9 out of 10 people who suffer cardiac arrest outside the hospital don’t survive. Most of the time, it’s because no one nearby performed CPR. Luckily, my mom was #10. She only survived because an anonymous stranger did CPR on her when she collapsed at work, and to this day she still doesn't know the identity of her savior.
You can watch a video of her story here: https://www.youtube.com/watch?v=0OhZ_6Ch5EI