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. Nevertheless, the evidence for that is totally limited in Japan and is dependent on the accumulation of actual real‐world data from other countries in order to be able to discuss the appropriate criteria for WCD use. This study will be conducted retrospectively and/or prospectively, and is an observational and multicenter study among Japanese institutions (J‐WCDR, Japan WCD Registry). This will provide evidence for WCD use in our own country and contribute to upcoming updates for the future guideline revisions.