Insights on Mechanical Circulatory Support Use in AMI Cardiogenic Shock

Jacob Møller, MD, PhD, an intensivist at Copenhagen University Hospital, discusses mechanical circulatory support (MCS) in AMI cardiogenic shock, including an evaluation of early IABP or Impella CP® heart pump use. Early use of IABP or Impella CP, as defined in his recently published paper, was use before PCI if shock developed pre-PCI, or immediately after PCI if shock developed during PCI.

Dr. Møller describes how data from his paper—“Contemporary trends in use of mechanical circulatory support in patients with acute MI and cardiogenic shock”—can inform clinical decision-making in areas such as type and timing of MCS use and vasoactive drug use. This cohort study of 903 patients studied between 2010 and 2017 made use of the unique patient tracking system in Denmark in which every inpatient or outpatient hospital contact in the country is documented.

Dr. Møller explains that after publication of the IABP-SHOCK II results in 2012, throughout Denmark “more or less overnight… we stopped using the balloon pump for the indication of shock and AMI.” This precipitous drop in IABP use was followed by a rise in the use of ECMO and Impella CP in the study.

Dr. Møller states that one of the most important take-home messages from this paper is: “The patients that we are selecting for different devices are completely different.” He explains that one of the reasons that the populations are so different is because during the later years of the study, when using Impella, researchers focused on ensuring patients were in a hemodynamic state that justified Impella use (eg, decreased cardiac output and hypoperfusion with lactate increase).

Regarding the use of vasoactive drugs, Dr. Møller states, “Today my approach would be as little vasopressor as possible. So, I’m happy as long as the lactate is stable or decreasing.” He explains that clinicians are still learning, but that studies have revealed that pressors strain the heart and increase myocardial oxygen consumption. “So, there is a cost to that. So, if you have to do it, you have to do it, but there has to be a reason.”

Regarding the timing for use of MCS, Dr. Møller cautions that timing is driven by the circumstances of each case. However, he believes that from a pathophysiologic standpoint, “it just makes good sense to put the Impella pre-PCI. If the patient is in a shock state, it’s hard for me to understand the rationale of waiting, where you will lose myocardium and you will increase the risk of losing the patient as well. So, if the patient is sick enough, we really go for putting the device in.” Although he adds, “I think you really do need randomized data to confidently say that.”

In summary, Dr. Møller emphasizes the importance of sufficiently evaluating the patient with AMI and cardiogenic shock and knowing the patient’s hemometabolic state. “My personal view,” Møller states, “would be that you should start the unloading of the heart as soon as you know that shock is there, cardiac output is down, but we still have to wait for the randomized data.”