Atrioventricular nodal re-entrant tachycardia unmasking cardiac sarcoidosis: a clinical case report.

Background: Sarcoidosis is a rare disease, and cardiac involvement is seen in the minority of patients. The clinical symptoms depend on the location of the noncaseating granulomas in the heart and vary from asymptomatic to atrioventricular (AV) conduction block, ventricular arrhythmia, heart failure, and sudden cardiac death. Clinically manifest cardiac sarcoidosis seldomly presents with supraventricular tachycardia. Case summary: We present a case where a female patient presented with AV nodal re-entrant tachycardia as an uncommon initial presentation of cardiac sarcoidosis. Her resting electrocardiogram showed a complete left bundle branch block and first-degree AV conduction block. During hospitalization, there was continuous switching between sinus rhythm with first-degree AV block, 2:1 AV block, and AV nodal re-entrant tachycardia. Discussion: It is important to be aware that cardiac sarcoidosis can rarely present with supraventricular tachycardia as initial symptom. Given the elevated risk of sudden cardiac death, early detection is crucial and all patients who require permanent pacing should be considered for implantable cardioverter-defibrillator implantation.