Smart Alerts Speed Volunteer Cardiac Arrest Response
A randomized trial in Freiburg, Germany found an algorithm that selects volunteer responders by travel time got help to suspected cardiac arrests before ambulances arrived.
Updated on Nov. 8, 2026 in Heart Disease
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A smart alerting algorithm that selects volunteer responders by estimated travel time raised pre-ambulance arrival to 58% in a randomized trial. The trial, conducted in Freiburg, Germany, compared the approach against two fixed-distance strategies.
Why it matters
Earlier arrival of trained volunteers and automated external defibrillators can shorten the time to first compression and first shock during suspected cardiac arrest. The results suggest that routing volunteers by real travel time, rather than straight-line distance alone, may improve early response in communities with volunteer networks.
In a randomized trial of 1,482 volunteers across 823 suspected cardiac arrests, pre-ambulance volunteer arrival reached 58% with smart alerts versus 31% under a 600 m fixed-distance strategy, a 27 percentage point gain. The study did not report patient survival outcomes, and its generalizability beyond Freiburg, Germany remains untested.
The players
American Heart Association
The American Heart Association is a nonprofit organization focused on cardiovascular health research, education and advocacy, and it hosts the Resuscitation Science Symposium where the results were presented.
The details
The system sends a pre-alert to volunteers, asks how they are traveling, and calculates their route, excluding anyone who would arrive after the ambulance. Under this approach, 31% of responders were rejected for arriving too late, and volunteers reached an average of 1.9 patients versus 0.8 under the 600 m strategy.
Timeline
January 2024 to July 2024: Prospective randomized trial conducted in Freiburg, Germany.
November 8, 2026: Results presented at the AHA Resuscitation Science Symposium in Chicago.
Heart Disease Landscape
The study extends community first-responder research, which has long tested whether trained laypeople and AEDs can reach cardiac arrest patients before EMS. It adds evidence that routing volunteers by real travel time, rather than fixed radius, may close the gap in early defibrillation.
Residents in communities with volunteer first-responder networks may see dispatch apps that route alerts by travel time rather than distance. For someone witnessing a collapse, the practical takeaway is that a nearby volunteer who can actually arrive first is the one who matters most.
The takeaway
Speed of arrival, not just proximity, can determine whether a bystander reaches a cardiac arrest victim first. Knowing your local volunteer or AED network and how to activate it can make a real difference in the minutes that follow a collapse.
Further reading
Explore more on Heart Disease and how emergency response programs are being studied.
Source note: This article includes information reported by Healio.
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