Left Ventricular Noncompaction Anatomical Phenotype or Distinct Cardiomyopathy ?

Fro Kin No ve He an stu ma no Ma BACKGROUND There is considerable overlap between left ventricular noncompaction (LVNC) and other cardiomyopathies. LVNC has been reported in up to 40% of the general population, raising questions about whether it is a distinct pathological entity, a remodeling epiphenomenon, or merely an anatomical phenotype. OBJECTIVES The authors determined the prevalence and predictors of LVNC in a healthy population using 4 cardiac magnetic resonance imaging diagnostic criteria. METHODS Volunteers >40 years of age (N 1⁄4 1,651) with no history of cardiovascular disease (CVD), a 10-year risk of CVD < 20%, and a B-type natriuretic peptide level greater than their gender-specific median underwent magnetic resonance imaging scan as part of the TASCFORCE (Tayside Screening for Cardiac Events) study. LVNC ratios were measured on the horizontal and vertical long axis cine sequences. All individuals with a noncompaction ratio of $2 underwent short axis systolic and diastolic LVNC ratio measurements, and quantification of noncompacted and compacted myocardial mass ratios. Those who met all 4 criteria were considered to have LVNC. RESULTS Of 1,480 participants analyzed, 219 (14.8%) met $1 diagnostic criterion for LVNC, 117 (7.9%) met 2 criteria, 63 (4.3%) met 3 criteria, and 19 (1.3%) met all 4 diagnostic criteria. There was no difference in demographic or allometric measures between those with and without LVNC. Long axis noncompaction ratios were the least specific, with current diagnostic criteria positive in 219 (14.8%), whereas the noncompacted to compacted myocardial mass ratio was the most specific, only being met in 61 (4.4%). CONCLUSIONS A significant proportion of an asymptomatic population free from CVD satisfy all currently used cardiac magnetic resonance imaging diagnostic criteria for LVNC, suggesting that those criteria have poor specificity for LVNC, or that LVNC is an anatomical phenotype rather than a distinct cardiomyopathy. (J Am Coll Cardiol 2016;68:2157–65) © 2016 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). L eft ventricular noncompaction (LVNC) is characterized as a primary genetic cardiomyopathy by the American Heart Association, but is characterized by the European Society of m the Department of Cardiovascular and Diabetes Medicine, College o gdom; NHS Tayside Medical Physics, Ninewells Hospital, Dundee, United rth York General Hospital, University of Toronto, Toronto, Ontario, Cana rsity Hospital of Wales, United Kingdom. The present study was funded art and Stroke Scotland Charity. Dr.Weir-McCall is supported by theWellco d Therapeutics Initiative (Grant no. WT 085664) in the form of a Clinical dy design, the collection, analysis, and interpretation of data; in the writin nuscript for publication. Dr. Houston has received grants from Guerbet; a logies. All other authors have reported that they have no relationships rel nuscript received April 18, 2016; revised manuscript received June 13, 20 Cardiologists as an “unclassified cardiomyopathy,” aptly demonstrating some of the controversy that surrounds this condition (1–3). Previously considered a rare cardiomyopathy, there has been a rapid f Medicine, University of Dundee, Dundee, United Kingdom; Department of Research and Innovation, da; and the Department of Clinical Radiology, Uniby the Souter Charitable Foundation and the Chest, me Trust through the Scottish TranslationalMedicine Research Fellowship. Neither group had any role in: g of the manuscript; nor in the decision to submit the nd is nonexecutive director for Tayside Flow Techevant to the contents of this paper to disclose. 16, accepted August 1, 2016. ABBR EV I A T I ON S