One of the hard men of his time.
One of the side effects of a hard racing career is an enlarged heart. It is not related to drug use, but rather to the heart muscle growing in size to adapt to the volume of blood required by the body in extended, hard competition. I don't know that Gerrie had one, or what caused his heart failure, but if an ex-pro does not keep the heart muscle in shape after he stops racing, heart problems can ensue. Sean Kelly has reported that he has, as he calls it, a sporting heart, and so he has to keep riding to keep it in shape.
They were able to detect amphetamines, steroids, and many other performance enhancing drugs back in the dark ages of the 70's and 80's.
We haven't even had a positive test here and people are jumping to conclusions. Please.