Derivation of a Personalized Congestion Score Using a Chronic Implantable Inferior Vena Cava Management System in Heart Failure: An Analysis from the FUTURE-HF Trial Portfolio.

Background: Congestion is a principal driver of worsening heart failure (HF) and hospitalisation. The large, compliant Inferior Vena Cava (IVC) enables detection of congestion before increases in filling pressures. We developed a novel, patient-individualised congestion score (NORM Score) using daily ambulatory IVC measurements-area and collapsibility-from an implantable sensor.

Methods: Using clinical data from 2 early feasibility trials (FUTURE-HF; NCT04203576 and FUTURE-HF2; NCT05763407), a congestion Score (range: 0-100) was derived from daily supine IVC area (breath hold and free breathing) and collapsibility in patients implanted with a novel IVC sensor. A clinical alert was triggered if the score exceeded 70% of a patient's maximum for 5 of 7 days. Performance was evaluated against adjudicated HF events (HFEs) and NT-proBNP levels.

Results: Among 63 patients (mean age 66-years, 75% NYHA III), 30 HFEs occurred in 18 individuals. Score predicted HFEs with 92.6% sensitivity, high predictive accuracy (C-statistic: 0.83) and low unexplained alert rate (0.57 per patient-year). Breaching the alert threshold was associated with an Odds Ratio of 18 (95% CI: 3.5-93.8) for hospitalization within 7 days. The congestion score was significantly associated with log-transformed NT-proBNP (β=5.64;95% CI: 3.23-8.05; p<0.001).

Conclusions: The unique congestion score, derived from an ambulatory implantable IVC management system, was associated with NT-proBNP levels and predicted worsening HF events with high sensitivity. These findings, once validated in a pivotal randomized trial, will support use of this novel congestion score for early detection of HF decompensation, streamline clinical response, and enable personalized patient self-management.

Lay summary: Heart failure often causes fluid buildup, a leading reason for hospitalization. Traditional monitors may miss early signs. This study evaluated the NORM score, which uses an implantable sensor in the inferior vena cava to track daily vein size and movement. The score accurately detected early congestion and monitored NT-proBNP levels, suggesting it could enable earlier intervention and reduce hospital visits for heart failure patients.