P54: Early mortality associated with combination Impella 5.5 and extracorporeal membrane oxygenation support as bridge to cardiac replacement therapy

Background: End stage heart failure is treated with durable left ventricular assist device (LVAD) or orthotopic heart transplant (OHT). Patients with severe ventricular dysfunction and/or cardiogenic shock may require temporary mechanical circulatory support (tMCS) while awaiting cardiac replacement therapy. Extracorporeal membrane oxygenation (ECMO) and the Impella 5.5 (Abiomed; Danvers, MA) are well-studied bridging therapies. However, investigations of concomitant ECMO and Impella 5.5 (ECpella 5.5) therapy are lacking. The aim of this study is to compare mortality at 30-days and at most recent follow-up across four groups with different tMCS bridging strategies. Methods: This is a retrospective study evaluating all patients who were bridged to durable LVAD or OHT between December 31, 2018 to January 31, 2023 at our institution. Patients were separated into the following groups: Group 1 (solo ECMO), Group 2 (solo Impella 5.5), Group 3 (ECMO followed by Impella 5.5), and Group 4 (Impella 5.5 followed by ECMO). Patient demographics and early (30-day) mortality were collected from chart review (table 1). Group comparisons for continuous variables were performed with analysis of variance (ANOVA), and chi-square test of independence and Fisher’s exact tests were used for outcome data comparisons between groups. Results: This study included 61 patients bridged to LVAD or OHT with ECMO and/or Impella 5.5. Mean (std) age was 49.4 (14.3) years and mean (std) time on tMCS was 10.5 (8.4) days. 49% of our cohort required solo ECMO (Group 1, n = 30), 25% required solo Impella 5.5 (Group 2, n = 15), 11% required Impella 5.5 following ECMO (Group 3, n = 7), and 15% required escalation to ECMO from Impella 5.5 (Group 4, n = 9). Mortality at 30-days for Group 1 was 16.7%. No patients died in the 30-day postoperative period in Groups 2-4. Mortality at most-recent follow-up was 33.3%, 6.7%, 28.6%, and 0% for Groups 1-4, respectively. ANOVA revealed significant between-group differences for days on tMCS (p < 0.01). Chi-square test of independence revealed no significant difference in overall mortality across treatment groups (p = 0.07). Further partitioning with pairwise Fisher’s exact tests between treatment groups revealed no significant differences in mortality at most recent follow-up. Conclusions: Limited data exists comparing mortality between different combinations of tMCS as bridge to cardiac replacement therapy, and even less is known about mortality associated with order of therapy initiation. This data demonstrates comparable mortality between solo ECMO, solo Impella 5.5, ECMO followed by Impella 5.5, and Impella 5.5 escalated to ECMO therapies. Large, randomized controlled trials are required to fully evaluate the impact of order of tMCS in bridging to cardiac replacement therapy. Table 1. - Patient demographics and outcomes ECMO (n = 30) Impella 5.5 (n = 15) ECMO + Impella 5.5 (n = 7) Impella 5.5 + ECMO (n = 9) Age, years 45.7 ± 17.3 55.1 ± 8.1 51.6 ± 11.7 51.0 ± 11.0 Female 20.0% 0.0% 14.3% 0.0% BMI 28.0 ± 6.2 26.5 ± 4.7 24.9 ± 4.0 29.8 ± 5.3 Time on MCS, days 9.0 ± 6.6 17.1 ± 11.6 6.7 ± 3.1 7.1 ± 3.1 Bridged to LVAD 50.0% 26.7% 85.7% 0.0% Bridged to OHT 50.0% 73.3% 14.3% 100.0% 30-day mortality 16.7% 0.0% 0.0% 0.0%