title: Long-term effects of smoking and smoking cessation on exercise stress testing: three-year outcomes from a randomized clinical trial.
abstract: BACKGROUND
  The long-term effects of smoking and smoking cessation on markers of cardiovascular disease (CVD) prognosis obtained during treadmill stress testing (TST) are unknown. The purpose of this study was to evaluate the long-term effects of smoking cessation and continued smoking on TST parameters that predict CVD risk.
  
  
  METHODS
  In a prospective, double-blind, randomized, placebo-controlled trial of 5 smoking cessation pharmacotherapies, symptom-limited TST was performed to determine peak METs, rate-pressure product (RPP), heart rate (HR) increase, HR reserve, and 60-second HR recovery, before and 3 years after the target smoking cessation date. Relationships between TST parameters and treatments among successful abstainers and continuing smokers were evaluated using multivariable analyses.
  
  
  RESULTS
  At baseline, the 600 current smokers (61% women) had a mean age of 43.4 (SD 11.5) years and smoked 20.7 (8.4) cigarettes per day. Their exercise capacity was 8.7 (2.3) METs, HR reserve was 86.6 (9.6)%, HR increase was 81.1 (20.9) beats/min, and HR recovery was 22.3 (11.3) beats. Cigarettes per day and pack-years were independently and inversely associated with baseline peak METs (P < .001), RPP (P < .01, pack-years only), HR increase (P < .05), and HR reserve (P < .01). After 3 years, 168 (28%) had quit smoking. Abstainers had greater improvements than continuing smokers (all P < .001) in RPP (2,055 mm Hg beats/min), HR increase (5.9 beats/min), and HR reserve (3.7%), even after statistical adjustment (all P < .001).
  
  
  CONCLUSIONS
  Smokers with a higher smoking burden have lower exercise capacity, lower HR reserve, and a blunted exercise HR response. After 3 years, TST improvements suggestive of improved CVD prognosis were observed among successful abstainers.
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Madison, 53792, USA.
authors.forename: Asha
authors.initials: A
authors.lastname: Asthana
authors.forename: Megan E
authors.initials: ME
authors.lastname: Piper
authors.forename: Patrick E
authors.initials: PE
authors.lastname: McBride
authors.forename: Ann
authors.initials: A
authors.lastname: Ward
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: D000328:Adult; D002318:Cardiovascular Diseases / Q000209:etiology / Q000503:physiopathology*; D004311:Double-Blind Method; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012907:Smoking / Q000009:adverse effects*; D016540:Smoking Cessation; D013995:Time