Key takeaways:

• Community first responder activation did not improve 30-day survival after cardiac arrest vs. standard emergency medical services (EMS) response.
• Community responders did not have much time before EMS arrived.

MUNICH — Community first responder activation did not improve 30-day survival in patients with out-of-hospital cardiac arrest, according to the HeartRunner trial presented at the European Society of Cardiology Congress.

“To try to improve survival, community first responder programs are now being implemented worldwide at a rapid pace, meaning that the dispatch center can actually alert community responders, normal citizens close to the cardiac arrest victim, to go start CPR and hopefully bring an [automated external defibrillator] and perform early defibrillation to improve survival, because CPR and defibrillation are the most important points for improving cardiac arrest survival,” Fredrik Folke, MD, PhD, senior consultant in the department of cardiology at Copenhagen University Hospital Gentofte in Denmark, said at a press conference. “However, despite these efforts, there are almost no randomized clinical trials within these topics. It’s mostly observational studies with a big risk of bias. So therefore we conducted the HeartRunner trial, a randomized superiority trial with a pragmatic approach ... to examine whether smartphone activation of nearby community first responders improved 30-day survival after cardiac arrest.”

Community first responder activation did not improve 30-day survival after cardiac arrest vs. standard emergency medical services (EMS) response. Image: Adobe Stock

The 2,060 patients with out-of-hospital cardiac arrest during the study period were randomly assigned to standard emergency medical services (EMS) response plus community first responder activation or standard EMS response alone, and randomization was done in two strata, cases in which there was a community responder within less than 3 minutes of the cardiac arrest (stratum 1) and cases in which there was a community responder within 3 to 9 minutes of the cardiac arrest (stratum 2).

“That was based on an expectation that we would see the biggest impact on outcomes if a community first responder was very close to the cardiac arrest site,” Folke said at the press conference.

The rates of bystander CPR were higher in the community first responder group compared with the control group in stratum 1 (85% vs. 78%; risk difference, 7.8 percentage points; 95% CI, 2.4-12.5; P = .004) and in stratum 2 (86% vs. 75%; risk difference, 11.6 percentage points; 95% CI, 7-16.2; P < .0001), and the same was true for rates of bystander defibrillation (stratum 1, 19% vs. 11%; risk difference, 7.6 percentage points; 95% CI, 3-12.3; P = .0014; stratum 2, 14% vs. 6%; risk difference, 8.6 percentage points; 95% CI, 5.1-12.1; P < .0001), Folke said.

However, he said, there was no difference between the groups in the primary outcome of 30-day survival in stratum 1 (community first responder group, 15%; control group, 17%; risk difference, 2.1 percentage points; 95% CI, 6.9 to 2.6; P = .42) or in stratum 2 (community first responder group, 13%; control group, 14%; risk difference, 1.7 percentage points; 95% CI, 5.6 to 2.3; P = .43).

“Why couldn’t we see a survival benefit?” Folke said. “I think there are three main things we need to consider in our trial. First of all, we had a high baseline bystander CPR rate of 75%, meaning there was little room for further absolute gains. Secondly, we saw that around 30% of our population had a shockable heart rhythm, and that’s the population that has the most benefit of a bystander bringing in an AED. Last but not least, time is a sensitive thing here. In our community response system, the EMS response time was fast. So from activating our community first responders to the ambulance was on-site was only 5 minutes. And within these 5 minutes, the community first responder needed to react to the app, they needed to find, locate and retrieve the AED, bring the AED into the private home, perform CPR [and] defibrillation. And even though the bystander defibrillation rate was double in the community first responder group, the ambulance arrived at almost the exact same time. So we were challenged positively by a fast ambulance response time.”