The American Heart Association claims that three different types of smoking cessation therapies do not pose serious heart risks, quashing concerns that certain products may increase the risks of heart attack, stroke or heart-related death.

Researchers looked at the results of 63 clinical trials involving 30, 508 people who were quitting smoking using either nicotine replacement gums and patches, the nicotine addiction treatment varenicline (Chantix), or taking the antidepressant bupropion (Wellbutrin), which can reduce cravings and other unwanted withdrawal effects.

The results, published in the journal Circulation, did not find evidence of any increased risk of serious heart events among participants.

The Centers for Disease Control and Prevention (CDC) estimates that 45.3 million Americans smoke and that it accounts for approximately 443,000 deaths a year - that is one in every five deaths.

However, the CDC also notes that there are more former smokers in the US today than there are current ones.

Irregular or rapid heart rates

Stopping smoking is associated with increased life expectancy, improved cardiovascular health, better quality of life and reduced health care costs.

But, the CDC acknowledges, nicotine dependency is a chronic condition that may require repeated interventions to achieve the goal. Withdrawal symptoms for nicotine include irritability, anxiety, difficulty in concentrating and increased appetite.

Scientists know that nicotine replacement therapies, such as patches and chewing gum, increase minor heart symptoms, such as irregular or rapid heartbeat.

The combination of both therapies, wearing a patch and chewing gum whenever there is the urge to smoke has been shown to be more effective but does lead to more side effects.

Edward J. Mills, study co-author and associate professor of medicine at Stanford University and Canada Research Chair at the University of Ottawa, explains:

"These more minor risks are well known to clinicians and usually pass with time. They occur most often when people are taking nicotine replacement therapy and smoking at the same time, which is a bad idea."

Benefits of quitting outweigh risks

But Prof. Mills is also quick to point out that the benefits of stopping smoking "outweigh any potential risks from smoking cessation therapies," especially among individuals who are relatively healthy.

He continues:

"It's possible that the risk factors might be different in people with multiple diseases. Patients should discuss with their health care provider any potential risk factors that they may have developed from their smoking history. For patients who have chronic lung disease or other associated cardiovascular risks, clinicians should determine which smoking cessation aid to use by their risk profiles."

The study also found that the antidepressant bupropion protected against serious heart events.

In spite of all the information about the dangers of smoking, a recent study showed that as many as 600 under-16s start smoking every day in the UK, compared with 1,000 Americans aged under 18.

The American Heart Association publishes advice about quitting smoking.