title: Transthoracic Doppler echocardiographic coronary flow imaging in identification of left anterior descending coronary artery stenosis in patients with left bundle branch block.
abstract: BACKGROUND
  Conventional noninvasive methods have well-known limitations for the detection of coronary artery disease (CAD) in patients with left bundle branch block (LBBB). However, advancements in Doppler echocardiography permit transthoracic imaging of coronary flow velocities (CFV) and measurement of coronary flow reserve (CFR). Our aim was to evaluate the diagnostic value of transthoracic CFR measurements for detection of significant left anterior descending (LAD) stenosis in patients with LBBB and compare it to that of myocardial perfusion scintigraphy (MPS).
  
  
  METHODS
  Simultaneous transthoracic CFR measurements and MPS were analyzed in 44 consecutive patients with suspected CAD and permanent LBBB. Typical diastolic predominant phasic CFV Doppler spectra of distal LAD were obtained at rest and during a two-step (0.56-0.84 mg/kg) dipyridamole infusion protocol. CFR was defined as the ratio of peak hyperemic velocities to the baseline values. A reversible perfusion defect at LAD territory was accepted as a positive scintigraphy finding for significant LAD stenosis. A coronary angiography was performed within 5 days of the CFR studies.
  
  
  RESULTS
  The hyperemic diastolic peak velocity (44 +/- 9 cm/sec vs 62 +/- 2 cm/sec; P=0.01) and diastolic CFR (1.38 +/- 0.17 vs 1.93 +/- 0.3; P=0.001) were significantly lower in patients with LAD stenosis compared to those without LAD stenosis. The diastolic CFR values of <1.6 yielded a sensitivity of 100% and a specificity of 94% in the identification of significant LAD stenosis. In comparison, MPS detected LAD stenosis with a sensitivity of 100% and a specificity of 29%.
  
  
  CONCLUSIONS
  CFR measurement by transthoracic Doppler echocardiography is an accurate method that may improve noninvasive identification of LAD stenosis in patients with LBBB.
authors.affiliation: Siyami Ersek Thoracic and Cardiovascular Surgery Training and Research Hospital, Cardiology Department, Istanbul, Turkey. drsoylu@hotmail.com
authors.forename: Ozer
authors.initials: O
authors.lastname: Soylu
authors.forename: Seden
authors.initials: S
authors.lastname: Celik
authors.forename: Gultekin
authors.initials: G
authors.lastname: Karakus
authors.forename: Aydin
authors.initials: A
authors.lastname: Yildirim
authors.forename: Mehmet
authors.initials: M
authors.lastname: Ergelen
authors.forename: Ertugrul
authors.initials: E
authors.lastname: Zencirci
authors.forename: Huseyin
authors.initials: H
authors.lastname: Aksu
authors.forename: Tuna
authors.initials: T
authors.lastname: Tezel
mesh_terms: D002037:Bundle-Branch Block / Q000000981:diagnostic imaging*; D023921:Coronary Stenosis / Q000175:diagnosis* / Q000000981:diagnostic imaging; D015150:Echocardiography, Doppler / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods; D015588:Observer Variation; D015203:Reproducibility of Results