title: Dynamic changes in microcirculatory blood flow during dobutamine stress assessed by quantitative myocardial contrast echocardiography.
abstract: BACKGROUND
  Although dobutamine-atropine stress echocardiography (DASE) has been widely used for evaluating patients with coronary artery disease (CAD), dynamic changes that occur at microcirculatory level during each stage of stress have not been demonstrated in humans.
  
  
  OBJECTIVE
  We sought to determine variations in myocardial blood flow (MBF) during DASE using quantitative real time myocardial contrast echocardiography (RTMCE).
  
  
  METHODS
  We studied 45 patients who underwent coronary angiography and RTMCE. Replenishment velocity of microbubbles in the myocardium (β) and MBF reserves were obtained at baseline, intermediate stage (70% of maximal predicted heart rate), peak stress, and recovery phase.
  
  
  RESULTS
  β and MBF reserves were lower in patients with than without CAD at intermediate (1.65 vs. 2.10; P=0.001 and 2.44 vs. 3.23; P=0.004) and peak (1.63 vs. 3.00; P<0.001 and 2.14 vs. 3.98; P<0.001, respectively). In patients without CAD, β, and MBF reserves increased from intermediate to peak and decreased at recovery, while in those without CAD reserves did not change significantly. Optimal cutoff values of β reserve at intermediate, peak, and recovery were 1.78, 2.09, and 1.70, with areas under the curves of 0.80 (95%CI=0.67-0.94), 0.89 (95%CI=0.79-0.99), and 0.69 (95%CI=0.53-0.85). Sensitivity, specificity and accuracy for detecting CAD at intermediate stage were 68% (95%CI=48-89), 85% (95%CI=71-98), and 78% (95%CI=66-90), at peak stress were 79% (95%CI=61-97), 96% (95%CI=89-100), and 89% (95%CI=80-98), and at recovery were 74% (95%CI=54-93), 65% (95%CI=47-84), and 69% (95%CI=55-82), respectively.
  
  
  CONCLUSIONS
  RTMCE allows for quantification of dynamic changes in microcirculatory blood flow at each stage of DASE. The best parameter for detecting CAD in all stages was β reserve.
authors.affiliation: Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil.
authors.forename: Wilson
authors.initials: W
authors.lastname: Mathias
authors.forename: Ingrid
authors.initials: I
authors.lastname: Kowatsch
authors.forename: Ally Nader
authors.initials: AN
authors.lastname: Saroute
authors.forename: Altamiro Filho Ferraz
authors.initials: AF
authors.lastname: Osório
authors.forename: João César Nunes
authors.initials: JC
authors.lastname: Sbano
authors.forename: Paulo Magno Martins
authors.initials: PM
authors.lastname: Dourado
authors.forename: José Antonio Franchini
authors.initials: JA
authors.lastname: Ramires
authors.forename: Jeane Mike
authors.initials: JM
authors.lastname: Tsutsui
mesh_terms: D000704:Analysis of Variance; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D016009:Chi-Square Distribution; D015897:Comorbidity; D003287:Contrast Media; D017023:Coronary Angiography; D003327:Coronary Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D025401:Echocardiography, Stress; D005260:Female; D005466:Fluorocarbons; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D045423:Microbubbles; D008833:Microcirculation / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve
chemical_list: D003287:Contrast Media; D005466:Fluorocarbons