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Eur Heart J. 2014 Oct 14;35(39):2706-13. doi: 10.1093/eurheartj/ehu154. Epub 2014 May 8.

Significance of left ventricular apical-basal muscle bundle identified by cardiovascular magnetic resonance imaging in patients with hypertrophic cardiomyopathy.

Author information

  • 1Division 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
  • 2PERFUSE 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.
  • 3Division of Cardiology and Cardiovascular Surgery, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada.
  • 4Hypertrophic Cardiomyopathy Center, Division of Cardiology, Tufts Medical Center, Boston, MA, USA.
  • 5Fred 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.
  • 6Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation, Minneapolis, MN, USA.



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).


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.


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.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email:


Cardiovascular magnetic resonance; Genotype; Hypertrophic cardiomyopathy; Muscle bundle

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