Electronic Cigarettes: No Adverse Effects on Coronary Microcirculation

Shelley Wood

August 31, 2013

AMSTERDAM, THE NETHERLANDS — Authors of a small study looking at the microcirculatory effects of electronic cigarettes say their findings offer more early reassurances of safety for the newfangled devices, given that long-term studies on hard end points will be a long time coming[1].

"This study adds to currently available evidence that supports that electronic cigarettes are significantly less harmful compared with tobacco," Dr Konstantinos Farsalinos (Onassis Cardiac Surgery Center, Kallithea, Greece) said here at the European Society of Cardiology (ESC) 2013 Congress . "Monitoring of consumers for several years will determine the long-term effects of electronic cigarette use."

At last year's ESC meeting, Farsalinos presented the results of a small study comparing effects on left ventricular function, blood pressure, and heart rate in 40 subjects, as reported by heartwire .

At this year's meeting, Farsalinos presented an analysis, this time in 60 subjects, looking at coronary flow velocity reserve (CFVR) and coronary vascular resistance index (CVRI). Thirty subjects were current smokers; in this group, CFVR/CVRI was measured in response to adenosine administration, 20 to 30 minutes after smoking two cigarettes and after using an electronic cigarette. Another 30 patients, made up of patients who had had their last cigarette at least one month previously, underwent the same tests, 20 to 30 minutes after using an electronic cigarette. Nonuse of cigarettes in this group was confirmed via testing of carboxyhemoglobin levels.

As Farsalinos showed here, no differences in CFVR and CVRI were seen following e-cigarette use, both in the nonsmoking group and in the group of smokers who were also studied after trying the e-cigarette. By contrast, smokers saw a 16% decrease in CFVR (p<0.001) and a 19% decrease in CVRI (p<0.001) 20 to 30 minutes after smoking their two cigarettes.

Harm Reduction?

"The electronic cigarette is not a product that is recommended for everyone as a new habit, it is recommended for smokers as an alternative to smoking to reduce consumption or to quit," Farsalinos said. "It is not for the general population; that should be clear."

Farsalinos acknowledged that the devices do emit low levels of harmful substances in addition to nicotine. "Both formaldehyde and acrolein have been found," he said. "They are produced in the heating and evaporation process, so they are not present in the liquid, but in the vapor. But the levels in electronic cigarettes are from 10 to 400 times lower compared with tobacco. The same was observed with nitrosamines, which are approximately 500 to 1000 times lower compared with tobacco cigarettes.

"The presence of such chemicals are found in very low levels; so we have to see for a long period of years if there are complications. But we can say [with confidence] that they are by orders of magnitude lower, and most likely it would be beneficial for smokers to switch to electronic cigarettes if they cannot quit by other methods."

Wait and See

Speaking with heartwire , both of the session chairs urged a wait-and-see approach. "These have been around for such a short time, we don't have all the data, and they are not controlled by the FDA," Dr Erika Sivarajan Froelicher (University of California, San Francisco), commented. "However, because smoking is such a serious problem, it seems like this is an attractive alternative, but definitely with the understanding that this is a means to an end, not a substitute for cigarettes."

What she likes about e-cigarettes is that unlike other smoking-cessation methods, electronic cigarettes "simulate the habit," or as she summed it up, "the component of holding something in your hand and sucking away at it.

"But we definitely need to have more research to see what the acute and long-term effects of the electronic cigarettes, including for how many people it has been the gateway to quitting."

Dr Chen Chen-Huan (National Yang-Ming University, Taipei, TW) had even stronger views, pointing out that Farsalinos et al's study, by design, did not measure microcirculatory response immediately after use of the electronic device. Farsalinos said this was in order to avoid measuring the direct effects of nicotine, but that, says Chen-Huan, may downplay important hazards.

"We must be very careful. The e-cigarette is suppose to be harm reduction, but its safety still needs more research. According to this study, the electronic cigarette does not affect the microcirculation or coronary circulation, but I'm not sure it's a true negative effect because the sample size is small, and they skipped the first few minutes after smoking."

He continued: "I'm worried . . . that if the public thinks it's safe, then some nonsmokers will want to try it."

During the session, Farsalinos pointed out that "five or six" volunteers in the study ended up quitting smoking in the months after the study, despite the fact that researchers did not recruit volunteers to be a part of a "quitting" study. But he agreed that researching the role of electronic cigarettes in smoking cessation will be key to understanding this field.

Farsalinos noted in his disclosures that he personally has no financial conflicts related to electronic cigarettes, although his institution received study funding from e-cigarette manufacturer Flavourart. Farsalinos has a website devoted to electronic cigarette research, which stresses that he and other contributors to the site have no financial ties to the tobacco or electronic cigarette industries.


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