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.