Heavy Cannabis Use Tied to Increased Cardiovascular Risk in Men With HIV
By Anne Harding
NEW YORK—Heavy marijuana use is associated with an increased risk of midlife cardiovascular events in men with HIV, independently of tobacco smoking, according to new research.
“The findings suggest that physicians should caution patients with existing or increased risk of cardiovascular disease about potential hazards of marijuana smoking for triggering acute cardiac events such as myocardial infarction, and increasing the risk of chronic cardiovascular conditions,” Dr. Dana Gabuzda of Dana-Farber Cancer Institute in Boston told Reuters Health by email. “These patients include HIV-positive individuals, since it is known that HIV infection is associated with increased cardiovascular risk.”
She added: “For young healthy patients without cardiovascular disease or known risk factors, these risks are likely to be much lower or negligible. Nonetheless, some information about potential cardiovascular risk should be shared with young healthy patients if they smoke marijuana daily or several times a week.”
Marijuana use is prevalent among HIV-positive individuals, but few studies have looked at how long-term cannabis use affects their health, Dr. Gabuzda and her colleagues note in their report, online April 25 in Clinical Infectious Diseases.
Recent studies have linked marijuana smoking to cardiovascular events in people without HIV, the researchers add, but just a single study has investigated marijuana and heart disease in HIV-positive patients.
Dr. Gabuzda and her team looked at 558 men enrolled in the Multicenter AIDS Cohort study from 1990 to 2010, including 182 HIV seroconverters and 376 who were virally suppressed on combination ART. They defined heavy marijuana use as smoking daily or weekly.
Twenty percent of study participants reported heavy marijuana use at 50% or more of their biannual follow-up visits. After adjustment for age, tobacco smoking, viral load and traditional risk factors, the odds ratio for cardiovascular events was 2.5 for heavy marijuana smokers aged 40 to 60 (p=0.016).
Both tobacco and marijuana smoking were independently associated with higher counts of white blood cells (WBC). Men in the highest quartile for WBC count, of 6,500 cells/mcl or more, had an OR of 4.3 for cardiovascular events (p=0.009).
Exposure to toxic smoke components such as polyaromatic hydrocarbons (PAH) and volatile organic components (VOC) - not plant-derived components such as THC and cannabidiol - is the most likely explanation for the association between marijuana smoking and increased cardiovascular risk, Dr. Gabuzda said. Marijuana’s transient effects on heart rate and blood pressure could also be a factor, she added.
“There is growing evidence that people who smoke both marijuana and tobacco on a frequent basis are likely putting themselves at higher risk from hazards of smoke exposure because they are exposed to ‘smoke on top of smoke,’” the researcher said. “Physicians should caution patients who smoke both substances about the importance of quitting tobacco smoking in order to minimize smoke exposure and optimize cardiovascular and pulmonary health.”
While many studies have shown an increased risk of cardiovascular events in marijuana users, “this paper emphasizes that the effect is independent of smoking,” said Dr. Shereif Rezkalla, a cardiologist at the Marshfield Clinic in Marshfield, Wisconsin, who has studied the cardiovascular effects of marijuana but was not involved in the new work.
“In previous studies most marijuana users smoked. Here some only used marijuana yet had increased cardiac events,” she told Reuters Health by email.
Clin Infect Dis 2017.
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