Cardiac sarcoidosis completely mimicking biventricular arrhythmogenic cardiomyopathy

Cardiac sarcoidosis (CS) is a chameleon of cardiology, and it can mimic different cardiac diseases; among them is arrhythmogenic cardiomyopathy (ACM). We admitted a 70‐year‐old female patient with heart failure symptoms in 2015, who fulfilled all major ECG and non‐invasive imaging criteria of biventricular ACM. She was well with the recommended medications for 3 years, showing only isolated cardiac involvement, but in 2018, cervical and mediastinal lymphadenopathy appeared and cervical lymph node core biopsy histology, bronchoalveolar lavage flow cytometry strongly suggested extracardiac sarcoidosis. Therefore, our suspicion was that sarcoidosis is responsible for the cardiac involvement, which was not confirmed by PET‐CT and gallium scintigraphy examinations. At the end of 2018, she died in septicaemia with multiorgan failure, and only autopsy verified her CS. A new ECG algorithm published in 2021 for the differential diagnosis of CS and biventricular ACM, when applied on her ECGs recorded in 2015, suggested the diagnosis of CS.