title: Prognostic value of vasodilator myocardial perfusion imaging in patients with left bundle-branch block.
abstract: BACKGROUND
  The prognostic value of tomographic myocardial perfusion imaging with dipyridamole or adenosine in patients with left bundle-branch block has not been established.
  
  
  RESULTS
  The study group consisted of 245 patients with left bundle-branch block who underwent tomographic (single photon emission tomography) myocardial perfusion imaging with thallium-201 (n=173) or technetium-99m sestamibi (n=72) and either dipyridamole (n=153) or adenosine (n=92) stress. Patients were prospectively classified into two groups. Patients were classified as "high risk" if they had (1) a large severe fixed defect (n=28), (2) a large reversible defect (n=36), or (3) cardiac enlargement and either increased pulmonary uptake (thallium) or a decreased resting ejection fraction (sestamibi) (n=20). The remaining 161 patients (66% of the study group) were at "low risk." Follow-up was 99% complete at 3+/-1.4 years. Three-year overall survival was 57% in the high-risk group compared with 87% in the low-risk group (P<.0001). Survival free of cardiac death/nonfatal myocardial infarction/cardiac transplantation was 55% in the high-risk group and 93% in the low-risk group (P<.0001). The presence of a high-risk scan had significant incremental prognostic value after adjustment for age, sex, diabetes, and previous myocardial infarction (P<.0001). Patients with a low-risk scan had an overall survival that was not significantly different from that of a US age-matched population (P=.86).
  
  
  CONCLUSIONS
  Tomographic myocardial perfusion imaging with adenosine or dipyridamole stress provides important prognostic information in patients with left bundle-branch block, which is incremental to clinical assessment.
authors.affiliation: Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, Minn 55905, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Wagdy
authors.forename: D
authors.initials: D
authors.lastname: Hodge
authors.forename: T F
authors.initials: TF
authors.lastname: Christian
authors.forename: T D
authors.initials: TD
authors.lastname: Miller
authors.forename: R J
authors.initials: RJ
authors.lastname: Gibbons
mesh_terms: D000241:Adenosine / Q000008:administration & dosage*; D000368:Aged; D002037:Bundle-Branch Block / Q000503:physiopathology*; D004176:Dipyridamole / Q000008:administration & dosage*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015425:Myocardial Reperfusion; D011237:Predictive Value of Tests; D011379:Prognosis; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D014665:Vasodilator Agents; D004176:Dipyridamole; D000241:Adenosine