CARC2: The Impella 5.5 and Impella 5.0: Emerging Role of Percutaneous Ventricular Assist Devices in the Management of Cardiogenic Shock

Background: The Impella 5.5 (Abiomed, Danvers, MA) is a percutaneous temporary left ventricular assist device (VAD) used in cardiogenic shock. Its motor housing is thinner and shorter than that of the Impella 5.0, allowing for easier pump insertion. The device can deliver greater peak flows than the Impella 5.0, up to over 6 liters per minute. Approved by the Federal Drug Administration in September 2019, the use of the Impella 5.5 has yet to be widely adopted and there is limited data available. This is an analysis from a high-volume, single center comparing the device complications and mortality rates between the Impella 5.0 and 5.5. Methods: A retrospective analysis was conducted of all patients supported by the Impella 5.0 (n = 156) and Impella 5.5 (n = 76) from 2014 to 2021 at a high-volume medical center. Between-group differences in continuous variables were evaluated using unpaired Student t tests. Categorical variables were compared using Fisher’s exact test. Results: The baseline characteristics were similar for patients implanted with the Impella 5.0 and 5.5 (Table 1). There was no difference in indication for implantation, with similar percentages of patients in the bridge to recovery, bridge to durable VAD (BTD), and bridge to transplant (BTT) groups. There were more INTERMACS 2 patients in the Impella 5.5 group and more INTERMACS 1 patients in the Impella 5.0 group. The rates of device complications did not differ between patients implanted with the Impella 5.0 and 5.5 (Table 2), except for INTERMACS-defined RV failure, with 9.3% vs 0% (p 0.006). Rates of INTERMACS-defined major hemolysis were 22.7% vs 20% (p 0.81), stroke 5.8% vs 2.6% (p 0.511), pump failure/thrombosis 6.4% vs 7.9% (p 0.783), and vascular/limb injury 3.9% vs 2.6% (p 1.0). Among patients in the intended BTT group, 73.2% vs 84.4% were transplanted in the Impella 5.0 and 5.5 groups respectively. For transplanted patients, mortality was 0% in both groups at time of discharge and 30 days post discharge. One-year mortality post-discharge was 3.33% vs 14.3% (p 0.107) with 6 patients in the 5.5 group excluded as they had not yet reached the time point. Among patients in the intended BTD group, 70% vs 23.1% of patients received the durable VAD. There was no difference in the mortality rates at all time points (Table 3). Conclusion: There is limited data on the Impella 5.5, which was recently introduced and not yet widely used. The device’s design makes for easier insertion, more durability, and support with greater peak flows, allowing for full LV support. This is an analysis from a high-volume, single center that showed Impella 5.5s had fewer rates of INTERMACS-defined RV failure and had no difference in the rates of other device complications compared to Impella 5.0s. There was no difference in mortality rates between the two groups. The findings are promising as we continue to explore the utility and clinical impact of the Impella 5.5 in patients with cardiogenic shock.