A Case of Atrial Standstill Misdiagnosed as Atrial Fibrillation: Diagnostic Insights and Clinical Implications

Atrial standstill (AS), a rare and diagnostically challenging cardiac disorder with total absence of atrial electrical and mechanical activity, often presents variably, mimicking atrial fibrillation (AF) in electrocardiogram (ECG). This report details a case of AS initially misdiagnosed as AF.

A 65-year-old Chinese female had 5-year intermittent palpitations. Prehospital ECG showed paroxysmal AF, and echocardiogram showed a giant atrium. A single-chamber pacemaker (ventricular pacing, ventricular sensing, inhibited) was implanted 6 months ago due to long ventricular intervals. During this hospitalization, AS was confirmed using electrophysiological examination, altering the treatment approach and prognosis.

AS is complex and overlooked. Early recognition and proper management are crucial. Accurate diagnosis via echocardiogram and electrophysiological testing is vital for at-risk patients. This case highlights the need for precise test interpretation and comprehensive evaluation for optimal patient care. AS is an infrequently encountered arrhythmia that eludes clear diagnosis using surface ECG. It is characterized by complete atrial electrical and mechanical inactivity, bradycardia, atrioventricular junction escape rhythm, and absence of P waves. Despite its rarity, patients may present with palpitations, syncope, or stroke, warranting diagnostic attention. Acquired AS can result from myocardial infiltrative diseases like amyloidosis, sarcoidosis, and hemochromatosis, as well as infections (viral myocarditis), autoimmune disorders, and certain medications. Here, we present a case of AS potentially due to long-term AF.