Survivors of ventricular fibrillation out-of-hospital cardiac arrest VF-OHCA due to potentially reversible causes such as acute coronary syndrome ACS , vasospastic angina and electrolyte abnormalities are considered low risk for recurrent arrhythmia. Accordingly, implantable cardioverter-de brillator therapy is not routinely recommended in such patients. We investigated the risk of mortality and the value of ICD therapy for VF-OHCA. Among 2,248 cardiopulmonary arrest patients presenting at our hospital, we retrospectively investigated 110 patients with VF-OHCA who were admitted for treatment. We divided the patients based on ICD n 71 or No-ICD status n 39 , and on reversible cause n 70 or irreversible cause n 40. The groups were compared for baseline characteristics, mortality and ICD therapies. Patients with a reversible cause had a signi cantly lower rate of ICD implantation than those with an irreversible cause P 0.03. Males in the ICD group presented more frequently than those in the No-ICD group, and cardiac mortality in patients with acute coronary syndrome was signicantly lower with ICD therapy than without ICD P 0.04. The rate of appropriate ICD therapies with a reversible cause was 28 , and the rst ICD therapy was highest within 1 year post-implantation. Patients with VF-OHCA due to a reversible cause remain at high risk of recurrent ventricular arrhythmias, suggesting that ICD implantation is a reasonable approach in such cases.