Father in law blacks out?

My father-in law blacks out uncontrollably and refuses to go to the hospital. He has always been a heavy drinker and smoker. He's blacked out while driving even. He is in his mid-50s.
What do you think is wrong with him medically?Father in law blacks out?
The answers above are excellent. it could be anything.
Can be from the alcohol, lack of Potassium is the one thing tha really can make the heart slow and then you pass out. Because of his health habits his minerals and vitamins are being depleted.
Heart Problems etc and the list goes on...
He should be reported as he may kill someone, his drivers license should be taken away unless he sees a doctor.
There's no way to tell from what we know about him.
He could have
low blood sugar
high blood pressure
pancreatic cancer
COPD with low O2
TIA/ mini stroke
or one of a million heart problems that cause "syncope"- AKA blacking out.
If he's driving he owes it to the world to get checked out- let alone his family and himself.
It could be a number of things. He is probably scared since he knows there is something wrong. With his heavy drinking and his smoking, he is suspecting the worse.
Keep working on him. He may have something really bad, but may also have something very treatable.
I know someone that had a problem like this and it was heart condition, and the prescription medicine that he was taking for it was causing a serious problem , so he had to go on a different medicine. If he blacks out while he is driving he might kill someone. He could possible have epilepsy. and if that's the case, he shouldn't be driving at all. Maybe that's' why he doesn't want to go to the DR, he is afraid he will told he cant drive anymore.