The more you smoke, the greater your risk of a heart rhythm disorder called atrial fibrillation, according to a study published in the European Journal of Preventive Cardiology.
The study found a 14% increase in the risk of atrial fibrillation for every ten cigarettes smoked per day. There was a linear dose-response relationship, meaning that the risk increased with each additional cigarette smoked.
Compared to people who had never smoked, current smokers had a 32% increased risk of atrial fibrillation, while ever smokers (current and former smokers combined) had a 21% increased risk, and former smokers had a 9% increased risk – providing further evidence of a dose-response relationship.
“If you smoke, stop smoking and if you don’t smoke, don’t start,” said study author Dr Dagfinn Aune, postdoctoral researcher at Imperial College London, UK, and associate professor at Bjørknes University College in Oslo, Norway. “We found that smokers are at increased risk of atrial fibrillation, but the risk is reduced considerably in those who quit.”
Atrial fibrillation is the most common heart rhythm disorder (arrhythmia). It causes 20-30% of all strokes and increases the risk of dying prematurely. One in four middle-aged adults in Europe and the US will develop atrial fibrillation. It is estimated that by 2030 there will be 14-17 million patients with atrial fibrillation in the European Union, with 120,000-215,000 new diagnoses each year.
Few studies have assessed whether there is a dose-response relationship between the number of cigarettes smoked and the risk of atrial fibrillation. The authors of the current study investigated this issue by conducting a meta-analysis of 29 prospective studies from Europe, North America, Australia and Japan with a total of 39,282 incident cases of atrial fibrillation among 677,785 participants.
Compared to zero cigarettes per day:
- Smoking five cigarettes per day was associated with a 9% increased risk of atrial fibrillation
- 10 cigarettes per day was associated with a 17% increased AF risk
- 15 cigarettes per day was associated with a 25% increased AF risk
- 20 cigarettes per day was associated with a 32% increased AF risk
- 25 cigarettes per day was associated with a 39% increased AF risk
- 29 cigarettes per day was associated with a 45% increased AF risk.
Every 10 pack-years of smoking was associated with a 16% increased risk of developing atrial fibrillation. Pack-years are calculated by multiplying the number of packs of cigarettes smoked per day by the number of years the person has smoked.
“Our results provide further evidence of the health benefits of quitting smoking and, even better, to never start smoking in the first place,” Aune said. “This is important from a public health perspective to prevent atrial fibrillation and many other chronic diseases.”