Issue link: https://viewer.e-digitaledition.com/i/1082532
SMOKING IS A well-established risk factor for cardiovascular disease, but an association between smoking and atria l fibril- lation is less settled. Neither the CDC nor the Heart Rhy thm Society names smoking as a risk factor for atria l fibrillation. Studies investigating a possible association have produced conflicting results. Most researchers would agree that smoking is associated with atria l fibrillation risk, says Elsayed Z . Solima n, MD, Professor of Public Hea lth Sciences at Wa ke Forest Baptist Medical Center and co-author of a 2017 study in the Journal of Cardiology that examines the relationship between smoking and atria l fibrillation risk. His research team concluded that smoking may affect atrial fibrillation risk through its influence on other risk factors, such as hypertension and obesity, and that variance in the streng th of the smoking-atrial fibrillation a ssociation a mong subg roups in the 2017 study may help explain previous studies' diverging results. "[T]here was no association [ between smoking and atria l f ibr i l lat ion] when we a dju s t ed for m a ny con fou nders," Dr. Soliman says. "When we adjusted only for age or sex, we saw an association, but when we adjusted for more confounders, the association disappeared. Once we started to look at differences between subgroups, we found the association was [stronger] in some groups compared to others. The association was stronger in younger people compared to older, and stronger in people with cardiovascular disease compared to those without. In black people, the association was significant, but not in whites." A DOSE-RESPONSE REL ATIONSHIP To shed more light on smoking's effect on atrial fibrillation risk, Dagfinn Aune, PhD, Associate Professor at Bjørknes University College in Oslo, Nor way, a nd a postdoctora l resea rcher at Imperia l College London, a nd three colleag ues conducted a systematic review of the literature a nd a meta-a na lysis of 29 cohort studies published through July 20, 2017. The authors found a dose-response relationship between smoking and atria l fibrillation risk. Compared with smok- i n g zero ci ga ret t es per day, t he relat ive r i sk for at r ia l fibrillation rose steadily when individuals smoked five, 10, 15, 20, 25 and 29 cigarettes per day. Smoking 10 cigarettes per day increased the relative risk of atrial fibrillation 14 percent, and smoking 10 pack-years — a pack-year is the number of cigarette packs smoked per day multiplied by the number of years a person has smoked — heightened the risk 16 percent. Compared with people who had never smoked, current smokers were 32 percent more likely to develop atrial fibrillation, and current and former RISK FOR ATRIAL FIBRILL ATION, THE MOST COMMON HE ART RHY THM DISORDER, INCRE A SES WITH E VERY CIGARE T TE A PERSON SMOKES PER DAY, ACCORDING TO A ME TA-ANALYSIS OF NE ARLY 30 PROSPECTIVE STUDIES. As Smoking Increases, So Does Atrial Fibrillation Risk BY THOMAS CROCKER META-ANALYSIS: 1 2 1 2❱❱❱❱❱ S P E C I A L C L I N I C A L S E C T I O N : C A R D I O L O G Y