Use of an Implantable Loop Recorder in Facilitating the Differential Diagnosis of Isolated Cardiac Sarcoidosis: A Case Report

Cardiac sarcoidosis is a relatively rare disease that can lead to arrhythmia or sudden death. Herein, we report a case of isolated cardiac sarcoidosis presenting as syncope with a paroxysmal atrioventricular block in a 34-year-old man. After reviewing the results of standard cardiac testing, we administered an implantable loop recorder, which confirmed paroxysmal atrioventricular block. Based on the information gathered from the loop recorder and subsequent testing, the patient underwent pacemaker implantation. After implantation, the ventricular thresholds rapidly increased due to the spread of inflammation related to cardiac sarcoidosis. Steroid therapy was initiated and subsequently weaned per protocol. An implantable loop recorder is commonly used to investigate the cause of unknown syncope. This modality can facilitate the identification of both the cause and the underlying disease, allowing for relatively early intervention. This case highlights the usefulness of implantable loop recorders in diagnosing or confirming the causes of syncope of unknown origin suspected to be of a cardiogenic nature.