Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is a well-established short-term mechanical circulatory support (MCS) modality used in the setting of cardiogenic shock (CS) and cardiac arrest, and it is advantageous as it provides immediate and complete biventricular and respiratory support.1 In addition, it serves as a bridge to either recovery or more advanced long-term therapies such as heart transplantation (HTx) or durable left ventricular assist device (LVAD).1

However, the mortality rates in patients requiring VA-ECMO remain high,2 and one of the main challenges is increased left ventricular (LV) afterload associated with VA-ECMO treatment.3 The basic principle of the VA-ECMO system is to draw deoxygenated blood from the venous system through a drainage cannula, pump the blood through a membrane lung, and return the blood to the arterial circulation through a return cannula.4 The retrograde aortic flow generated by the arterial return cannula increases the LV afterload which causes LV distension and elevated LV end-diastolic pressure leading to pulmonary congestion, increased myocardial oxygen demands, and multiorgan dysfunction.4, 5 Thus, unloading the left ventricle is an important aspect to consider during VA-ECMO therapy, and a wide range of interventions have been used such as inotropes, intra-aortic balloon pump (IABP), Impella, and percutaneous or surgical vent of the left atrium.5

Although previous work has shown favourable outcomes of LV unloading during VA-ECMO therapy,6 there is no consensus on the indication and timing of LV unloading in the setting of VA-ECMO treatment. In fact, the available evidence is contradictory and is mainly based on few observational or retrospective studies,7, 8 and to date there exists no well-controlled randomized trial addressing whether early LV unloading during VA-ECMO therapy is beneficial.