The patients also were 11 times more likely to suffer a stroke after their angioplasty, although the overall risk remained low, with about 0.3% of marijuana users suffering a stroke.
“The odds are markedly increased. The absolute difference is small, but to the patient who suffers that excess stroke, that’s a devastating complication,” said study co-author Dr. Hitinder Gurm, associate chief clinical officer at the University of Michigan.
The second study evaluated data from the largest publicly accessible database of U.S. hospitalization records, to see how pot users treated for heart problems tended to fare.
Researchers found that 67% of heart attack survivors who used pot had a subsequent heart attack, compared with 41% of nonusers.
Marijuana users also were more likely to land in the hospital for another round of angioplasty or bypass surgery, the researchers found.
“The frequency of recurrent heart attacks and cardiac interventions was higher among cannabis users, even though they were younger and had fewer risk factors for heart disease,” lead researcher Dr. Rushik Bhuva said in an AHA news release. He’s a cardiology fellow with the Wright Center for Community Health in Scranton, Pa.
Not all the data related to pot use was negative, however.
Yoo’s study found that marijuana smokers were less likely to suffer acute kidney injury as a result of their angioplasty compared with nonsmokers, and Bhuva’s study found that cannabis users had significantly lower rates of high blood pressure, diabetes and high cholesterol.
Researchers said there’s still too little known about how marijuana affects the body.
“We know previous studies have shown marijuana affects multiple organ systems in the body, including the heart, including the platelets,” Yoo said. “It’s an important research question that needs to be further pursued.”
Until more is known, patients and doctors should be on alert for potential side effects related to pot, said AHA marijuana expert Robert Page, a professor of clinical pharmacy at the University of Colorado in Aurora.
“I treat cannabis as a pharmacist just like I would any other medication, and when you prescribe any medication, it’s going to have drug interactions and side effects,” he said.