title: Patients with symptomatic ischemia have larger thallium perfusion abnormalities and more adverse prognosis than patients with silent ischemia.
abstract: OBJECTIVE
  To evaluate the mechanism for silent ischemia and the effect on prognosis.
  
  
  METHODS
  To test the hypothesis that patients with silent (compared with symptomatic) ischemia have less severe ischemia and a more favorable prognosis, the authors prospectively evaluated 152 consecutive patients with a positive exercise electrocardiogram with exercise thallium scintigraphy and followed them for two years.
  
  
  METHODS
  Tertiary care university-based hospital.
  
  
  RESULTS
  Asymptomatic patients during the exercise test had a greater exercise duration (9.4 +/- 3.1 versus 6.3 +/- 2.5 mins, P < 0.01), maximal heart rate (155 +/- 20 versus 136 +/- 20 beats/min, P < 0.01), systolic blood pressure (184 +/- 21 versus 176 +/- 23 mmHg, P < 0.05) and double product than patients who were symptomatic with chest pain. Although there was no difference in the magnitude of ST depression, time to ST depression was greater in the asymptomatic (5.6 +/- 2.7 mins), compared with symptomatic (4.6 +/- 2.6 mins), group (P < 0.01). Thallium ischemic score was smaller during asymptomatic ischemia (2.1 +/- 2.7) compared with symptomatic ischemia (3.9 +/- 3.1, P < 0.01). These findings were also demonstrated in a subgroup of 107 patients with both a positive exercise electrocardiogram and positive thallium scan. The patients with asymptomatic ischemia had a two-year cardiac event rate of 5.1% compared with 13.8% in the symptomatic patients (P = 0.065).
  
  
  CONCLUSIONS
  Patients with asymptomatic ischemia have less severe myocardial ischemia and a better prognosis than patients with symptomatic myocardial ischemia during exercise testing.
authors.affiliation: Department of Nuclear Medicine, St Michael's Hospital, University of Toronto, Ontario.
authors.forename: A L
authors.initials: AL
authors.lastname: Hendler
authors.forename: N D
authors.initials: ND
authors.lastname: Greyson
authors.forename: M G
authors.initials: MG
authors.lastname: Robinson
authors.forename: M R
authors.initials: MR
authors.lastname: Freeman
mesh_terms: D000787:Angina Pectoris / Q000000981:diagnostic imaging* / Q000401:mortality; D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000401:mortality; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000401:mortality; D011379:Prognosis; D011877:Radionuclide Imaging; D015996:Survival Rate; D013794:Thallium Radioisotopes
chemical_list: D013794:Thallium Radioisotopes