About two weeks back I had smoked marijuana and felt really lightheaded, clammy, cold, racing pulse . and since then Ive experienced really faint lightheadedness from time to time. Well, Tuesday evening right after dinner, my heart began racing at an extremely fast speed. I went to the ER and they performed blood tests, an ekg , and gave me saline . They told me that the bloodwork came back fine, and the heartwork did as well. They said it was palpatations (irregular heartbeat). They said to follow up with my doctor and to get a holter monitor just to be safe. Can you tell me if this is life threatening or is this tachycardia and will it ever go away?