Myocardial extracellular volume in the longitudinal assessment of amyloid burden: a case for caution
Myocardial extracellular volume in the longitudinal assessment of amyloid burden: a case for caution
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淀粉样蛋白负荷纵向评估中的心肌细胞外容量：一个需要谨慎的例子
DOI：
10.1093/ehjci/jead021
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Dohi Kaoru
中科院分区：
文献类型：
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作者：
Nakamori Shiro;Fujimoto Naoki;Ishida Masaki;Masuya Masahiro;Dohi Kaoru
一位64岁的女性类风湿性关节炎被转介到我们的心脏科劳力性呼吸困难和下肢水肿。实验室检查结果如下：脑钠肽（BNP），1093 pg/mL，肌钙蛋白I，300 pg/mL，红细胞压积，34.8%。此外，观察到单克隆蛋白和无血清轻链（FLC）比值升高，558（正常范围; 0.26-1.65）。肌内膜活检样本显示肌细胞丢失、细胞外间隙增加和直接坚牢猩红4 BS阳性，与心脏淀粉样变性一致（图A）。化疗后，FLC比率、BNP、肌钙蛋白水平在1年时显著降低（图B）。患者在3 T扫描仪上接受了3次心血管磁共振（CMR）研究，基线和随访成像间隔为1年和2年（图C，见在线补充材料，视频S1-S3）。T1、细胞外容积（ECV）和T2值（分别为1623 ms、69%和66 ms）弥漫性显著增加，并主要累及侧壁。虽然在1年随访时ECV值降低至57%，贫血改善，但在2年随访成像时再次增加至诊断时的值。相比之下，在基线、1年和2年时间间隔内，天然心肌T1、T2值和透壁晚期钆增强模式相似，反映了不可逆的淀粉样蛋白负荷和心肌水肿（1年随访时分别为1620 ms、69 ms，2年随访时分别为1635 ms、69 ms）。虽然CMR-ECV是淀粉样蛋白浸润的替代标志物，但该病例强调了依赖基于CMR-ECV的方法进行淀粉样蛋白负荷纵向评估时的谨慎性。计算的ECV与1-红细胞比容成正比，1-红细胞比容定义为全血中红细胞的体积百分比。实际上，在这种情况下，第一次随访的红细胞压积为43.2%，与基线红细胞压积34.8%有很大差异。治疗期间红细胞压积的变化可能导致对该标志物如何纵向表现的错误计算。
A 64-year-old woman with rheumatoid arthritis was referred to our cardiology department with exertional dyspnea and lower extremity edema. Laboratory test results were as follows: brain natriuretic peptide (BNP), 1093 pg/mL, troponin I, 300 pg/mL, and hematocrit, 34.8%. In addition, an elevated monoclonal protein and serum-free light chain (FLC) ratio, 558 (normal range; 0.26–1.65) was noted. Endomyocardial biopsy samples depicted myocyte loss, an increased extracellular space, and positive direct fast scarlet 4BS, consistent with cardiac amyloidosis (Panel A). After chemotherapy, the FLC ratio, BNP, troponin levels remarkably decreased by 1 year (Panel B). The patient underwent three cardiovascular magnetic resonance (CMR) studies at a 3 T scanner, with baseline and follow-up imaging performed at 1-year and 2-year intervals (Panel C and see Supplementary material online, Videos S1–S3). There were diffusely and markedly increased T1, extracellular volume (ECV) and T2 values (1623 ms, 69% and 66 ms, respectively) and predominant involvement of the lateral wall. Although the ECV value decreased to 57% at the 1-year follow-up with improvement of anemia, this increased again to the value at the time of diagnosis by the 2-year follow-up imaging. In comparison, native myocardial T1, T2 values and transmural late gadolinium enhancement pattern were similar among the baseline, 1-year and 2-year intervals, reflecting irreversible amyloid burden and myocardial edema (1620 ms, 69 ms at the l-year follow-up, 1635 ms, 69 ms at the 2-year follow-up, respectively). Although CMR-ECV is a surrogate marker of amyloid infiltration, this case highlights caution when relying on a CMR-ECV based approach for the longitudinal assessment of amyloid burden. The calculated ECV is directly proportional to the 1-hematocrit, which is defined as the volumetric percentage of red blood cells in whole blood. Actually, in this case, the first follow-up hematocrit of 43.2% was quite different from baseline hematocrit of 34.8%. A change in hematocrit during therapies can result in a miscalculation on how this marker may behave longitudinally.