Institute of Cardiovascular Science, University College London, London, United Kingdom; Barts Heart Centre, The Cardiovascular Magnetic Resonance Imaging Unit and The Inherited Cardiovascular Diseases Unit, St Bartholomew's Hospital, London, United Kingdom.
Barts Heart Centre, The Cardiovascular Magnetic Resonance Imaging Unit and The Inherited Cardiovascular Diseases Unit, St Bartholomew's Hospital, London, United Kingdom; Kings College Hospital, London, United Kingdom.
JACC Cardiovasc Imaging. 2024 May;17(5):501-512. doi: 10.1016/j.jcmg.2023.07.012. Epub 2023 Oct 11.
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.
The authors aimed to define normal apical wall thickness thresholds in healthy subjects and use these to accurately identify ApHCM.
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.
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 with an accuracy of 0.94 (the unindexed equivalent being 11 mm). This threshold was categorized as abnormal in 99% (71/72) of overt ApHCM patients, 78% (25/32) of relative ApHCM patients, 3% (122/4,112) of UK Biobank subjects, and 3% (13/489) of healthy volunteers.
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.
目前尚无可接受的最大壁厚度（MWT）阈值来诊断心尖肥厚型心肌病（ApHCM），指南中提到所有肥厚型心肌病亚型的 MWT 均≥15mm。正常心肌自然向心尖逐渐变细；固定的诊断阈值未能考虑到这一点。使用心脏磁共振成像，可以描述具有典型心电图特征、心尖变细丧失和心腔闭塞的“相对”ApHCM，但 MWT＜15mm。
作者旨在确定健康受试者的正常心尖壁厚度阈值，并利用这些阈值准确识别 ApHCM。
本研究招募了以下健康受试者：英国生物库成像子研究的健康受试者（n=4112）和独立的健康志愿者组（n=489）。纳入了 104 例 ApHCM 患者的临床定义疾病人群，其中 72 例为显性（MWT≥15mm），32 例为相对（MWT＜15mm，但具有典型心电图/影像学表现）ApHCM。使用发表的临床验证机器学习算法测量了 16 个节段的心脏磁共振衍生的 MWT。创建并索引了节段性正常参考范围（针对年龄、性别和体表面积），并评估了诊断性能。
在健康队列中，心尖壁厚度没有明显的年龄相关差异。存在性别相关差异，但在索引到体表面积后没有临床意义。因此，心尖肥厚的节段性参考范围仅需要索引到体表面积（而不是年龄或性别）。正常上限（测量的 4 个心尖节段中的最大值）对应于健康受试者最大心尖 MWT 为 5.2 至 5.6mm/m，准确率为 0.94（未索引的等效值为 11mm）。这一阈值在 99%（71/72）的显性 ApHCM 患者、78%（25/32）的相对 ApHCM 患者、3%（122/4112）的英国生物库受试者和 3%（13/489）的健康志愿者中被归类为异常。
节段性指数化心尖壁厚度阈值对检测心尖肥厚非常准确，为读者提供了信心，使其能够在未达到当前国际公认标准的情况下诊断 ApHCM。
