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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.”

13 responses to “Heart expert says: More research needed about marijuana’s effects”

  1. gregg budzinski

    Seems the for profit medical field is not in favor for obvious reasons. There are so many positives in my opinion that far out number rumored negatives. I'm been using CBD products with pretty profound benefits . It should be legalized asap to bring natural relief to so many in need.

  2. selinacantrell

    Herbal medicine are more likely be the choice of many now a days specially prescription drugs are not only over the top when it come to price but I also kills your liver along the way. Had a lot of experience with medical cannabis since it's working for me. I learn a lot from this website blimburnseeds.com/news/marijuana/cooking/recipes/potato-cake-with-sour-diesel-cannabis-from-blimburn-seeds-part-2/. That different strains of cannabis was a use for each diseases.

  3. David Hamel

    Harmful effects are relative. The most harmful thing about illegal marijuana is that it is illegal. Illegal pipelines finance criminality just as in the days of "prohibition" years ago. Lives and reputations ruined by conviction of "possession of paraphernalia" during "routine" traffic stops. Worse than alcohol?

    1. Kirsten Shakal, Shine365 Editor

      Thank you for commenting, David.

      If you're interested, Dr. Rezkalla has also shared his research on effects of alcohol:
      https://shine365.marshfieldclinic.org/wellness/alcohol-consumption-good-bad/
      https://shine365.marshfieldclinic.org/heart-care/red-or-white-wine-consider-this/

  4. Chris

    I suffer from extreme lower back pain. I have tried everything to get some relief. I have tried prescribed opioides but that did not help. Would you prescribe marijuana from someone with this issue? I have considered trying it just for this reason.

    1. Kirsten Shakal, Shine365 Editor

      Hi, Chris. This article and Dr. Rezkalla's comments are about the use of marijuana for recreational purposes. For your back, you need to start with your primary care provider to see if there is any way to treat it, other than the medications that have not worked for you in the past.

      This gives you an opportunity to ask about cannabis oil for treating back ache. You might also ask your provider if physical therapy could be helpful.

      Best wishes. -Kirstie

  5. Elizabeth

    Here's my experience. I am a marijuana user. I grow my own, and have seen multiple benefits from using. More than I ever I had with opioids and tons of prescription drugs that almost killed me. There are studies out there but they are not FDA approved through communicating with the marijuana community and reading books on marijuana. And the fact that the plant in itself has been around for centuries, and people have used it. There are two categories of plants, one is Indica and the other sativa. I grow sativa, for multiple problems and no head buzz. I've never been calmer. Last August and I wasn't using, just didn't need to, had a bunch of very stressful things happen. It was scary, then I decided to start using my blood pressure went down. And I now have these stomach issues which marijuana is helping. I use edibles and make my own salves for pain. I think that the researchers should really get together with the growers and users. Here their stories and experiences. That's where you will learn more. I know I have. The doctors I see know that I use, and if they told me I couldn't use I wouldn't. It's not an everyday use for me. And stopping has never given me withdrawal, like I have have had with other medications.

  6. Mel

    Double edge sword. You cannot get more studies done until it is no longer illegal.

    Secondly, using too much of anything is bad for you. Period. Why waste money to do studies to prove this? Also, smoking is very bad for the heart and body, which is the regular route of those who are illegal users of this substance. (And even many who are legal users.)

    It would hard to keep with good science to rule possible harm versus possible benefits.

    (And to add further, I'm sure there's a genetical component to use too. There's always a genetical component. Oh, and exercise and diet!)

  7. Linda July

    I am grateful to see one of our doctors taking a medical stand though it may not fit the agenda of advocates for marijuana. Thank you for being concerned with people's short and long term health. Marshfield Clinic Health System is truly a great place to work at.

  8. Lucy

    several people Have recommended that my husband who has Parkinson’s try medical marijuana. He also has arterial fibulation . I have been reluctant to have him try the medical marijuana, and this article confirms that it would not be good for him to try it. Thank you very much for the article.

    1. Husband with his diabetes, I have a heart disease and my doctor recommended I didn’t use it but my husband is fine a cy

      I was wondering if CBD oil would help my Husband with his diabetes, I have a heart disease and my doctor recommended I didn’t use it but my husband is fine

  9. Joe Brickweg

    Dr. Rezkalla, is there a difference between smoking versus eating a gummy? Does the relaxation and stress relief outweigh the potential side effects? Is it similar to having that glass of wine every evening that you told me I needed? Just curious… I am living in Colorado now while not a user of marijuana, I wonder if smoking is much worse than consuming gummies?

    1. Kirsten Shakal, Shine365 Editor

      Hey, Joe. Thank you for reaching out.

      Here's the answer Dr. Rezkalla gave in response to your question, "To the best of my knowledge, there are no articles or research to differentiate between various methods of use. I believe it is the dose of the active drug that makes a difference. However, that is not proven by solid research yet."

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