Fraser Horton
Fraser Horton
Last Updated on April 14, 2021

Marijuana use is on the rise, and especially recreational use among young adults according to an article by CNN, while scientific studies also confirm the same. A 2019 study by the Center for Disease Control and Prevention (CDC), concluded that the use of marijuana in college students has increased compared to students who smoke tobacco. 

This trend of increased cannabis use has serious consequences on public health since long-term cannabis use may affect complex neuroadaptive processes, and cause other health problems.

Therefore, cannabis users might ask themselves whether smoking weed can also have cardiovascular implications and affect heart health. In order to answer this question, we’ll dive into the effects of cannabis, and its main cannabinoids, tetrahydrocannabinol (THC) and cannabidiol (CBD) on the cardiovascular system.

The 411 on Heart Disease 

There are a lot of different types of heart disease, but they can all be grouped together into 4 groups on account of how they affect the function of the heart:

  • Coronary artery and vascular disease (Coronary heart disease);
  • Heart rhythm disorder (Arrhythmia);
  • Structural heart disease (Heart valve disease);
  • Heart failure.

Coronary Heart Disease

Coronary heart disease (CHD) is the most common type of heart disease that limits the blood flow to the heart as a result of plaque buildup in the walls of the coronary arteries. If left untreated, it can lead to a heart attack. A classic symptom of CHD is angina, or a squeezing pain in the chest, arms, neck, back, that often feels like indigestion. Risk factors for CHD are high-LDL cholesterol, low-HDL cholesterol, diabetes, obesity, high blood pressure, etc.

Arrhythmia

Arrhythmias are changes in normal electrical impulses of the heart, or the heart beating too quick or too slow. People experience arrhythmias as a fluttering feeling in the chest, or the heart skipping a bit.

Heart valve disease

Heart valve disease happens as a result of one or more of the heart valves not working properly. It can be caused by the thickening of the valve flaps, leakage of a valve, congenital absence of a valve, etc. Common signs of structural heart disease include heart murmurs, shortness of breath, swelling in the ankles, feet, or legs, fatigue, and other symptoms.

Heart Failure

Heart failure is a condition in which the pumping capacity of the heart isn’t parallel to the demands for blood and oxygen inside the body which happens as a result of other conditions that ultimately lead to the weakening of the heart muscle. Conditions that can influence the development of heart failure are CHD, a heart attack, abnormal heart valves, congenital heart disease, hypertension, and others. The symptoms of heart failure are similar to the symptoms of heart valve disease.

How Does Smoking Marijuana Affect Cardiovascular Health?

Even though all the health implications that come from cannabis use haven’t been fully researched, an article in the Harvard Heart letter gives an elaborate review of how cannabis affects cardiovascular health. Scientists have discovered that marijuana use in people who have established heart disease may experience chest pain, a higher risk of atrial fibrillation or ischemic stroke, an increased heart rate that results in dilating blood vessels which make the heart pump harder, as well as increasing the risk of heart attacks.

On the other hand, an article in the Journal of the American College of Cardiology states that more than two million Americans that have a history of heart disease have used or currently use cannabis. So, can the use of marijuana worsen their heart problems?

Since cannabis is classified as a Schedule I controlled substance that has no medical use by the Drug Enforcement Agency (DEA), there aren’t that many studies that focus on researching it and uncovering all its potential. For that reason, the American Heart Association (AHA) published a study reviewing the use of recreational cannabis and possible cardiovascular health effects and suggested that the DEA remove the Schedule I substance classification. 

Scientific Research From the American Heart Association

The American Heart Association has been researching the effects of marijuana use on cardiovascular health for a while now. One statement claimed that cannabis use poses a risk to cardiovascular health, though more research is critical. 

Firstly their research shows that after one hour of smoking or vaping cannabis, THC can cause heart rhythm abnormalities including:

  • Tachycardia;
  • Premature ventricular contractions;
  • Atrial fibrillation;
  • Ventricular arrhythmias.

Secondly, THC stimulates the sympathetic nervous system which can cause:

  • Higher heart rate;
  • Increased oxygen demand by the heart;
  • Higher blood pressure;
  • Dysfunction in the arterial walls.

Furthermore, smoking and inhaling cannabis may cause cardiomyopathy, angina, heart rhythm abnormalities, heart attacks, other serious cardiovascular conditions, and even a sudden cardiac death as a result of the THC content in weed. 

However, consuming CBD products derived from industrial hemp plants didn’t have the same results on users.

Effects of Inhaling Carbon Monoxide

The most common method of cannabis consumption is through inhalation that includes both smoking and vaping cannabis, which can also affect the heart and blood vessels. Cannabis smoke has similar components as tobacco smoke. Hence, the inhalation of cannabis results in increased concentrations of carbon monoxide in the body. Excess carbon monoxide in the body is associated with problems with cardiovascular health including chest pain, heart muscle disease, heart attacks, and other conditions.

And vaping isn’t much safer than smoking according to a study done by the Department of Internal Medicine at Truman Medical Centers in Kansas City. Health risks from vaping include potential harm to the blood vessels, heart, and lungs.

Cardiovascular Effects as a Result of Marijuana Use

A number of studies have researched the connection between marijuana use and cardiovascular health in relation to an increased risk of heart attacks, heart failure, atrial fibrillation, and other conditions.

The first study, done in 2017, compared lifetime marijuana use and cardiovascular diseases and followed over 5,000 people for 25 years. The research concluded that marijuana use didn’t relate to cardiovascular disease, coronary heart disease, stroke, ischemic stroke, or cardiovascular disease mortality in middle age.

The second study, done by the Department of Psychology at Arizona State University and the Department of Psychology and Neuroscience at Duke University, examined the association between cannabis use and midlife health problems by comparing cannabis smokers and tobacco smokers. The study didn’t find associations between cannabis use and cardiovascular problems like elevated blood pressure, or higher cholesterol.

However, there are some studies that link the use of cannabis to heart attack patients under 50, a higher risk of strokes, heart failure, and other conditions. Hence, the 2019 study explored whether the use of cannabis is worth the potential cardiovascular side effects. The conclusion of the research indicated that further research is needed in order to understand the potential health consequences of using cannabis.

Can Smoking Cannabis Cause a Heart Attack?

Studies on the effects of cannabis use on the body are generally short-term studies, so more research is needed for scientists to be able to make recommendations for patients with cardiovascular disease. In addition to that, the focus is also on potential interactions between cannabis and other medications like blood thinners, antidepressants, antipsychotics, antiarrhythmics, and statin drugs that lower cholesterol levels.

When talking about the connection between cannabis use and the potential of a heart attack, the AHA (along with other organizations), will need more research in order to give a recommendation in regards to cannabis. Still, the AHA states that cannabis may influence heart health, and the CDC’s position is that weed can affect the cardiovascular system as well as the heart rate and blood pressure.

One study done in 2001 by the Institute for the Prevention of Cardiovascular Disease at Harvard Medical School in Boston found that smoking cannabis can result in an increased risk of a heart attack a few hours after cannabis use since it elevates the heart rate and blood pressure. The study states that cannabis use is a “rare trigger of myocardial infarction.” Other studies have also focussed on researching this subject, although as legalization laws increase, there’s no doubt that more research will be done in the future. (Aronow et al, 1974; Sidney, 2002)

What About Consuming CBD Products?

Cannabidiol (CBD), as opposed to tetrahydrocannabinol (THC), doesn’t have psychoactive effects on users. Therefore, a study done in 2013 at the School of Graduate Entry Medicine & Health at the University of Nottingham in the UK proved that while CBD doesn’t affect the resting heart rate and blood pressure in the long run, it does lower blood pressure and heart rate in response to stress. Moreover, CBD can decrease inflammation which is one of the main causes of atherosclerosis, and therefore help with the narrowing of the arteries in the body.

Conclusion on Cannabis and Heart Health

When choosing whether or not patients should use cannabis despite other health issues they may have, it’s always best to first consult your healthcare provider. They will give you recommendations that will take into consideration your current health status, as well as potential cardiovascular complications and other health implications that may come as a result of cannabis use.

In order to reduce the risk of developing heart disease, you can consider:

  • Starting to exercise moderately at least 30 minutes a day;
  • Eating a healthy and balanced diet rich in fruits, vegetables, whole grains, and unprocessed sources of fats, protein, and carbs;
  • Quitting smoking;
  • Maintaining a good weight and BMI.

If you’re required to take certain medications for existing cardiovascular conditions, do so regularly. And if you still need cannabis as a medical marijuana therapy, choose oral and topical cannabis products in order to reduce the potential harm that can come from smoking a joint or a vape pen. Also, make sure you’re always buying high-quality cannabis products.

Additional Sources

Aronow, W. S., & Cassidy, J. (1974). Effect of marihuana and placebo-marihuana smoking on angina pectoris. The New England journal of medicine, 291(2), 65–67. https://doi.org/10.1056/NEJM197407112910203

Sidney S. (2002). Cardiovascular consequences of marijuana use. Journal of clinical pharmacology, 42(S1), 64S–70S. https://doi.org/10.1002/j.1552-4604.2002.tb06005.x

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