Challenges in the conduct of randomised controlled trials in cardiogenic shock complicating acute myocardial infarction.

Cardiogenic shock (CS) following acute myocardial infarction (AMI) is a major challenge in cardiovascular care. Mortality remains high with 40%-50% after thirty days. Randomised controlled trials (RCTs) play a key role to generate evidence on optimal care in this field. However, the number of completed or ongoing RCTs is still relatively low compared to the gaps in evidence. Challenges in the conduct of these trials are in particular the selection of patients and ethical issues in the informed consent process. When determining eligibility criteria, special attention should be paid to the severity of CS, to the inclusion of patients with cardiac arrest and to potential age limits. Median age of AMI-CS patients is increasing. Age limits are therefore controversial as it is important to include elderly patients in RCTs in order to make the results generalisable and to address the special needs of this group. As patients with AMI-CS are in most cases unable to provide informed consent themselves, a step-wise approach with acute consent by a legal representative or independent physicians and later informed consent by the patient if possible might be established depending on regularities of the respective ethical review board and country legislation. Multicenter studies should be sought to generate adequate power.