Key takeaways

• The HeartRunner trial assessed whether community first responder activation improved survival after an out-of-hospital cardiac arrest.

• 30-day survival was not significantly improved with community first responders vs. standard practice, but bystander CPR and defibrillation increased and there were no safety concerns.

• Further studies on the impact of first responders in regions with slower ambulance times are warranted.

Munich, Germany – 31 August 2026: Community first responders did not improve 30-day survival in patients with out-of-hospital cardiac arrest, according to results presented in a Hot Line session today at ESC Congress 2026.¹

Out-of-hospital cardiac arrest is a time-critical emergency in which survival depends on early recognition, early cardiopulmonary resuscitation (CPR) and early defibrillation. Many countries have developed smartphone-based systems whereby volunteer first responders are mobilised to perform CPR and defibrillation before the arrival of the emergency medical services.

“Although community first responders are becoming more widespread, we only have observational studies to support their use,” said Principal Investigator of the HeartRunner trial, Professor Fredrik Folke from Copenhagen University Hospital, Denmark. “We conducted a randomised study to firstly evaluate the impact of community responders on patient outcomes and secondly, to answer the question about whether using non-trained volunteers is safe.”

In the HeartRunner trial, emergency calls for suspected out-of-hospital cardiac arrest in the Capital Region of Denmark were randomised (1:1) to community first responder activation plus standard response or standard response alone. In total, 2,060 suspected cardiac arrests were analysed in two strata based on the estimated time from community first responder activation to arrival at the patient’s side: less than three minutes (0−358 metres away) and three to nine minutes (360−1,080 metres away).

The researchers found that the primary endpoint of 30-day survival was the same whether first responders were present or not. When estimated responder arrival time was less than three minutes, 30-day survival was 15% in patients with community first responder activation vs. 17% with no community responder activation (p=0.42). When estimated responder arrival time was three to nine minutes, 30-day survival was 13% in patients with community first responder activation vs. 14% with no community first responder (p=0.43).

However, community first responder activation did significantly increase the rate of bystander CPR and doubled the rate of bystander defibrillation. For example, when responder arrival time was three to nine minutes, the bystander CPR increased from 75% to 86% (p<0.0001) and bystander defibrillation from 6% to 14% (p<0.0001). Return of spontaneous circulation and survival with a favourable neurological outcome were similar between the two groups.

Explaining why he thought the primary results were neutral, Professor Folke said: “The trial was conducted in an area where ambulance response times were very short, around seven minutes.” He continued, “Importantly, the trial showed that community first responder systems may significantly improve bystander CPR and defibrillation, but their effect on survival is highly dependent on the time available for responders to intervene before arrival of the ambulance. When this interval is short, the incremental benefit of responder-initiated defibrillation may be limited. It would be interesting to assess their impact in regions with slower ambulance responses, including more rural areas.”

ENDS