title: Association of exercise capacity on treadmill with future cardiac events in patients referred for exercise testing.
abstract: BACKGROUND
  Little is known about the association between exercise capacity and nonfatal cardiac events in patients referred for exercise treadmill testing (ETT). Our objective was to determine the prognostic importance of exercise capacity for nonfatal cardiac events in a clinical population.
  
  
  METHODS
  A cohort study was performed of 9191 patients referred for ETT. Median follow-up was 2.7 years. Exercise capacity was quantified as the proportion of age- and sex-predicted metabolic equivalents achieved and categorized as less than 85%, 85% to 100%, and greater than 100%. Individual primary outcomes were myocardial infarction, unstable angina, and coronary revascularization. All-cause mortality was a secondary outcome.
  
  
  RESULTS
  Patients with lower exercise capacity were more likely to be female (55.38% vs 42.62%); to have comorbidities such as diabetes (23.16% vs 9.61%) and hypertension (59.43% vs 44.05%); and to have abnormal ETT findings such as chest pain on the treadmill (12.09% vs 7.63%), abnormal heart rate recovery (82.74% vs 64.13%), and abnormal chronotropic index (32.89% vs 12.20%). In multivariable analysis, including other ETT variables, lower exercise capacity (<85% of predicted) was associated with increased risk of myocardial infarction (hazard ratio [HR], 2.36; 95% confidence interval [CI], 1.55-3.60), unstable angina (HR, 2.39; 95% CI, 1.78-3.21), coronary revascularization (HR, 1.75; 95% CI, 1.46- 2.08), and all-cause mortality (HR, 2.90; 95% CI, 1.88-4.47) compared with exercise capacity greater than 100% of predicted.
  
  
  CONCLUSIONS
  Adjusting for patient characteristics and other ETT variables, reduced exercise capacity was associated with both nonfatal cardiovascular events and mortality in patients referred for ETT.
authors.affiliation: Division of Cardiology, Department of Medicine, Denver Health Medical Center, Denver, Colorado 80204, USA. Pamela.Peterson@uchsc.edu
authors.forename: Pamela N
authors.initials: PN
authors.lastname: Peterson
authors.forename: David J
authors.initials: DJ
authors.lastname: Magid
authors.forename: Colleen
authors.initials: C
authors.lastname: Ross
authors.forename: P Michael
authors.initials: PM
authors.lastname: Ho
authors.forename: John S
authors.initials: JS
authors.lastname: Rumsfeld
authors.forename: Michael S
authors.initials: MS
authors.lastname: Lauer
authors.forename: Ella E
authors.initials: EE
authors.lastname: Lyons
authors.forename: Scott S
authors.initials: SS
authors.lastname: Smith
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Masoudi
mesh_terms: D000368:Aged; D015331:Cohort Studies; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006331:Heart Diseases / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012307:Risk Factors