Background: While the hemodynamic benefits of durable LVADs and intra-aortic balloon pumps (IABPs) in patients with acute-on-chronic heart failure are well described, the hemodynamic effects of the minimally-invasive Impella 5.5 in this patient population are not. Methods: Patient and hemodynamic data on all Impella 5.5 and IABP recipients between August 2020-November 2022 were extracted from a single-institutional database. Only patients with a history of decompensated chronic congestive heart failure were included. Patients requiring Impella support after myocardial infarction or immediately after cardiac surgery were excluded. The primary outcome was survival at 30 days after implantation. Secondary outcomes included changes in pulmonary vascular resistance (PVR), pulmonary capillary wedge pressure (PCWP), and cardiac index (CI) between device implantation and removal. Results: We identified 25 Impella 5.5 patients (12.0% female), 68 IABP patients (19.1% female), and 21 patients who had IABP exchanged for Impella 5.5 (14.2% female). There were no significant differences in baseline characteristics or hemodynamics between Impella 5.5 and isolated IABP patients (Table). Median support duration was significantly longer in the Impella 5.5 cohort (11 days vs. 8 days, p = 0.04). There was no significant difference in survival at 30 days between groups (Figure). PVR and PCWP significantly decreased in both cohorts, while CI significantly increased (Table). The percent increase in CI was significantly greater in Impella 5.5 patients than in IABP patients (67.8% vs 33.6%, p=0.01). However, only the IABP cohort demonstrated significantly decreased mean pulmonary artery pressure (PAP) (-7.0 mmHg, p<0.01) and central venous pressure (CVP) (-3.5 mmHg, p=0.03). Exchanging IABP to Impella 5.5 significantly improved PVR (-50.92 dynes sec cm-5, p=0.03), but not other hemodynamic parameters. Conclusion: Both IABP and Impella 5.5 improve hemodynamics by decreasing pulmonary congestion and increasing cardiac output. While only the IABP significantly decreased mean PAP and CVP, the Impella 5.5 provided greater improvements in CI, and exchanging IABP for Impella 5.5 provided further reductions in PVR.Figure 1. 30-day survival after Impella 5.5 or IABP. - IABP (n=68) Impella 5.5 (n=25) P-value Age 59.10 (47.12-64.97) 44.58 (40.3-63.2) 0.1824 Female 19.1% (13/68) 12.0% (3/25) 0.5442 ICM 30.9% (21/68) 40.3% (10/25) 0.4585 Pre-op PVR 240.0 (176.0-344.0) 231.0 (191.8-344.0) 0.4294 Pre-op PCWP 30.0 (26.0-34.0) 27.0 (20.5-34.0) 0.1186 Pre-op mean PAP 41.5 (37.8-48.0) 40.0 (32.5-49.3) 0.1964 Pre-op CVP 14.0 (10.0-12.5) 14.0 (10.0-22.0) 0.3746 Pre-op CO 3.6 (3.0-4.4) 3.6 (3.0-4.6) 0.3184 Pre-op CI 1.7 (1.5-2.1) 1.9 (1.5-2.2) 0.3184 IABP => Impella 5.5 Pre-exchange Pre-explant P-value PVR 184.4 (111.9-253.1) 148.2 (94.45-214.2) 0.0290 PCWP 23.0 (18.8-27.8) 22.0 (16.0-31.0) 0.3398 Mean PAP 34.5 (29.0-38.3) 35.0 (32.0-38.0) 0.2142 CVP 12.0 (7.50-20.5) 13.0 (9.8-18.8) 0.4431 CO 4.3 (3.3-5.4) 4.9 (4.0-6.1) 0.1832 CI 2.1 (1.6-2.8) 2.3 (2.1-2.6) 0.1526