REMAP ECMO - Beta Receptor Modulation Trial

Inclusion Criteria: * Age ≥ 18 years, * Having received V-A ECMO support for severe circulatory insufficiency due to left- or bi-ventricular failure. * ≤ 16 hours after initiation of V-A ECMO support * Receiving ≥ 2 mcg/kg/min of dobutamine. * Norepinephrine infusion ≤ 0.4 mcg/kg/min * Heart rate ≥ 80 bpm (being sinus rhythm, atrial fibrillation or atrial flutter) after V-A ECMO initiation Exclusion Criteria: * Objection during the deferred consent procedure * V-A ECMO usage confined to the period during surgery or another intervention (the ECMO was removed at the end of the intervention). * Concomitant durable Left Ventricular Assist Device (LVAD) * Polymorphic ventricular tachycardia necessitating BB therapy * Isolated right ventricular failure (e.g. due to pulmonary embolism) * Need of high dose dobutamine \> 6.0 mcg/kg/min * Epinephrine infusion * Signs of insufficient trans cardiac flow: * Absence of aortic valve opening * Pulse pressure \<10 mmHg (with intra-aortic balloon pump (IABP) standby) * Spontaneous contrast in the heart at echocardiography * Contraindications for-, intolerance to- or allergy to esmolol * Second- or third- degree AV block * Pregnancy * Life expectancy of less than 24 hours * Participation in another randomized clinical trial (e.g. On Scene trial or Left Ventricular unloading trial) * Inability to start study treatment within 4 hours after randomization * Post heart transplantation patients