title: Preserved diagnostic utility of dobutamine stress echocardiography in pacemaker-dependent patients with absolute chronotropic incompetence.
abstract: BACKGROUND
  The mechanism by which dobutamine induces ischemia is thought to depend on both increased chronotropy and inotropy. No data have been reported on the diagnostic power of dobutamine stress echocardiography (DSE) among patients with fixed-rate pacemakers and absolute chronotropic incompetence. The purpose of this study was to determine the diagnostic and prognostic utility of DSE in patients with fixed-rate, demand ventricular pacing who had no heart rate (HR) increase during DSE.
  
  
  METHODS
  From 1990 to 1997, 22 patients remained pacemaker dependent with a fixed HR (69.7 +/- 5.7 beats/min) throughout DSE. Myocardial perfusion single-photon emission computed tomography and coronary angiographic studies were reviewed when available. Clinical follow-up was determined for all patients at 15.4 +/- 7.7 months.
  
  
  RESULTS
  In spite of absolute chronotropic incompetence during DSE, 11 (50%) of 22 patients had test results consistent with inducible ischemia. Coronary artery disease was confirmed in 6 (75%) of 8 who had coronary angiograms. Three of 11 patients with negative DSE underwent coronary angiography that confirmed the absence of significant coronary artery disease. DSE had a sensitivity of 100% and specificity of 60% in pacemaker-dependent patients with absolute chronotropic incompetence. At the time of clinical follow-up, none of the patients with no inducible ischemia on DSE had an adverse ischemic cardiac event.
  
  
  CONCLUSIONS
  This study suggests that DSE has preserved diagnostic and prognostic utility in pacemaker-dependent patients with absolute chronotropic incompetence.
authors.affiliation: Division of Cardiology, Department of Medicine, University of Michigan, USA.
authors.forename: H
authors.initials: H
authors.lastname: Oral
authors.forename: W F
authors.initials: WF
authors.lastname: Armstrong
authors.forename: D S
authors.initials: DS
authors.lastname: Bach
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000000981:diagnostic imaging*; D002316:Cardiotonic Agents; D003327:Coronary Disease / Q000175:diagnosis; D004280:Dobutamine; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011237:Predictive Value of Tests; D011379:Prognosis; D015899:Tomography, Emission-Computed, Single-Photon; D014463:Ultrasonography
chemical_list: D002316:Cardiotonic Agents; D004280:Dobutamine