New Study Tells Nothing About Marijuana’s Role in Heart Disease

A new study on marijuana appeared in Journal of the American Heart Association. These are interesting data, but we have to interpret them very carefully.

Sure, we know cannabis can raise heart rate briefly, but most users develop tolerance to the effect. We’ve also seen (in a much larger sample) that it doesn’t increase mortality rates even among survivors of heart attacks.

But the new study made the news anyway. Investigators specifically searched a French database where physicians are legally bound to report any drug-related case that they view as “leading to temporary or permanent functional incapacity or disability, to inpatient hospitalization or prolongation of existing hospitalization, to congenital anomalies, or to an immediate vital risk or death.”

They then looked for cannabis users and found a shade less than 2,000 in the past 5 years. It’s impossible to know what that number means without knowing the number of people these physicians saw or how many patients used cannabis and did not end up reported to this database.

They then found a whopping 35 of these who had cardiac complications. It is impossible to know what to make of this number without knowing the number of cannabis users in France, which the authors report is 1.2 million. If you divide 35 by 1.2 million you get roughly .00003. I’m guessing that not all these cannabis users went to the doctor and not every person who used cannabis and had cardiac complications fessed up to the doctor, so let’s say that we’re off by two orders of magnitude. Let’s give the prohibitionists the benefit of the doubt and multiply by 100. That’d put the rate of problems up to .003.

If those are the chances of having cardiac complications as a French cannabis user, my first thought is that using cannabis protects people from cardiac problems. We need a comparison group of people who don’t use cannabis to know their rate of cardiac problems, but, as the authors point out, we simply don’t have those data. The closest estimates were 57 per 10,000 people, based on another study, which is .0057, or almost twice as bad as the rate among the cannabis users (after our generous overestimation). I’m not going to hold my breath for the the headline, “Cut your heart disease in half with cannabis.”

In short, this study tells us a lot about what kinds of cardiac complications appeared in people who were reported to the French government for cannabis-related problems, but tells us little about the link between cannabis use and cardiovascular disease.

50 thoughts

  1. I’ve been hearing this on the news.Ten years ago when the doctor was telling me about my heart problem he stopped halfway in a sentence and walked out of the room. Guess he recenyly lost someone close.

    When my pressure is too high I burn one and it brings it down. When my pulse is racing I burn one and it comes down. I think I’ll keep using.

    1. I’m a heart patient, heart attack, tia, and quad bypass, and pace maker/defibulator, I’m torn at this point, was looking forward on our trip to Colorado having some cannibus, been along time since ive had any, now I don’t know what to do.

  2. They are really grasping at straws now. The prohibitionists can’t ignore the science anymore, so they’re desperately combing through scientific studies to find this kind of stuff.

  3. Great blog! Everytime there is a negative study about cannabis, I come to this website to find out the whole truth.

    I especially look out for Dr. Mitch Earleywine’s blogs. Thanks, and keep at it!

  4. First they ignore you, then they laugh at you, then they fight you, then you win.

    Mahatma Gandhi

    I think we get a little closer to winning everyday!

  5. If the Feds would get off their asses and reclassify MJ to a lower risk than it now is, then MAYBE we can start to get more non biased info on its potential medical benefits (and harm if any).

  6. There seems to be a trend with these ‘medical findings’. If you ever get any news that cannabis can help with a medical condition (such as aiding a patient in cardiac arrest ) you also find a study that completely contradicts it like this one. It is a basic disinformation tactic to create confusion and obscure the truth. Disinformation plants the doubt in people’s minds so that is why there are always some people who are undecided about medical cannabis and some that think it is a bad thing. Without the disinformation there would 100 % support for this wonder drug not the 75 % or so there is now !

  7. Dear Dr. Earleywine,
    I’m a MD, and president of Italian Association for Therapeutic Cannabis (Associazione Cannabis Terapeutica). I think that I’ve found a little error in your article. You wrote about the rate of cardiac problems between the non-users: “The closest estimates were 57 per 10,000 people, based on another study, which is .0057”. But in the study we find: “average incidence rates of myocardial infarction and coronary deaths in patients aged 35 to 44 years were estimated to be 57 of 100 000 among men”. So the real number is .00057; not “almost the twice” of the cannabis users, but ten time less. I hope I’ve made a mistake…

  8. This article is truly terrible. As a clinician I want to see MJ leagized, but when you are extrapolating information from clinical trial that had nothing to do with MJ in the first place I don’t believe it. Further more we have no evidence of what diet and exercise regimen these patients were on which is clearly tied to heart disease. Also the rate of heart disease in known to be lower in Europe. Further more the 57 per 10,000 study you were talking about, could have included cannabis users, but we won’t know because no one asks. No conclusions can be drawn from this for us Americans. Need double blind, placebo controlled studies to make appropriate conclusions!

  9. Dear Dr. Crestani-
    You’re right! Sorry for the error. My joking hypothesis about cannabis as a protector just became more tenable! Thank you so much for pointing out the mistake.

  10. To revisit the math, the number of *deaths* was 9, over a period of 4 years. Using Dr. Earleywine’s 100x correction, that’s 225 deaths per year in a population of 1.2 million, for a death rate of 19 per 100,000. You also have to account for the fact that 22 of the 35 smoked tobacco as well.

  11. While I find the math fascinating, I believe what these “grasping at straws” studies fail to reveal, as Galileo well points out, is that we are looking at stratified sampling of evidence that does not look at the greater function of marijuana within the endocannabinoid system.
    How can anyone determine the health or cause of the heart without examining the whole human body and environment in which the heart eats and lives?
    Sure, cannabis exelerates heart beat. It also increases nutritional absorbtion, unlike synthetic Kraft foods, which decreases intestinal growths such as divirticulitis, Fibroids, pollups and non malignant tumors, therebye decreasing anemically-induced strokes.
    Vaporize marijuana and get a sonogram or cat scan of your abdomen. We may all be surprised at the results.

  12. Two local news channels 8 and 3 news have been pushing this study big the last few days.
    When it comes to matters of the heart, THEY will never win mine. My heart is with my friends the cats, and with sweet marry jane. Thanks Norml.

  13. what are you ideas on Dr. Wolff Cannabis-related Stroke Myth or Reality, Cannabis really helps me but I want to make sure I’m safe.

  14. Put me in the cardiac-issues group. When I was younger, I could (and did) smoke all day, with no ill-effects, except perhaps psychological dependence. Got married and gave it up, over time, and not without difficulty (I really liked pot). Twenty years later, if I light up, my heart races really bad. Not a fluke … over the last few years I’ve smoked maybe 3-4 times, and the heart condition always follows, within about 20 minutes. Anyway, just a data point for y’all.

  15. The stroke data- only about 60 cases reported as far as I can tell. Seems like the tobacco and alcohol confounds are not controlled well. It’s early to tell. Definitely watch out for nicotine. If you’ve got a prior stroke, stay away from the plant and anything that raises heart rate. Diabetes is another risk factor. In short, take care of yourself.

  16. Assuming the worst prediction is correct, you’d be much safer staying at home and using cannabis than being sober and driving a car.

    I’ve always been fascinated by studies, statistics and how the mainstream media interpret them. These studies are always just ‘starting points, where new studies can be done to try and prove or disprove the findings. But they need headlines, so – and the UK press is particularly bad at this – we get a massive story based on a few studies and little understand of probability in the wider context.

    I hope any newspaper that writes an article about this will give equal time to this issue –

    Paracetamol/acetaminophen is a drug anyone can buy at the grocery store. Where’s the outrage?

  17. Dear Dr Earleywine,
    apart from statistical calculations, here is a brief review of the cases reported in the research.

    35 patients
    associated tobacco 21
    associated alcohol 6
    associated cocaine 1
    associated alcohol tobacco exctasy lsd 1
    associated alcohol tobacco adulteration product 1
    associated benzodiazepine 1

    8 of the patients with associated substances had a positive personal cardiovascular history (following the list of the Table S1 of the paper): case 1 high blood pressure, acute coronary syndrome and artheriopathy; case 7 BMI 25.4; case 10 BMI 32.1; case 15 intermittent claudication, Raynauds disease; case 23 deep venous thrombosis, acute coronary syndrome, claudication (and under oral contraception); case 27 high blood pressure; case 32 Buerger’s disease; case 33 high blood pressure, atherogenous hypercholesterolemia, BMI 27.4.

    7 of these cases had positive familiar cardiovascular history (patients 3, 4, 7, 9, 13, 22, 23)

    cannabis only (11 cases, but read the notes):

    case 1 (following the list of the Table S1 of the paper): autopsy concluded in death caused by a “probable cannabis-related acute coronary syndrome since cannabis was found positive”. NOT AVAILABLE cardiovascular history. Exposure to cannabis “recent” (between 1 and 9 uses in the past 30 days). Toxicology THC+. Remenber that positivity for THC stands about 30 days. It’s difficult to prove a casualty relation.

    case 11: no case description (death). Only Cannabis quoted in medical file, but toxicology NOT available, and cardiovascular history NOT available.

    case 12: no case description (death). Only Cannabis quoted in medical file, but toxicology NOT available, and cardiovascular history NOT available.

    case 15: no case description (angioplasty and circulatory assistance). Cardiovascular history NOT available.

    case 19: BMI 25.5 (overweight). Toxicology positive for paracetamol (at therapeutic dosage) and for cannabinoids at dose compatible with “recent” intoxication (see case 1).

    case 20: BMI 26.7 (overweight). Toxicology positive for paracetamol (traces) and for cannabinoids at dose compatible with “recent” intoxication (see case 1).

    case 21: supposedly nothing to say

    case 25: patient with history of Cutis marmorata teleangiectasica CONGENITA and Raynaud’s disease. Arteriopathy with recovery after the interruption of the use.

    case 28: cardiovascular history NOT available.

    case 29: Acute cerebral angiopathy AFTER SEVERAL REPEATED EPISODES OF CEPHALALGIA. Interestingly, he had used cocaine one month earlier. Cocaine is notoriously a cause of headache and stroke.

    case 34: supposedly nothing to say

    Ultimately, only few cases could represent a signal of risk of cardiovascular disorders. But we need more anamnestical, clinical, autoptical and laboratory informations because we have recently read of “putative healthy young men” that conversely had history of polyabuse and dilatative myocardiopathy(1).

    1)Hartung B, Kauferstein S, Ritz-Timme S, Daldrup T. Sudden unexpected death under acute influence of cannabis. Forensic Sci Int. 2014 Apr;237:e11-3.

  18. Not to mention that all of the research from the French connection
    DID NOT take into account smoking and drinking habits of the so-called participants.

    Clinical Supervisor-addiction medicine.

  19. Its all so confusing, especially when you have Dr. David Allen Recommending cannabis daily if you high risk for heart attack or stroke because it can halved infarct size.

  20. what about this study “Cerebrovascular perfusion in
    marijuana users during a month
    of monitored abstinence”

  21. Thanks Dr. Crestani! It’s great to see all the details about the sample. Sounds as if we have a lot more data to gather before we can say that cannabis is causal in cardiac problems. Let’s see if we can educate the media about jumping ahead of the research.

  22. Thank you Dr. Crestani. You give my heart a craving of a little more Italian wine, olive oil and balsamic vinegar to go with my native herbs. The diet of too much beer wasn’t cutting it for my cardiovascular fitness. Thank God I finally smoked marijuana my senior year of high school and unwittingly kicked a bad, developing Marlboro cigarette habit.

  23. Makes total sense. Cannabis users experience far lower levels of stress and anxiety than those who don’t use. Stress is one of the greatest contributing factors to heart complications. I believe the actual act of inhaling deeply and holding one’s breath is what really contributes to temp-increased heart rates.

  24. There needs to be more studies done on how increased nutritional absorbtion from the consumption of cannabis decreases heart failure or high blood pressure by reducing anemic growths in the abdomen. Dr. Crestani? Any references?

  25. for any study to be accurate the subject would have to consume cannabis alone no spice tobaco nor perscription drugs wth the dna factors in heart disease along wth the munchies if a person is forced to hide in thier home allienated from society wth only tv an food this curvatures the experiment totaly too (its unimagionable the stress factors from fear of loss of life liberty an the pursuit of happyness (the pcycological damages bleat over unto the physical relm (wthout the legal stigmata many of our elders would be alive an well an wth us today

  26. why cant illinois decriminalize wth the best set of legislation (in order to perform adjustments to increase tax rate revenues along wth opening up a system of environmental air springs an purification unto the environment (such as marijuana would make cattle feed in cases of weakening crops creek filters an ultimatly food an oil imagine the 16ercent increase in cows an breathable air wth deforestation an chemical caustic effects its the only logical thing to do

  27. Dr. Earleywine there saying heavy use decreases blood flow is the cause, not increase.

  28. I had an afib attack one time after smoking a strong hit. I’ve used less intense smoke with little or no heart racing. It’s all about strength.

  29. How do we know these people with cardiac problems weren’t smoking ciggs also? That would greatly increase risk of cardiac problems. That is the problem with a lot of studies on marijuana. Cant have two variables when it is known that ciggs cause cardiac issues.

  30. Yesterday my 35 year old nephew, Bradley, suffered a cardiac arrest while playing tennis. He does not smoke pot, is active and a real sweet heart. I’ll be giving him MMJ pain cream for his after surgery.

    The prohibitionist are grasping at anything with more pseudo science.

    On another note; AARP magazine has two articles this month where Stars Willie Nelson and Beau Bridges mention consuming MJ.

  31. 71% of males, is what worried me? The cannabis user were also tobacco smokers. Why don’t RCVS studies count other vasoactive studies like caffeine or Tobacco as Triggers? Also BMI? Since ld50 scores are very high for oral cannabinoids, is this most likely an underlying/predisposed condition? Also Earleywine new study shows BHO doesn’t increase hospital use, so obviously the cannabinoids are most likely no the causes. Lastly many people use cannabis for headaches.

  32. Thanks Franceso! The tachycardia and decreased BP are all true, and as we’ve emphasized, folks with a lot of risk factors probably should avoid caffeine, animal fats, cannabis, and just about everything else.

  33. 2 stress test performed on me reveal a healthy cardiovascular system. However my brother, a few years older has had 2 heart attacks that nearly kill him. I smoked ciggaretts and pot for 27 years, and I quit ciggarets a year and a half ago, but continue smoking cannabinoids 🙂 my 2 seperated cardiologist are baffled to how I have no heart diesese considering the fact that my father died from a heart attack and brother following dad’s footsteps. I had high cholesterol but I’m working on that real hard.I truly believe that cannabis, my anti cancer,anti depression medicine is saving my life. Cannabis helps in every way it can.

  34. The proof is here. I have a twin brother who is a health junky, dosnt smoke cannabis or ciggarette. Last year my brother suffered a massive heart attack that merely kills him.On the other hand , I smoked cigarettes since 12 and smoked canabis since 12.i have quit smoking and had a stress test and all is amazing. He believed cannabis is saving my life and he is starting a low dose thc/cbd oil treatment. However the downside is that he will be on blood thinners for the rest of his life, that come with sides. I believe cannabis helps with hardend arteries. That goes to say the least.

  35. lve smoked cannabis since i was fifteen now i43 got heart dis
    ease only got 20percent of heartfuntion left was looking at having to go on tranplant list aswell as smoking it was ingesting dope seeds in fruit drinks when i went for my last echo heart has gone down in size and for now dont hav to go on the list amymore or go bac to hospital for op they were going to try and have more energy now than before

  36. Wonderful article. All I ever see is negative responses on this subject. I have been diagnosed with “Mitral AND Tricuspid regurgitation. My disease acts up during any type of stress. When I started smoking again my fibrillation’s and “as I call them”, episodes(Feels like a heart attack), became less frequent. Now as crazy as it sounds, I spark up and head to the gym. Yes started going to the gym when I started smoking again. And I can stay there hard for a good 2 hours. I smoke after I get out of the gym. Now my episodes are far and few between. I don’t see a down side to this.

  37. I’ve been doing research on marijuana and heart. It is minipulated by the person studying oppion. I have heart problems that stress triggers my heart to clamp up n not pump. I smoke a jay n it helps. I have emergency nitrostat that is a sloppy dangerouse drug but really helps. But I have been using marijuana to help and haven’t had to take my nitrostat in a long time. Plus I don’t have all the bad side effects from marijuana like I do nitrostat. Sometimes I get a migraine from nitrostat. Marijuana no headaches calms me down n help my heart quit hurting. I’m trying to eat it so I don’t have the lung, oxegen problem but it takes a few hours for it to work when I need it fast.

  38. Hi, I actually am a great example for a Patient with Heart Disease. I had Kawasakis Disease at 4 years old (diagnosed in 1993 at U of M). I had anurysms in my right and left coronary arteries. I was sent home with a daily dose of an 81mg baby asprin. And 9-12 months later had a Heart Attack from a fully clotted right coronary artery. Rushed from Petoskey Michigan’s (Burns Clinic)Emergency room on September 11th, 1993 and transported to University of Michigan Pediatric where Dr. Crowley diagnosed me. He put me on Coumidan and to continue my asprin. I was placed on Crippled Childrens fund of Michigan untill i was 21 and supervised by Cardiologist in Petoskey as well as yearly check ups with Dr. Crowley at U of M untill i was 18.

    I stared smoking marijuana at 13 years old while taking my medicine. It helped me with my stomach nausea i had developed from taking daily medication. It also helped me cope with the stess of all the experience getting poked, proded and tested year after year. I had alot of post traumatic stress as a child going though those things. The law didn’t see it that way though… Neither did my mother or the schools at the time. So as this new medication marijuana I had “prescribed” myself seemed to help me physically, mentally and emotionally, I defiantly backed my position and opinions about this plant. I was then placed in a maximum security juvenile facility for 22 months “for my safety”. They thought smoking marijuana would effect my Heart Condition.

    As the years went on as i became an adult i took control of my life and started smoking Only. And taking no Heart Medication or drinking alcohol. Ive donr this for the last 6 years straight. I’ve recently taken an echocardiogram at Mclearen in Petoskey Michigan and my Ejection Fraction Rate of my heart has IMPROVED from 46% TO %60. I am experiencing issues as well though. I have signs of lack of Oxygen to my heart muscle. I am scheduled to have a heart cath September 8th to see the real anatomy of my heart since my last heart cath approximately 8 years ago.

    Im in Cardiology at McClearen Hospital currently and seeing Dr. Cortiville. His first idea is the improvement in the Ejection Fraction rate could be the old piece of heart from my heart attack regrowing and improving. And that the blood vessels rejuvenating are so tiny that the EKG leads are finding lack of Oxygen. I smoke cigarettes and are currently quitting to improve oxygen levels before my heart cath. Secondly and worse off if its not my heart repairing itself then it would be narrowing and/or scar tissue build up in my left coronary artery. Which was anticipated by the time i was 30 by Dr. Levenovich of Petoskey cardiologist as well as U of M.

    My biggest accomplishment in this was the fact that Ejection Fraction rates do not SIMPLY IMPROVE. And as big of an Improvement as 14%. That to me definitely shows regrowth without a doubt. I have been an avid smoker for 14 years and as of November of last year I’ve acquired my Medical Marijuana card and still reside in Petoskey. I am very eager to find a physician willing to test me for positive benefits to Heart Disease BECAUSE I have firmly believe it has been helping me. And I firmly believe it has an anti-coagulant effect. If others are interested in my story or NORML would like to help me find more research please contact me directly on Facebook or my Email- Will provide my number as well. I found this article trying to find more information myself. Thank you anyone who reads my story!

    Adam Irelan

    Med patient since November 2013
    Heart patient since 1992
    Heart attack in 1993
    Im 27, im a real person with a real story.

  39. I just had a heart stent put in for a mild MI….Im nervous about the risk of a problem but love getting high. not a cig smoker now. Can i enjoy getting high again? help inform me.

  40. Ah, go ahead and ignore those pesky little studie. Marijuana may not hurt your heart, it will just give you lung cancer from smoking it.

  41. I’m a heart patient, heart attack, tia, and quad bypass, and pace maker/defibulator, I’m torn at this point, was looking forward on our trip to Colorado having some cannibus, been along time since ive had any, now I don’t know what to do. Great blog! Everytime there is a negative study about cannabis, I come to this website to find out the whole truth. There seems to be a trend with these ‘medical findings’. If you ever get any news that cannabis can help with a medical condition (such as aiding a patient in cardiac arrest ) you also find a study that completely contradicts it like this one.Thank you for sharing your article about New Study Tells Nothing About Marijuana’s Role in Heart Disease.

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