Can marijuana use cause atrial fibrillation (afib)?

Marijuana and Atrial Fibrillation

Marijuana use can trigger atrial fibrillation in susceptible individuals, particularly through its cardiovascular effects, though the evidence for causation is mixed with some studies showing increased risk and others showing no significant association.

Pathophysiological Mechanisms

• Cannabis produces several cardiovascular changes that can result in proarrhythmic effects on the heart, potentially triggering atrial fibrillation in predisposed individuals 1
• Marijuana smoking affects the circulatory system and can trigger various cardiovascular events, including atrial fibrillation as documented in multiple case reports 2
• The arrhythmogenic effects may be related to alterations in calcium homeostasis, which is an important factor in the pathogenesis of atrial fibrillation 3

Evidence on Marijuana and AF Risk

• A 2022 longitudinal analysis of over 23 million Californians found that cannabis use was associated with a 35% increased risk of developing incident atrial fibrillation (HR 1.35,95% CI 1.30-1.40) after adjusting for potential confounders 4
• However, a 2024 prospective cohort study of over 150,000 participants from the UK Biobank found no statistically significant differences in incident AF among occasional cannabis users (HR 0.98; 95% CI 0.89-1.08) or frequent users (HR 1.03; 95% CI 0.81-1.32) compared to never users 5
• Case reports have documented atrial fibrillation occurring after marijuana smoking in otherwise healthy individuals with no other identified risk factors 1, 6

Clinical Considerations

• When evaluating patients with new-onset atrial fibrillation, particularly younger patients without traditional risk factors, marijuana use should be considered as a possible etiology 1
• The 2024 ESC guidelines for atrial fibrillation management emphasize the importance of identifying modifiable risk factors in AF prevention and treatment 7
• Patients with marijuana-induced AF may experience typical symptoms of AF including palpitations and shortness of breath 1
• The EHRA symptom score can be used to assess symptom severity in patients with AF, ranging from no symptoms (score 1) to disabling symptoms (score 4) 7

Risk Assessment and Management

• For patients with marijuana-associated AF, standard diagnostic workup should include:

  • 12-lead ECG to confirm the diagnosis 7
  • Blood tests including thyroid function, electrolytes, and cardiac markers to rule out other causes 7
  • Transthoracic echocardiography to assess for structural heart disease 7

• Management considerations:

  • Cessation of marijuana use should be strongly recommended as a modifiable risk factor 6
  • Standard AF management principles apply, including assessment for stroke risk and consideration of rate or rhythm control strategies 7
  • Patients should be counseled about the potential cardiovascular risks of marijuana use 2

Special Populations

• Young patients with no traditional risk factors for AF who present with new-onset AF should be specifically questioned about marijuana use 6
• Consideration should be given to testing for cannabis in unexplained cases of AF in younger populations 6
• Patients with pre-existing cardiovascular conditions may be at higher risk for marijuana-induced arrhythmias 2

Clinical Implications

• With increasing legalization and use of marijuana, clinicians should be aware of its potential cardiovascular effects, including the risk of atrial fibrillation 4
• Efforts to mitigate marijuana use may represent a novel approach to AF prevention in susceptible individuals 4
• Patient education about this potential risk is important, especially for those with other risk factors for AF 2