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Background- There have been few studies on the effectiveness of bystander automated external defibrillator (AED) use in out-of-hospital cardiac arrest. The objective of this study was to determine whether actual use of onsite or dispatched AED reduces the time to first shock compared with no AED use and thereby improves survival. Methods and Results- We performed a population-based cohort study of 2833 consecutive patients with a nontraumatic out-of-hospital cardiac arrest before emergency medical system arrival between 2006 and 2009. The primary outcome, neurologically intact survival to discharge, was compared by use of multivariable logistic regression analysis. An onsite AED had been applied in 128 of the 2833 cases, a dispatched AED in 478, and no AED in 2227. Onsite AED use reduced the time to first shock from 11 to 4.1 minute. Neurologically intact survival was 49.6% for patients treated with an onsite AED compared with 14.3% without an AED (unadjusted odds ratio, 5.63; 95% confidence interval, 3.91-8.10). The odds ratio remained statistically significant after adjustment for confounding (odds ratio, 2.72; 95% confidence interval, 1.77-4.18). Dispatched AED use reduced the time from call to first shock to 8.5 minutes. Neurologically intact survival was 17.2% for patients treated with a dispatched AED (unadjusted odds ratio, 1.07; 95% confidence interval, 0.82-1.39). Every year, onsite AEDs saved 3.6 lives per 1 million inhabitants; dispatched AEDs saved 1.2 lives. Conclusions- The use of an onsite AED leads to a doubling of neurologically intact survival. In our system, the survival benefit of dispatched AED use was much smaller than that of onsite AED use. [ABSTRACT FROM AUTHOR]

Background: Over the last decades, a gradual decrease in ventricular fibrillation (VF) as initial recorded rhythm during resuscitation for out-of-hospital cardiac arrest (OHCA) has been noted. We sought to establish the contribution of implantable cardioverter-defibrillator (ICD) therapy to this decline., Methods and Results: Using a prospective database of all OHCA resuscitation in the province North Holland in the Netherlands (Amsterdam Resuscitation Studies [ARREST]), we collected data on all patients in whom resuscitation for OHCA was attempted in 2005-2008. VF OHCA incidence (per 100 000 inhabitants per year) was compared with VF OHCA incidence data during 1995-1997, collected in a similar way. We also collected ICD interrogations of all ICD patients from North Holland and identified all appropriate ICD shocks in 2005-2008; we calculated the number of prevented VF OHCA episodes, considering that only part of the appropriate shocks would result in avoided resuscitation. VF OHCA incidence decreased from 21.1/100 000 in 1995-1997 to 17.4/100 000 in 2005-2008 (P<0.001). Non-VF OHCA increased from 12.2/100 000 to 19.4/100 000 (P<0.001). VF as presenting rhythm declined from 63% to 47%. In 2005-2008, 1972 ICD patients received 977 shocks. Of these shocks, 339 were caused by a life-threatening arrhythmia. We estimate that these 339 shocks have prevented 81 (minimum, 39; maximum, 152) cases of VF OHCA, corresponding with 33% (minimum, 16%; maximum, 63%) of the observed decline in VF OHCA incidence., Conclusions: The incidence of VF OHCA decreased over the last 10 years in North Holland. ICD therapy explained a decrease of 1.2/100 000 inhabitants per year, corresponding with 33% of the observed decline in VF OHCA.

Background: Current resuscitation guidelines (2005 guidelines [G2005]) accelerate ventricular fibrillation (VF) recurrence. We investigated whether patients resuscitated under G2005 spend more time in VF and have better survival rates than patients treated under the 2000 guidelines (G2000)., Methods and Results: We analyzed continuous ECG recordings of out-of-hospital cardiac arrests prospectively collected from January 2006 to January 2008. Patients treated according to G2000 (n=282) or G2005 (n=240) with VF as initial rhythm were included. We measured the total time a patient was in recurrent VF (the sum of all intervals from each onset of recurrent VF to each next successful shock) and the time a patient was in initial VF (time interval from rescuer arrival to first effective shock). The primary outcome measure was neurologically intact survival to discharge. The median time in recurrent VF was 2.7 minutes (quartile 1 to 3, 0.4 to 9.0 minutes) under G2000 versus 4.0 minutes (quartile 1 to 3, 0.2 to 11.6 minutes) under G2005 (P=0.03). Median time in initial VF was 2.7 minutes (quartile 1 to 3, 1.7 to 4.3 minutes) versus 3.9 minutes (quartile 1 to 3, 2.3 to 6.5 minutes), respectively (P<0.001). Increased time in recurrent VF was significantly associated with decreased neurologically intact survival in both G2000 use (odds ratio, 0.92; 95% confidence interval, 0.87 to 0.97; P=0.001) and G2005 use (odds ratio, 0.94; 95% confidence interval, 0.90 to 0.99; P=0.02). Neurologically intact survival decreased significantly with increasing time in initial VF under G2000 (odds ratio, 0.86; 95% confidence interval, 0.74 to 0.99; P=0.04). This observation was nonexistent in patients treated under G2005. Neurologically intact survival was 29% (82 of 282) under G2000 versus 27% (65 of 240) under G2005 (P=0.61)., Conclusions: With G2005, the time in recurrent VF remains associated with worse outcome. Studies of immediate defibrillation for recurrent VF are warranted.