The Impella CP Device for Acute Mechanical Circulatory Support in Refractory Cardiac Arrest
Vase H, Christensen S, Christiansen A, et al. Resuscitation 2017. [paper]
Why I chose this study
While perusing LITFL R&R I stumbled on this interesting study. As we have started seeing with increased use of ECMO and the development of tools such as REBOA, the future of resuscitation is going to include taking mechanical control of the cardiovascular system. So, why not emergent placement of temporary LVADs?
Refractory cardiac arrest (rCA) in a patient who you believe might have a good outcome is insanely frustrating to EM and IM docs. Especially when it is a young person. These are the cases that follow you home, make you question why we do what we do, and cause existential crisis; but also drive us to come up with new and different therapies.
Extracorporeal membrane oxygenation (ECMO) has become a more accepted therapy in patients with rCA but has its limitations. Availability being the major one. Emergent placement of a left ventricular assist device (LVAD), in this study they used the Impella CP device, is another therapy to consider and has promising data in a porcine model. An Impella can be placed in a cath lab by a trained interventional cardiologist making it much more widely available than ECMO. It also reduces afterload, which ECMO does not, and can improve left ventricular (LV) recovery.
Can Impella CP device be used in the setting of rCA?
Single site, dual case series of patients with rCA and presumed LV failure (N=8) and patients with cardiogenic shock treated with Impella CP device (N=12).
Subjects were included at the discretion of the treating physicians. Patients who were included had:
- rCA which was defined as persistent cardiac arrest for at least 10 min despite advanced life support resuscitation
- Witnessed arrest
- Patients showed signs of life during arrest
- Cardiac arrest was caused/complicated by presumed or known LV failure
- All patients in arrest either received coronary angio immediately before or after arrest
In-hospital and out-of-hospital arrests were included and chest compressions were provided by a LUCAS II system.
No official primary or secondary outcomes as this was mostly a “can we even do this” pilot study. The results that were reported are:
- return of circulation
- survival to discharge
- neurologic status at discharge
- complications of Impella placement
- survival to 6 months
- length of hospital stay
- LV ejection fraction at discharge
Reported data was in means ± SD or absolute numbers. Student’s t-test or Mann-Whitney test as appropriate. Proportions used chi-squared test. Significance was p<0.05.
100% of patients had return of spontaneous circulation (ROSC), 50% of these patients survived to hospital discharge with good neurologic outcomes. Survival to discharge was similar to a group of patients in cardiogenic shock treated with Impella (58% survival). Major vascular complications were much more frequent in patients in rCA than cardiogenic shock (50% v 0%).
This is a super small case study looking at the potential of emergent LVAD placement in rCA. The results they present are encouraging but there are a lot of limitations to this study. First, the subjects included in this study were chosen at the discretion of the treating physician. This brings up the question of bias immediately. Also, these patients were the best case scenario type patients. All had witnessed arrests, all had immediate CPR, and 50% of them arrested in the cath lab! So, you have to take the 100% return of circulation and the 50% neuro intact survival rates with a grain of salt.
I think that they proved that the Impella device may have a practical application in rCA and that further trials are warranted. The authors argue that ECMO has become more popularized as a treatment in rCA without data to support it and so why not Impella as it is more widely available and has physiologic benefit in LV failure physiology that ECMO does not.
Will this change my practice? I want to say no, not enough data, but I think they proved a point in a very select patient population. We have almost no access to adult ECMO at the sites we rotate at and if the thought crossed my mind “what about ECMO” the argument can be made “what about Impella”. All of our sites have 24/7 cath lab availability, even the VA.
At this point we have just moved from theoretical to possible but no known benefit. I am excited for a larger trial to be done with a more diverse patient cohort to know when it might be applicable in practice. But, if the situation arises where I have a young patient in rCA with signs of life but ROSC just cannot be achieved or maintained and there is a high likelihood that LV failure is the cause of the arrest I will probably call interventional cardiology to discuss this Hail Mary intervention.
Elspeth Pearce is an EM/IM Resident, Class of 2019.
EM/IM Sessions are reviewed in journal club style by the current attendings and residents, as well as alumni of the UIC IM/EM program prior to publication. This post was specifically reviewed by Carissa Tyo, MD, IM/EM Program Director. Elspeth Pearce, MD Editor.