Might have some heart benefits
By University
of California, San Francisco
Edited by Sadie Harley, reviewed by Robert Egan
.webp)
The study, published in the Journal
of the American College of Cardiology, is among the first to examine
the acute cardiovascular effects of inhaled cannabis in people living their
normal daily lives. While the findings challenge assumptions drawn largely from
observational studies, the researchers caution that they should not influence
medical or behavioral decisions around cannabis use.
With millions of Americans using cannabis, studies like this
are increasingly important for understanding its health effects, the
researchers said.
"We were surprised by the results because they
contradicted our original hypothesis," said Gregory Marcus, MD, MAS, an
endowed professor of atrial fibrillation research in the UCSF Division of
Cardiology. "That's why randomized trials are so important. When the data
challenge our expectations, our job as scientists is to understand them, not
ignore them."
The trial enrolled 108 adults who regularly smoked or vaped
cannabis but had no history of clinically diagnosed cardiac arrhythmias. Over
14 days, participants were randomly assigned each day to either inhale cannabis
or abstain while wearing a continuously recording electrocardiographic monitor,
activity tracker, sleep monitor and continuous glucose monitor.
Participants served as their own controls, allowing
investigators to compare physiological changes during cannabis use and
abstinence days.
Strongest predictor of premature atrial contractions
Unlike previous studies that relied largely on participants'
self-reports or medical records, this randomized crossover trial continuously
monitored every heartbeat, enabling researchers to measure physiological
changes in real time under everyday conditions.
Researchers found that cannabis inhalation was associated
with a statistically significant reduction in extra or early heartbeats, known
as cardiac ectopy. The reduction was driven by fewer extra heartbeats that
began in the heart's upper chambers, known as premature atrial contractions
(PACs).
The frequency of PACs is the single most potent predictor of
atrial fibrillation, while PVCs can predict heart failure. Although these early
heartbeats are common, researchers still know relatively little about what
determines their frequency.
No significant change was observed in extra heartbeats
originating in the lower chambers, called premature ventricular contractions
(PVCs).
A clue, not a health endorsement
The researchers found no significant differences in daily
step counts, sleep duration or glucose levels, which was also surprising.
Together, the findings illustrate how randomized trials can produce a different
and more nuanced picture than observational research alone.
Marcus emphasized that the findings should not be
interpreted as evidence that cannabis benefits cardiovascular health.
"This study examined the acute effects of cannabis in
people who use it regularly and was not designed to evaluate the long-term
health consequences," he said.
"The overall health effects of inhaled cannabis may
still be net negative, but these findings suggest there may be something about
cannabis that can teach us more about the biological mechanisms that produce
premature atrial contractions. That knowledge could eventually lead to new
approaches for preventing or treating abnormal heart rhythms."
Publication details
Acute Effects of Cannabis Inhalation on Cardiac Ectopy,
Physical Activity, Sleep, and Glucose, Journal of the American College
of Cardiology (2026). DOI:
10.1016/j.jacc.2026.07.014
Journal information: Journal
of the American College of Cardiology
