Supplementary Material for: Clinical Utility of Continuous Non-contact Cardiac Function Monitoring via Fiber‐Optic Micro‐Vibration Sensing System-based Myocardial Performance Index in Heart Failure Patients with Reduced Ejection Fraction

Introduction Continuous monitoring of cardiac function may contribute to improving clinical outcomes in heart failure (HF) patients. A fiber‐optic micro‐vibration sensing system (FO‐MVSS) that was previously developed by our group could make possible the non-contact and continuous measurement of the myocardial performance index (MPI) to assess cardiac function. However, the utility of MPI obtained by FO-MVSS (MPIFO-MVSS) in HF patients requires investigation. Methods Utilizing a case-control design, 72 HF patients and 72 control patients matched for age, gender and body mass index were recruited. Both FO-MVSS and echocardiography were used to measure the duration of the various phases of the cardiac cycle, thereby deriving the corresponding MPI. The MPIFO‐MVSS of 23 hospitalized patients with HF was continuously monitored to evaluate its predictive value for the improvement of cardiac function. Results The MPIFO‐MVSS was in excellent agreement with the MPI obtained by echocardiography (MPIecho) (intra-class correlation coefficient: 0.94, p<0.001). The MPIFO-MVSS exhibited statistically significant correlations with left ventricular ejection fraction (LVEF) (r=-0.78, p<0.001) and N-terminal prohormone brain natriuretic peptide (NT-proBNP) (r=0.66, p<0.001). The MPIFO-MVSS had an excellent performance in discriminating HF patients from control patients, with an area under the curve (AUC) of 0.98 (p<0.001). Moreover, among continuously monitored patients, the change in MPIFO‐MVSS was predictive of clinical outcomes (the kappa coefficient: 0.91, p<0.001). Conclusion Our study presents a novel approach to using non-contact MPIFO‐MVSS for continuous cardiac function evaluation in patients with HF. The MPIFO‐MVSS may serve as an accurate, sensitive, and non-invasive indicator of cardiac dysfunction.