"The consulting HelloMD doctor told my wife to be careful if she has high blood pressure when using cannabis, because it could cause a heart attack. Now she’s freaked out. Please provide some background on what circumstances would cause a heart attack."
Heart attacks are generally caused by cardiovascular disease that has caused plaquing in the arteries and when a piece of plaque breaks away it can lodge in one of the arteries feeding the heart with oxygen and nutrients. When the plaque blocks the artery the heart muscle no longer receives the necessary oxygen and that part of the heart muscle dies often causing severe pain and a very dangerous irregular heartbeat that can cause the heart to stop beating and we call this a heart attack.
There was one study along time ago that said people were more likely to have a heart attack within 24 hours of using cannabis but very few other variables were even looked that in that study. In other words we also know that the most prevalent time for heart attacks to occur is Monday morning when people are returning to work after a weekend.
These kind of studies only point out that we need more studies with better control over variables such as cigarette smoking, stress, anger and anxiety, lack of sleep and vitamin D deficiency. Having high blood pressure alone increases the risk of heart attack with or without cannabis. She may want to look into using CBD with a low THC.