Phase Angle at Completion of Cardiac Rehabilitation Predicts Unplanned All-cause Readmission: A Retrospective Cohort Study.

Abstract

Objectives Phase angle (PhA) reflects cellular integrity and systemic physiological resilience. This study investigated whether PhA measured at the completion of late-recovery-phase cardiac rehabilitation (CR) predicts unplanned all-cause readmission in patients with cardiovascular disease (CVD), comparing its predictive value with baseline PhA and exercise capacity. Methods We analyzed 83 patients with CVD. PhA, peak oxygen uptake (peak V̇O 2 ), and anaerobic threshold (AT) were assessed at both CR initiation and completion. The primary endpoint was unplanned all-cause readmission. Results During a median follow-up of 615 days, 21 patients (25.3%) experienced unplanned all-cause readmission. Multivariable Cox analysis revealed that PhA at CR completion was a significant independent predictor of readmission [adjusted hazard ratio (aHR) = 0.49, 95% confidence interval (CI) 0.26-0.93, P = 0.03], whereas neither PhA at initiation (P = 0.08) nor the change in PhA (ΔPhA; P = 0.41) showed significant associations. Receiver operating characteristic analysis indicated that no statistically significant difference in the area under the curve (AUC) was observed between PhA (AUC = 0.69) and AT (AUC = 0.78, P = 0.14) or peak V̇O 2 (AUC = 0.75, P = 0.27). Conclusions PhA measured at the completion of late-recovery-phase CR is an independent predictor of unplanned readmission, whereas baseline PhA and ΔPhA were not significantly associated with readmission risk. Assessing PhA at this transition point may provide useful information for risk stratification and individualized long-term management in patients with CVD.