Improved Diagnostic Criteria for Apical Hypertrophic Cardiomyopathy.

BACKGROUND

There is no acceptable maximum wall thickness (MWT) threshold for diagnosing apical hypertrophic cardiomyopathy (ApHCM), with guidelines referring to ≥15 mm MWT for all hypertrophic cardiomyopathy subtypes. A normal myocardium naturally tapers apically; a fixed diagnostic threshold fails to account for this. Using cardiac magnetic resonance, "relative" ApHCM has been described with typical electrocardiographic features, loss of apical tapering, and cavity obliteration but also with MWT <15 mm.

OBJECTIVES

The authors aimed to define normal apical wall thickness thresholds in healthy subjects and use these to accurately identify ApHCM.

METHODS

The following healthy subjects were recruited: healthy UK Biobank imaging substudy subjects (n = 4,112) and an independent healthy volunteer group (n = 489). A clinically defined disease population of 104 ApHCM subjects was enrolled, with 72 overt (MWT ≥15 mm) and 32 relative (MWT <15 mm but typical electrocardiographic/imaging findings) ApHCM subjects. Cardiac magnetic resonance-derived MWT was measured in 16 segments using a published clinically validated machine learning algorithm. Segmental normal reference ranges were created and indexed (for age, sex, and body surface area), and diagnostic performance was assessed.

RESULTS

In healthy cohorts, there was no clinically significant age-related difference for apical wall thickness. There were sex-related differences, but these were not clinically significant after indexing to body surface area. Therefore, segmental reference ranges for apical hypertrophy required indexing to body surface area only (not age or sex). The upper limit of normal (the largest of the 4 apical segments measured) corresponded to a maximum apical MWT in healthy subjects of 5.2 to 5.6 mm/m

CONCLUSIONS

Per-segment indexed apical wall thickness thresholds are highly accurate for detecting apical hypertrophy, providing confidence to the reader to diagnose ApHCM in those not reaching current internationally recognized criteria.

Informations de copyright

Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Déclaration de conflit d'intérêts

Funding Support and Author Disclosures This research has been conducted using the UK Biobank Resource (project 71702). Dr Hughes is supported by the British Heart Foundation (grant number FS/17/82/33222). Dr Burke is supported by the British Heart Foundation (grant number FS/19/63/34902). Dr Jiang is funded by the British Heart Foundation (grant number FS/4yPhD/F/20/34134). Dr Davies is funded by the British Heart Foundation Accelerator Award (AA/18/6/34223). Dr Lopes is funded by a Medical Research Council Clinical Academic Research Partnership award. Dr Captur is supported by the National Institute for Health Research Rare Diseases Translational Research Collaboration (NIHR RD-TRC, #171603) and the National Institutes of Health University College London Hospitals Biomedical Research Centre. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.