# Cannabis use and heart rhythm research

> Live situation record from CLSTR: https://clstr.news/situations/cannabis-use-and-heart-rhythm-research
> Updated: 2026-08-31T04:30:00.000Z. Sources: 12. Developments: 3.

Researchers at the University of California, San Francisco, conducted the MARY-JANE trial to investigate the relationship between cannabis use and heart rhythm. The study, involving approximately 100 to 108 adults, utilized a crossover design where participants wore continuous electrocardiographic, activity, and glucose monitors over a 14-day period.

Findings published in the Journal of the American College of Cardiology indicate that habitual cannabis users experienced approximately 9 percent fewer premature heartbeats on days they inhaled the substance compared to days they abstained. This reduction was primarily attributed to a 10 percent decline in premature atrial contractions, while premature ventricular contractions showed no significant change. The study also reported no significant differences in sleep duration, physical activity, or average glucose levels.

Senior author Gregory Marcus noted that these results contradict previous observational data and initial hypotheses that expected cannabis to increase irregular heartbeats. While the study showed consistent correlations in heart rate variability, researchers cautioned that these findings do not imply absolute health safety and should not be used to influence medical or behavioral decisions regarding cannabis consumption.

## Claims

- A new study was published in the Journal of American College of Cardiology. (corroborated by 3 sources)
- Regular marijuana users experienced fewer ectopic heartbeats on days they inhaled cannabis compared to days they abstained. (corroborated by 3 sources)
- No significant differences were found in premature ventricular contractions, physical activity, sleep duration, or average glucose levels related to cannabis use. (corroborated by 3 sources)
- Gregory Marcus stated that correlations between random assignment and heart rate variability were significant and consistent. (corroborated by 3 sources)
- The study does not indicate absolute health safety regarding cannabis use. (corroborated by 3 sources)
- The study involved regular cannabis users without a history of cardiac arrhythmia. (corroborated by 3 sources)
- Participants were required to either inhale or abstain from marijuana daily for a period of 14 days. (corroborated by 3 sources)

## Timeline

### 2026-08-31: University of California study finds cannabis inhalation reduces ectopic heartbeats

A University of California study found that inhaled cannabis was associated with a 9% reduction in ectopic heartbeats among regular consumers.

2 sources. https://clstr.news/cluster/medical-studies-report-findings-on-cannabis-inhalation-and-heart-failure-treatments

### 2026-08-28: Cannabis use linked to fewer ectopic heartbeats in new study

A study in the Journal of American College of Cardiology found that regular marijuana users had fewer ectopic heartbeats on days they used cannabis compared to days they abstained.

10 sources. https://clstr.news/cluster/cannabis-use-linked-to-fewer-ectopic-heartbeats-in-new-study

### 2026-08-12: University of California study finds cannabis use linked to fewer premature heartbeats

A University of California, San Francisco study found that habitual cannabis users had 9% fewer premature heartbeats on days they inhaled cannabis compared to days of abstinence.

2 sources. https://clstr.news/cluster/university-of-california-study-finds-cannabis-use-linked-to-fewer-premature-heartbeats

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Cite as: Cannabis use and heart rhythm research. CLSTR, https://clstr.news/situations/cannabis-use-and-heart-rhythm-research