Previous studies have already shown that smoking increases the probability of arrhythmias (heart rhythm disorders) and is an important factor in the development of cardiovascular diseases. In contrast, electronic cigarettes and heated tobacco products have gained popularity due to the general perception that they are less harmful than smoking tobacco.
But according to a new study by a team of researchers at the University of California, San Francisco, the harmful effects of e-cigarettes and marijuana on the heart are similar to those of tobacco cigarettes.
“We found that cigarettes, e-cigarettes, and marijuana significantly disrupt the electrical activity, structure, and neural regulation of the heart,” says lead author Huiliang Qiu, MD, Ph.D., a postdoctoral fellow in the UCSF department of cardiology.
“Often, a single change can cause an arrhythmia.” Unfortunately, these adverse effects on the heart are quite extensive.
Effects of vapors
The heart must pump blood efficiently and in time to function properly. Thanks to the nerves that control it, the heart has its own electrical control system. It also has the ability to conduct electrical impulses through the heart muscle in a way that synchronizes the entire pumping time of the heart.
When the heart cannot properly process electrical signals, it can cause life-threatening arrhythmias because different areas of the heart work out of sync—essentially fighting each other instead of working as one efficient pump.
In this study, the research team conducted an eight-week experiment in rats in which they exposed rats to cigarette smoke (Marlboro Red), JUUL “vapor” from the popular e-cigarette, heated tobacco products (IQOS aerosol), marijuana smoke, and modified marijuana smoke that lacks all cannabinoids compared to air alone.
Rats breathed clean air for a total of five minutes between five-second bursts of smoke or aerosol. This process was done once a day, five days a week, for eight weeks. During this time, rats exposed to the products had a decrease in heart rate but not in breathing and an increase in blood pressure.
After eight weeks, the team performed various tests on the rats to determine the electrical and physical properties of their hearts.
The final results showed that all the tested products caused an increase in scarring of the heart, a decrease in the number of blood vessels, a negative change in the type of nerve found in the heart, a significant weakening of the ability to change the heart rate, and an increased likelihood of arrhythmias.
“It’s remarkable that all these tobacco and marijuana products had similar effects,” said senior author Matthew Springer, Ph.D., professor of cardiology at UCSF. “And what’s really striking is that it was caused by one realistic smoking or vaping session per day.”
“Although rats are a good model for many cardiovascular effects in humans, there are differences, and firm conclusions about human effects cannot be drawn from rat studies alone,” he added to explain the study’s limitations.
Bottom line: E-cigarettes, IQOS, and marijuana-infused cigarettes share many of the potentially harmful effects of smoking.
But he also noted that the results are consistent with various reports of cardiac arrhythmias associated with e-cigarettes or marijuana.
The results of the present study on various physical disorders of the heart, such as scarring and nerve changes, suggest a similar explanation.
“The bottom line is that e-cigarettes, IQOS, and marijuana cigarettes still contain many of the potentially harmful effects of smoking,” Springer said. “None of these products should be a safe substitute for smoking.” In other words, just breathe air.