Without AEDs, paramedics arrive in time to save lives just 9% of the time
The European Society of Cardiology has completed a study of AED deployment at 252 fitness centers in Italy across an 18-year period beginning at the turn of of the century.
Fitness Centers equipped with an AED had an average time-to-shock of 3.3 minutes, and their members / employees survived Sudden Cardiac Arrest 93% of the time
Fitness Centers without AEDs saw an average time-to-shock of 7.3 minutes (better than we'd expect from paramedics in the United States), and their members / employees survived Sudden Cardiac Arrest just 9% of the time
The study also notes that the probability of Sudden Cardiac Arrest (SCA) is three times higher in athletes than non-athletes, bucking the common belief that SCA is more likely to affect someone who is out of shape.
Details of the study can be found here: http://bit.ly/ESC_AED_Study