Abstract 4369691: Effects of Impella 5.5 on Right Ventricular Load and Adaptation

Background: Right ventricular failure (RVF) is a leading source of morbidity following durable LVAD implantation. Some propose using Impella 5.5 support as a surrogate “RV stress test” to evaluate RV reserve preoperatively. However, the physiologic effects of Impella 5.5 on RV performance and the validity of this approach remain poorly defined. Objective: To characterize the trajectory of RV hemodynamics during Impella 5.5 support. Methods: We retrospectively identified 124 patients supported with Impella 5.5 for cardiogenic shock between 2020 and 2024. After excluding those on ECMO or lacking serial invasive hemodynamic data, 65 patients were included. Right heart catheterization metrics—including central venous pressure (CVP), pulmonary artery pulsatility index (PAPi), pulmonary vascular resistance (PVR), RV stroke work index (RVSWi), effective arterial elastance (Ea), and RA:PCWP ratio—were assessed at baseline and every 12 hours up to 96 hours. Vasoactive inotrope score (VIS) and total diuretic dosing (in IV furosemide equivalents) were also recorded. RVF was defined per 2015 INTERMACS criteria as requiring RVAD or persistent RV dysfunction post-LVAD, necessitating prolonged inotropic or mechanical support. Results: Baseline demographics and destination therapies are summarized in Table 1. Hemodynamic changes over the 96-hour window are shown in Table 2. RAP, PCWP, and mPAP decreased significantly, indicating effective biventricular unloading (Figure 1). PVR and Ea declined, while PAPi and RVSWi remained stable to modestly improved, reflecting reduced RV afterload and preserved contractility (Figure 2A). RA:PCWP remained consistently <0.6 without significant change. These shifts occurred without escalation in pharmacologic therapy: both VIS and total diuretic dosing declined or remained stable over time (Figure 2B), supporting mechanical unloading as the primary driver. Among the 23 patients who underwent LVAD, 10 (43.5%) developed RVF. Five of these had a pre-Impella PAPi <1.85; however, 7 of 13 patients without RVF also had PAPi <1.85, limiting the discriminative value of this threshold. Group-level PAPi values are shown in Table 3. Conclusion: Impella 5.5 support preserved or improved RV hemodynamics without unmasking dysfunction. These findings challenge the use of Impella as a diagnostic stress test for RV reserve and suggest intraoperative factors—such as septal distortion or pericardiotomy—may better explain post-LVAD RVF.