A lot depends on heredity and bad genes that pass from generation to generation. Still, cannabis could act like a catalyst to speed up the heart disease process...

I have a young relative, in his 20's, that recently had a heart attack and multiple bypass surgery. He used to smoke pot on a regular basis, so did his dad. His dad died young and was in his 50's. Major organ failure, kidney failure, and diabetes, killed the father and the doctors believed it was the heavy use of recreation cannabis that aided in the onset of his illness and death...