title: Anginal threshold between stress tests: exercise versus dobutamine stress echocardiography.
abstract: OBJECTIVE
  Dobutamine echocardiography (DOB) can be substituted to exercise testing when necessary for clinical reasons. Current literature suggests DOB is maximal when 85% of maximal predicted heart rate (%PHR) is achieved (similar to EX), but there is little evidence to determine whether this target has the same clinical significance as during EX. We therefore performed this study to compare the ischemic threshold between EX and DOB.
  
  
  METHODS
  Twenty men with stable angina underwent in a random order DOB and EX echocardiograms after being weaned off their cardiac medications. Electrocardiography, heart rate (HR), and systolic blood pressure were recorded every minute. Ischemic threshold was defined as the precise time at which clinical angina occurred.
  
  
  RESULTS
  Anginal threshold appeared consistently at a higher level for DOB than EX as evidenced by the higher rate-pressure product (RPP) values (22,492 +/- 4,300 vs 20,371 +/- 5,367 bpm x mm Hg, DOB vs EX, respectively, P = 0.02), HR (126 +/- 23 vs 119 +/- 15 bpm, P = 0.01), and %PHR (79 +/- 15% vs 74 +/- 10%, P < 0.01). Thirty-two percent of the subjects presented an ischemic HR above 85% of PHR and 60% had a higher ischemic HR during DOB versus EX.
  
  
  CONCLUSIONS
  This study shows that estimation of anginal threshold during DOB is feasible and is slightly higher (approximately 10%) than during EX. Extrapolation of a cut off target heart rate from an exercise modality to a pharmaceutical one may not be valid.
authors.affiliation: Quebec Heart and Lung Institute/Laval Hospital, Ste-Foy, Quebec, Canada G1 V 4G5.
authors.forename: Marie
authors.initials: M
authors.lastname: Arsenault
authors.forename: Sébastien
authors.initials: S
authors.lastname: Bergeron
authors.forename: Jean-G
authors.initials: JG
authors.lastname: Dumesnil
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Fortin
authors.forename: Paul
authors.initials: P
authors.lastname: Poirier
mesh_terms: D000787:Angina Pectoris / Q000175:diagnosis* / Q000503:physiopathology; D001794:Blood Pressure; D025401:Echocardiography, Stress / Q000379:methods* / Q000592:standards; D004562:Electrocardiography; D015444:Exercise; D005080:Exercise Test / Q000379:methods*; D006339:Heart Rate; D006801:Humans; D008297:Male