BACKGROUND The cause of hypertrophic cardiomyopathy (HCM) in the young is highly varied. Ventricular preexcitation (preexcitation) is well recognized, yet little is known about the specificity for any cause and the characteristics of the responsible accessory pathways (AP). METHODS Retrospective cohort study of patients <21 years of age with HCM/preexcitation from 2000 to 2022. The cause of HCM was defined as isolated HCM, storage disorder, metabolic disease, or genetic syndrome. Atrioventricular AP (true AP) were distinguished from fasciculoventricular fibers (FVF) using standard invasive electrophysiology study criteria. AP were defined as high risk if any of the following were <250 ms: shortest preexcited RR interval in atrial fibrillation, shortest paced preexcited cycle length, or anterograde AP effective refractory period. RESULTS We identified 345 patients with HCM and 28 (8%) had preexcitation (isolated HCM, 10/220; storage disorder, 8/17; metabolic disease, 5/19; and genetic syndrome, 5/89). Six (21%) patients had clinical atrial fibrillation (1 with shortest preexcited RR interval <250 ms). Twenty-two patients underwent electrophysiology study which identified 23 true AP and 16 FVF. Preexcitation was exclusively FVF mediated in 8 (36%) patients. Five (23%) patients had AP with high-risk conduction properties (including ≥1 patient in each etiologic group). Multiple AP were seen in 8 (36%) and AP plus FVF in 10 (45%) patients. Ablation was acutely successful in 13 of 14 patients with recurrence in 3. One procedure was complicated by complete heart block after ablation of a high-risk midseptal AP. There were significant differences in QRS amplitude and delta wave amplitude between groups. There were no surface ECG features that differentiated AP from FVF. CONCLUSIONS Young patients with HCM and preexcitation have a high likelihood of underlying storage disease or metabolic disease. Nonisolated HCM should be suspected in young patients with large QRS and delta wave amplitudes. Surface ECG is not adequate to discriminate preexcitation from a benign FVF from that secondary to potentially life-threatening AP.

中文翻译：

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年轻的肥厚性心肌病和心室预激：原因和辅助途径特征。

背景技术 年轻人肥厚型心肌病（HCM）的病因多种多样。心室预激（预激）已广为人知，但对其病因的特异性以及相关旁路 (AP) 的特征知之甚少。方法 对 2000 年至 2022 年年龄<21 岁的 HCM/预激患者进行回顾性队列研究。HCM 的病因定义为孤立性 HCM、贮积症、代谢性疾病或遗传综合征。使用标准侵入性电生理学研究标准将房室 AP（真 AP）与束室纤维（FVF）区分开来。如果以下任何一项<250 ms，则 AP 被定义为高风险：房颤中最短预激 RR 间期、最短起搏预激周期长度或顺行 AP 有效不应期。结果 我们确定了 345 名 HCM 患者，其中 28 名 (8%) 患有预激（孤立性 HCM，10/220；储存障碍，8/17；代谢性疾病，5/19；遗传综合征，5/89）。六名 (21%) 患者患有临床心房颤动（其中 1 名患者的最短预激 RR 间期<250 毫秒）。22 名患者接受了电生理学研究，确定了 23 名真正的 AP 和 16 名 FVF。8 名 (36%) 患者的预激完全由 FVF 介导。5 名 (23%) 患者患有具有高风险传导特性的 AP（包括每个病因组中≥1 名患者）。8 名 (36%) 患者出现多发 AP，10 名 (45%) 患者出现 AP 加 FVF。14 名患者中有 13 名消融非常成功，其中 3 名患者复发。其中一名患者在高危中间隔 AP 消融后因完全心脏传导阻滞而导致手术复杂化。组间QRS波幅和δ波波幅存在显着差异。没有表面心电图特征可以区分 AP 和 FVF。结论 患有 HCM 和预激的年轻患者很可能患有潜在的贮积病或代谢性疾病。对于 QRS 波和 δ 波振幅较大的年轻患者，应怀疑非孤立性 HCM。体表心电图不足以区分预激、良性 FVF 和继发性 AP。