title: Comparison of ischemic patterns in myocardial bridge and syndrome X: evaluation by dobutamine stress echocardiography and stress thallium-201 SPECT.
abstract: OBJECTIVE
  Ischemic patterns in patients with syndrome X are thought to differ from those in patients with myocardial bridge, because the mechanisms of coronary flow reduction in these two diseases are different. The aim of this study was to compare the ischemic patterns in patients with syndrome X and those with myocardial bridge through the use of dobutamine stress echocardiography (DSE) and stress thallium-201 single-photon emission computed tomography (SPECT).
  
  
  METHODS
  Twenty-six patients with typical angina and stress-induced ST-segment depression were enrolled. All patients underwent coronary angiography, DSE, and stress thallium-201 SPECT within 7 days after enrollment.
  
  
  RESULTS
  Of the 26 patients enrolled, 10 had myocardial bridge of the left anterior descending artery and 16 had syndrome X. Among patients with myocardial bridge, myocardial dyssynergy was found by DSE in five patients and reversible or fixed thallium-201 perfusion defects were found in four. Seven patients with myocardial bridge had reverse redistribution patterns on thallium-201 scintigraphy. In the 16 patients with syndrome X, myocardial dyssynergy was found by DSE in only one patient (p = 0.018 vs myocardial bridge group) and reversible or fixed thallium-201 perfusion defects were found in nine (p > 0.05 vs myocardial bridge group). Four patients with syndrome X had reverse redistribution patterns on thallium-201 scintigraphy. The resting left ventricular end-diastolic pressure was higher in patients with myocardial bridge than in those with syndrome X (17 +/- 4 vs 12 +/- 5 mm Hg, p = 0.02).
  
  
  CONCLUSIONS
  The most common ischemic patterns in patients with syndrome X were chest pain and stress-induced ST-segment depression, followed by myocardial perfusion defects. Dobutamine-induced dyssynergy was rare. Left ventricular end-diastolic pressure elevation and dobutamine-induced wall motion abnormalities were more common in patients with myocardial bridge than in those with syndrome X.
authors.affiliation: Department of Internal Medicine (Cardiology), National Taiwan University Hospital, 7 Chung-Shan South Road, Taipei, Taiwan.
authors.forename: Y L
authors.initials: YL
authors.lastname: Ho
authors.forename: C C
authors.initials: CC
authors.lastname: Wu
authors.forename: R F
authors.initials: RF
authors.lastname: Yen
authors.forename: S R
authors.initials: SR
authors.lastname: Hung
authors.forename: M F
authors.initials: MF
authors.lastname: Chen
authors.forename: P J
authors.initials: PJ
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D004280:Dobutamine; D004452:Echocardiography; D005260:Female; D006801:Humans; D008297:Male; D017566:Microvascular Angina / Q000175:diagnosis*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D017202:Myocardial Ischemia / Q000175:diagnosis*; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D013794:Thallium Radioisotopes; D004280:Dobutamine