FYI: Defibrillators don’t start the heart, they stop it.

The heart doesn’t stop in many heart attacks. Instead it just beats erratically and in a way that doesn’t pump blood well. Shocking the heart to stop it (what a defib does) causes the nerve cells to “reboot” and start beating regularly again.

Shocking a victim who’s heart has stopped is useless and automatic defibrillators won’t go off until they’ve detected the arrhythmia.