The more a person smokes, the greater the risk of developing a heart rhythm disorder, according to a new study published July 11 in the European Journal of Preventive Cardiology.
“Epidemiological studies on smoking and atrial fibrillation (AFib) have been inconsistent, with some studies showing a positive association while others have found no association,” wrote Dagfinn Aune, PhD, of the Bjørknes University College in Oslo. “It is also unclear whether there is a dose-response relationship between the number of cigarettes smoked or pack-years and the risk of atrial fibrillation.”
The researchers conducted a review of 29 studies from Europe, North America, Australia and Japan with more than 39,000 incident cases of atrial fibrillation among 677,785 participants.
For every 10 cigarettes smoked per day, the researchers found a 14 percent increase in the risk of atrial fibrillation. They also found every 10 pack-years correlated with a 16 percent increase in risk of AFib.
Additionally, compared to individuals who have never smoked, current smokers had a 32 percent increased risk of developing AFib, while “ever smokers,” or current and former smokers combined, had a 21 percent increased risk and former smokers had a 9 percent increased risk.
“There was a clear dose-response relationship between the increasing number of cigarettes smoked per day and the risk of atrial fibrillation and no evidence that the association was non-linear,” Aune et al. wrote. “The strength of the association by smoking status is also consistent with a dose-response relationship as the association was strongest for current smokers, intermediate for ever smokers and lowest for former smokers.”
Dose-response relationship between smoking and AFib may suggest an underlying biological relationship. They noted smoking increases diabetes, chronic obstructive pulmonary disease and heart failure—all risk factors for AFib.
Nicotine also stimulates sympathetic neurotransmission increasing plasma catecholamine concentrations and increasing the resting heart rate, blood pressure and increasing the risk of hypertension, which is associated with an increased risk of AFib.
“Our findings have important clinical and public health implications as they provide evidence of a dose-response relationship between the increasing number of cigarettes smoked and the risk of atrial fibrillation, but also evidence of a reduced risk among former smokers compared to current smokers,” Aune and colleagues said. “The findings therefore underscore the importance of avoiding smoking among non-smokers and smoking cessation among current smokers to prevent atrial fibrillation, although further studies are needed to quantify the duration of cessation that is needed before risk is reduced, and if the risk at some point reaches that of never smokers."