Wednesday, August 24, 2016

Anti-Tobacco Researcher: Cardiovascular Effects of E-Cigarettes are Nearly as Big as Smoking

Dr. Stan Glantz has posted a commentary on his blog in which he asserts that the results of a paper published earlier this summer in the Journal of the American College of Cardiology demonstrate that "the [cardiovascular] effects of e-cigarette use are nearly as big as smoking."

Dr. Glantz nicely summarizes the major study results: "One of the many ways that smoking damages the cardiovascular system is by stiffening major blood vessels. How stiff the aorta (the big vessel leading directly out of the heart) is can be measured by how fast the pressure wave moves down the aorta, the pulse wave moving faster when the aorta is stiffer. Following use of an e-cigarette for just 5 minutes, the pulse wave velocity increased by about 40% as much as smoking a conventional cigarettes and about 80% after 30 minutes of use."

The Rest of the Story

I agree that the study reveals that vaping has acute adverse effects on the cardiovascular system. However, I would not describe the effects of vaping as being "nearly as big as smoking." After all, smoking causes heart disease and stroke. All this study demonstrates is that vaping causes acute arterial stiffness. The study does not demonstrate whether over time, this acute effect will actually translate into vascular disease.

The results of the study are not at all surprising, since we already knew that nicotine itself causes arterial stiffness. Thus, it would have been shocking if vaping was not found to increase arterial stiffness.

What Dr. Glantz failed to note was that the adverse effect of vaping on arterial stiffness disappeared within 30 minutes after discontinuation of vaping. In contrast, the adverse effect of smoking was sustained at the 60 minute mark. The effect is reversible, and therefore it cannot be assumed that vaping will cause sustained injury that over time will lead to cardiovascular disease. It would take decades of vaping before it is even plausible that vascular disease could occur. It is quite premature to conclude that the effects of vaping are "as bad as smoking."

There are some other important things that Dr. Glantz failed to note and which anti-vaping groups will not tell you. For one, drinking coffee also causes arterial stiffness. But coffee consumption is not known to be associated with the development of cardiovascular disease and no one would state that the cardiovascular effects of drinking coffee are "as bad as smoking," even though caffeine, like nicotine, causes changes in arterial compliance acutely that are similar to the acute arterial compliance changes seen with smoking.

Sadly for my students, taking an exam has also been shown to increase aortic stiffness, just like smoking. However no one would argue that the cardiovascular effects of taking an exam are as bad as smoking. Hopefully none of my students has read Dr. Glantz's post because I can just see them trying to get out of my next exam by claiming that it will cause aortic stiffness and their doctor has advised them against any exposures that have adverse cardiovascular effects.

Watching a suspense movie also increases aortic stiffness, but no one would argue that watching a movie has cardiovascular effects that are "as bad as smoking," and as far as I know, no one has claimed that watching scary movies is a risk factor for cardiovascular disease. I didn't see too many people keeling over with heart attacks when watching Anthropoid.

High intensity resistance training also increases aortic stiffness, but I don't see a sign in the gym warning people that this type of exercising has cardiovascular effects that are "as bad as smoking."

Listening to classical or rock music actually decreases aortic stiffness, although I find that listening to Justin Bieber increases my annoyance level to extremes and I'm sure my aorta is as stiff as a lead pipe under those conditions. But I'm aware of no evidence that Beliebers have increased rates of cardiovascular disease.

Tilting your head up also increases vascular resistance.

Watching World Cup soccer also increases vascular resistance but we don't tell soccer fans that they are engaging in a habit that has health effects that are as bad as smoking.

I am not trying to downplay the finding that vaping results in acute, adverse changes in vascular function that - if repeated and sustained over decades - could plausibly increase cardiovascular disease risk. However, it is premature to draw such a conclusion and disingenuous to tell the public that the cardiovascular effects of vaping as as bad as those of smoking.

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