Hokuriku-plus Heart Failure Registry Study　― Rationale and Study Design ―

Background: Heart failure (HF) is an increasing public health concern in Japan, largely related to the aging population. This protocol describes the rationale, objectives, and methods of the Hokuriku-plus Heart Failure Registry (HpHFR), designed to establish a comprehensive clinical and digital database to assess novel prognostic indicators in patients with HF. Methods and Results: HpHFR is a prospective, multicenter observational cohort study that has enrolled patients with acute or chronic HF from 5 Japanese centers. Eligible patients provided informed consent and underwent baseline clinical, laboratory, and biometric assessment, including digital phonocardiography and wearable device data. Follow-up assessment will be conducted at 4, 12, 26, and 52 weeks. Primary outcomes include all-cause death, HF-related hospitalization, and worsening HF. Secondary outcomes are the changes in clinical parameters over time. A digital substudy will investigate continuous biometric monitoring, and a genomic substudy explores the loss of chromosome Y as a prognostic biomarker. Conclusions: In conclusion, this study protocol summarizes the development of a valuable prospective cohort resource. This registry will provide a unique dataset enabling multifaceted investigations to improve HF prediction and management by systematically integrating comprehensive clinical and laboratory data with biometric indicators derived from digital devices and genomic markers.