Cardiac sarcoidosis presenting with syncope and rapidly progressive atrioventricular block: a case report

BACKGROUND: Cardiac sarcoidosis (CS) accounts for a substantial morbidity and mortality. Early recognition of CS is important to prevent such detrimental consequences. A definite diagnosis of cardiac sarcoidosis remains challenging. Even after the diagnosis of CS is established, the appropriate dose and duration of corticosteroids in the treatment of CS have not been well-defined. CASE SUMMARY: In this report, we discuss a case of a 50-year-old man who presented with recurrent syncope. Electrocardiogram revealed sinus rhythm with left bundle branch block. Telemetry captured high-grade atrioventricular block. Coronary angiogram showed no coronary artery disease. Left ventriculography revealed left ventricular ejection fraction (LVEF) of 35-40%. A dual-chamber pacemaker was implanted. Cardiac magnetic resonance revealed mid-myocardial scarring suggestive of sarcoidosis. Computed tomography of the chest showed lymphadenopathy. Transbronchial biopsy was unrevealing; however, mediastinoscopy and lymph node biopsy showed non-caseating granulomas diagnostic of sarcoidosis. He became pacemaker dependent as noted in outpatient pacemaker interrogations. A biventricular implantable cardioverter-defibrillator upgrade was performed for primary prevention of sudden cardiac death. He was started on prednisone taper over the course of 6 months. After 1-year, his LVEF improved to 55% and native atrioventricular (AV) conduction had recovered as noted in outpatient device interrogations. DISCUSSION: This case highlights the importance to include CS in the differential diagnosis of a young patient with conduction system disease and non-ischaemic cardiomyopathy for appropriate treatment. Patients with left ventricular systolic dysfunction and AV nodal disease could potentially benefit from a slow prednisone taper over the course of 6 months.