Is there a cause-effect relation between cannabis and tachycardia?

Marijuana is sort of famous for increasing heart rate. Some websites talk about it effecting an increase of 40 bpm, while others mention an increase of 50% over resting heart rate.

Personally, my heart rate goes from a resting rate of 70 bpm, to about 120 bpm (as if I’m jogging). But I have measured it to go as fast as 156 bpm, which is about 80% the maximum heart rate for my age group. This >120 bpm heart rate can persist for an hour, sometimes two.

Of course, if I were running a marathon, this would be considered normal. But all of this is when I am at rest and not exerting myself at all. Is such an elevated heart rate for such a long time dangerous to the body? Would this become risky as I age and the heart and blood vessels deteriorate, and maximum heart rate lowers to 130? 

Originally posted in SR 2.0 16/10/2013. Reviewed 20/2/22

Cannabis increases heart rate by a different mechanism than stimulants. The main effect is relaxation of veins and arteries. This effect lowers blood pressure. To compensate this and mantaining blood flow heart beats more quickly. Im general, cardiovascular toxicity related with cannabinoids is limited, compared to stimulants.

There are some cases reports of cardiovascular damage induced by cannabis, but are anecdotal and uncommon. But the main risk is fainting using cannabis too strong or too quickly. So if you feel dizzy, lie down to avoid hurting if you fall as a result of loss of consciousness.

The increase in frecuency you report is important and long-lasting. Possibly it does not mean a health problem.Or maybe you are particularly sensible to that effect. It is possible that it is just related to cannabis potency (you should try another variety or use less quantity).

But, also, it is theoretically possible that cannabis use could trigger an asymptomatic arrhythmia or pathological tachycardia.So, it should be interesting to have an electrocardiography test to rule out this possibility.