title: Exercise Strain Echocardiography in Patients With a Hemodynamically Significant Myocardial Bridge Assessed by Physiological Study.
abstract: BACKGROUND
  Although a myocardial bridge (MB) is often regarded as a benign coronary variant, recent studies have associated MB with focal myocardial ischemia. The physiological consequences of MB on ventricular function during stress have not been well established.
  
  
  RESULTS
  We enrolled 58 patients with MB of the left anterior descending artery, diagnosed by intravascular ultrasound. Patients underwent invasive physiological evaluation of the MB by diastolic fractional flow reserve during dobutamine challenge and exercise echocardiography. Septal and lateral longitudinal strain (LS) were assessed at rest and immediately after exercise and compared with strain of matched controls. Absolute and relative changes in strain were also calculated. The mean age was 42.5±16.0 years. Fifty-five patients had a diastolic fractional flow reserve ≤0.76. At rest, there was no significant difference between the 2 groups in septal LS (19.0±1.8% for patients with MB versus 19.2±1.5% for control, P=0.53) and lateral LS (20.1±2.0% versus 20.0±1.6%, P=0.83). With stress, compared with controls, patients with MB had a lower peak septal LS (18.9±2.6% versus 21.7±1.6%, P<0.001) and lower absolute (-0.1±2.1% versus 2.5±1.3%, P<0.001) and relative change (-0.6±11.2% versus 13.1±7.8%, P<0.001) in septal LS, whereas there was no significant difference in lateral LS. In multivariate analysis, diastolic fractional flow reserve and length were independent determinants of lower changes in septal LS.
  
  
  CONCLUSIONS
  Patients with a hemodynamically significant MB, determined by invasive diastolic fractional flow reserve, have significantly lower change in septal LS on exercise echocardiography, suggesting that septal LS may be useful for noninvasively assessing the hemodynamic significance of an MB.
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.) Stanford Cardiovascular Institute, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.).
authors.forename: Yukari
authors.initials: Y
authors.lastname: Kobayashi
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.) Stanford Cardiovascular Institute, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.).
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Tremmel
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.) Stanford Cardiovascular Institute, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.).
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Kobayashi
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.) Stanford Cardiovascular Institute, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.).
authors.forename: Myriam
authors.initials: M
authors.lastname: Amsallem
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.) Stanford Cardiovascular Institute, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.).
authors.forename: Shigemitsu
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.) Stanford Cardiovascular Institute, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.).
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Yamada
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.) Division of Pediatric Cardiology, Stanford University School of Medicine, Stanford, CA (I.S.R.) Stanford Cardiovascular Institute, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.).
authors.forename: Ian S
authors.initials: IS
authors.lastname: Rogers
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.) Stanford Cardiovascular Institute, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.).
authors.forename: Francois
authors.initials: F
authors.lastname: Haddad
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.) Stanford Cardiovascular Institute, Stanford, CA (Y.K., J.A.T., Y.K., M.A., S.T., R.Y., I.S.R., F.H., I.S.).
authors.forename: Ingela
authors.initials: I
authors.lastname: Schnittger
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006328:Cardiac Catheterization; D016022:Case-Control Studies; D003326:Coronary Circulation; D018618:Echocardiography, Doppler, Color; D025401:Echocardiography, Stress / Q000379:methods*; D005080:Exercise Test; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006346:Heart Septum / Q000000981:diagnostic imaging / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D054084:Myocardial Bridging / Q000000981:diagnostic imaging* / Q000503:physiopathology; D009200:Myocardial Contraction; D011237:Predictive Value of Tests; D013314:Stress, Mechanical; D016277:Ventricular Function, Left
keywords: coronary physiology; deformation imaging; myocardial bridge; myocardial strain