title: Variation in the use of stress testing and outcomes in patients with non-ST-elevation acute coronary syndromes: insights from GUSTO IIb.
abstract: OBJECTIVE
  Non-invasive risk stratification of low- and intermediate-risk non-ST-elevation acute coronary syndromes (NSTE ACS) patients has been recommended, but limited data exist about the variation in clinical practice of stress testing in these patients and the impact of such testing on their outcomes.
  
  
  RESULTS
  Patients with NSTE ACS enrolled in the GUSTO IIb (Global Use of Strategies To Open occluded coronary arteries in acute coronary syndromes-IIb) trial (n = 8011) were analysed to evaluate patterns of stress testing in US and non-US patients and to further evaluate the clinical characteristics, procedure use, and outcomes of patients who underwent stress testing compared with those who did not. Stress testing was performed in 1878 (24%) patients. Compared with patients not undergoing stress testing, those undergoing stress testing had low-risk characteristics and significantly lower death (0.6% vs. 4.8%), and death or myocardial infarction (MI, 3.9% vs. 11%) rates at 30 days. Stress testing was performed as often after as before coronary angiography. Importantly, stress testing was helpful in stratifying patients into low (equivocal or negative test) or high (positive test) risk groups (30 day death 3.1% vs. 5%). Stress testing was performed more often in non-US than US patients, and US patients were 3.5 times more likely to undergo imaging as part of stress testing. However, the risks of 30-day death or MI; 6-month death, MI or revascularization; and 1-year death did not differ between US and non-US patients.
  
  
  CONCLUSIONS
  Stress testing is commonly performed in low-risk NSTE ACS patients and provides modest additional prognostic information in this cohort. Significant geographical variation exists in the use of stress testing. Therefore, in the current practice environment where cardiac catheterization is often the first diagnostic modality used in patients with NSTE ACS, the role of non-invasive testing both before and after invasive procedure is in need of further study.
authors.affiliation: Duke Clinical Research Institute, Duke University Medical Center, Box 17969, Durham, NC 27715, USA. mehta007@dcri.duke.edu
authors.forename: Rajendra H
authors.initials: RH
authors.lastname: Mehta
authors.forename: Sunil V
authors.initials: SV
authors.lastname: Rao
authors.forename: E Magnus
authors.initials: EM
authors.lastname: Ohman
authors.forename: Eric R
authors.initials: ER
authors.lastname: Bates
authors.forename: Gretchen
authors.initials: G
authors.lastname: Marcucci
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.forename: Karen S
authors.initials: KS
authors.lastname: Pieper
authors.forename: Paul W
authors.initials: PW
authors.lastname: Armstrong
authors.forename: Harvey D
authors.initials: HD
authors.lastname: White
authors.forename: Frans
authors.initials: F
authors.lastname: Van de Werf
authors.forename: Robert M
authors.initials: RM
authors.lastname: Califf
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Granger
mesh_terms: D054058:Acute Coronary Syndrome / Q000175:diagnosis* / Q000401:mortality; D000368:Aged; D003657:Decision Making; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D009203:Myocardial Infarction / Q000175:diagnosis / Q000401:mortality; D009204:Myocardial Revascularization / Q000401:mortality / Q000523:psychology*; D015588:Observer Variation; D011379:Prognosis; D016032:Randomized Controlled Trials as Topic; D012008:Recurrence; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D016896:Treatment Outcome