Validation of non-invasive monitoring of cardiac output using a wearable patch device against invasive measurements by right heart catheterization

Hemodynamic monitoring with cardiac output (CO) assessment is often required in heart failure patients, providing important indications and early recognition of patient deterioration. These measurements are usually based on invasive methods associated with clinical complications. Exercise right heart catheterization is considered the gold-standard test to diagnose heart failure with preserved ejection fraction (HFpEF). However, performing exercise during right heart catheterization is technically complex and not universally available. Thus, simple, non-invasive, wireless monitoring systems are needed to allow advanced hemodynamic monitoring in heart failure patients for early identification and prevention of cardiovascular morbidity. 

 

This study compared CO measurements obtained from a non-invasive photoplethysmography (PPG)-based chest patch wearable monitor to invasive measurements by thermodilution-based exercise right heart catheterization in HFpEF patients.

 

Invasive right heart catheterization using the thermodilution method was conducted in HFpEF patients between July 2023 and September 2024. CO was assessed at rest, during passive leg raise, and during 20 W, 40 W, and 60 W of bicycle exercise.

The wearable monitoring platform includes a PPG-based chest patch sensor for continuous monitoring of numerous vital signs including cardiac output (CO), mean arterial pressure, and systemic vascular resistance. Hemodynamic parameters were assessed automatically every 5 seconds. Data were uploaded via a smartphone-based app to a cloud server, enabling remote patient monitoring and data analysis. 

 

Ten patients with a total of 36 measurements during rest (n=10), passive leg raise (n=10), and different levels of exercise (20 W with n=10, 40 W with n=4, 60 W with n=2) were included in the final analysis. The participants had a mean age of 72.8 ± 12.7 years and were predominantly female (n=8; 80%). Heart rates adequately increased during exercise (at rest 69.2 ± 10.0 bpm vs. 20 W 88.9 ± 12.7 bpm; p<0.001) assessed by the PPG-patch. Mean CO at rest was 5.5 ± 1.2 L/min and 5.1 ± 0.7 L/min for thermodilution and PPG-patch, respectively. Bland-Altman showed that the PPG-patch had a bias of -0.25 L/min with –3.81 and 3.32 L/min 95% limit of agreement. The CO values obtained by thermodilution and PPG-patch were well correlated (r=0.654; p<0.001).

 

The novel PPG‑based wireless patches offer high accuracy for CO assessment when compared to the measurements obtained from the invasive thermodilution method by exercise right heart catheterization in HFpEF patients. These wearable devices could offer advanced hemodynamic monitoring capabilities in several clinical settings without the complications of invasive devices. Therefore, wearable devices could be used in hospital and out-of-hospital settings to make non-invasive hemodynamic monitoring available for personalized heart failure treatment.