Dr. Lester Grinspoon of Harvard has said that smoking
marijuana can cause your heart to race- just as if you had jogged up one flight of stairs. Not quite racing but it can panic people. The risk is 40x less then moving your bowels as far as your heart is concerned.
Infact cannabinoids directly protect against damage from ischemia
, or drowning ect) They also block TNF and ROS which is released when plaque is in your arteries (this reverses artery hardening).
Tobacco however is bad- 3 grams of it will actually stop your heart and if you mix tobacco smoke with marijuana smoke, it is worse then just tobacco. Even though smoking marijuana will NOT give you COPD, empysema- or lung cancer
. You did not mention tobacco- but if you use it stop. Also have you lost a substantial amount of muscle density in your chest? This can cause certain positions (typically when laying down) to start causing intense chest pains.