Feasibility of a noninvasive photoplethysmography-based wearable chest patch for cardiac output assessment during exercise compared with thermodilution right heart catheterization

Abstract Hemodynamic monitoring with cardiac output (CO) assessment is usually based on invasive methods that are associated with potential complications. This study compared CO measurements during exercise obtained from a noninvasive photoplethysmography (PPG)-based chest patch monitor with those obtained from invasive thermodilution-based right heart catheterization in patients with heart failure with a preserved ejection fraction (HFpEF). CO was assessed at rest, during passive leg raises, and during 20 Watt (W) of bicycle exercise. Nine patients (67% female) with a mean age of 74.1 ± 12.1 years provided a total of 27 paired measurements. Bland–Altman analysis showed a bias of -0.72 L/min (95% CI − 1.16 to − 0.29) with 95% limits of agreement of − 2.88 to 1.43 L/min and a percentage error of 33%. The CO values obtained by thermodilution and the PPG patch were strongly correlated (r = 0.774; p < 0.001) with a concordance of r = 0.88 ( p = 0.002) for the rest-to-20 W change. In this single-center feasibility study, a noninvasive PPG-based chest patch was feasible during exercise right heart catheterization and tracked exercise-induced changes in cardiac output well. Wearable monitoring may offer a low-risk, complementary approach to hemodynamic assessment, but these findings require confirmation in a larger validation cohort.