Clinical Research & Data, ECMO, Unloading, AMI Cardiogenic Shock
Better Than Anticipated Survival with Impella CP® and ECMO in Cardiogenic Shock
Steven P. Keller, MD, PhD, discusses left ventricular (LV) unloading strategies in extracorporeal membrane oxygenation (ECMO), the topic of his recently published paper in the Journal of Cardiac Surgery. Dr. Keller’s paper—“Left Ventricle Unloading Strategies in ECMO: A single-center experience”–explores the optimal forms of mechanical circulatory support (MCS) for patients in cardiogenic shock.
Dr. Keller explains the physiologic effects of ECMO and underlying rationale for two major categories of LV unloading strategies. Indirect unloading strategies, such as the intra-aortic balloon pump (IABP), attempt to decrease flow into the LV to help prevent the ventricle from distending. Direct unloading strategies, such as support with the Impella CP heart pump, directly unload the LV. “One of the major challenges,” Dr. Keller states, “is determining when to initiate venting strategies.”
The initial focus of Dr. Keller’s paper was to look at reactive venting (patients initiated on ECMO support with an unloading strategy added if indicated) versus immediate venting (patients initiated on LV support as soon as they were placed on ECMO or having a pre-existing MCS device in place when ECMO was added). While noting the challenges of the small sample size in this study, Dr. Keller reports, “We found that even though the two groups were quite similar, looking across the various patient populations, what was most compelling, and even though this didn’t rise to the level of statistical significance, we did find a survival benefit for those patients who underwent immediate venting.”
Dr. Keller also reports that although the IABP and Impella CP groups were heterogenous and hard to compare, “there again appeared to be a benefit to the patients who were supported by Impella® over those supported by balloon pump, looking at their survival statistics. Again, this was something that didn’t rise to the level of statistical significance, p-value of .11 or so, but again, this was in the setting of relatively small patient groups.”
“And one of the compelling aspects of this paper,” Dr. Keller adds, “was that our group that is initiated on ECMO and then Impella support had lower predicted survival than the balloon pump group based on the SAVE score, but actually ended up doing better than the balloon pump group. So, the Impella actually helped increase their survival likelihood significantly.”
Dr. Keller’s paper also reveals that the likelihood of needing heart replacement or VAD therapy was different between the Impella and IABP groups. He explains that Impella provides an “elegant step-down of support” option for patients. “Impella goes from being a primary venting support to maintain forward flow through the cardiopulmonary circulation during ECpella™, to then providing a further weaning modality once the patient’s decannulated from ECMO, so that way the heart can have time to recover and the clinician can then step down, as it were, mechanical support.” Keller notes, “the action of the Impella itself and then the opportunity for, really, higher levels of support immediately post-decannulation, and then gradual weaning, I think likely contribute to the better survival that we see.”