Daily marijuana use increases risk of heart disease, study finds


According to a new study, daily marijuana use can increase a person’s risk of coronary heart disease by a third compared to those who never use it.

“A growing body of evidence suggests that cannabis is not entirely safe and may in fact cause cardiovascular disease,” said the study’s lead author, Dr Ishan Paranjpe, resident physician at the University of Stanford. The study – which has not yet been published – will be presented at the annual meeting of the American College of Cardiology on Sunday.

“Thus, the decision to use cannabis must be carefully weighed against the potential for serious heart disease,” Paranjpe said.

Coronary heart disease is caused by the buildup of plaque in the walls of the arteries that supply blood to the heart. Also called atherosclerosis, coronary artery disease is the most common type of heart disease, according to the US Centers for Disease Control and Prevention.

Signs of the disease include having angina pectoris or chest pain, feeling weak, dizziness or stomach pain, or shortness of breath. However, for “some people, the first sign of coronary artery disease is a heart attack”, the CDC says on its website.

The study extracted data from people participating in the All of Us research program. Administered by the National Institutes of Health, the program is designed to collect health information over time from 1 million or more persons in the United States.

Marijuana increases heart rate and blood pressure immediately after use, according to the CDC.

When enrolling in the study, participants completed a survey about their cannabis use. The research team used this information to classify those who responded into five categories: daily users (4,736 people), weekly users (2,720), monthly users (2,075), those who used one or twice in three months (8,749) and those who never used used (39,678 people). The researchers then compared these categories with the participants’ medical records a few years later.

They found that daily cannabis users were 34% more likely to be diagnosed with coronary heart disease than those who had never used drugs.

People who only used weed once a month or less had no significant risk, according to the study.

The results held true even after the researchers took into account other potential causes of coronary heart disease, such as age, gender and major cardiovascular risk factors – high blood pressure, high cholesterol, diabetes mellitus. type 2, obesity, smoking and alcohol consumption.

The study used Mendelian randomization (MR) to determine risk, which other studies on the subject have not done, Paranjpe said in an email. The RM method measures genetic variations known to be linked to a modifiable risk factor to determine the causal influence of the risk factor.

“While other work has also linked cannabis to coronary artery disease, there are several potential confounders that may explain this relationship. Our MR analysis suggests that this relationship may be directly causal,” Paranjpe said.

Why does marijuana seem to damage the heart and blood vessels? First, it increases heart rate and blood pressure immediately after each use, according to the CDC.

“Marijuana smoke also contains many of the same substances that researchers have found in tobacco smoke – these substances are harmful to the lungs and cardiovascular system,” the agency says.

Smoking or vaping any substance, including cannabis, should be avoided due to the risk of damage to the heart, lungs and blood vessels, the American Heart Association warned in 2020.

The published AHA guidelines then pointed to studies that found abnormal heart rhythms, such as tachycardia and atrial fibrillation, could occur in a hour after weed containing delta-9-tetrahydrocannabinol, or THC, has been smoked. (THC is the part of the marijuana plant that creates a high.)

Other research has shown that smoking weed has triggered heart attacks and led to a higher risk of strokes and heart failure in people with underlying heart disease.

Notably, the new study was unable to determine whether different types of cannabis use – such as edible consumption versus weed consumption, for example – made a difference in the risk of developing coronary heart disease . However, because THC reaches the brain faster when smoked, researchers argue that future research should investigate various methods of use and their impact on the heart.

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