Comparison of device-based and bioelectrical impedance methods for volume status assessment in heart failure patients with cardiac implantable electronic devices (CIED vs. BIA fluid assessment in heart failure)

BACKGROUND: Accurate assessment of volume status is essential in heart failure (HF). This study evaluated the association between cardiac implantable electronic device (CIED)-derived fluid monitoring and bioelectrical impedance analysis (BIA) for systemic volume assessment. METHODS: In this prospective cross-sectional study, 57 patients with HF carrying implantable cardioverter-defibrillators or cardiac resynchronization therapy devices with intrathoracic impedance-based fluid monitoring were enrolled. Patients were classified according to the presence of device-detected fluid alerts. Body composition and total body water (TBW) percentage were assessed by BIA (Tanita). Clinical, laboratory, echocardiographic, and device-derived data were compared. Logistic regression identified variables independently associated with fluid alerts. RESULTS: Patients with device-detected fluid alerts had higher TBW and lower body fat percentages than those without alerts (both p < 0.001). TBW showed a strong positive correlation with device-detected fluid alerts (r = 0.675, p < 0.001). A TBW threshold of 57.15% predicted fluid alerts with 80% sensitivity and 80% specificity (AUC 0.938, 95% CI 0.856-0.999; p < 0.001). Patients with fluid alerts also demonstrated more pronounced echocardiographic signs of right-sided congestion. In multivariable analysis, TBW remained the only independent predictor of device-detected fluid alerts (OR 1.33, 95% CI 1.07-1.66; p = 0.011). CONCLUSION: BIA-derived TBW was strongly associated with device-detected fluid alerts and may serve as a practical complementary method for systemic volume assessment, particularly when device-based fluid monitoring is unavailable.