What gradient prompts intervention for supravalvular aortic stenosis?

From the Guidelines

Intervention for supravalvar aortic stenosis is recommended when the mean gradient is greater than 50 mm Hg or peak instantaneous gradient by Doppler echocardiography is greater than 70 mm Hg, regardless of symptoms, as stated in the ACC/AHA 2008 guidelines 1.

Key Considerations

• The decision to intervene should be based on the severity of the obstruction, as well as the presence of symptoms such as angina, dyspnea, or syncope.
• Surgical repair is the primary intervention, as there are no effective medical therapies for this congenital narrowing of the aorta just above the aortic valve.
• The gradient measurement reflects the pressure difference across the stenotic area and serves as an objective marker of obstruction severity.
• Higher gradients indicate more severe obstruction to left ventricular outflow, which increases cardiac workload and can lead to left ventricular hypertrophy, heart failure, and sudden cardiac death if left untreated.

Important Factors to Consider

• Associated cardiac anomalies, such as coronary artery involvement, should be taken into account when deciding on intervention.
• The patient's overall clinical status, including the presence of LV hypertrophy, desire for greater degrees of exercise, or planned pregnancy, should also be considered.
• Post-intervention follow-up should include regular echocardiographic assessment to monitor for restenosis, which can occur in some cases.

Recommendations

• Operative intervention should be performed for patients with supravalvular LVOT obstruction with symptoms and/or mean gradient greater than 50 mm Hg or peak instantaneous gradient by Doppler echocardiography greater than 70 mm Hg 1.
• Surgical repair is recommended for adults with lesser degrees of supravalvular LVOT obstruction and symptoms, LV hypertrophy, desire for greater degrees of exercise, or planned pregnancy 1.

From the Research

Intervention Gradient for Supravalvar Aortic Stenosis

The decision to intervene for supravalvar aortic stenosis is based on several factors, including the severity of the stenosis, symptoms, and associated anomalies.

• The mean preoperative gradient in patients with supravalvar aortic stenosis has been reported to be around 57.2±21.9 mm Hg, with a mean peak gradient of 99.5±34.8 mm Hg 2.
• A study found that a median pressure gradient across the left ventricular outflow tract of 70 mm Hg was an indication for intervention 3.
• Another study reported a mean preoperative peak gradient of 77 ± 27 mm Hg, with a range of 20 to 139 mm Hg 4.
• The exact gradient at which to intervene may vary depending on individual patient factors and institutional preferences.

Surgical Techniques and Outcomes

Different surgical techniques have been used to repair supravalvar aortic stenosis, including single-patch, two-patch, and three-patch repairs.

• A systematic review and meta-analysis found that two-patch repair had a lower rate of reintervention compared to single-patch and three-patch repairs 5.
• The same study found that three-patch repair had a lower rate of aortic insufficiency compared to single-patch and two-patch repairs, but had the longest cross-clamping time 5.
• A study reported excellent medium-term results with a simple, extended single-patch technique for repair of supravalvar aortic stenosis, with a mean follow-up peak left ventricular outflow tract gradient of 10 ± 12 mm Hg 4.

Balloon Angioplasty as an Alternative

Balloon angioplasty has been used as an alternative to surgical repair for supravalvar aortic stenosis, particularly in cases where the stenosis is discrete and accessible.

• A case report described two patients who underwent balloon angioplasty for supravalvular aortic stenosis as an early complication following arterial switch operation, with improvement in postangioplasty gradients and angiographic appearance 6.