CHICAGO — Sudden cardiac arrest statistics are chilling. In the United States, 350,000 people’s heartbeats, breathing, pulse, and blood circulation will all halt outside hospitals this year, seemingly out of the blue. These are not heart attacks. Only 1 in 10 people will survive them.
CPR and defibrillation can save their lives (and brains), but that depends on bystanders and emergency response systems being both nearby and prepared to step in — immediately. Survival chances drop by 10% for every minute that goes by without CPR.
Hints from observational studies suggested better, more comprehensive community training can help, which means educating 911 dispatchers, first responders, and potential bystanders. But results from a randomized controlled trial presented Sunday at the American Heart Association’s scientific sessions and published in the New England Journal of Medicine on Sunday show that approach has not worked, or at least not yet. But examples in Denmark may point the way forward.
“We performed an efficient, large, and high-quality trial engaging large segments of the community in emergency response, and in spite of this, survival remained low and unchanged,” Carolina Malta Hansen, the study’s lead author, said at a media briefing. “A multifaceted community and EMS implementation strategy did not improve survival with a favorable neurologic outcome for patients with out-of-hospital cardiac arrest. However, in the final year, there appeared to be an improvement in bystanders.”
Starting in 2021, researchers randomly assigned participants in 60 counties in North Carolina to receive intensive education on cardiac arrest intervention or to continue with standard practice. The intervention entailed training 911 dispatchers to improve their rapid recognition of cardiac arrest and better guide bystanders through CPR. First responders were educated on the use of automated external defibrillators before emergency services arrived. Community members in workplaces, religious groups, government offices, and other settings received training in CPR.
About 8.5 million people live in these counties. During the study’s five years, 22,459 adult residents experienced cardiac arrest outside the hospital. Their median age was 64; 37% were women, 33% were Black; and 29% lived in rural areas.
The numbers were split this way: 11,615 people experienced out-of-hospital cardiac arrest in counties that received intensive education, and 10,844 people had out-of-hospital cardiac arrest in communities that did not receive the intervention.
Amrish Deshmukh, a cardiac electrophysiologist who treats patients with heart rhythm disorders at the University of Michigan Health Frankel Cardiovascular Center, called the study results disappointing, but not surprising.
“Many interventions that have been studied in out-of-hospital cardiac arrest and in post-arrest care unfortunately have not been shown to improve survival or neurologic outcomes,” he told STAT in an email. He was not involved in the new trial. “Prior studies have shown that mobile phone alerts, volunteer training, and increased automated external defibrillator (AEDs) availability can increase the performance of CPR and use of AEDs, but not all have shown improvements in survival.”
And yet, study author Malta Hansen, a cardiologist and clinical research associate professor at Herlev and Gentofte Hospital and Copenhagen EMS in Denmark, is hopeful. In the trial’s fourth year, an exploratory analysis showed the percentage of patients who underwent CPR performed by a bystander increased, suggesting that this component of the intervention was effective. More time may be needed to see which elements mattered and whether they affect survival.
“In light of the apparent improvement in CPR for the last year, further evaluation in the longer, more intense intervention is important,” she said.
Malta Hansen cites the case of Denmark, where rates of bystander CPR and survival are much higher than in the United States. The North Carolina study trained almost 5% of the population, at which point researchers started seeing a difference in delivery of CPR between the group that received training and the group that did not.
“Obviously, that’s not enough. We have observational evidence from other countries like Denmark, where 80% of the population is trained and 75% of patients receive high-speed care,” she said.
In Denmark, the defibrillation rate is 11%, compared to 2% in the U.S. In Denmark, survival is about 16%, compared to 10% in the U.S.
That CPR-trained rate in Denmark climbed from 20% in the early 2000s to 80% now, Malta Hansen said. “It’s not something that’s done in two or three years.”
Here’s what helps: To get your driver’s license in Denmark, you have to show that you have certification in CPR. “It’s just an incredibly efficient way to reach everybody,” she said.
Brahmajee Nallamothu, an interventional cardiologist and editor in chief of the AHA journal Circulation: Cardiovascular Quality and Outcomes, had another theory on timing. Starting the trial right as Covid-19 was emerging could have affected educational efforts and could explain why effects of the training were delayed. He also asked if the educational intervention was the right approach.
“I don’t think anyone would argue with the importance of early treatment in out-of-hospital cardiac arrest. When we think about bystander CPR, early defibrillation with AEDs, the challenge is: How do you translate that?” Nallamathu, who was not involved in the trial, said. “I think we still struggle with what’s the best way to train individuals so that they have sustained ability to understand and then utilize that tool when that situation arises, that’s an area that’s still complicated and still unknown.”
What’s next?
Malta Hansen’s team will follow this population in North Carolina for at least another year.
“We have established a fantastic infrastructure and network and collaboration, and everybody’s very excited to keep working on this,” she said. “What we need are communities who are very engaged and very eager to keep working on this. So we believe that future efforts to guide us will be successful.”
That won’t be easy, Michigan’s Deshmukh said.
“Implementation science is challenging (as evidenced by this and other negative trials), but is what I suspect will move the needle the most,” he wrote.
STAT’s coverage of chronic health issues is supported by a grant from Bloomberg Philanthropies. Our financial supporters are not involved in any decisions about our journalism.
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