Well, Raiden, the real chances that you would have a sudden-death heart attack or such overwhelming tachycardia (racing heartbeat) that you might die are still quite low. Sounds like your friend might have had something else working against him besides weed, like perhaps anxiety, too, and possibly also other substances in his system? People's hearts can lose their ability to pace themselves, but in young folks--and I'm assuming you and your friend are both somewhere in the 16 - 20 range--that doesn't happen terribly often. That's why I wondered if he might also have panicked, too, or perhaps had other meds in his system. Panic attacks are common occurrences after smoking.

You'll have to decide whether, for you, the benefits of smoking weed outweigh the risks. If you're really worried about it, don't smoke. And if you're worried enough that you want to check out your potential cardiac risk, go to your doctor and get referred to a cardiologist so you can have an echocardiogram, which'll tell you once and for all whether you have anything at all heart-related to worry about. Better safe than sorry!