My dad dropped dead from an arrhythmia whilst at work. People nearby performed CPR on him immediately, the ambulance was there within 7 minutes and he was rushed to the Alfred hospital in Melbourne.
He was literally dead for 20 minutes, but they managed to revive him and a few weeks later, with a newly installed pacemaker, better than new.
He had a very, very, very high probability of dying, or requiring specialised care due to brain damage from brain hypoxia. Those that knew CPR, and did it properly for those excruciating 7 minutes gave him his life back.
The moral of the story is, if something feels awry, go and see a doctor (he wasn't taking it seriously), and learn CPR, you might just save someone's life.
Oh, and our hospitals and doctors/nurses are top notch. He was in intensive care for a few days and the final bill was a few hundred dollars. Hooray for universal healthcare!