Abstract
BACKGROUND: Unexplained cardiac arrest is often attributed to a patient's underlying disease. However, it is well known that an autopsy can reveal pathologies that were not noticed before death. CASE SUMMARY: Multiple micro-scars (MMS) found in the myocardium of 3 patients who died of unexplained cardiac arrest were presented at our clinicopathology conference. Upon review of the clinical record, patients with MMS before death had arrhythmia (ie, atrial fibrillation and nonsustained ventricular tachycardia, including new onset). Interestingly, MMS were found in the left ventricle, the junction of the pulmonary vein and left atrium, and the right ventricle and right atrium. All 3 patients had histories of COVID-19 booster vaccination, and 1 of the 3 patients had a history of COVID-19. DISCUSSION: For patients with unexplained cardiac arrest complicated with arrhythmia, cardiac MMS is given as the differential background disease.