Reassessment of practical usage and accumulation of real-world data of wearable cardioverter defibrillator (WCD) in Japan-Design paper for J-WCDR study.

Although implantable cardioverter defibrillators (ICDs) are a powerful preventive therapy for cardiac sudden death, there are some populations in whom ICDs cannot be applied because of a lack of a definitive indication (grey-zone patients), such as in patients during the acute phase of cardiac injury with a susceptible risk for lethal arrhythmias. In such patients, wearable cardioverter defibrillators (WCDs) provide safer bridging period during the acute phase until the final decision-making for the ICD use and it may eliminate any inappropriate overuse of ICDs in the subacute phase. The JCS/JHRS practical guidelines provide the criteria for WCD use in Japan.