Do you know CPR? If you do you’ll want to read this!

Of the people who received only chest compressions and had at least an erratic heartbeat by the time emergency medical staff arrived 19% survived without any brain damage, whereas 11% of those who received CPR had this favorable outcome. Only 8% of those with a heartbeat who received no assistance from bystanders survived without brain damage.
Source: NewScientist

It’s definitely something to keep in mind in case you need to perform it on someone who’s had a heart attack.