Coming at a time when marijuana, medically known as cannabis, is on
track to become legal for medical or recreational use in more than half
of the United States, a new study sheds light on how the drug affects
Using marijuana raises the risk of stroke and heart failure even
after accounting for demographic factors, other health conditions and
lifestyle risk factors such as smoking and alcohol use, revealed a
research scheduled for presentation at the American College of
Cardiology's 66th Annual Scientific Session.
‘Marijuana use is associated with a significantly increased risk for stroke, heart failure, coronary artery disease and sudden cardiac death.’
While previous marijuana research has focused
mostly on pulmonary and psychiatric complications, the new study is one
of only a handful to investigate cardiovascular outcomes.
"Like all other drugs, whether they're prescribed or not prescribed,
we want to know the effects and side effects of this drug," said Aditi
Kalla, Cardiology Fellow at the Einstein Medical Center in
Philadelphia and the study's lead author. "It's important for physicians
to know these effects so we can better educate patients, such as those
who are inquiring about the safety of cannabis or even asking for a
prescription for cannabis."
The study drew data from the Nationwide Inpatient Sample, which
includes the health records of patients admitted at more than 1,000
hospitals comprising about 20 percent of U.S. medical centers.
Researchers extracted records from young and middle-aged patients - age
18-55 years - who were discharged from hospitals in 2009 and 2010, when
marijuana use was illegal in most states.
Marijuana use was diagnosed in about 1.5% (316,000) of more
than 20 million health records included in the analysis. Comparing
cardiovascular disease rates in these patients to disease rates in
patients not reporting marijuana use, researchers found marijuana use
was associated with a significantly increased risk for stroke, heart
failure, coronary artery disease and sudden cardiac death.
Marijuana use was also linked with a variety of factors known to
increase cardiovascular risk, such as obesity, high blood pressure,
smoking and alcohol use. After researchers adjusted the analysis to
account for these factors, marijuana use was independently associated
with a 26% increase in the risk of stroke and a 10%
increase in the risk of developing heart failure.
"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
Research in cell cultures shows that heart muscle cells have
cannabis receptors relevant to contractility, or squeezing ability,
suggesting that those receptors might be one mechanism through which
marijuana use could affect the cardiovascular system. It is possible
that other compounds could be developed to counteract that mechanism and
reduce cardiovascular risk, Kalla said.
Because the study was based on hospital discharge records, the
findings may not be reflective of the general population. The study was
also limited by the researchers' inability to account for quantity or
frequency of marijuana use, purpose of use (recreational or medical), or
delivery mechanism (smoking or ingestion).
Kalla suggested that the growing trend toward legalization of
marijuana could mean that patients and doctors will become more
comfortable speaking openly about marijuana use, which could allow for
better data collection and further insights into the drug's effects and