Cannabis and Cardiovascular Risk: A Systematic Review and Meta-Analysis
Abstract
Systematic review of 24 studies found cannabis use associated with increased risk of myocardial infarction (OR 1.49), stroke (OR 1.17), and atrial fibrillation (OR 1.35). Risk was highest with smoked cannabis and in users under 45.
Study Summary
This systematic review and meta-analysis searched PubMed, EMBASE, and Cochrane Library through October 2023, identifying 24 observational studies (n=66,000+) examining cannabis use and cardiovascular outcomes. Primary outcomes were myocardial infarction (MI), stroke, and atrial fibrillation (AF). Cannabis use was associated with significantly increased risk of MI (OR 1.49, 95% CI 1.28–1.74), stroke (OR 1.17, 95% CI 1.06–1.30), and AF (OR 1.35, 95% CI 1.14–1.59). Risk was highest with smoked cannabis (vs. other routes), in users under 45, and with daily use. Proposed mechanisms include sympathomimetic effects (tachycardia, hypertension), platelet activation, carboxyhemoglobin from combustion, and coronary vasospasm. The authors note that all included studies were observational, limiting causal inference, and that confounding by tobacco co-use was incompletely controlled in most studies.
Key Findings
- 1Cannabis use associated with OR 1.49 for MI, OR 1.17 for stroke, OR 1.35 for AF
- 2Risk highest with smoked cannabis — combustion products may contribute independently
- 3Younger users (<45) showed disproportionately elevated cardiovascular risk
- 4Daily use associated with higher risk than occasional use across all outcomes
- 5All included studies were observational — causal inference limited
Clinical Implications
- Patients with cardiovascular risk factors should be counseled on cannabis-associated CV risks
- Smoked cannabis carries additional risk from combustion products — vaporization may be safer
- Young cannabis users presenting with MI or stroke should be screened for cannabis use
- Clinicians should include cannabis use in cardiovascular risk assessment
Study Limitations
- All studies observational — cannot establish causation
- Tobacco co-use incompletely controlled in most studies
- Cannabis potency, frequency, and route not consistently reported
- Publication bias possible — studies showing no association may be underreported