Using marijuana every day can raise a person’s risk of coronary artery disease, or CAD, by a third compared with those who never used Marijuana, a new study has found.
“A growing body of evidence suggests that cannabis is not entirely without harm and may actually cause cardiovascular disease,” said lead study author Dr. Ishan Paranjpe, a resident physician at Stanford University.
The study which has not yet been published will be presented on Sunday, February 26 at the annual meeting of the American College of Cardiology.
“Thus, the decision to use cannabis must be carefully weighed against the potential for serious heart disease,” Paranjpe said.
Coronary artery disease is caused by plaque buildup in the walls of the arteries that supply blood to the heart. Also called atherosclerosis, CAD is the most common type of heart disease, according to the US Centers for Disease Control and Prevention.
Signs of the condition include having angina, or chest pain, feeling weak, dizzy or sick to your stomach, or experiencing shortness of breath. However, for “some people, the first sign of CAD is a heart attack,” according to the CDC .
Administered by the National Institutes of Health, the All of Us Research Program is designed to gather health information over time from 1 million or more people in the United States.
When enrolling in the study, participants completed a survey on their cannabis use. The research team used that information to place those who responded into five categories: Daily users (4,736 people), weekly users (2,720), monthly users (2,075), those who used once or twice in three months (8,749) and those who never used (39,678 people). The researchers then compared those categories with participants’ medical records a few years later.
They found that daily cannabis users were 34% more likely to be diagnosed with coronary artery disease than those who had never used the drug.
People who used weed only once a month or less had no significant risk, the study found.
The results came out after researchers factored out other potential causes of coronary heart disease, such as age, sex and major cardiovascular risk factors — high blood pressure, high cholesterol, type 2 diabetes, obesity, smoking and alcohol use.
The study used Mendelian randomization (MR) to determine risk, which other studies on the topic have not, Paranjpe said in an email. The MR method measures gene variations known to be related to a modifiable risk factor to determine the causal influence of the risk factor.
“While other work has also linked cannabis with CAD, there are several potential confounders that may explain this relationship. Our MR analysis suggests this relationship may be directly causal,” Paranjpe said.
“Marijuana smoke also delivers many of the same substances researchers have found in tobacco smoke — these substances are harmful to the lungs and cardiovascular system,” the agency says.
Other research has shown smoking weed has triggered heart attacks and leads to a higher risk of strokes and heart failure in people with underlying heart disease.