title: Characteristics and outcomes of patients who achieve high workload (≥10 metabolic equivalents) during treadmill exercise echocardiography.
abstract: OBJECTIVE
  To determine the frequency and prognostic significance of abnormal exercise echocardiographic results for patients achieving a workload of 10 or more metabolic equivalents during treadmill exercise echocardiography.
  
  
  METHODS
  Patients who underwent treadmill exercise echocardiography from November 1, 2003, through December 31, 2008, and exercised for 9 or more minutes using the Bruce protocol (N=7236) were included. Clinical and exercise echocardiographic characteristics and outcomes were evaluated. Variables associated with abnormal exercise echocardiographic results and mortality were identified.
  
  
  RESULTS
  Exercise echocardiographic results were positive for ischemia in 862 patients (12%). Extensive ischemia developed in 265 patients (4%). For patients with normal exercise echocardiographic results, all-cause and cardiovascular mortality rates were 0.30% and 0.05% per person-year of follow-up, respectively. For patients who had extensive ischemia, all-cause and cardiovascular mortality rates were 0.84% and 0.25% per person-year of follow-up, respectively. Patients at highest risk were those who had extensive and severe regional wall motion abnormalities at rest (n=58), and their all-cause and cardiovascular mortality rates were 2.65% and 0.76% per person-year of follow-up. Exercise echocardiographic variables did not identify sizable patient subgroups at risk for death and did not provide incremental prognostic information (C statistic was 0.74 compared with 0.73 for the clinical plus exercise electrocardiography model).
  
  
  CONCLUSIONS
  Patients achieving a workload of 10 or more metabolic equivalents during treadmill exercise testing do not often have extensive ischemic abnormalities on exercise echocardiography. Although exercise echocardiographic results provide some prognostic information, it is not of incremental value for these patients, whose short-term and medium-term prognosis is excellent.
authors.affiliation: Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Mayo Foundation, Rochester, MN.
authors.forename: Nowell M
authors.initials: NM
authors.lastname: Fine
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Pellikka
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Scott
authors.forename: S Michael
authors.initials: SM
authors.lastname: Gharacholou
authors.forename: Robert B
authors.initials: RB
authors.lastname: McCully
mesh_terms: D000328:Adult; D000368:Aged; D015897:Comorbidity; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D025401:Echocardiography, Stress; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D055686:Metabolic Equivalent; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology
keywords: CAD; ECG; HR; IDI; LV; LVEF; LVESV; MAPHR; MET; MI; MPI; OR; RWMAs; coronary artery disease; electrocardiographic; hazard ratio; integrated discrimination improvement; left ventricular; left ventricular ejection fraction; left ventricular end-systolic volume; maximal age-predicted heart rate; metabolic equivalent; myocardial infarction; myocardial perfusion imaging; odds ratio; regional wall motion abnormalities