Venoarterial extracorporeal membrane oxygenation or standard care in patients with cardiogenic shock complicating acute myocardial infarction: the multicentre, randomised EURO SHOCK trial

Selected in EuroIntervention Journal by E. Asher

The EUROSHOCK trial aimed to determine if early use of VA-ECMO could improve outcomes in patients with persistent CS following pPCI.

Reviewer

Elad Asher

@AsherElad

Interventional cardiologist / Cardiologist

Jerusalem, Israel

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My Comment

Designed by Elad Asher

Designed by Elad Asher

Why this study – the rationale/objective? 

Cardiogenic shock (CS) occurs in ~10 % of patients presenting with acute myocardial infarction (MI). In-hospital mortality rates following CS complicating acute MI remains high (40-50 %) despite revascularisation.

The EUROSHOCK trial aimed to determine if early use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) could improve outcomes in patients with persistent CS following primary percutaneous coronary intervention (pPCI).

How was it executed? - the methodology

A total of 15 centers from 6 countries participated in the trial (the study aimed to recruit 428 patients to demonstrate a 27.5 % reduction in the primary endpoint with 80 % power and a = 0.05. This was based on an anticipated 30-day mortality of 50 % in the standard therapy group).

Patients presenting with CS due to MI and who have had attempted/successful pPCI of the culprit lesion were enrolled if there was persistent CS 30 mins following pPCI.

CS was defined as the presence of SBP < 90 mmHg or maintained above 90 mmHg with the addition of vasopressor or inotropic support, with evidence of hypoperfusion.

Patients with either ventricular septal rupture, ischemic mitral regurgitation or left ventricular (LV) free-wall rupture were excluded.

ECMO vs. Control therapy groups

Patients were randomised to receive V-A ECMO as soon as possible and within 6 hours of randomisation or continue standard therapy in a 1:1 fashion.

Intra-aortic balloon pump (IABP) use was permitted as a means of LV unloading in patients receiving V-A ECMO therapy.

The use of mechanical support devices in the control therapy group was discouraged, although the use of IABP was permitted in this group. However, if physicians felt this was in the patients’ interests to manage clinical deterioration, it was permitted but acknowledged as a protocol violation.

Only IABP was permitted as a means of LV unloading in the V-A ECMO group.

Primary endpoint:

30-day all-cause mortality

Secondary endpoints:

• in hospital major bleeding complications (BARC type 3-5)
• cerebrovascular events
• vascular complications as defined by the valve academic research consortium-2 (VARC-2) criteria
• 12-month all-cause mortality
• composite endpoint of 12-month mortality and readmission with heart failure

What is the main result?

• From 21^st January 2020 to January 2022, a total of 333 patients were screened at the recruiting centers. Of them, 35 patients (13.25 %) were recruited to the trial.
• 18 patients were randomised to standard therapy and 17 patients to early V-A ECMO.
• Main reasons for screen failure included out-of-hospital cardiac arrest without return of spontaneous circulation (ROSC) or bystander cardiopulmonary resuscitation (CPR) within 10
  minutes (20 %), recovery from CS after PCI (18 %), CS secondary to another cardiac cause and not associated with AMI (14 %).
• Among patients randomised to the V-A ECMO group, 5 patients did not receive V-A ECMO therapy (complications with vascular access or difficulty with peripheral cannulation leading
  to abandoning the implantation of V-A ECMO n = 3; patient refusal n = 1; withdrawal of consent n = 1).
• In the standard therapy arm, one patient received V-A ECMO after this 6-h period due to clinical deterioration. This patient has been included in the standard therapy arm for the “intention to
  treat” and the “as treated” analysis. Hence, for the “as treated” population, 22 patients received standard therapy and 12 patients received V-A ECMO.
• Baseline characteristics were similar between the 2 treatment groups. Nevertheless, The admission and peak lactate levels were numerically higher in the standard therapy group.
• Median time from CS onset to V-A ECMO was 4.8hrs and median time from first medical contact to V-A ECMO insertion was 4.4hrs.
• 30-day all-cause mortality occurred in 43.8 % (7/17) and in 61.1 % (11/18) of patients randomised to the V-A ECMO and standard therapy groups, respectively (HR = 0.56, 95 % CI = 0.21 – 1.45, p = 0.22).
• There were a numerically higher number of vascular complications and major bleeding events in the patients randomised to V-A ECMO group.
• The all-cause mortality at 12 months was numerically lower in the V-A ECMO group (51.8 % vs. 81.5 %, HR = 0.52, 95 % CI = 0.21-1.26, p = 0.14).

Critical reading and the relevance for clinical practice

The results of this study show that in patients with persistent CS complicating acute MI, early implantation of V-A ECMO resulted in a numerically lower rate of 30-day and 1-year mortality.

The overall recruitment to the trial was significantly impacted by the covid-19 pandemic, and less than 10 % of the initial planned recruitment was completed. Unfortunately, as a result, no definitive conclusions can be drawn from these data.

However, the results do indicate a trend to benefit from early use of V-A ECMO in this setting supporting further clinical trials in this area.

Similarly, the recently reported ECMO-CS trial showed no difference in the primary composite endpoint of death from any cause, resuscitated circulatory arrest and implementation of another circulatory support device at 30 days between those patients receiving immediate V-A ECMO compared with those that did not.

Should common practice and guidelines be changed?

The Euro-Shock trial has several limitations, but the key limitation is the low recruitment due mainly to the covid-19 pandemic. Hence, the reported results are significantly underpowered to draw meaningful conclusions on the utility of V-A ECMO in this setting.

Moreover, the timing of use of V-A ECMO, either before or after PCI attempt, remains an area of interest and uncertainty, and the use of Impella for LV unloading was discouraged in this trial as this may have
confounded any effect of V-A ECMO in the intervention arm of the trial (especially as Impella may also have a role in the management of cardiogenic shock).

Importantly, the trial shows the feasibility of randomizing patients with CS complicating acute MI, but also illustrates the challenges.

What do you think would be the future of ECMO in patients with CS complicating acute MI?