The Introduction of Impella 5.5 in Cardiogenic Shock: A Single-Center, Retrospective Propensity Score-Matched Analysis.

Background/

Objectives

Impella 5.5 provides a higher flow rate than smaller microaxial pumps and has been increasingly adopted for cardiogenic shock (CS). This study aimed to evaluate whether its introduction into our Shock Team program in 2023 improved outcomes compared with a historical cohort supported with other mechanical circulatory support (MCS) devices.

Methods

We retrospectively analyzed patients with CS treated with MCS between 2020 and 2024 at a tertiary center. The Impella 5.5 group (n = 17) included patients managed after device implementation, either as stand-alone or sequential therapy. The historical cohort comprised 40 patients treated with ECMO, Impella CP, CentriMag, or IABP prior to 2023. Propensity score matching (age, sex, etiology, lactate, SCAI stage) generated 17 matched pairs. The primary outcome was survival at discharge, 30 days, 3 months, and 6 months. Secondary outcomes included bridging to recovery, heart transplantation (HTx), durable LVAD, and major complications.

Results

Impella 5.5 was associated with higher survival at discharge (94.1% vs. 58.8%, p = 0.039), 30 days (94.1% vs. 58.8%, p = 0.039), and 3 months (94.1% vs. 58.8%, p = 0.039). At 6 months, survival remained higher (88.2% vs. 58.8%) but did not reach statistical significance in point analysis (p = 0.118). Bridging occurred more frequently with Impella 5.5 (HTx 64.7% vs. 52.9% (p = 0.464), recovery 17.6% vs. 5.9% (p = 0.292)), while LVAD implantation rates were similar (11.8% vs. 17.6%, p = 1.0). Major bleeding (17.6% vs. 47.1%, p = 0.141), stroke/TIA (5.9% vs. 17.6%, p = 0.601), and the need for renal replacement therapy (5.9% vs. 23.5%, p = 0.335) were numerically lower with Impella 5.5.

Conclusions

In this single-center, retrospective analysis, the introduction of Impella 5.5 was associated with higher short-term survival and favorable bridging metrics; estimates are imprecise due to small, heterogeneous samples. These hypothesis-generating findings warrant confirmation in larger, prospective multicenter cohorts.