Cannabis linked to damaged heart

Regular cannabis use could cause structural changes to the heart which is a precursor to heart failure, a new study suggests.

Cannabis

Researchers from Queen Mary University of London found that regular use of the drug was associated with an increase in the size of the heart’s left ventricle – the main pumping chamber of the heart – in 47 people compared to 3,255 people who never or rarely use it.

A thickening of the muscle wall can make it harder for blood to be pumped out of the heart and flow around the rest of the body to vital organs. This reduced blood flow can increase the risk of heart and circulatory diseases such as stroke and heart attack.

The team, led by Dr Mohammed Khanji, also saw early signs of reduced heart function in recreational cannabis users. The muscle fibres in the left ventricle became deformed when the heart contracted and the amount of blood left in the heart after each heart beat was increased.

No changes were seen to the size or function of the other three heart chambers.

The study looked at heart MRI scans from 3,407 people in the UK Biobank study with an average age of 62, who did not have cardiovascular disease. Participants were divided into three categories: 1) never or rarely used cannabis with less than monthly occurrences, 2) previously regular users but more than five years before they were interviewed and 3) current regular users.

Need for more research

Professor Jeremy Pearson, Associate Medical Director at the British Heart Foundation, said:

"This is the first study to suggest that regularly using cannabis recreationally may affect the heart's ability to perform it's vital role pumping blood around the body.

"This study looked at a small number of cannabis users. We now urgently need a much larger study looking at how cannabis use impacts our heart health, so that people who do choose to use it can be made fully aware of any and all adverse effects."

The results are published today in JACC Cardiovascular Imaging.