Marijuana use may be linked to increased risk of heart disease: Study

More than two million adults with cardiovascular disease in the US reported that they have used, or are currently using marijuana, according to a review of studies which says the effects of the drug on heart health are understudied.

Earlier research has linked marijuana use to a range of heart health risks, including stroke, arrhythmia, and diseases that make it hard for the heart muscle to pump properly, according to the study, published in the Journal of American College of Cardiology.

"More patients are curbing their cigarette smoking, and we're seeing big improvements in cardiovascular health for those who quit," said study co-author Muthiah Vaduganathan, a cardiologist at Brigham and Women's Hospital in the US.

"In contrast, we're seeing an accelerating use of marijuana and now, for the first time, marijuana users are exceeding cigarette smokers in the U.S. We now need to turn our attention and public health resources toward understanding the safety profile of its use," Vaduganathan said.

According to the researchers, clinical trials to understand the health effects of marijuana are not feasible in the US, due to a number of legal restrictions in place.

However, they said real-world data can be used to study the drug's effects by comparing before-and-after statistics on health in US states where marijuana has been legalised for recreational use, medical use, or both.

The scientists added that as marijuana use increases in the US, large epidemiologic studies may clarify the link between marijuana and cardiovascular risk.

In the study, the researchers estimated that 2 million of the nearly 90 million adults who reported marijuana use in the US had cardiovascular disease.

"Marijuana use, both recreational and medical, is increasing nationally yet many of its cardiovascular effects remain poorly understood," said study lead author Ersilia M. DeFilippis.

"Notably, many of our cardiology patients are on medications that can interact with marijuana in unpredictable ways depending on the formulation. This highlights that we need more data so that we can better counsel providers as well as patients," DeFilippis added.

Based on the findings, the researchers said, many of the same chemicals found in cigarettes, which are toxic to the heart, are also found in marijuana smoke.

They added that the inhalation of cannabis can also increase heart rate and blood pressure, and may be a trigger of heart attack.

According to the study, marijuana use is also associated with abnormal heart rhythms and cerebrovascular diseases, such as a stroke.

"In the clinic, patients often ask us about the safety of marijuana use, and we're pressed to offer the best scientific evidence," said Vaduganathan.

"Our current approach is that patients who are at high risk of cardiovascular events should be counselled to avoid ,or at least minimise marijuana use, and that rigorous scientific research should be conducted to further inform recommendations for patient care," Vaduganathan added.