Can you use a defibrillator to treat a heart attack?

If not that, then what do you do to treat a heart attack?

[bijendrabhandari]

Technically, a defibrillator is used to stop a heart from an ongoing fibrillation i.e a heart beating at a very high rate.
More importantly, as we see in the movies 'zapping the heart' is also used to start a heart that has stopped, may it be any reason.  
A heart attack can stop the heart, if it is severe enough. Then defibrillators are used as the final resuscitation procedure.  

[bijendrabhandari]

There is a mnemonic i use for the treatment of heart attacks.
MONA

Morphine
Oxygen 100%
Nitroglycerine
Aspirin

This is the immediate treatment of a heart attack.

There are many variations in heart attack, thus other drugs a also used.
After the first heart attack a patient mostly stays on certain drugs for a long time.