title: Electrocardiographic changes associated with smoking and smoking cessation: outcomes from a randomized controlled trial.
abstract: BACKGROUND
  Cardiovascular disease (CVD) can be detected and quantified by analysis of the electrocardiogram (ECG); however the effects of smoking and smoking cessation on the ECG have not been characterized.
  
  
  METHODS
  Standard 12-lead ECGs were performed at baseline and 3 years after subjects enrolled in a prospective, randomized, placebo-controlled clinical trial of smoking cessation pharmacotherapies. ECGs were interpreted using the Minnesota Code ECG Classification. The effects of (i) smoking burden on the prevalence of ECG findings at baseline, and (ii) smoking and smoking cessation on ECG changes after 3 years were investigated by multivariable and multinomial regression analyses.
  
  
  RESULTS
  At baseline, 532 smokers were (mean [SD]) 43.3 (11.5) years old, smoked 20.6 (7.9) cigarettes/day, with a smoking burden of 26.7 (18.6) pack-years. Major and minor ECG criteria were identified in 87 (16.4%) and 131 (24.6%) of subjects, respectively. After adjusting for demographic data and known CVD risk factors, higher pack-years was associated with major ECG abnormalities (p = 0.02), but current cigarettes/day (p = 0.23) was not. After 3 years, 42.9% of subjects were abstinent from smoking. New major and minor ECG criteria were observed in 7.2% and 15.6% of subjects respectively, but in similar numbers of abstinent subjects and continuing smokers (p>0.2 for both). Continuing smokers showed significant reduction in current smoking (-8.4 [8.8] cigarettes/day, p<0.001) compared to baseline.
  
  
  CONCLUSIONS
  In conclusion, major ECG abnormalities are independently associated with lifetime smoking burden. After 3 years, smoking cessation was not associated with a decrease in ECG abnormalities, although cigarettes smoked/day decreased among continuing smokers.
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America.
authors.forename: Adam D
authors.initials: AD
authors.lastname: Gepner
authors.forename: Megan E
authors.initials: ME
authors.lastname: Piper
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Leal
authors.forename: Asha
authors.initials: A
authors.lastname: Asthana
authors.forename: Michael C
authors.initials: MC
authors.lastname: Fiore
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Baker
authors.forename: James H
authors.initials: JH
authors.lastname: Stein
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012907:Smoking; D016540:Smoking Cessation; D055815:Young Adult