Women who smoke even just one cigarette per day increase their risk of sudden cardiac death, a new study indicates.

Sudden Cardiac Death (SCD) is a dramatic and/or spontaneous death that is thought to be, and usually is, caused by a heart condition. In many cases, the person would have been unaware that they even had a heart problem and sometimes, no definite cause of death can be determined.

"Cigarette smoking is a known risk factor for SCD, but until now, we didn't know how the quantity and duration of smoking affected the risk among apparently healthy women, nor did we have long-term follow-up," explained the study's lead author, Dr Roopinder Sandhu, of the University of Alberta in Canada.

The research team looked at the incidence of SCD in over 101,000 healthy women who were taking part in an ongoing health study spanning at least 30 years. All of the participants were aged between 30 and 55 at the start of the ongoing study and most smokers said they had taken up the habit during their teenage years.

The researchers found that even light to moderate smokers - defined as one to 14 cigarettes daily - were almost twice as likely to suffer SCD compared to their non-smoking peers.

Furthermore, smokers with no history of heart disease, stroke or cancer were nearly two-and-a-half times more likely to suffer SCD compared with non-smokers.

Meanwhile, for every five years that a woman kept smoking, her risk of SCD rose by 8%.

However, even among women known to have heart disease, the risk of SCD fell to that of a non-smoker within 15 to 20 years of quitting the habit. The news was even better for quitters without heart disease - their risk of SCD fell within five years.

"SCD is often the first sign of heart disease among women, so lifestyle changes that reduce that risk are particularly important. Our study shows that cigarette smoking is an important modifiable risk factor for SCD among all women. Quitting smoking before heart disease develops is critical," Dr Sandhu added.

Details of these findings are published in the medical journal, Circulation: Arrhythmia & Electrophysiology.