Hi Miss K,
Unless something was physically done to him that induced a heart attack then I would say no.
In order for you to be liable you would have had to either assault him or had to perform some act of negligence. Provided you didn't punch him in the chest for example and that induced a heart attack, you are probably safe on the assault side of things. In order to establish negligence - you need to owe some duty of care to him, which I doubt that you would unless you were for example his carer etc . Then whether you are negligent would depend on whether you have failed to prevent exposure to a foreseeable risk of injury. So the heart attack must have also been foreseeable.
It's hard to say without knowing all the circumstances, but from what you are describing I don't think you would be liable under civil or criminal law for anything.
