Episodic long-lasting atrial standstill associated with an SCN5A variant resulting in atrial pacing failure: Is an atrial lead necessary for familial atrial standstill?

Atrial standstill (AS) is a rare arrhythmogenic condition characterized by the absence of electrical and mechanical atrial activity.1 Electrocardiographically, AS manifests with transient or permanent absence of P waves and junctional escape rhythm (JER).2 Familial AS has been associated with pathogenic variants of the SCN5A gene, which encodes the α-subunit of the Nav1.5 cardiac sodium channel protein. Pathogenic SCN5A variants have also been linked to other cardiac conditions, such as long QT syndrome, Brugada syndrome, atrial fibrillation, sick sinus syndrome (SSS), cardiac conduction defect, and rarely, dilated cardiomyopathy.