JOURNAL OF MEDICAL

Arrhythmias can be life-threatening, and their treatment with an automated external defibrillator (AED) has be-come prevalent in some countries [1]. It is important to identify the underlying disease [2,3]. Coronary artery spasm is a major cause of life-threatening arrhythmia. In general, myocardial ischemia due to coronary artery spasm is associated with chest pain or discomfort that occurs during rest or ordinary exercise, and this symp-tom is a key indicator of possible coronary artery spasm. However, if there are no chest symptoms, clinicians may not suspect this disease. We encountered a patient who had recovered from ventricular fibrillation treated by using an AED, and silent coronary artery spasm was considered to be the cause of this life-threatening arrhythmia. In this case, I-123 metaiodobenzylguanidine (MIBG) scintigraphy was a useful screening tool for a si-lent coronary artery spasm. Case presentation A 72-year-old Japanese man was transferred to our hos-pital after recovering from ventricular fibrillation treated by using AED. He had suddenly collapsed during a walk * Correspondence