A case report of recovery of sinus node abnormalities associated with right atrial involvement of 'early-stage' cardiac sarcoidosis.

Background: Cardiac sarcoidosis (CS) is a chronic inflammatory disease characterized by impaired contractility of the myocardium secondary to cardiac conduction system abnormalities, which result in atrio-ventricular (AV) conduction block and ventricular tachyarrhythmias. Notably, sinus node (SN) abnormalities are rarely associated with CS. Case summary: We herein present a case of CS presenting with SN abnormalities associated with atrial involvement of the CS and describe the utility of cardiac magnetic resonance imaging (cMRI), fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18-FDG-PET-CT) scans, and cardiac biopsy, in making an initial early diagnosis of early-stage CS. Fortunately, an initial appropriate immunosuppression therapy with methylprednisolone for the CS thus far can help the SN and AV conduction function recover and has provided a good clinical course without the implantation of a pacemaker or implantable cardio-defibrillator. Discussion: Although the diagnosis of CS may be elusive, the initial clinical suspicion and use of advanced imaging may be important for an early diagnosis of CS. Furthermore, because CS may sometimes rapidly progress, the early diagnosis and treatment of early-stage CS may also be important to help the SN and AV conduction function recover, and avoid implantation of a pacemaker, as in this present case.