Atrial Standstill in the Pediatric Population: A Multi-Institution Collaboration

Area of Science:

• Cardiology
• Genetics
• Pediatric Electrophysiology

Background:

• Atrial standstill (AS) is a rare condition with limited prior research.
• Characterized by a complete absence of electrical activity in the atria.

Purpose of the Study:

• To investigate the clinical features, genetic underpinnings, and patient outcomes in pediatric atrial standstill.
• To identify risk factors and management strategies for AS.

Main Methods:

• Retrospective multicenter study of patients under 18 years diagnosed with AS.
• Defined AS by absence of atrial activity confirmed via electrophysiology, device placement, or rhythm tracings and echocardiogram.
• Excluded acquired causes; collected clinical data and genetic variants.

Main Results:

• Diagnosed in 20 pediatric patients (median age 6.6 years).
• High prevalence of atrial/supraventricular arrhythmias (80%) and ventricular tachycardia (40%), with 4 cardiac arrests.
• SCN5A variants identified in 65% of patients; biallelic variants linked to ventricular arrhythmias and cardiac arrest.
• 90% required pacemakers, with challenges in achieving atrial pacing (4/15).
• 35% experienced thromboembolic events, primarily in those not on anticoagulation.

Conclusions:

• Atrial standstill is associated with SCN5A loss-of-function variants.
• Patients present with complex arrhythmias and device implantation difficulties.
• Risk of thromboembolic events necessitates anticoagulation in patients unable to achieve atrial pacing.