The ARREST Trial

Survival from out of hospital cardiac arrest varies from region to region. This makers sense as it depends on resources, such as medical and nursing staff, expertise of that staff and resources available to them. it also depends on the infrastructure which includes the timely response of emergency services and the rapid delivery of patients to a centre that can provide advanced resuscitation and post arrest care including cardiac reperfusion and intensive care management.

We know that immediate coronary angiography in post OHCA patients with no ST elevation provides no survival benefit (1-3). But does the transfer of patients without ST elevation OHCA, to a cardiac arrest centre rather than a standard care hospital result in better survival and neurological outcomes? 

A previous Meta-analysis (4) has shown that treatment in a cardiac arrest centre resulted in improved survival and neurological outcome. This was based mostly on observational data, with potential inherited biases.. The ARREST Trial(5) is the first randomised trial to look at this question. 

What They Did

This was a prospective parallel, multi centre, open-label, randomised superiority trial. It was not blinded.

They compared transfer of post OHCA patients to an arrest centre with those delivered to the closest emergency department.

It was conducted in 35 hospitals in London (7 were cardiac arrest centres). Randomisation was performed using a secure online system.

N = 827

Inclusion Criteria included:

• Patients > 18 years old
• ROSC post OHCA

Exclusion Criteria included:

• Presumed non-cardiac cause,

• Pregnancy

• ST-elevation myocardial infarction on the post-resuscitation

• Do-not-attempt-resuscitation order.

Primary Outcome: all-cause mortality at 30 days

Secondary Outcomes:

• mortality at 3 months,
• neurological(functional) outcomes at discharge and 3 months

What They Found

The cause of cardiac arrest was not determined in 16% of the cardiac centre group and 22% in the standard care group.

63% of patients who were taken to a cardiac arrest centre had a cardiac cause for arrest and 59% taken to standard care had a cardiac cause of arrest.

Those patients taken to a cardiac arrest centre:

• Had higher rate of ICU admission ( 80% vs 69%)
• Received haemodynamic support ( 72% vs 62%)
• Received ventilatory support (86% vs 76%)
• Received renal support (11% vs 8%)
• Had coronary angiography performed (56% vs 37%), with median time to angiography being shorter in the cardiac arrest centre group.

What They Found

Primary Outcome: 30 day all-cause mortality was 63% in the cardiac arrest centre group versus 63% in the standard group ie., there was no difference in patients with cardiac arrest with no ST elevation.

Secondary Outcomes: There was no difference in 3 month mortality outcomes. Neurological outcomes were similar at discharge and at 3 months.

Conclusion: There is no difference in the two groups.

My Take on This

There are a few points worth making:

• More patients going to the cardiac arrest centre were in cardiogenic shock.
• Only 60% of patients with a pre-hospital presumed cardiac cause of arrest were given a cardiac cause diagnosis.
• Subgroup analysis showed a potential survival benefit for patients < 57 years old taken to a cardiac arrest centre.
• Subgroup analysis showed greater survival in patients 57 to 71 years old, when taken to a standard care centre.

This study was conducted in London, a large metropolitan city, with many hospitals and short ambulance transit times. It may not be reproducible in the rural setting or in other countries. Perhaps the sicker patients (cardiogenic shock) were treated at the cardiac centres, lowering their overall survival.

If the study findings are really true, there is concern that what we do, perhaps provides little benefit. My instinct would say that if the patient goes to a cardiac arrest centre, they would do better, however the standard hospital care, in this study, may be of a significant level, that great care is provided.

It would be interesting to have study that included smaller rural centres. I would hypothesise that the results may be different. More studies are needed.

References

1. Lemkes JS, et al. Coronary Angiography After Cardiac Arrest Without ST Segment Elevation: One-Year Outcomes of the COACT Randomized Clinical Trial. JAMA Cardiol 2020;5:1358-1365.
2. Desch S, et al. Coronary Angiography After Out-of-Hospital Cardiac Arrest Without ST-Segment Elevation: One-Year Outcomes of a Randomized Clinical Trial. JAMA Cardiol 2023.
3. Kern KB, et al. Randomized Pilot Clinical Trial of Early Coronary Angiography Versus No Early Coronary Angiography After Cardiac Arrest Without ST- Segment Elevation: The PEARL Study. Circulation 2020;142:2002-2012.
4.  JW, et al. Impact of cardiac arrest centers on the survival of patients with nontraumatic out-of-hospital cardiac arrest: a systematic review and meta-analysis. J Am Heart Assoc 2022; 11: e023806.

5. Patterson T et al. Expedited transfer to a cardiac arrest centre for non-ST-elevation out-of hospital cardiac arrest (ARREST):a UK prospective , multi centre, parallel, randomised trial. Lancet 2023; 402: 1329-1337.