A healthy living blog from Marshfield Clinic Health System

Heart expert says: More research needed about marijuana’s effects

Marijuana shaped in a heart - Marijuana's effects on the heart

Should marijuana be legalized? A heart expert and researcher thinks more study needs to be done to understand marijuana’s effects on the heart and overall health.

Researchers may not yet know all there is to know about marijuana’s effects and related safety concerns but a Marshfield Clinic Health System heart expert and researcher continues his work to find answers to keep people safe.

Marshfield Clinic Health System Cardiologist Dr. Shereif Rezkalla believes more research needs to be done, especially in light of more states having legalized marijuana’s use for recreational and medical purposes.

Recreational marijuana is now legal in 11 states – Washington, Oregon, Nevada, Maine, Massachusetts, Alaska, Michigan, California, Colorado, Illinois and Vermont along with the District of Columbia. Medical marijuana is legal in 33 states. Marijuana use is not legal in Wisconsin.

Heart research shows issues

As long as 18 years ago, a study conducted by Rezkalla showed heavy marijuana use produced ventricular tachycardia and cardiac arrest.

A patient came to me, a heavy marijuana user every day, with ventricular tachycardia yet he had normal coronary arteries and normal heart,” he said. After this patient stopped using marijuana, ventricular tachycardia was no longer there and coronary flow was normal.

That study’s publication, he said, was a warning that marijuana affects the heart.

“People in America respect our Surgeon General and his recommendations about health care,” Rezkalla said. “An example is the campaign started by Dr. C. Everett Koop years ago about smoking. The country learned smoking was a risk factor and there was marked improvement in decreasing tobacco use.”

Over 40 years ago, a different Surgeon General issued a warning about medical problems caused by marijuana smoking, Rezkalla explained. It interfered with driving ability and had cardiac toxicity in young people with no significant heart risk factors, the only obvious trigger being marijuana use.

“Years pass, people forget and there really wasn’t enough publicity at that time, “ he said.

Research continues

Fifteen years ago, Rezkalla’s research found marijuana use can precipitate myocardial infarction, or heart attack, atrial fibrillation and ventricular irregularities.

Not only that but patients with these conditions secondary to marijuana use are sicker and have higher death rates compared to patients who have these conditions because of other reasons,” Rezkalla said. “So it not just produces heart events but the events have a worse prognosis.”

Interest in marijuana has grown over the last decade, mainly driven by economic incentives, and that has led Rezkalla to look at marijuana use more closely. This work has resulted in another research paper authored by Rezkalla, titled “Cardiovascular Effects of Marijuana,” published Nov. 14, 2018, in Trends in Vascular Medicine.

The bottom line, Rezkalla said, “is that it’s too early to continue to legalize marijuana before more study is done to look at its safety. I strongly believe you need to have safety studies before you legalize marijuana for personal and recreational use. And, if it affects your mental function, your heart and your driving ability you should abstain.”

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