Mortality in Cardiogenic shock, historically speaking, is around 50%. Everyone knows that we need to get better. An amazing push in sepsis management has significantly decreased the mortality of that pathology. The last decade has seen many advances towards improving mortality but without robust results, unfortunately. Inotropes and vasopressor have failed at saving lives. There is a trend to use mechanical circulatory support (MSC) devices inserted percutaneously such as VA-ECMO and Impella to save more lives. If you’d like an introduction to MCS devices, click here. I have to thank Dr. Jay Mohan for bringing this article to my attention.

This is a retrospective study that is taken from a database looking at cases from 2105-2017. This is important because other studies have shown, given that the Impella (by Abiomed) is a newer technology, that we are all getting better at managing it as we become more experienced with it. They have the typical exclusion criteria but in addition it caught my eye that they also excluded the patients who had both the VA-ECMO and the Impella. In my lecture titled “Cardiogenic Shock: Rise of the Machines“, I cover a a study by Pappalardo that looked at outcomes when combining the two. Needless to say, it was a favorable outcome although mortality was still a terrible 47%. If you have general questions about ECMO, I have covered that here.

Fun Facts: Impella vs. VA-ECMO

How many people were in the study?
Impella: 5730
VA-ECMO: 560
There’s obviously a large disparity in sample size here. Things working against the Impella population include that those patients were older and were less likely to be at a teaching hospital. They also had more COPD and ESRD.

There are other points hidden in there but it certainly caught my eye that the use of pulmonary artery catheters was so low between the cohorts. Between 13.6-14.3%. The National Cardiogenic Shock Initiative (of which many of these authors participate) are likely cringing. I’m sure that they’re looking at this like, “we could have done better”. These patients need a PA catheter to help calculate Cardiac Power Output (CPO) and the Pulmonary Artery Pulsatility Index (PAPi). Without it, we are flying blind.

The ECMO group also used more IABP. There is data by Dr. Aso in Critical Care Medicine (11/2016) that shows this may improve mortality.

Which Impella did they use? They were unable to distinguish. The database didn’t provide that information. There are three different Impellas that were in use at this time: 2.5, CP, and 5.0.

Study Outcomes

Primary outcome: In-hospital mortality.
Mortality was higher in both the gross calculation as well as the propensity matched cohort for those on VA-ECMO. In the propensity matched group it was 43.3% to 26.7% (p=0.021). If you do additional statistical jumping jacks, which I am not sure are recommended here, that would provide a NNT of 6. Needless to say, 26.7% is far lower than the constantly seen 50% in the literature.

Secondary outcomes: procedural outcomes and clinical outcomes.
Procedural outcomes: more respiratory failure and vascular complications in the ECMO group.
Clinical Outcomes: a “trend” in the Impella group (not statistically significant) towards fewer strokes, blood transfusions, and acute liver failure.

Miscellaneous
The Impella device and management costs were also lower when you factor in the length of stay shortening from 11 to 7 days ($66,078 vs $122,996, p<0.001).

Wrapping it up.

For me, and many who are not at ECMO centers, this is encouraging data because many of us are already using Impella’s. This helps us see that we’re doing right for our patients by implanting these devices. That is at least my opinion.
There are prospective studies in the works looking further into this questions. If you look up “Impella”, “ECMO” and “cardiogenic shock” in clinicaltrials.gov you’ll find some studies that are cooking. Hope this helps.
-EJ

Citation:
A. Lemor, S.H.H. Dehkordi, M.B. Basir, et al. Impella versus extracorporeal membrane oxygenation for acute myocardial infarction cardiogenic shock. Cardiovascular Revascularization Medicine (2020). https://doi.org/10.1016/j.carrev.2020.05.042
Link to Abstract

I recommend you read the article and not trust me.

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