title: Physiologic evaluation of myocardial bridging: a new analysis for an old disease.
abstract: BACKGROUND
  Myocardial bridging (MB) is the most common congenital coronary anomaly. However, the functional relevance of MB is not well understood.
  
  
  METHODS
  Eighteen patients with lone MB were consecutively enrolled. Fractional flow reserve (FFR) was measured before and after dobutamine infusion. Diastolic FFR was calculated by offline analysis. Cutoff values for functional significance of FFR and diastolic FFR were 0.75 and 0.76, respectively.
  
  
  RESULTS
  Baseline systolic percent diameter stenosis and lesion length of MB were 70 ± 16% and 24 ± 7 mm. FFR and diastolic FFR were 0.92 ± 0.05 and 0.89 ± 0.07 at maximal hyperemia induced by adenosine, respectively (P = 0.006). Despite the angiographic stenosis, only 1 lesion was functionally significant. After dobutamine infusion, percent diameter stenosis (84 ± 11%, P = 0.002) and lesion length (26 ± 6 mm, P = 0.019) were aggravated and diastolic FFR was lowered (0.84 ± 0.10, P = 0.006). Two additional lesions became functionally significant after dobutamine infusion. Angiographic percent diameter stenosis at diastole was correlated with dobutamine diastolic FFR (R = -0.58, P = 0.04), but stenosis at systole was not. During median follow-up of 54 months, 2 patients underwent target-lesion revascularization.
  
  
  CONCLUSIONS
  Dobutamine increased the morphologic and functional severity of MB. Dobutamine-FFR seems to be helpful in the functional assessment of MB.
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, South Korea.
authors.forename: Kyungil
authors.initials: K
authors.lastname: Park
authors.forename: Tae-Jin
authors.initials: TJ
authors.lastname: Youn
authors.forename: Kyung-Woo
authors.initials: KW
authors.lastname: Park
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Na
authors.forename: Hae-Young
authors.initials: HY
authors.lastname: Lee
authors.forename: Hyun-Jae
authors.initials: HJ
authors.lastname: Kang
authors.forename: Woo-Young
authors.initials: WY
authors.lastname: Chung
authors.forename: Bon-Kwon
authors.initials: BK
authors.lastname: Koo
authors.forename: In-Ho
authors.initials: IH
authors.lastname: Chae
authors.forename: Dong-Ju
authors.initials: DJ
authors.lastname: Choi
authors.forename: Hyo-Soo
authors.initials: HS
authors.lastname: Kim
authors.forename: Byung-Hee
authors.initials: BH
authors.lastname: Oh
authors.forename: Young-Bae
authors.initials: YB
authors.lastname: Park
mesh_terms: D058665:Adrenergic beta-1 Receptor Agonists / Q000494:pharmacology*; D000368:Aged; D017023:Coronary Angiography; D004280:Dobutamine / Q000494:pharmacology*; D005260:Female; D053805:Fractional Flow Reserve, Myocardial / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D054084:Myocardial Bridging / Q000503:physiopathology*; D012720:Severity of Illness Index
chemical_list: D058665:Adrenergic beta-1 Receptor Agonists; D004280:Dobutamine