What are the indications for closing an atrial septal defect (ASD) with bidirectional shunting?

From the Guidelines

Atrial septal defects (ASDs) with bidirectional shunting should be closed when there is evidence of right heart volume overload, significant left-to-right shunting with a pulmonary-to-systemic flow ratio (Qp:Qs) greater than 1.5:1, and PA systolic pressure is less than 50% of systemic arterial systolic pressure, as recommended by the 2018 AHA/ACC guideline for the management of adults with congenital heart disease 1.

Indications for Closure

The indications for closing an ASD with bidirectional shunting include:

• Evidence of right heart volume overload
• Significant left-to-right shunting with a Qp:Qs greater than 1.5:1
• PA systolic pressure less than 50% of systemic arterial systolic pressure
• Pulmonary vascular resistance less than one third of the systemic resistance
• Symptoms such as exercise intolerance, fatigue, palpitations, or dyspnea on exertion attributable to the ASD

Contraindications for Closure

Closure should not be performed in adults with:

• PA systolic pressure greater than two thirds systemic
• Pulmonary vascular resistance greater than two thirds systemic
• A net right-to-left shunt, as stated in the 2018 AHA/ACC guideline 1

Procedure

The procedure can be done percutaneously with a closure device for secundum ASDs or surgically for primum or sinus venosus defects. Patients require antiplatelet therapy (typically aspirin 81-325 mg daily) for at least six months after device closure. Bidirectional shunting indicates some degree of elevated right heart pressures, so careful hemodynamic assessment is essential before proceeding with closure to ensure the benefits outweigh the risks. Early closure prevents long-term complications such as atrial arrhythmias, right heart failure, and paradoxical embolism.

Key Considerations

• The majority of secundum ASDs can be closed with a percutaneous catheter technique, but sinus venosus, coronary sinus, and primum defects are not amenable to device closure and require surgical closure 1.
• An ASD with a large septal aneurysm or a multifenestrated atrial septum requires careful evaluation by and consultation with interventional cardiologists before device closure is selected as the method of repair 1.

From the Research

Indications for Closing ASD with Bidirectional Shunting

The indications for closing an atrial septal defect (ASD) with bidirectional shunting are as follows:

• Patients with anatomically large ASDs and a high probability of reversible pulmonary vascular disease may benefit from closure, despite severe pulmonary hypertension and elevated pulmonary vascular resistance (PVR) 2.
• Patients with significant left-to-right shunt at baseline and a high probability of reversible PVR may also benefit from ASD closure and pulmonary vasodilators 2.
• Symptomatic patients with borderline shunt (Qp:Qs ratio ≤ 1.5) may experience significant improvement in exercise capacity and quality of life after transcatheter closure of ASD 3.
• Patients with paradoxical embolism, including those with cryptogenic stroke, may benefit from ASD closure to prevent recurrent ischemic events 4, 5.

Considerations for ASD Closure

When considering ASD closure, the following factors should be taken into account:

• The size and location of the ASD, as well as the presence of any associated cardiac anomalies 4, 5.
• The presence and severity of pulmonary hypertension and PVR, as well as the potential for reversibility 2.
• The patient's symptoms and quality of life, as well as their risk of recurrent ischemic events 4, 3, 5.
• The potential risks and benefits of transcatheter closure versus surgical closure or medical therapy 4, 6.