March 30, 2017

Stanton A. Glantz, PhD

First evidence that e-cig use increases heart attacks, independent of the effect of smoking cigarettes

Every time I have posted a comment on a new study showing that e-cigarettes adversely affect blood vessels and blood in ways that increase risk of a heart attack, a friend and colleague who remains part of the (shrinking) collection of e-cigarette enthusiasts emails me and with he comment that, “if they are so bad where’s the evidence that e-cigarettes increase the risk of a heart attack?”
 
The first evidence just appeared.
 
Using the National Health Interview Survey (NIHS), a large national survey done in the US, Nardos Temesgen and colleagues at George Washington University, found that the odds of a heart attack  increased by 42% among people who used e-cigarettes. 
 
This increase in risk was on top of the increases in risk due to any smoking that the e-cigarette users were doing.  This  is a particularly important finding because most e-cigarette users are dual users who keep on smoking at the same time that they use e-cigarettes.  What this means is that dual use of e-cigarettes with cigarettes is substantially more dangerous than smoking alone.
 
The assumption of most people – including me – has been that e-cigarette use would not add much risk to cigarettes.  That is not the case.  E-cigarette use increases the risk of a heart attack about as much as having diabetes.
 
The work also controlled for a wide range of confounding variables.  In addition, the risks associated with other factors (like smoking, diabetes, and high blood pressure) in this study were similar to those established in earlier work.  This fact strengthens the conclusions that e-cigarettes represent an independent cause of heart attacks.
 
The abstract of the study, “A cross sectional study reveals an association between electronic cigarette use and myocardial infarction,” is available here.
 
Here is the abstract:
 
Background: E-cigarettes (E-cigarettes) have grown in popularity as an alternative to traditional cigarettes especially among consumers who want to reduce the risk of morbidity and mortality associated with smoking. Nonetheless, a recent study showed both E-cigarettes and traditional cigarettes cause an increase in oxidative stress and endothelial dysfunction, however this effect is less pronounced with E-cigarettes. Currently, there is a limited study that shows the impact of E-cigarette in the cardiovascular system. Therefore, data from the 2014 National Health Interview Survey (NHIS) was used to evaluate the effect of E-cigarettes on the cardiovascular system, specifically the effect on myocardial infarction (MI).
Methods: Analysis of the 2014 National Health Interview Survey (NHIS) database was performed to examine the effect of E-cigarettes on MI. Initially, subjects were assigned to one of two groups: those with a history of MI and those without a history of MI. The t-test and chi-square test were subsequently applied to compare the different demographics and health characteristics between these two groups. A logistic regression model was then used to measure the association between E-cigarettes and history of MI. Data was adjusted for multiple risk factors for MI including age, gender, race, body mass index, income, the status of smoking cigarettes, and history of hypertension, diabetes, and hypercholesterolemia.
Results: A total of 35,156 subjects were included in the final logistic model. This model showed that increasing age (OR, 1.04; p Conclusions: Our findings indicate that Electronic cigarette use, when adjusted for other risk factors, is associated with a 42 % increased odds of myocardial infarction. This increase in odds is consistent regardless of traditional cigarette smoking history. More studies are needed to further assess this risk.
 

Comments

Comment: 

Heart attacks&nbsp;<em;cause</em;&nbsp;quit attempts. So <em;why </em;would we<em; not expect </em;to find increased e-cigarette use among&nbsp;smokers with a history of&nbsp;myocardial infarction?
Also if more dependent smokers are more likely to use e-cigarettes, then EC use is likely correlated heavier smoke exposure.

Comment: 

While this is a theoretical problem, if what you are suggesting is what was happening, the e-cig effect would not have been significant, since it would be captured in the cig smoking variables.&nbsp; The fact that the other covariates (including the smoking effect) are all similiar to other estimates, including longitudinal studies, also argues against this idea.
&nbsp;
In addition, the fact that, as I said in the original blog post, this is exactly what would be expected based on the biology, strengthens the confidence one can have in the epidemiological results,

Comment: 

"The work also controlled for a wide range of confounding variables."
&nbsp;
Did it control for whether the subjects had their heart attack <em;before </em;or <em;after </em;they started vaping? The reason I ask is that I started vaping <strong;because </strong;I had a heart attack.&nbsp;

Comment: 

This is only a poster by a group of new young MDs with no apparent expertise in tobacco control, toxicology, statistics or any branch of relevant science - are you confident it is a rigorous study that demonstrates significant association between e-cigs and heart attacks?&nbsp;

Comment: 

I have checked.&nbsp; The authors are postdoctoral fellows and medical residents, some with formal statistical training.&nbsp; (Those are the people who do a lot of the medical research that gets published.)
&nbsp;
This poser was presented at the American College of Physicians meeting in San Diego, which is peer reviewed.&nbsp; It won an award there.

Comment: 

As I noted in the original blog post, the data are still accumulating on the effects of e-cigarettes.
&nbsp;
I agree that <em;if you switch entirely from conventional cigarettes to e-cigarettes</em; that is less dangerous.&nbsp; You get a much lower dose of cancer-causing chemicals.&nbsp;
&nbsp;
But the evidence is rapidly accumulating that e-cigarettes substantially increased hearts and non-cancer lung disease risk.
&nbsp;
My advice:&nbsp; Now that you have stopped cigarettes, stop the e-cigarettes.
&nbsp;
(Most e-cigarette users continue to smoke; for most people e-cigarettes make it harder to quit cigarettes.)

Comment: 

Dr Glantz, Nicotine itself has been shown to damage heart tissue, in lab studies, has it not?

Comment: 

I don't know about direct damage to the heart muscle.  Nicotine does activate the autonomic nervous system which, over time, increases heart disease risk.

Comment: 

I had to search some, and thought that there were more recent studies on this topic, but this is the kind of research I was referring to. https://www.sciencedaily.com/releases/2013/12/131215160852.htm Excerpt from the Science Daily recap follows, here.
"In Dr. Hai's experiments, nicotine appeared to drive the formation of a kind of cellular drill called podosome rosettes, which are members of the invadosome family, consisting of invadopodia, podosomes and podosome rosettes. These specialized cell surface assemblies degrade and penetrate the tissue during cell invasion. Invasion of vascular smooth muscle cells from the middle layer of the arterial wall (media) to the inner layer of the arterial wall (intima) contributes substantially to plaque formation in atherosclerosis."

Comment: 

This is a summary of some of the research, by Dr Hai, of Brown University, that I thought showed direct damage to heart tissue.

https://qa1.medicalbag.com/vital-signs/theyre-the-cigarette-of-the-21st-...

Excerpt: "Chi-Ming Hai, a molecular pharmacology professor at Brown University, believes the answer lies in nicotine. Hai exposed heart cells to nicotine and found that after 6 hours, podosome rosettes formed and ate through the tissue. The nicotine acted as "a kind of cancer of the blood vessel, which is waking up these cells and breaking them away from their surrounding matric [sic] and then migrating having an effect like it is almost like digging a hole through the wall," he said."

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