Smoking is the most preventable risk factor for cardiac and
lung disease and is expected to cause 1 billion deaths
during the 21st century. Electronic cigarettes have been
marketed in recent years as a safer habit for smokers, with
several millions of people already using them worldwide.
Electronic cigarettes simulate the effect of smoking by
producing an inhaled vapor. The device consists of a
battery, a cartridge containing liquid and a heating
element which gets warm and evaporates the liquid.
Laboratory analyses of the liquids show that they are less
toxic than regular cigarettes. Most studies have found no
nitrosamines, but even in studies where nitrosamines were
found, the levels detected were 500-1400 times less than
the amount present in one tobacco cigarette. This means
that electronic cigarettes must be used daily for 4-12
months to get the amount of nitrosamines present in a
single tobacco cigarette.
Since heart disease is the main cause of morbidity and
mortality in smokers, with 40% of deaths in smokers due to
coronary artery disease alone, the research team decided to
perform the first clinical study of the acute effects of
electronic cigarettes on cardiac function.
They decided to compare their results with the acute
effects of regular cigarettes on cardiac function since
electronic cigarettes are marketed to smokers only, as an
Previous studies from the research group and several others
have shown that acute smoking inhalation produces
significant defects in myocardial function. This indicates
that subclinical dysfunction is already present in
apparently healthy asymptomatic young people who smoke
tobacco cigarettes. The goal was to evaluate whether these
signs of preclinical disease appear in a similar population
after using electronic cigarettes.
The researchers measured myocardial function in 20 healthy
young daily smokers aged 25-45 years before and after
smoking one tobacco cigarette and 22 daily electronic
cigarette users of similar age before and after using the
device for 7 minutes.
Experienced users of electronic cigarettes were studied
because they use the device more intensively than
first-time users. Although both groups were of equal age,
users of electronic cigarettes had a 44% higher lifetime
tobacco smoking exposure compared to current smokers.
For the electronic cigarettes, a commercially available
liquid with a nicotine concentration of 11mg/ml was used
(NOBACCO USA Mix). This was tested by an independent
toxicology laboratory and found to contain no nitrosamines
or polycyclic aromatic hydrocarbons.
Myocardial function was examined using cardiac ultrasound
(echocardiography) and hemodynamic measurements (blood
pressure and heart rate).
The researchers found that smoking one tobacco cigarette
led to significant acute myocardial dysfunction but
electronic cigarettes had no acute adverse effects on
cardiac function. Smoking a tobacco cigarette had important
hemodynamic consequences, with significant increases in
systolic and diastolic blood pressure and in heart rate. In
contrast, electronic cigarettes produced only a slight
elevation in diastolic blood pressure. Dr Farsalinos said:
"This is an indication that although nicotine was present
in the liquid used (11mg/ml), it is absorbed at a lower
rate compared to regular cigarette smoking."
The echocardiography examination focused on the function of
the left ventricle, the part of the heart that receives
oxygenated blood from the lungs (filling or diastolic
phase) and then delivers the blood to the whole body
(pumping or systolic phase). The investigators found
significant defects in the diastolic phase of left
ventricular function after smoking one cigarette, with four
echocardiographic parameters indicating worsening function.
In contrast, none of the echocardiographic parameters
showed any significant worsening in subjects after using
the electronic cigarette. "Diastolic dysfunction is very
important because it is usually the first defect that is
detected before any clinically-evident cardiac disease
develops," said Dr Farsalinos.
He added: "It is too early to say whether the electronic
cigarette is a revolution in tobacco harm reduction but the
potential is there. It is the only available product that
deals with both the chemical (nicotine delivery) and
psychological (inhaling and exhaling 'smoke', holding it,
etc) addiction to smoking, laboratory analyses indicate
that it is significantly less toxic and our study has shown
no significant defects in cardiac function after acute
Dr Farsalinos continued: "More clinical studies need to be
done before suggesting that this is a revolutionary
product. However, considering the extreme hazards
associated with cigarette smoking, currently available data
suggest that electronic cigarettes are far less harmful and
substituting tobacco with electronic cigarettes may be
beneficial to health."
Dr Farsalinos will also present his results during an ESC
Congress 2012 scientific session tomorrow.
Konstantinos Farsalinos, MD1, Dimitris Tsiapras, MD1,
Stamatis Kyrzopoulos, MD1, and Vassilis Voudris, MD1
1 Onassis Cardiac Surgery Center, Athens, Greece