Mechanical circulatory support with the Impella® LP5.0 pump and an intra-aortic balloon pump for cardiogenic shock in acute myocardial infarction: The IMPELLA-STIC randomized study.

BACKGROUND: Percutaneous assist devices may be used as a bridge to recovery in patients with acute myocardial infarction complicated by cardiogenic shock (CS-AMI).

AIM: To test the hypothesis that the Impella® LP5.0 pump (Abiomed Europe GmbH, Aachen, Germany) provides haemodynamic benefits and improves left ventricular ejection fraction (LVEF) in patients with CS-AMI already managed with an intra-aortic balloon pump (IABP).

METHODS: This was a prospective randomized study. The primary endpoint was change in cardiac power index (CPI) from baseline to 12hours after implantation, measured with a Swan-Ganz catheter. Secondary endpoints included LVEF at 30 days.

RESULTS: Fifteen patients with CS-AMI were randomized; 12 were available for primary endpoint analysis (IABP group, n=6; Impella LP5.0+IABP group, n=6). Baseline characteristics were similar in both groups. Change in CPI after 12hours was not significantly different between the two groups (IABP group: ΔCPI=0.08±0.08W/m2 ; Impella LP5.0+IABP group: ΔCPI=-0.02±0.25W/m2 ; P=0.4). There was no significant change from baseline CPI in either group over 96hours, and no difference in CPI between groups at each timepoint. In the Impella LP5.0+IABP group, the part of the CPI provided by the native heart decreased from 0.37±0.10 to 0.10±0.20 (P=0.01). LVEF was similar at baseline (29.7%±8.4% and 29.3%±6.7%) and 1 month (40.6%±12.5% and 38.6%±14.4%) in the IABP and Impella LP5.0+IABP groups, respectively. Adverse events, especially major bleeding, were common, and occurred mainly in the Impella LP5.0+IABP group.

CONCLUSIONS: In patients with CS-AMI stabilized by initial treatment with inotropes and an IABP, the Impella LP5.0 did not provide additional haemodynamic support or improvement in LVEF at 1 month; its use in this setting might be futile and possibly harmful.