Heart-rate reduction during microaxial flow pump support and short-term outcomes in patients with cardiogenic shock

Heart rate (HR) is a surrogate of systemic conditions, cardiac performances, and effect of chronotropic agents in patients with critical illness. The current study aimed to elucidate the association between HR during mechanical circulatory support with the Impella microaxial flow pump and clinical outcomes in patients with cardiogenic shock (CS). This study evaluated 92 patients (mean age: 67 ± 13 years; male: 77%) with CS who received temporary circulatory support with Impella. The absolute HR immediately before Impella implantation, at 24 h after implantation, immediately before explantation, and at 24 h after explantation, and its association with short-term outcomes were assessed. In total, 47 (51%) patients concomitantly used venoarterial extracorporeal membrane oxygenation. Patients who died or those who were bridged to left ventricular assist device (LVAD) implantation during Impella support (n = 20) were excluded from the outcome analysis. Four patients died within 24 h after Impella initiation. During Impella support, 14 patients died, and two had LVAD implantation. A high HR and a higher lactate level at Impella explantation were independently associated with 30 day mortality in 18 (25%) patients. An HR of < 82 bpm at Impella explantation was the optimal cutoff value for indicating a lower incidence of 30 day mortality. Up-titrated beta-blockers and decreases in the vasoactive-inotropic score were correlated with HR reduction during Impella support. In patients with CS receiving Impella support, a lower HR at weaning was associated with a decreased incidence of short-term mortality. HR reduction was a simple prognostic indicator, and chronotropic interventions including beta-blockers may be therapeutic options for patients with CS receiving Impella support.