Community First Responders Fail to Improve Cardiac Arrest Survival Rates

Community first responder systems mobilized via smartphone apps do not improve 30-day survival rates for out-of-hospital cardiac arrest patients when professional emergency medical services arrive quickly, according to clinical trial findings presented on August 31, 2026, at the ESC Congress in Munich, Germany. Despite failing to alter overall survival, the randomized study showed that dispatching nearby volunteers significantly increased bystander cardiopulmonary resuscitation and doubled the rate of bystander defibrillation before ambulances arrived.

Out-of-hospital cardiac arrest remains an acute medical emergency where patient survival relies heavily on prompt recognition, immediate CPR, and rapid defibrillation. To bridge the gap before professional help arrives, many countries deploy smartphone-based networks to alert nearby volunteer responders. To test the clinical efficacy and safety of this approach, researchers launched the HeartRunner trial in the Capital Region of Denmark, examining whether volunteer intervention genuinely saves lives.

Design and Findings of the HeartRunner Trial

During the trial, emergency calls regarding suspected cardiac arrests were randomized in a one-to-one ratio between standard emergency response alone or standard response paired with the activation of community first responders. Investigators analyzed a total of 2,060 suspected cardiac arrest cases, dividing them into strata based on how quickly volunteers were estimated to reach the patient. The first stratum covered estimated arrival times under three minutes, while the second covered arrival times between three and nine minutes.

According to the principal investigator of the trial, Professor Fredrik Folke from Copenhagen University Hospital in Denmark, the primary endpoint of 30-day survival showed no significant difference between the two study groups. When estimated responder arrival times were under three minutes, 30-day survival reached 15% for patients with community responder activation compared with 17% for those receiving standard response alone, yielding a p-value of 0.42. For estimated arrival times between three and nine minutes, 30-day survival stood at 13% with responder activation versus 14% without it, yielding a p-value of 0.43.

Although community first responders are becoming more widespread, we only have observational studies to support their use. 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.

Professor Fredrik Folke

Impact on Bystander Interventions and Response Times

While the trial did not find an increase in 30-day survival, the data demonstrated a clear behavioral shift in immediate care. Activating volunteer networks significantly boosted the proportion of patients receiving bystander CPR and doubled the frequency of public defibrillation efforts. In the three-to-nine-minute arrival window, bystander CPR climbed from 75% to 86% with a p-value below 0.0001, while bystander defibrillation rose from 6% to 14% with a p-value below 0.0001. Secondary metrics, including the return of spontaneous circulation and survival accompanied by favorable neurological outcomes, remained comparable across both cohorts.

Professor Folke noted that the neutral survival findings were likely influenced by the operational environment of the study. Ambulances in the area where the trial was conducted maintain notably rapid response times, around seven minutes. Consequently, when professional medical crews arrive that quickly, the added value provided by volunteer-initiated interventions becomes statistically limited. Researchers suggest that these smartphone dispatch systems warrant evaluation in geographic regions with slower ambulance response times, such as rural areas.