We read the recent report Adverse Cardiovascular, Cerebrovascular, and Peripheral Vascular Effects of Marijuana: What cardiologists need to know by Thomas et al. The investigators summarized the literature concerning the adverse vascular effects of marijuana, the most widely used illicit drug in the world. We would like to point out an omission in the review.

In 2013, we published a study of 160 patients with ischemic stroke and transient ischemic attack aged 18 to 55 years and 160 age-, gender-, and ethnicity-matched control patients without cardiovascular or neurologic diagnoses. Cases and controls had urine screens for cannabis within 72 hours of hospital admission. Twenty-five patients (15.6%) with stroke and transient ischemic attack had positive cannabis drug screens. Thirteen control participants (8.1%) had positive cannabis screens. Cannabis use was associated with increased risk of ischemic stroke and/or transient ischemic attack in a logistic regression analysis adjusted for age, gender, and ethnicity (odds ratio 2.30, 95% confidence interval 1.08 to 5.08). However, an association independent of tobacco has not been confirmed as all but one of the patients who tested positive for cannabis also used tobacco.

Finding an association is not the same as finding causality. However, we agree that it is important for cardiologists and other physicians caring for patients with vascular disease to be aware of this potential association. We suggest that younger patients presenting with acute cardiac and cerebral ischemia are screened for cannabis, particularly in cases when there are no other vascular risk factors. Those patients with positive screens could then be informed of a potential association between cannabis and vascular disease and be counseled against further use. The wave of decriminalization of cannabis use in the United States and elsewhere in the world makes it imperative that further research is undertaken to clarify the relation between cannabis and vascular disease.