Cigarette smoking induces atrial fibrosis in humans via nicotine.
BACKGROUND
Cigarette smoking (CS) promotes endothelial dysfunction and atherosclerosis in the vascular bed. The impact of smoking on atrial myocardium is not defined in humans.


OBJECTIVE
To determine the effect of CS on the development of interstitial fibrosis in atrial myocardium.


METHODS
Case-control study.


METHODS
95 patients (46 smokers and 49 non-smokers) undergoing coronary artery bypass grafting (CABG).


METHODS
Amount of atrial fibrosis, collagen I, III and IV expression pattern, and quantitative reverse transcriptase-PCR. Occurrence of postoperative atrial fibrillation (AF).


RESULTS
In the study population, patient age correlated significantly with the amount of atrial fibrosis (r = 0.18; p<0.05). Nicotine misuse (pack years) was identified as the only factor related to atrial fibrosis in smokers (r = 0.311; p<0.05). The amount of fibrosis was higher in patients with postoperative AF (22.9% (6.2%) vs. 27.0% (8.2%); p<0.05). To show a causal relationship between CS and atrial fibrosis, atrial tissue slices from non-smokers (n = 8) were cultured in the presence of nicotine base (185 and 740 nmol/l). Nicotine base induced mRNA expression of collagen III (up to 10-fold) in a concentration-dependent manner resembling the immunohistological collagen expression pattern observed in CS.


CONCLUSIONS
CS contributes to the development of atrial fibrosis via nicotine. Atrial fibrosis by itself has been shown to provide an arrhythmogenic substrate, which may increase the likelihood of the occurrence of atrial arrhythmias, including postoperative AF.
Goette
Andreas
A
Institute of Experimental Internal Medicine, Division of Cardiology, Department of Cardiovascular Surgery, University Hospital Magdeburg, Magdeburg, Germany. andreas.goette@medizin.uni-magdeburg.de
Lendeckel
Uwe
U
Kuchenbecker
Anja
A
Bukowska
Alicja
A
Peters
Brigitte
B
Klein
Helmut U
HU
Huth
Christof
C
Röcken
Christoph
C
D000368:Aged; D001281:Atrial Fibrillation / Q000209:etiology; D016022:Case-Control Studies; D003094:Collagen / Q000235:genetics / Q000378:metabolism; D001026:Coronary Artery Bypass; D005355:Fibrosis / Q000209:etiology; D005786:Gene Expression Regulation / Q000187:drug effects; D006325:Heart Atria / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D009538:Nicotine / Q000633:toxicity*; D011183:Postoperative Complications; D012333:RNA, Messenger / Q000235:genetics; D012907:Smoking / Q000009:adverse effects*; D046509:Tissue Culture Techniques
D012333:RNA, Messenger; D009538:Nicotine; D003094:Collagen