Towards a More Standardized Bicuspid Aortic Valve Repair: Rationale and Design of CONTOUR Trial

Background: Between one-third and one-half of patients with bicuspid aortic valve (BAV) disease develop significant aortic regurgitation (AR) at a young age, leading to cardiomyopathy and heart failure. Aortic valve repair is an evolving and still underused strategy in BAV patients with AR. The lack of sufficient standardization remains the main limitation of current repair techniques, resulting in an increased risk of AR recurrence and reoperation. The most controversial issue is the stabilization of the BAV annulus. The CONTOUR trial aims to compare two different BAV annuloplasty concepts in a prospective randomized study.

Methods: CONTOUR is a multicenter, randomized controlled trial designed to enroll 100 consecutive BAV patients with AR across four sites in Germany. BAV AR patients with an asymmetric configuration and without concomitant root aneurysm will be randomized 1:1 to undergo aortic valve repair using an internal HAART 200 annuloplasty device (i.e., INTERNAL group) (n=50) or external annuloplasty (i.e., double external ring annuloplasty) in the EXTERNAL group (n=50). 4D flow MRI will be performed preoperatively (t1), postoperatively at discharge (t2), and at 1-year follow-up (t3) for rater-blinded assessment of hemodynamic profiles (i.e., flow eccentricity) and regurgitation fraction at the MRI core-lab. Two hierarchically ordered primary endpoints will be considered: (1) postoperative reduction of flow eccentricity at hospital discharge and (2) regurgitation fraction (%) at 1-year follow-up.

Discussion: The CONTOUR trial is designed to test the hypothesis that an internal annuloplasty device, creating a completely symmetric post-repair BAV geometry, achieves superior aortic valve repair outcomes compared to external annuloplasty. If our hypothesis is confirmed, our study will significantly influence aortic valve repair practice and contribute to the refinement of guideline recommendations in the management of BAV patients with AR.


Eligibility Criteria:
Inclusion Criteria:

1. Presence of fused BAV phenotype with an asymmetric configuration (commissural orientation \< 170 degree) \[14\]
2. Severe aortic regurgitation (vena contracta (vc) \> 6mm and/or pressure half-time (PHT) \< 200 ms and/or effective regurgitant orifice area (EROA) \> 30 mm2 and/or regurgitant volume (RV) \> 60 ml/beat and/or left ventricular end-systolic diameter (LVESD) \> 50mm (or indexed LVESD \> 20mm/m2 BSA) and/or regurgitation fraction (RF) in cardiothoracic MRI \> 40%) (at least one parameter is required) \[15\]
3. Isolated aortic valve surgery or concomitant procedure (including CABG and/or mitral/tricuspid valve surgery and/or ascending aortic surgery)
4. Willingness to participate and written informed consent
5. Age at surgery \> 18 years

Exclusion Criteria:

1. Moderate/severe BAV stenosis (pmean \> 20mmHg)
2. Moderate/severe BAV cusp calcifications extending beyond the raphe region and/or necessitating patch implantation (deemed irreparable based on preoperative TOE (as by decision of the operating surgeon)
3. Concomitant aortic root aneurysm \> 45mm requiring simultaneous aortic root surgery \[16\]
4. Acute/subacute BAV endocarditis
5. Contraindication to MRI