As cannabis use becomes more widespread, a new systematic review and meta-analysis has identified potential cardiovascular risks associated with its use.

Researchers analyzed data from 24 observational studies, encompassing more than 432 million individuals, and found that cannabis use was associated with an increased risk of major adverse cardiovascular events, defined as acute coronary syndrome (ACS), stroke, and cardiovascular mortality.

The pooled relative risk (RR) estimates were:

• ACS: RR = 1.29 (95% CI, 1.05–1.59),

• Stroke: RR = 1.20 (95% CI, 1.13–1.26),

• Cardiovascular mortality: RR = 2.10 (95% CI, 1.29–3.42).

No statistically significant association was found for the composite outcome of ACS and stroke (RR = 1.04; 95% CI, 0.54–1.99).

The included studies, published between 2016 and 2023, varied in design—primarily cross-sectional, with some cohort and one case-control study. Most evaluated recreational cannabis use, although one focused on individuals prescribed medical cannabis. A random-effects model was used to pool adjusted risk estimates.

Cannabis exposure was determined by self-report, urine drug screening, or diagnostic codes. Sources included hospital records, national health surveys, and administrative databases. Among studies that reported demographics, cannabis users tended to be younger, with a weighted mean age of 38.4 years, and predominantly male.

One U.S. study found that young adults who reported cannabis use more than once per week had increased odds of myocardial infarction (odds ratio [OR], 2.31; 95% CI, 1.18–4.50), while occasional users did not show a similar association. A French analysis reported that cannabis use was more strongly associated with myocardial infarction risk than cocaine or opioids.

Stroke risk was notably elevated in younger users. An Australian cohort showed that weekly use was associated with a nearly fivefold increased risk of stroke or transient ischemic attack (incidence rate ratio, 4.7; 95% CI, 2.1–10.7). However, studies with longer follow-up or narrow exposure definitions often did not detect statistically significant associations, highlighting heterogeneity in exposure measurement.

Three studies reported cardiovascular mortality outcomes. One found that younger adults with a history of myocardial infarction had a higher risk of cardiovascular death if they also used cannabis. Another, based on US survey data, reported a significant association between cannabis use and cardiovascular mortality but not with all-cause mortality (hazard ratio, 1.14; 95% CI, 0.81–1.59).

The authors noted limitations: cannabis exposure was inconsistently defined; study populations may have overlapped; and most studies had a high risk of bias, especially due to confounding and exposure misclassification. Cross-sectional designs dominated, limiting the ability to infer causality.

Nevertheless, the consistent associations between cannabis use and individual cardiovascular endpoints underscore potential harms. The investigators recommended that clinicians consider cannabis use in cardiovascular risk assessments, particularly among younger patients.

No conflicts of interest were reported.

Source: Heart