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ESC Congress 2004: Mobile Automated External Defibrillators (AEDs) would be necessary for a successful Public Access Defibrillation (PAD) scheme

August 31, 2004

Despite improved survival from heart disease over the last 25 to 30 years, the incidence of Sudden Cardiac Death outside hospital has remained unchanged.

The majority of sudden cardiac arrests occurring outside hospital are due to Ventricular Fibrillation (VF); an abnormal heart rhythm which requires an electric shock across the chest called defibrillation. The greatest determinant of survival from cardiac arrest outside hospital is the time to defibrillation. PAD schemes can shorten time to defibrillation if an appropriate strategy is employed. In accordance with the recent European recommendations for the use of AEDs, we examined where cardiac arrests outside hospital occur and the Call-To-Response (CTR) times for the Emergency Medical Services (EMS) in Belfast City to determine how a PAD scheme could best be implemented.

Data were collected prospectively between August 2003 to November 2003 inclusive for all cardiac arrests outside hospital in Belfast from 4 sources; Doctor-led ambulances, Paramedic-led Ambulances, Death Certificates and Autopsy reports. CTR was defined as time from call to EMS dispatcher to arrival of EMS vehicle at site of the collapsed victim. We also examined survival to admission and discharge.

There were 116 sudden cardiac arrests outside hospital in the 4 month period, 40% female, 60% male. Average age was 73 years and age range 27-99 years. 68% of the arrests occurred at home, around 15% in nursing homes, 15% in public places and 1% on public transport. Sixty one percent of the arrests were attended to by the EMS; 62% by doctor-led ambulance, 93% by paramedic led ambulance. The presenting heart rhythm was VF in 35% of cases. Average CTR was 7.5 min and CTR ranged from 1 to 36 min. In those attended by the EMS, 17% were admitted to hospital alive and 11% discharged from hospital alive. All of the patients who were discharged alive had VF as their initial rhythm. The average call to response interval of the EMS was significantly shorter for those patients who were discharged alive compared to those who died. Fifty four percent of the arrests were witnessed by a bystander. Sixty percent of these witnessed arrests had VF as initial rhythm and 21% of the witnessed arrests were discharged alive.

Conclusions: Almost 70% of cardiac arrests outside hospital occurred at home, therefore for a PAD scheme to be effective it would require mobile defibrillators with nearby trained lay volunteers sent to arrests by the ambulance dispatch room.

Those who survived cardiac arrests outside hospital had a significantly shorter EMS response time. A PAD scheme using mobile defibrillators could decrease the time taken to reach victims of cardiac arrest outside hospital.

The proportion of cardiac arrests with VF as initial rhythm was low (35%) and other investigators have shown that VF prevalence is falling, however 60% of the witnessed arrests had VF as initial rhythm suggesting that the low proportion of VF may be due to prolonged call to response interval.

M Moore (Belfast, GB)



European Society of Cardiology (ESC)