Occasional current and lifetime cumulative use of cannabis are not associated with increases in heart abnormalities at middle age, suggests a new study by researchers from Switzerland and the U.S.

Evaluating the prevalence of electrocardiogram (ECG) abnormalities in cannabis users, researchers found “no evidence that current or lifetime cumulative use of marijuana was associated with a higher prevalence or incidence of major or minor ECG abnormalities,” according to a blog by the National Organization for the Reform of Marijuana Laws (NORML). 

Published last week inAddiction, the finding was despite controlling for potential confounders, such as alcohol and tobacco use, physical activity, body mass index, sex and age, notes the study abstract.

That said, “ECG abnormalities seemed to be less frequent in current marijuana users,” adds the NORML blog.

Researchers considered the experiences of 2,585 middle age subjects in four U.S. communities who currently used weed or used it intermittently over their lifetimes. In all, 83 per cent of subjects — all part of the ongoing longitudinal trial, Coronary Artery Risk Development in Young Adults — had past exposure to cannabis and 11 per cent were using marijuana currently, according to the study abstract.

Of the 2,585 subjects, seven per cent (173) had major abnormalities and 37 per cent (944) had minor abnormalities, it notes.

“This adds to the growing body of evidence that occasional marijuana use and cardiovascular disease events and markers of sub-clinical atherosclerosis are not associated,” researchers write.

Of the 2,585 subjects, seven per cent (173) had major abnormalities and 37 per cent (944) had minor abnormalities. / Photo: iStock / Getty Images Plus / Photo: iStock / Getty Images Plus

Within the available evidence, however, different researchers have come to different conclusions regarding cannabis use and the heart.

A new review in the Journal of the American College of Cardiology, for example, cites U.S. survey data estimating that more than two million people with established cardiovascular diseases currently use or have used weed, including by inhalation and vaping. “Observational data suggest associations between marijuana and a broad range of adverse cardiovascular risks,” the review notes.

And a study published this year in the Journal of Clinical Medicine notes that “marijuana has been strongly linked to various cardiovascular adverse events over the years.” Researchers write that these events include myocardial infarction, especially in young healthy men with no other risk factors, arrhythmias, stress cardiomyopathy and arteritis.

“With the rise in cannabis use among older patients, who are the most vulnerable to cardiovascular events, it is expected that these reports will increase in the next few years.” / Photo: Getty Images / Getty Images

“With the rise in cannabis use among older patients, who are the most vulnerable to cardiovascular events, it is expected that these reports will increase in the next few years,” they point out.

Acknowledging that drawing conclusions continues to be challenging, researchers, nonetheless, add, “the alarming rate of adverse cardiovascular events reported over the past decade necessitates that physicians remain vigilant in everyday practice to recognize these effects and counsel their patients accordingly.”