title: Correlation of the non-invasive Cardiopulmonary Management (CPM) wearable device with measures of congestion in heart failure- CONGEST- HF
Creators: name: Curtain, James Peter
Publisher: name: University of Glasgow
Year: 2024

description: Background 
The development of congestion is a leading cause of symptoms in people with heart failure (HF) and a major driver of prognostically important hospitalizations in these patients. Remote monitoring with implantable haemodynamic sensors has shown that subclinical elevations in intra-cardiopulmonary pressures occur days to weeks before a person may exhibit clinical indicators of congestion such as breathlessness or ankle oedema. Randomized controlled trials of implantable haemodynamic monitors have reported a benefit in reducing HF related events (hospitalizations or urgent outpatient visits) when treatment is guided by this monitoring. However, such sensors require a dedicated implant or an indication for an implantable device such as a defibrillator that can also provide diagnostic data for monitoring congestion markers. More recently, wearable devices have been developed that could also provide a remote monitoring option that is more generalizable to all patients with heart failure irrespective of ejection fraction and without the need for an invasive implant. The Cardiopulmonary Management (CPM) wearable device provides multi-parametric data on third heart sound energy (S3), thoracic impedance, tidal volume, heart rate and ECG.

Aims 
The Correlation of the non-invasive Cardiopulmonary Management (CPM) wearable device with measures of congestion in heart failure (CONGEST-HF) study was a prospective, observational study designed to examine whether the CPM device measures correlated with clinical measures of congestion in patients who were at risk of or actively receiving treatment for congestion.

Methods 
I enrolled 3 cohorts into the CONGEST-HF study. Cohort A were patients undergoing a clinically indicated right heart catheterization as part of an advanced heart failure evaluation. Cohort A were assessed on one occasion on the day of the catheterization. Cohort B were patients with end-stage renal disease receiving haemodialysis. Cohort B had study assessments immediately before and after a scheduled dialysis session. Cohort C were patients admitted to hospital with decompensated heart failure who were being decongested with intravenous diuretics and were assessed for the study on day 1 on IV diuretics, day 2 on IV diuretics, the day of first dose of oral diuretics and on the day of discharge.
The primary analyses were the patient-individual Spearman correlations per cohort of: CPM device S3 and pulmonary capillary wedge pressure (PCWP) in cohort A; CPM device thoracic impedance and lung ultrasound (LUS) B-lines and change in thoracic impedance and change in B-lines and the volume of fluid removed by dialysis in cohort B; and CPM device thoracic impedance and device S3 and LUS B-lines and change in thoracic impedance and S3 and change in B-lines and change in weight in cohort C. Secondary analyses included Spearman correlations between CPM device tidal volume and tidal volume on bedside spirometry and between the CPM device measures and other right heart catheterization parameters (cohort A only) and (in all cohorts) echocardiography, blood biomarkers, physical signs and symptoms and ECG findings.

Results 
66 patients in total were enrolled. In cohort A (20 patients), device S3 and PCWP measured at a single time point were not significantly correlated (rsp = 0.296, p=0.204). In cohort B (21 patients), device thoracic impedance was strongly correlated with LUS B-lines both before (rsp = -0.710, p&lt; 0.001) and after (rsp = -0.769, p&lt; 0.001) dialysis but the correlation between change in both parameters was weaker and not statistically significant. Change in device thoracic impedance was correlated with volume of fluid removed by dialysis (rsp = 0.495, p=0.024). In Cohort C (25 patients), change in both device thoracic impedance (rsp = -0.638, p=0.002) and change in device S3 (rsp = -0.530, p=0.014) were correlated with change in weight. CPM device S3 and LUS B-lines were correlated on the day of discharge (rsp = 0.48, p = 0.029). There were no device related adverse events.

Conclusions 
The CPM device demonstrated correlations with markers of intravascular and extravascular volume and change in these measures but not with haemodynamic pressures obtained at a single time point.