Most of the studies about this kind of thing get messed up because they are studying it with smoked marijuana. Let's assume that such a study uses vaporized or oral cannabis. I would be surprised to see reduced heart disease as a result of cannabis consumption but I would expect to see reduced cancer of some forms and lower rates of Alzheimer's.
Seems to indicate that THC stops inflammation of blood vessels by suppressing the immune system's response. Also seems that oral delivery was used vs. smoking.