Survivors of out-of-hospital cardiac arrest (OHCA) without ST-segment elevation who were transported to the nearest hospital emergency department had outcomes similar to those of patients 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.
senior author Simon R. Redwood, MD, principal investigator of ARREST, from Guy’s and St. Thomas’ NHS Trust Hospitals and King’s College, London, 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 Dr. Redwood, presented the trial findings at the annual congress of the European Society of Cardiology in Amsterdam, on Aug. 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 benefited 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, Dr. 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 cochairs, Rudolf de Boer, MD, PhD, of Erasmus University Medical Centre, Rotterdam, the Netherlands, and Faiez Zannad, MD, PhD, from University of Lorraine–Vandoeuvre-lès-Nancy, France, each congratulated the researchers on a well-done study.
Dr. 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. Dr. Patterson replied that the paramedics excluded obvious noncardiac causes and the findings were based on current facilities.
“Does this trial provide a definitive answer?” Dr. de Boer asked. Dr. Patterson replied that for the moment, subgroup analysis did not identify any subgroup that might benefit from expedited transport to a cardiac arrest center.
Dr. Zannad wanted to know how informed consent was obtained. Dr. 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.