Noninvasive Analysis of Pump Parameter Responses to Orthostatic Transitions in Patients with Fully Magnetically Levitated Left Ventricular Assist Devices

Background Despite the excellent clinical outcomes of the HeartMate 3 (HM3) left ventricular assist device, the current pump monitoring limits in-depth pump data analysis. This study investigated HM3 pump parameters collected noninvasively with HM3 Snoopy during orthostatic transitions (OTs). Methods In this single-center cohort study, a standardized OT protocol was developed, involving postural changes between supine, seated, and standing. Data were recorded using the HM3 Snoopy and a Holter electrocardiogram. Pump flows (QMIN, QMEAN, QMAX), pulsatility index (PI), pump speed, MagLev parameters, and heart rate were synchronized per-second. The primary outcome was the identification of distinct orthostatic pump flow response phenotypes. Further a binary classifier using MagLev parameters, to differentiate between supine and upright patient positions, was developed and assessed. Results In 25 HM3 patients (age: 61.2 ± 9.6 years, female: 12%, BMI: 26.8 ± 4.7 kg/m2), greater flow alterations were observed during transitions from supine to standing vs. seated to standing, with most significant changes in QMIN (3 (-13; 10)%). Phenotypes were identified across 75 OTs as no flow response (60%), undesired unloading with a loss in QMIN ≥ 50% (20%), and loss of pulsatility ≥ 50% (16%). The MagLev patient position classifier achieved a median sensitivity of 88% and specificity of 86% across the entire cohort. Conclusion Three HM3 pump flow response phenotypes were identified in response to OTs, challenging the utilization of PI events to detect undesired unloading events. A MagLev-based position classifier revealed potential for differentiation of HM3 patient position.