How is suspected transthyretin-related cardiac amyloidosis diagnosed? Role 99mTc-HDMP scintigraphy: a substitute for biopsy?

Cardiac amyloidosis (CA) is characterized by extracellular deposition of protein-derived fibrils and lead to heart failure. Gold standard for its etiological diagnosis is endomyocardial biopsy and laboratory tests, both high-cost and invasive procedures. Technetium- 99m hydroxymethylene diphosphonate (99mTc-HMDP) scintigraphy is important tool for defining CA, specifically transthyretin subtype (ATTR). From July 2020 to February 2021, we retrospectively analyzed 18 pts [14 males, 4 females; aged 32-86y] with suspected ATTR, underwent to scintigraphy 150 min after iv administration of 740 MBq 99mTc-HMDP.Myocardial uptake was assessed optically based on Perugini Score (0- 3). Biopsy confirmed diagnosis. Intense (Score 3) and moderate (Score 2) myocardial uptake verified in 8 patients by 99mTc-HDMP scintigraphy, was consistent with ATTR suspect. In 10 patient's cardiac radiotracer uptake was absent (Score 0) avoiding biopsy. Our data indicate a 99mTc-HDMP scintigraphy key role in the early diagnosis but even more in the exclusion of patients with ATTR subtype, optimizing the management of pts who do not require high costs and invasive procedures.

心脏淀粉样变性（Cardiac amyloidosis, CA）以蛋白质源性纤维的细胞外沉积为特征，可引发心力衰竭。其病因诊断的金标准为心内膜心肌活检与实验室检查，但二者均为高成本且有创的操作。锝[99mTc]亚甲基二膦酸盐（99mTc-HMDP）闪烁显像是明确CA分型、尤其是转甲状腺素蛋白亚型（ATTR）的重要手段。2020年7月至2021年2月期间，我们对18例疑似ATTR的患者[其中男性14例，女性4例；年龄32~86岁]进行了回顾性分析：所有患者均在静脉给予740兆贝可（MBq）的99mTc-HMDP后150分钟接受闪烁显像检查。基于佩鲁基尼评分（Perugini Score，0~3分）对心肌摄取情况进行视觉评估，并以活检结果作为确诊依据。结果显示，8例患者的99mTc-HMDP闪烁显像提示心肌摄取强烈（3分）或中度（2分），与ATTR疑似诊断相符；另有10例患者未出现心脏放射性示踪剂摄取（0分），从而避免了有创活检。本研究数据表明，99mTc-HMDP闪烁显像在ATTR亚型的早期诊断中，尤其是在排除ATTR疑似患者方面发挥关键作用，可优化无需高成本有创操作的患者的管理流程。