Ambulance Routing Might Not Matter After Cardiac Arrest

AMSTERDAM -- Sending resuscitated cardiac arrest patients who weren't clearly having a heart attack to specialty centers rather than the nearest emergency department didn't help outcomes, a U.K. study showed.

For the primary endpoint, patients had an identical 30-day mortality rate of 63% whether sent to cardiac arrest specialty centers or the usual strategy of taking them to the closest facility (P=0.96).

Nor were there any differences in neurologic outcomes, reported Tiffany Patterson, PhD, of Guy's and St. Thomas' NHS Foundation Trust in London, at the European Society of Cardiology (ESC) congress. The findings also were published in The Lancet.

"Ambulances should take patients to the nearest emergency department," concluded co-author Simon Redwood, MD, also of Guy's and St. Thomas' NHS Foundation Trust, who added at an ESC press conference that this is "excluding patients that have clear signs of a heart attack as a cause of their cardiac arrest, because we know those patients should go to a heart attack center, straight to a cath lab and have the artery reopened."

For non-ST segment elevation patients, the findings run counter to registry data that had shown an absolute 30% survival advantage to making the first port of call these tertiary care centers that offer 24/7 catheterization laboratory availability, advanced critical care with advanced ventilation, temperature management of patients, and hemodynamic support, as well as neuroprognostication and rehabilitation.

However, the big question was generalizability.

"This was in a densely populated area in London where there are 32 accident and emergency departments," said Redwood. "The transfer times to hospital are relatively short. And London ambulance are a very advanced ambulance organization with very good paramedics, a team of advanced paramedics who will make quite advanced decisions and do a lot of things that perhaps wouldn't happen in other healthcare environments. So it's very difficult to generalize it to other places."

Median time from cardiac arrest to hospital arrival was 84 versus 77 minutes for the specialist center and closest center transport groups.

Even with those relatively ideal circumstances for the specialty center transfers, patients were better off going to their nearest emergency department, he said. "If it was in a rural situation, where perhaps the transfer times could be much longer to get to a cardiac arrest center. I would imagine that would just make the results even worse."

"I'm not sure it's even applicable to major cities in the U.S.," commented B. Hadley Wilson, MD, president of the American College of Cardiology and a past leader of its Global Heart Attack Treatment Initiative. For example, few ambulance services in the U.S. can offer 12-lead ECG readout in the field or transmitted ahead to the hospital to identify ST-segment elevation myocardial infarction, he noted.

"I think this shouldn't be seen simply as a negative trial but as a new evidence-based starting point," said ESC session study discussant Lia Crotti, MD, PhD, of the IRCCS Istituto Auxologico Italiano and University Milano-Bicocca in Milan.

The findings suggest resources might be best spent on the basics, Carolina Malta Hansen, MD, PhD, of Copenhagen University in Denmark, and colleagues wrote in an accompanying editorial.

"Whether regions with fewer resources would benefit most from assuring a minimum standard of care at local hospitals (similar to those in London) or from routinely performing longer transportation to specialized centers (or a combination of those approaches) remains uncertain," they wrote. "Prioritizing 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 centers."

Patterson acknowledged that there's room to better identify cardiac arrest patients in the prehospital setting for whom specialty care might make a difference in outcomes.

About half of the specialty center transport-first group had angiography, compared with some 30% of the standard-of-care group, albeit with a difference in time to angiography, Patterson noted. About half had nonshockable rhythm, and there were low rates of coronary disease.

The ARREST trial included 862 patients 18 and older who had return of spontaneous circulation following out-of-hospital cardiac arrest without ST elevation in London from January 15, 2018, through December 1, 2022. They were randomized at the scene of their cardiac arrest to either standard delivery to the geographically closest emergency department or to the cardiac catheter laboratory at one of seven cardiac arrest centers out of the 32 hospitals in the city. Consent was obtained once the patient regained capacity or from their family or other surrogate decision-maker.

A cardiac cause of arrest was identified in 63% of the group transported to the cardiac arrest specialty center and 59% of the standard-care group. Of those with a cardiac cause of arrest, coronary disease was identified as the cause in around 40% and an acute coronary cause in around 20%. Primary arrhythmia accounted for one-third; primary cardiomyopathy for just under 20%.

Neurological outcomes were similar at hospital discharge (OR 1.00 for modified Rankin Scale score and OR 0.98 for cerebral performance category score) and at 3 months (OR 0.98 for both). Among those alive at 3 months, patients transported to the specialist center had worse neurological outcomes at discharge than the standard-care group (OR 1.55, 95% CI 1.00-2.41).

The only subgroup that favored cardiac arrest specialty center transport was patients under age 57. "Although chance is a likely explanation for these findings, an explanation for the survival benefit in participants younger than 57 years could be due to the pathogenesis of arrest in this younger age group, with greater potential for reversibility and increased physiological reserve," the researchers noted.