ACC.17: Research at ACC shows that marijuana increases risk for heart failure, stroke

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 - Aditi Kalla
Aditi Kalla

Though cannabis has increasingly been making its way into healthcare as a method for treating a series of conditions, new research on the drug, presented at the American College of Cardiology (ACC)’s Scientific Session beginning March 17, finds that it could cause severe cardiovascular events.

The research was led by Aditi Kalla, MD, a cardiology fellow at the Einstein Medical Center in Philadelphia, who presented the findings March 18. This is the first study to utilize a large national patient database to demonstrate such an association between cannabis, heart failure and stroke, Kalla said in a March 7 web briefing with reporters. The findings give physicians valuable knowledge on the drug, which is now legal in 28 states.

“Cannabis is currently the most commonly used drug in the U.S. and worldwide,” Kalla said. “From a physician’s perspective, we now need to be more knowledgeable about the risks and benefits of cannabis.”

Her research was based on data from the Nationwide Inpatient Sample database, which includes the health records of patients admitted at more than 1,000 hospitals, which is about 20 percent of medical centers in the U.S. The researchers specifically looked at records from patients aged 18 to 55 years old, who were discharged from hospitals in 2009 and 2010 when marijuana use was still illegal in most states, according to the study. About 1.5 percent, or 316,000, of the patients used marijuana.

Study results showed that marijuana use was associated with a significantly increased risk for stroke, heart failure, coronary artery disease and sudden cardiac death. It was also associated with a variety of risk factors known to cause cardiovascular disease, including obesity, high blood pressure, smoking and alcohol consumption. But even after the researchers adjusted their analysis to account for these factors, cannabis use was independently associated with a 26 percent increase in the risk of stroke and a 10 percent increase in the risk of developing heart failure.

By examining heart muscle cell cultures, the researchers found they have cannabis receptors relevant to contractility, or squeezing ability, which suggests those receptors might be on way that cannabis use affects the cardiovascular system, Kalla said.

One limitation of the study is that the findings were based on hospital discharge records, so it may not be reflective of the general population.

“Even when we corrected for known risk factors, we still found a higher rate of both stroke and heart failure in these patients, so that leads us to believe that there is something else going on besides just obesity or diet-related cardiovascular side effects,” Kalla said. “More research will be needed to understand the pathophysiology behind this effect.”