Survival After Ventricular Fibrillation in Sao Paulo Metro

Background: Automated external defibrillators (AEDs) in public places can improve the rate of survival among patients who have had an out-of-hospital cardiac arrest (OHCA). Sao Paulo Metro carries about 4.5 million people per day and since 2006, the security officials of metro (lays rescuers) are trained in cardiopulmonary resuscitation (CPR) and handling of AED. This program also included the installation of AEDs in every metro station. Methods: From September 1, 2006, through November 31, 2012, we conducted a prospective, longitudinal, observational study involving patients who had cardiac arrest in Sao Paulo Metro and were attempted by security officials of metro. The outcome of each patient was followed through medical records of the hospitals to which patients were referred. Reading the AED registration of each patient was performed. The primary end-point was minimal neurologic impairment after hospital discharge. Results: A total of 102 sudden collapses were included in the study; 86 were cardiac arrest and 62 of these patients had ventricular fibrillation with initial cardiac rhythm. The percentage of patients who achieved sustained return of spontaneous circulation was 45 (73%), 34 (55%) of patients arrived alive at the hospital and 23 (37%) were discharged and were alive at 1 year with minimal neurologic impairment. Comparing the periods of the Sep/2006-Nov/2009 with Oct/2009-Nov/2012, respectively, the rate of patients without neurological impairment before discharge and at 1 year was 22% versus 45% (p=0.072). Multivariate logistic regression analysis revealed that the time interval in minutes between collapse and first shock was the only variable independently associated with the primary end point (odds ratio = 0.13, 95 % CI 0.05 to 0.38, p <0.0001). Conclusion: The study supports a significant beneficial impact of implementation of PAD program in Sao Paulo Metro. Shorter intervals between arrest and defibrillation are necessary to achieve the highest survival rates. These results support strategic expansion of PAD programs in similar places in Brazil.