title: Blunted heart rate response as a predictor of cardiac death in patients undergoing vasodilator stress technetium-99m sestamibi gated SPECT myocardial perfusion imaging.
abstract: BACKGROUND
  The prognostic value of a blunted heart rate response (BHR) during ECG-gated vasodilator stress SPECT MPI in relation to ventricular function on long-term cardiovascular events is not well established. We performed this study to evaluate the incremental prognostic value of BHR during pharmacological stress SPECT MPI.
  
  
  METHODS
  Consecutive patients who underwent dipyridamole stress Tc-99m sestamibi ECG-gated SPECT MPI (without exercise) were identified. The ratio of peak stress heart rate to baseline was noted. If the ratio was <1.20, it was considered blunted (BHR). The images were interpreted using the standard ASNC 17 segment model. Patients were followed up for a mean time period of 2.3 +/- 1.5 years.
  
  
  RESULTS
  Sixty-four percent (2,890/4,484) of patients demonstrated BHR during dipyridamole stress testing. Cardiac death, the primary end point, occurred in 6.8% of patients. Patients with BHR had a significantly lower cardiac death-free survival as compared to NO BHR group in total population (83% vs 94%; P < .001) as well as in subgroup with normal ejection fraction (89% vs 96%; P < .001). BHR was an independent predictor of cardiac death after adjusting for multiple clinical, perfusion, and function-related gated SPECT variables.
  
  
  CONCLUSIONS
  Blunted heart rate response during vasodilator stress SPECT MPI is an important prognostic marker for cardiac death.
authors.affiliation: Nuclear Cardiology Laboratory, Henry Low Heart Center, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA. smathur@harthosp.org
authors.forename: Shishir
authors.initials: S
authors.lastname: Mathur
authors.forename: Anuj R
authors.initials: AR
authors.lastname: Shah
authors.forename: Alan W
authors.initials: AW
authors.lastname: Ahlberg
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Katten
authors.forename: Gary V
authors.initials: GV
authors.lastname: Heller
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000401:mortality*; D003237:Connecticut / Q000453:epidemiology; D016757:Death, Sudden, Cardiac / Q000453:epidemiology*; D004176:Dipyridamole / Q000008:administration & dosage; D004562:Electrocardiography / Q000187:drug effects / Q000706:statistics & numerical data; D005080:Exercise Test / Q000706:statistics & numerical data; D005260:Female; D015637:Gated Blood-Pool Imaging / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D008297:Male; D055414:Myocardial Perfusion Imaging / Q000706:statistics & numerical data*; D011379:Prognosis; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D015996:Survival Rate; D017256:Technetium Tc 99m Sestamibi; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D019275:Radiopharmaceuticals; D014665:Vasodilator Agents; D004176:Dipyridamole; D017256:Technetium Tc 99m Sestamibi