Cannabis itself is harmful to cardiovascular health and increases the chance of early death regardless of related factors such as smoking tobacco, new research reveals.
Data taken from more than 1,000 US hospitals found that people who used the drug had a 26 per cent higher chance of suffering a stroke than those who did not, and a 10 per cent higher chance of having a heart attack.
The findings held true after taking into account unhealthy factors known to affect many cannabis smokers, such as obesity, alcohol misuse and smoking.
This leads us to believe that there is something else going on besides just obesity or diet-related cardiovascular side effects
Dr Aditi Kalla, Einstein Medical Center, Philadelphia
They indicate there is something intrinsic about cannabis which can damage the proper functioning of the human heart.
"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,” said Dr 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.”
Previous research in cell cultures has shown 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.
The research team analysed more than 20 million records of young and middle-aged patients aged between 18 and 55 who were discharged from 1,000 hospitals in 2009 and 2010, when marijuana use was illegal in most states.
It identified 316,000 patients - 1.5 per cent - where marijuana use was diagnosed in the notes.
Their cardiovascular disease rates were compared to those who shunned the drug.
The research was published yesterday at a meeting of the American College of Cardiology in Washington DC.