Transthyretin amyloid cardiomyopathy (ATTR-CM) is caused by the cardiac deposition of insoluble amyloid fibrils formed by misfolded transthyretin proteins and is associated with various cardiac symptoms, such as progressive heart failure, conduction disturbance, and arrhythmia. The implementation of ^99mtechnetium (^99mTc)-labelled bone radiotracer scintigraphy for diagnosing ATTR-CM has enabled accurate diagnosis of the disease with high sensitivity and specificity and positioned this diagnostic modality as an integral part of disease diagnostic algorithms. In 2020, ^99mTc-pyrophosphate scintigraphy received exceptional approval for Japanese national health insurance reimbursement as a diagnostic method of ATTR-CM. Nevertheless, the utility of ^99mTc-labelled bone radiotracer scintigraphy and the importance of an early diagnosis of suspected ATTR-CM using this technique have yet to be internalized as common practice by general cardiologists, and guidance on daily clinical scenarios to consider this technique for a diagnosis of suspected ATTR-CM is warranted. In this review, we discuss the utility of ^99mTc-labelled bone radiotracer scintigraphy for the early diagnosis of ATTR-CM based on published literature and the outcomes of an advisory board meeting. This review also discusses clinical scenarios that could support early diagnosis of suspected ATTR-CM as well as common pitfalls, correct implementation, and future perspectives of ^99mTc-labelled bone radiotracer scintigraphy in daily clinical practice. The clinical scenarios to consider ^99mTc-labelled bone radiotracer scintigraphy in daily practice may include, but are not limited to, patients with a family history of the hereditary type of disease; elderly patients (aged ≥60 years) with unexplained cardiac findings (e.g. cardiac hypertrophy associated with abnormalities on an electrocardiogram, heart failure with preserved ejection fraction associated with unexplained left ventricular hypertrophy, and heart failure with reduced ejection fraction associated with atrial fibrillation and left ventricular hypertrophy); and patients with cardiac hypertrophy associated with diastolic dysfunction, right ventricular/interatrial septum/valve thickness, left ventricular sparkling, or apical sparing. Cardiac hypertrophy and persistent elevation in cardiac troponin in elderly patients are also suggestive of ATTR-CM. ^99mTc-labelled bone radiotracer scintigraphy is also recommended in patients with characteristic cardiac magnetic resonance findings (e.g. diffuse subendocardial late gadolinium enhancement patterns, native T1 increase, and increase in extracellular volume) or patients with cardiac hypertrophy and bilateral carpal tunnel syndrome.

中文翻译：

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99m焦磷酸锝闪烁显像：转甲状腺素蛋白淀粉样蛋白心肌病早期诊断的实用指南

转甲状腺素蛋白淀粉样蛋白心肌病 (ATTR-CM) 是由错误折叠的转甲状腺素蛋白形成的不溶性淀粉样蛋白原纤维在心脏沉积引起的，并与各种心脏症状有关，例如进行性心力衰竭、传导障碍和心律失常。实施用于诊断 ATTR-CM 的^99m锝 ( ^99m Tc) 标记的骨放射性示踪剂闪烁扫描能够以高灵敏度和特异性准确诊断疾病，并将这种诊断方式定位为疾病诊断算法的组成部分。2020 年，^99m Tc-焦磷酸闪烁显像作为 ATTR-CM 的诊断方法获得了日本国民健康保险报销的特别批准。尽管如此，^99m的效用Tc 标记的骨放射性示踪剂闪烁显像以及使用该技术对疑似 ATTR-CM 进行早期诊断的重要性尚未被普通心脏病专家内化为普遍做法，以及在日常临床情况下考虑使用该技术诊断疑似 ATTR-CM 的指导。 CM是有保证的。在这篇综述中，我们根据已发表的文献和咨询委员会会议的结果，讨论了^{99m Tc 标记的骨放射性示踪剂闪烁显像在 ATTR-CM 早期诊断中的效用。}这篇综述还讨论了可以支持疑似 ATTR-CM 早期诊断的临床场景，以及常见的陷阱、正确的实施和^{99m的未来前景}日常临床实践中 Tc 标记的骨放射性示踪剂闪烁显像。需要考虑的临床场景^99m日常实践中 Tc 标记的骨放射性示踪剂闪烁扫描可能包括但不限于具有遗传类型疾病家族史的患者；有不明原因心脏表现的老年患者（≥60 岁）（例如，与心电图异常相关的心脏肥大、与不明原因左心室肥厚相关的射血分数保留的心力衰竭，以及与心房颤动和左心室颤动相关的射血分数降低的心力衰竭）肥大）；心脏肥大与舒张功能障碍、右心室/房间隔/瓣膜厚度、左心室闪烁或心尖保留有关的患者。老年患者的心脏肥大和心肌肌钙蛋白持续升高也提示 ATTR-CM。^99m Tc 标记的骨放射性示踪剂闪烁显像也推荐用于具有特征性心脏磁共振检查结果的患者（例如弥漫性心内膜下晚期钆增强模式、天然 T1 增加和细胞外体积增加）或心脏肥大和双侧腕管综合征的患者。