Pulmonary 99mTc-HMDP uptake correlates with restrictive ventilatory defects and abnormal lung reactance in transthyretin cardiac amyloidosis patients

Background: Pulmonary involvement in individuals with transthyretin cardiac amyloidosis is unclear. The aim of this study was to quantify 99mTc- hydroxy methylene diphosphonate (HMDP) lung retention in hereditary transthyretin (ATTRv) cardiac amyloidosis patients and to relate tracer uptake intensity to pulmonary function and aerobic capacity.
Methods: We prospectively enrolled 20 patients with biopsy-proven ATTRv cardiac amyloidosis and 20 control subjects. Cardiac involvement was confirmed by echocardiography and nuclear imaging using 99mTc-HMDP. Semi-quantitative analysis of the heart, rib and lung retention was assessed using a simple region of interest technique. Pulmonary function was evaluation by the means of whole-body plethysmography, diffusing capacity of the lung for carbon monoxide, forced oscillation technique and cardiopulmonary exercise testing.
Results: Pulmonary tracer uptake estimated by lung to rib retention ratio was higher in ATTRv amyloidosis patients compared with control subjects: median 0.62 (0.55–0.69) vs 0.51 (0.46–0.60); p=0.014. Analysis of relation between lung 99mTc-HMDP retention and pulmonary function parameters shown statistically significant correlations with total lung volume (% predicted), lung reactance (Xrs 5Hz) and peak VO2, suggesting total lung capacity restriction impaired elastic properties of the lung and poor aerobic capacity.
Conclusion: Our study suggests that some grade of pulmonary retention of 99mTc-HMDP may occur in patients with cardiac ATTRv amyloidosis, which can elicit deleterious effects on patient’s lung function and aerobic capacity.

背景：转甲状腺素蛋白心脏淀粉样变性（transthyretin cardiac amyloidosis）患者的肺部受累情况尚未明确。本研究旨在量化遗传性转甲状腺素蛋白（hereditary transthyretin, ATTRv）心脏淀粉样变性患者的99mTc-羟基亚甲基二膦酸盐（hydroxy methylene diphosphonate, HMDP）肺滞留率，并探讨显像剂摄取强度与肺功能及有氧代谢能力的关联。
方法：本研究前瞻性纳入经活检证实的ATTRv型心脏淀粉样变性患者20例，以及健康对照受试者20例。通过超声心动图及99mTc-HMDP核素显像确认心脏受累情况。采用简易感兴趣区技术对心脏、肋骨及肺部的显像剂滞留率进行半定量分析。肺功能评估采用全身体积描记法、肺一氧化碳弥散量、强迫振荡技术及心肺运动试验完成。
结果：通过肺/肋骨滞留比值评估的肺部显像剂摄取率，在ATTRv型心脏淀粉样变性患者中高于对照受试者：中位数0.62（四分位间距0.55~0.69） vs 0.51（0.46~0.60）；p=0.014。对肺部99mTc-HMDP滞留率与肺功能参数的相关性分析显示，其与肺总量（预测值百分比）、肺电抗（Xrs 5Hz）及峰值摄氧量（peak VO2）存在统计学显著相关性，提示肺总量受限可损害肺部弹性功能，并导致有氧代谢能力下降。
结论：本研究表明，心脏型ATTRv淀粉样变性患者可出现不同程度的99mTc-HMDP肺部滞留，这可能对患者的肺功能及有氧代谢能力产生不良影响。