Posture-dependent changes in left atrial pressure: insights from the VECTOR-HF studies

Abstract Background Implantable hemodynamic monitoring devices were designed to collect intracardiac pressures in ambulatory heart failure (HF) patients on a day-to-day basis. Understanding posture-related hemodynamic shifts is essential for optimizing pressure-guided heart failure management. While pulmonary capillary wedge pressure, measured in the supine position, remains the standard for left-sided filling pressures, remote left atrial pressure (LAP) monitoring may provide more dynamic, posture-adapted pressure targets for ambulatory chronic heart failure (CHF) patients. The V-LAP, an interatrial device, has been proven to be safe and accurate in invasively collecting LAP in patients with HF. Patients are advised to measure LAP twice daily in a fixed posture, specifically while sitting with legs down. However, posture-related effects on LAP interpretation have not been assessed previously. Purpose This analysis aimed to evaluate left atrial pressure across various body postures using an implanted pressure sensor in CHF patients. Methods This study included patients from the VECTOR-HF I, II, and IIa trials. LAP was measured in three distinct postures: sitting upright with legs down (knees bent at a 90-degree angle), sitting upright with passive leg elevation (knees extended at a 180-degree angle, rested on a table chair), and supine (lying flat with knees extended at a 180-degree angle). Each posture was maintained for at least 3 minutes to ensure hemodynamic stabilization before obtaining multiple independent LAP measurements. The mean LAP value for each patient at each posture was then analyzed. Results A total of 13 CHF patients implanted with the LAP sensor were included (mean age 69.1 ± 10.2 years, 23% female, body mass index BMI 30.1 ± 4.2 kg/m², left ventricular ejection fraction LVEF 42.8 ± 15.3%). Variations in mean LAP were observed in all patients in relation to posture. A clinically relevant LAP increase of more than 5 mmHg was observed in 69% of patients. The mean maximum LAP change across postures was 5.8 mmHg, with the highest individual variation reaching 9.6 mmHg. Mean LAP was 12.8 ± 7.6 mmHg when sitting with legs down, 17.1 ± 9.6 mmHg when sitting with legs up, and 18.4 ± 7.2 mmHg in the supine position (Figure 1). LAP increased significantly by 5.61 mmHg (p0.001) when transitioning from sitting with legs down to supine and by 4.35 mmHg (p=0.008) from legs down to legs up. The shift from legs up to supine also showed a significant rise of 1.26 mmHg (p=0.02). Conclusions Marked variations in left atrial pressures were observed in relation to posture, particularly when transitioning from sitting with legs down to either sitting with legs up or supine. These findings highlight the significant impact of posture on LAP. Therefore, body posture should be routinely considered in HF pressure-guided management. These insights may support posture-adapted LAP target strategies for remote monitoring and optimal therapy titration.Distribution of LAP Across Postures