Valve: A 5-Year Follow-Up

Background
Bicuspid aortic valve (BAV) is the underlying pathology in as many as 1/3 of patients who undergo aortic valve replacement (AVR). It is now widely accepted that an inherent aortopathy exists independent of functional valvular pathology in many patients with BAV. The mean ascending aortic (AA) dimensions in patients with BAV exceed those of patients with tricuspid aortic valves, and progressive enlargement or dilatation of the aorta, even after AVR, has been documented1. Because aortic dilatation is associated with an increased risk for aortic dissection and rupture2,3, prophylactic replacement of the AA at the time of AVR has been advocated. However, any incremental operative risk imposed by such intervention4-6 will have a significant clinical impact.

Knowledge Gap
There have been few previous studies concerning the risk for aortic complications after AVR for BAV and, accordingly, the indications for surgical repair. Current data suggest risk stratification on the basis of aortic dimension at the time of AVR. Unfortunately, the limited size of the study populations, duration of follow-up, and number of aortic events lead investigators to use potentially misleading composite end points that render true risk assessment problematic.

Aim of the Study
The study aimed:
a) To examine the fate of the remaining aorta in patients with BAV who underwent AVR or aortic valve repair (ARR)
b) To compare the group of BAV with tricuspid aortic valve (TAV) patients in terms of dilation and early and midterm outcomes (aortic dissection, rupture, and death)

Methods
Single-center, prospective, longitudinal study including all patients undergoing aortic valve surgery but without aortic intervention (recruitment period: 2005-2009). Various imaging modalities (echocardiogram, computed tomography, magnetic resonance imaging) assessed aortic diameters before and after surgery. An AA diameter ≥45mm or more was regarded as aneurysmal. Images were obtained preoperatively and postoperatively at 6 months and 1, 3, and 5 years after operation (mean follow-up, 4.5 years). Aortic surgery (aortic root or AA replacement) was performed when aortic diameters exceeded 45mm.
In-hospital mortality was recorded. Follow-up data included all-cause mortality, aortic measurements, intervention related to the AA and arch, and whether the patient required reoperation. Comparisons between BAV and TAV patients were performed.

Results
BAV patients (n= 192) were significantly younger (p <0.05) that TAV patients (n=203), had and had significantly larger diameters of the sinuses of Valsalva (p <0.01). In all groups postoperatively, there was no dilatation of the remaining aorta after 5 years of follow-up. None of the patients required operation to replace any part of the aorta because of aneurysm formation or dissection. One patient with TAV and an associated aneurysm presented with aortic type B dissection 9 months after his first operation and was managed conservatively. The overall mortality (12%) during the follow-up was not significantly different between groups (p=0.3)

Conclusion
Various points deserve to be emphasized:
• Progressive dilatation of the remaining aorta or the aortic arch leading to reoperation after aortic surgery in anerurysmal BAV patients in infrequent
• No significant difference in morbidity or mortality was found comparing AVR with aortic replacement in patients with BAV. Neither was it comparing BAV with TAV patients.
• The cut-off point of 45mm for AA surgery in patients with BAV with concominant valvular disease seems a good strategy from a risk-benefit point of view.

Clinical Impact:
Current guidelines recommend AA replacement when AA diameter is ≥45mm if valve surgery is indicated or ≥50mm if other risk factors are present. The results of this study reinforce this attitude in order to achieve the best risk-benefit balance between aortic surgery and the risk of aortic complications for unreplaced aorta. Progressive dilation of nonreplaced sinuses is not evident after AVR. Therefore, separate valve and graft repair remains a reasonable option for BAV with AA dilation, provided the sinuses of Valsalva are not significantly enlarged. In addition, the results reported by Abdulkareen et al, are in line with several previous studies showing that dilation of the aortic arch leading to reoperation after AA surgery is rare.

Corresponding author from original paper
Dr Jahangiri, Department of Cardiothoracic Surgery, St. George’s Hospital, Blackshaw Road, London, SW17 0QT, UK;
e-mail: marjan.jahangiri@stgeorges.nhs.uk
.

References:
1.-Yasuda H, Nakatani S, Stugaard M, Tsujita-Kuroda Y, Bando K, Kobayashi J, Yamagishi M, Kitakaze M, Kitamura S, Miyatake K. Failure to prevent progressive dilation of ascending aorta by aortic valve replacement in patients with bicuspid aortic valve: comparison with tricuspid aortic valve. Circulation 2003;108(suppl):II291–II294.
2.- Edwards WD, Leaf DS, Edwards JE. Dissecting aortic aneurysm associated with congenital bicuspid aortic valve. Circulation 1978;57: 1022–1025.
3.- Davies RR, Goldstein LJ, Coady MA, Tittle SL, Rizzo JA, Kopf GS, Elefteriades JA. Yearly rupture or dissection rates for thoracic aortic aneurysms: simple prediction based on size. Ann Thorac Surg 2002;73:17–27.
4.- Girardi LN, Krieger KH, Mack CA, Lee LY, Tortolani AJ, Isom OW. Reoperations on the ascending aorta and aortic root in patients with previous cardiac surgery. Ann Thorac Surg 2006;82:1407–1412.
5.- Zehr KJ, Orszulak TA, Mullany CJ, Matloobi A, Daly RC, Dearani JA, Sundt TM III, Puga FJ, Danielson GK, Schaff HV. Surgery for aneurysms of the aortic root: a 30-year experience. Circulation 2004;110:1364–1371.
6.- Reece TB, Singh RR, Stiles BM, Peeler BB, Kern JA, Tribble CG, Kron IL. Replacement of the proximal aorta adds no further risk to aortic valve procedures. Ann Thorac Surg 2007;84:473– 478.

Citation: Ann Thorac Surg 2013;96:43–9

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