Survivors of out-of-hospital cardiac arrest (OHCA) without ST-segment elevation who were transported to the nearest hospital emergency department had similar outcomes as those transported to specialist cardiac arrest centers, in the ARREST trial.
Both groups had the same 30-day survival, the primary outcome, as well as 3-month survival and neurologic outcomes.
"The take-home message is that this trial does not support transporting cardiac arrest patients direct to a cardiac arrest center in London; they would fare better going to their nearest emergency department," senior author Simon R. Redwood, MD, principal investigator of ARREST, from Guy's and St. Thomas' NHS Trust Hospitals and King's College, London, United Kingdom, said during a press briefing. "These results may allow better resource allocation elsewhere."
Importantly, this study excluded patients who clearly had myocardial infarction (MI), he stressed. Cardiac arrest can result from cardiac causes or from other events, including trauma, overdose, drowning, or electrocution, he noted.
On the other hand, patients with MI, "will benefit from going straight to a heart attack center and having an attempt at reopening the artery," he emphasized.
Tiffany Patterson, PhD, clinical lead of ARREST, with the same affiliations as Redwood, presented the trial findings at the European Society of Cardiology (ESC) 2023 Congress in Amsterdam, the Netherlands, on August 27. The study was simultaneously published online in The Lancet .
Observational studies of registry data suggest that postarrest care for patients resuscitated after cardiac arrest, without ST-segment elevation, may be best delivered in a specialized center, she noted.
The International Liaison Committee on Resuscitation called for a randomized clinical trial of patients resuscitated after cardiac arrest without ST-segment elevation to clarify this.
In the ARREST trial, among 800 patients with return of spontaneous circulation following OHCA without ST-segment elevation who were randomly assigned to be transported to specialized centers or an emergency department, there was no survival benefit, she summarized.
ARREST was "not simply a negative trial, but a new evidence-based starting point," according to the trial discussant Lia Crotti, MD, PhD, IRCCS Istituto Auxologico Italiano and University Milano Bicocca, Italy.
She drew attention to two findings: First, among the 862 patients who were enrolled, whom paramedics judged as being without an obvious noncardiac cause of the cardiac arrest, "only 60% ended up having a cardiac cause for their cardiac arrest and only around one quarter of the total had coronary artery disease."
The small number of patients who could have benefitted from early access to a catheterization laboratory probably contributed to the negative result obtained in this trial, with the loss of statistical power, she said.
Second, London is a dense urban area with high-quality acute care hospitals, so the standard of care in the nearest emergency department may be not so different from that in cardiac arrest centers, she noted. Furthermore, four of the seven cardiac arrest centers have an emergency department, and some of the standard care patients may have been transported there.
"If the clinical trial would be extended to the entire country, including rural areas, maybe the result would be different," she said.
The study authors acknowledge that the main limitation of this study was that "it was done across London with a dense population in a small geographic area," and "the London Ambulance Service has rapid response times and short transit times and delivers high quality prehospital care, which could limit generalizability."
Asked during the press conference here why the results were so different from the registry study findings, Redwood said, "We've seen time and time again that registry data think they are telling us the answer. They're actually not."
The session co-chairs, Rudolf de Boer, MD, PhD, from Erasmus University Medical Centre, Rotterdam, the Netherlands, and Faiez Zannad, MD, PhD, from University of Lorraine–Vandoeuvre-Les-Nancy, France, each congratulated the researchers on a well-done study.
de Boer wanted to know whether, for example, 100% of these resuscitated OHCA patients without ST-segment elevation had a cardiac cause, "Would results differ? Or is this just real life?" he asked. Patterson replied that the paramedics excluded obvious noncardiac causes and the findings were based on current facilities.
"Does this trial provide a definitive answer?" de Boer asked. Patterson replied that for the moment, subgroup analysis did not identify any subgroup that might benefit from expedited transport to a cardiac arrest center.
Zannad wanted to know how informed consent was obtained. Patterson noted that they have an excellent ethical committee that allowed them to undertake this research in vulnerable patients. Written informed consent was obtained from the patient once the initial emergency had passed if they had regained capacity.
Rationale and Trial Findings
"It's very well established that early bystander CPR [cardiopulmonary resuscitation], early defibrillation, and advanced in-hospital care improves survival," Redwood noted. "Despite this, only 1 in 10 survive to leave the hospital."
Therefore, "a cardiac arrest center has been proposed as a way of improving outcome." These centers have a catheterization laboratory, open 24 hours a day, 7 days a week, advanced critical care including advanced ventilation, temperature management of the patient, hemodynamic support, and neuroprognostication and rehab "because often these patients will have brain injury."
"There's quite overwhelming registry data to suggest that these cardiac arrest centers improve outcome," he said, "but these are limited by bias."
Between January 2018 and December 2022, London Ambulance paramedics randomly assigned 862 patients who were successfully resuscitated and without a confirmed MI to be transported the nearest hospital emergency department or the catheterization laboratory in a cardiac arrest center.
Data were available for 822 participants. They had a mean age of 63 years, and 68% were male.
The primary endpoint, 30-day mortality, occurred in 258 (63%) of 411 participants in the cardiac arrest center group and in 258 (63%) of 412 in the standard care group (unadjusted risk ratio for survival, 1.00; 95% CI, 0.90 - 1.11; P = 0.96).
Mortality at 3 months was similar in both groups: 64% in the standard care group and 65% in the cardiac arrest center group.
Neurologic outcomes at discharge and 3 months were similar in both groups.
Eight (2%) of 414 patients in the cardiac arrest center group and three (1%) of 413 in the standard care group had serious adverse events, none of which were deemed related to the trial intervention.
A cardiac cause of arrest was identified in roughly 60% of patients in each group, and of these, roughly 42% were coronary causes, 33% were arrhythmia, and 17% were cardiomyopathy.
The median time from cardiac arrest to hospital arrival was 84 minutes in the cardiac arrest center group and 77 minutes in the standard care group.
"Surprising and Important RCT Evidence"
In an accompanying editorial, Carolina Malta Hansen, MD, PhD, University of Copenhagen, Denmark, and colleagues write that "this study provides randomized trial evidence that in urban settings such as London, there is no survival advantage of a strategy of transporting patients who have been resuscitated to centres with specialty expertise in care of cardiac arrest.
"This result is surprising and important, since this complex and critically ill population would be expected to benefit from centres with more expertise."
However, "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 caution.
"Where does this leave the medical community, researchers, and society in general?" they ask rhetorically. "Prioritising a minimum standard of care at local hospitals caring for this population is at least as important as ensuring high-quality care or advanced treatment at tertiary centres.
"This trial also calls for more focus on the basics, including efforts to increase bystander cardiopulmonary resuscitation and early defibrillation, aspects of care that are currently being assessed in two ongoing clinical trials (NCT04660526 and NCT03835403) and are most strongly associated with improved survival, when coupled with high-quality prehospital care with trained staff and short response times," they conclude.
The study was fully funded by the British Heart Foundation. The authors report that they have no relevant financial disclosures. The financial disclosures of the editorialists are listed with the editorial.
European Society of Cardiology (ESC) 2023 Congress. Presented August 27, 2023.
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Cite this: Marlene Busko. Cardiac Arrest Centers No Benefit in OHCA Without STEMI - Medscape - Aug 27, 2023.