Cardiac Arrest Centers Don’t Benefit OHCA Patients Without STEMI: ARREST

AMSTERDAM, the Netherlands—Taking resuscitated out-of-hospital cardiac arrest (OHCA) patients who are not having a myocardial infarction directly to a specialized cardiac arrest center offers no survival advantage when compared with taking them directly to the emergency department, according to the ARREST trial.

The study, which was presented today by lead investigator Tiffany Patterson, MBBS, PhD (King’s College London, England), during a Hot Line session at the European Society of Cardiology Congress 2023 and published simultaneously in the Lancet, challenges the benefit seen in observational studies. Its results are leading investigators to conclude that resources would be better directed elsewhere to improve outcomes after OHCA.

“What really matters in these patients is bystander CPR,” senior investigator Simon Redwood, MD (Guy's and St Thomas’ NHS Foundation Trust, London, England), told TCTMD. “There are a lot of initiatives around the world where they are teaching the public and children bystander CPR—that needs to be pushed even more, because it’s really what makes a difference. Regardless of anything we do [as physicians], once a patient arrives in hospital, we do all this ‘highfalutin’ stuff which probably doesn’t make a great deal of difference to their outcomes. What really matters is prompt CPR.” 

Redwood pointed out that ARREST was conducted in Greater London, a densely populated area where paramedics could get OHCA patients quickly to any of the high-quality regional hospitals. The London Ambulance Service is also a highly qualified, highly trained group capable of providing advanced care. This might explain why they were unable to detect any difference in 30-day mortality between OHCA patients taken to specialized cardiac arrest centers versus those shipped to regional emergency departments.

What really matters in these patients is bystander CPR. Simon Redwood

Lia Crotti, MD, PhD (IRCSS Istituto Auxologico Italiano/University of Milan, Italy), the scheduled discussant following the presentation, made a similar point. “The standard of care for patients getting to the nearest emergency department might not be so different from the standard obtained from cardiac arrest centers,” she said.

In the US, there are no dedicated cardiac arrest centers, but they are being explored, B. Hadley Wilson, MD (Wake Forest University School of Medicine, Winston-Salem, NC), president of the American College of Cardiology, told TCTMD.

“These patients are some of the highest-risk patients you can imagine,” he commented. “The question has been, ‘Can you differentiate the ones who might be helped versus the ones where you can’t really make a difference?’ Importantly, this showed that there is a group—the cardiac arrest patients that don’t have a definite diagnosis of STEMI—where you can’t make a difference.”

Wilson said he doesn’t see the study as entirely negative, noting that shifting OHCA patients to these more specialized centers may unburden some of the regional emergency departments to allow them to care for other patients.

No Difference in Deaths at 30 Days

ARREST is the first randomized trial investigating the benefits of expediting patients directly to a specialized cardiac arrest center following resuscitated OHCA in the community. Current clinical practice in the UK is to deliver OHCA patients without STEMI to the nearest emergency department.

Speaking with the media, Redwood noted that observational studies have shown that taking patients directly to a cardiac arrest center instead of the emergency department was associated with improved survival. “In fact, if you look at the registry data, there’s actually a 30% [relative] difference in mortality between a cardiac arrest center and a district general hospital,” he said.

On that basis, it’s been speculated that direct delivery to a specialized center, much like with STEMI and trauma care, would result in better patient outcomes. This led International Liaison Committee on Resuscitation to ask for a randomized trial to compare the two strategies.

Performed by the London Ambulance Service NHS Trust, which is the primary provider of prehospital emergency care in Greater London, ARREST included all 35 hospitals who receive patients from service. Seven of those hospitals are dedicated cardiac arrest centers with 24/7 access to interventional cardiology, cardiac surgery, and emergency intensive care, including advanced ventilation, temperature management, hemodynamic support, and neuroprognostication.

Overall, 862 patients (mean age 63 years; 68% male) who had a return of spontaneous circulation after OHCA, and in whom STEMI had been ruled out, were randomized to either transfer to the cath lab of the cardiac arrest center or a district hospital. Three-quarters of the OHCAs were witnessed and bystander CPR was attempted in more than 70% of patients. In the others, the initial CPR attempt was made by the London Ambulance Service.

At 30 days, 63% of patients taken to the cardiac arrest center and 63% taken to the emergency department died (RR 1.00; 95% CI 0.90-1.11). Similarly, mortality at 3 months was not significantly different between the two triage strategies. Additionally, there was no difference in neurological outcomes at discharge or at 3 months.

Cardiac and Noncardiac Causes of OHCA

Redwood believes there is a need to home in on specific subgroups, suggesting there may be some OHCA patients who might benefit from going directly to a cardiac arrest center. “If all comers don’t benefit, there might be a subset who do,” he told TCTMD. Researchers did perform a prespecified subgroup analysis and there was a suggestion of benefit in younger patients, but Patterson cautioned against overinterpreting that finding. 

In her deep dive into ARREST, Crotti pointed out that while paramedics tried to exclude patients with obvious noncardiac causes, OHCA was determined to originate from cardiac causes in just 60%. Only one-quarter of all patients had coronary artery disease. As a result, there was a relatively small number of patients with cardiac-caused OHCA who would benefit from expedited transfer to a cardiac arrest center.

“It probably contributed to the negative result obtained in this trial, because there was a dilution of the potential positive effect and a loss of statistical power,” she said.

Patterson said it’s difficult to say if the results would have differed had only OHCA patients with cardiac causes were included in the trial.

“It could well be that if we’re better able to identify patients in the community who would benefit from delivery to a cardiac arrest center that the outcomes may be different,” she said. “We’re planning on looking at that [OHCA with cardiac etiology] cohort. What this does show us is that based on current facilities, our current screening criteria—everything was performed the same as it is during standard practice—delivery of all these patients to a cardiac arrest center doesn’t reduce deaths.   

In an accompanying editorial, Carolina Malta Hansen, MD, PhD (Copenhagen University, Denmark), and colleagues called ARREST “surprising and important, since this complex and critically ill population would be expected to benefit from centers with more expertise.” Like the others, they suggest that basic high-quality care offered at local London emergency departments is really what matters most to optimize survival. “It would be a mistake to conclude that the trial results apply to regions where local hospitals provide a lower quality of care than those in this trial,” they stress.

The editorialists point out that there have been numerous trials of higher technology care in OHCA, such as hypothermia targets, routine angiography, or specific oxygen and blood-pressure targets, but none have proven to be beneficial. ARREST, they add, is yet another example where the positive results seen in observational studies didn’t pan out in a randomized trial setting.