title: Significance of left ventricular apical-basal muscle bundle identified by cardiovascular magnetic resonance imaging in patients with hypertrophic cardiomyopathy.
abstract: OBJECTIVE
  Cardiovascular magnetic resonance (CMR) has improved diagnostic and management strategies in hypertrophic cardiomyopathy (HCM) by expanding our appreciation for the diverse phenotypic expression. We sought to characterize the prevalence and clinical significance of a recently identified accessory left ventricular (LV) muscle bundle extending from the apex to the basal septum or anterior wall (i.e. apical-basal).
  
  
  RESULTS
  CMR was performed in 230 genotyped HCM patients (48 ± 15 years, 69% male), 30 genotype-positive/phenotype-negative (G+/P-) family members (32 ± 15 years, 30% male), and 126 controls. Left ventricular apical-basal muscle bundle was identified in 145 of 230 (63%) HCM patients, 18 of 30 (60%) G+/P- family members, and 12 of 126 (10%) controls (G+/P- vs. controls; P < 0.01). In HCM patients, the prevalence of an apical-basal muscle bundle was similar among those with disease-causing sarcomere mutations compared with patients without mutation (64 vs. 62%; P = 0.88). The presence of an LV apical-basal muscle bundle was not associated with LV outflow tract obstruction (P = 0.61). In follow-up, 33 patients underwent surgical myectomy of whom 22 (67%) were identified to have an accessory LV apical-basal muscle bundle, which was resected in all patients.
  
  
  CONCLUSIONS
  Apical-basal muscle bundles are a unique myocardial structure commonly present in HCM patients as well as in G+/P- family members and may represent an additional morphologic marker for HCM diagnosis in genotype-positive status.
authors.affiliation: Division of Cardiology and Cardiovascular Surgery, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada Division of Cardiology, Cardiovascular Center, University Hospital, Raemistrasse 100, 8091 Zurich, Switzerland christiane.gruner@gmx.ch Christiane.Gruner@usz.ch.
authors.forename: Christiane
authors.initials: C
authors.lastname: Gruner
authors.affiliation: PERFUSE Core Laboratory and Data Coordinating Center, Harvard Medical School, Boston, MA, USA Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Raymond H
authors.initials: RH
authors.lastname: Chan
authors.affiliation: Division of Cardiology and Cardiovascular Surgery, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Crean
authors.affiliation: Division of Cardiology and Cardiovascular Surgery, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada.
authors.forename: Harry
authors.initials: H
authors.lastname: Rakowski
authors.affiliation: Hypertrophic Cardiomyopathy Center, Division of Cardiology, Tufts Medical Center, Boston, MA, USA.
authors.forename: Ethan J
authors.initials: EJ
authors.lastname: Rowin
authors.affiliation: Fred A. Litwin and Family Centre in Genetic Medicine, Mount Sinai Hospital & University Health Network, Toronto, ON, Canada Department of Medicine, University of Toronto and Samuel Lunenfeld and Toronto General Research Institutes, Toronto, ON, Canada.
authors.forename: Melanie
authors.initials: M
authors.lastname: Care
authors.affiliation: Division of Cardiology and Cardiovascular Surgery, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada.
authors.forename: Djeven
authors.initials: D
authors.lastname: Deva
authors.affiliation: Division of Cardiology and Cardiovascular Surgery, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada.
authors.forename: Lynne
authors.initials: L
authors.lastname: Williams
authors.affiliation: PERFUSE Core Laboratory and Data Coordinating Center, Harvard Medical School, Boston, MA, USA Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Evan
authors.initials: E
authors.lastname: Appelbaum
authors.affiliation: PERFUSE Core Laboratory and Data Coordinating Center, Harvard Medical School, Boston, MA, USA Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: C Michael
authors.initials: CM
authors.lastname: Gibson
authors.affiliation: Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation, Minneapolis, MN, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Lesser
authors.affiliation: Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation, Minneapolis, MN, USA.
authors.forename: Tammy S
authors.initials: TS
authors.lastname: Haas
authors.affiliation: Hypertrophic Cardiomyopathy Center, Division of Cardiology, Tufts Medical Center, Boston, MA, USA.
authors.forename: James E
authors.initials: JE
authors.lastname: Udelson
authors.affiliation: PERFUSE Core Laboratory and Data Coordinating Center, Harvard Medical School, Boston, MA, USA Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Warren J
authors.initials: WJ
authors.lastname: Manning
authors.affiliation: Fred A. Litwin and Family Centre in Genetic Medicine, Mount Sinai Hospital & University Health Network, Toronto, ON, Canada Department of Medicine, University of Toronto and Samuel Lunenfeld and Toronto General Research Institutes, Toronto, ON, Canada.
authors.forename: Katherine
authors.initials: K
authors.lastname: Siminovitch
authors.affiliation: Division of Cardiology and Cardiovascular Surgery, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada.
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Ralph-Edwards
authors.affiliation: Hypertrophic Cardiomyopathy Center, Division of Cardiology, Tufts Medical Center, Boston, MA, USA.
authors.forename: Hassan
authors.initials: H
authors.lastname: Rastegar
authors.affiliation: Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation, Minneapolis, MN, USA.
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Maron
authors.affiliation: Hypertrophic Cardiomyopathy Center, Division of Cardiology, Tufts Medical Center, Boston, MA, USA.
authors.forename: Martin S
authors.initials: MS
authors.lastname: Maron
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002312:Cardiomyopathy, Hypertrophic / Q000235:genetics / Q000473:pathology*; D016022:Case-Control Studies; D004252:DNA Mutational Analysis; D005838:Genotype; D006352:Heart Ventricles; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000235:genetics / Q000473:pathology; D018810:Magnetic Resonance Angiography / Q000379:methods; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D009206:Myocardium / Q000473:pathology*; D010375:Pedigree; D010641:Phenotype; D014694:Ventricular Outflow Obstruction / Q000235:genetics / Q000473:pathology
keywords: Cardiovascular magnetic resonance; Genotype; Hypertrophic cardiomyopathy; Muscle bundle