Integrated diagnostic approach to wild-type transthyretin cardiac amyloidosis with the use of high-sensitivity cardiac troponin T measurement and 99mTc-pyrophosphate scintigraphy

Background: The diagnosis of wild-type transthyretin cardiac amyloidosis (ATTRwt) is frequently missed or delayed because of the limited specificity of manifestations. We investigated the utility of combined assessment of high-sensitivity cardiac troponin T (hs-cTnT) measurement and Tc-99m-pyrophosphate (Tc-99m-PYP) scintigraphy as diagnostic modalities in ATTRwt. Methods: We divided 39 consecutive ATTRwt patients into two groups depending on whether serum hscTnT measurement and Tc-99m-PYP scintigraphy were adopted as diagnostic tools: group A patients (n = 8) who were diagnosed before the introduction of these two tools and group B patients (n = 31) who were diagnosed after the introduction of the two tools. We retrospectively evaluated the two groups. Results: Diagnostic yield was higher in group B than in group A (1.2 vs. 5.4 ATTRwt patients per 1000 hospitalized patients, p < 0.01). Group B patients presented broad clinical features that were different from group A patients with classical characteristics. Atrial fibrillation was more frequent (12.5% vs. 58.1%, p = 0.044) and inter-ventricular septum (IVS) thickness and relative wall thickness (RWT) were smaller in group B patients than in group A patients (IVS thickness: 16.1 +/- 2.4 mm vs. 13.6 +/- 2.8 mm, p = 0.023; RWT: 0.71 +/- 0.11 mm vs. 0.58 +/- 0.13 mm, p = 0.014). Furthermore, left ventricular hypertrophy (LVH) (IVS thickness >= 15 mm) was more frequent in patients in group A than in patients in group B (87.5% vs. 33.3%, p = 0.013). No significant difference was observed in the mean value of left ventricular ejection fraction (LVEF), whereas the dispersion of LVEF was high in group B (interquartile range: 47-58% vs. 3957%). Conclusions: An integrated approach consisting of hs-cTnT measurement and Tc-99m-PYP scintigraphy significantly increases the diagnostic rate of ATTRwt and has a high potential to identify ATTRwt patients with a variety of clinical phenotypes. (C) 2019 Published by Elsevier Ltd on behalf of Japanese College of Cardiology.