The findings were published Dec. 18 in JACC Cardiovascular Imaging.
McLaughlin characterized the study as “hypothesis-generating,” rather than a solid result.
“It’s not a definitive answer by any means, but it gives us reason to investigate the effect of marijuana on heart structure,” she said.
Because the study was observational, it’s hard to know whether other factors might have caused the heart structure changes associated with marijuana use, McLaughlin said.
“Alcohol can also cause similar types of changes in the left ventricle with chronic drinking, which can get better when people stop drinking,” she said. “They said they adjusted for alcohol use in this study, but the question is whether the use was adequately assessed.”
Europeans also are known to mix their marijuana with tobacco, which has notoriously harmful effects on the heart, said Paul Armentano, deputy director of NORML, a group advocating reform of U.S. marijuana laws.
Experts also noted that the number of pot users in this study was very small.
“Replications with more extensive measures and a dramatically larger sample of cannabis users do seem quite justified,” said Mitch Earleywine, a professor of psychology at the University at Albany-State University of New York and a NORML advisory board member.
If marijuana is indeed the cause, it’s hard to say what exactly about pot is affecting the heart, physicians say.
It could be the smoke that’s being inhaled that places strain on the heart, or it could be THC, the chemical in pot that gets you high, said Dr. Larry Allen, a professor of cardiology at the University of Colorado School of Medicine in Aurora.
THC has been shown to increase heart rate and blood pressure, cause blood to clot more easily, and affect the inner lining of blood vessels, he said.
“We have some basic laboratory data that suggests there may be adverse health effects of THC,” Allen said.
Until there are more answers, people with heart problems might want to avoid pot, the experts said.
“If you have heart disease, you should really use marijuana with caution,” Gulati said. “In fact, I, as a cardiologist, would recommend you not to use it because of the physiologic effects of increasing your heart rate and putting more demand and stress on the heart.”
WebMD News from HealthDay
SOURCES: Mary Ann McLaughlin, M.D., cardiologist and associate professor, medicine, The Mount Sinai Hospital, New York City; Martha Gulati, M.D., M.S., editor-in-chief, CardioSmart.org, Washington, D.C.; Paul Armentano, deputy director, National Organization for the Reform of Marijuana Laws, Washington, D.C.; Mitch Earleywine, Ph.D., professor, psychology, University at Albany-SUNY, Albany, N.Y.; Larry Allen, M.D., professor, cardiology, University of Colorado School of Medicine, Aurora;JACC Cardiovascular Imaging, Dec. 18, 2019
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