Diagnostic and prognostic value of right ventricle uptake at 99m-PYP scintigraphy in patients with ATTR cardiac amyloidosis
Authors: Glavam A , Bittencourt M I , De Castro P H R , Xavier De Brito A S , Carneiro M P , De Almeida S A , De Albuquerque D C 
Published: June 2023

Abstract

Funding Acknowledgements
Type of funding sources: Private company. Main funding source(s): Pfizer.

Introduction
Bone-seeking tracers scintigraphy has assumed a central role in the diagnosis of Amyloid Transthyretin Cardiac Amyloidosis (ATTR-CA) since it is currently the only non-invasive imaging method capable of accurately diagnosing ATTR-CA.
It is well known that right ventricle (RV) involvement is associated with poor clinical prognosis in patients with heart failure. Non-invasive imaging methods such as echocardiography and cardiac magnetic resonance have shown that RV involvement is common and related to poor outcomes. However, there is a paucity of data regarding scintigraphy in such a particular group of ATTR - CA patients.

Purpose
The present study was primarily designed to evaluate the diagnostic and incremental prognostic value of RV uptake of technetium-99m (99mTc) pyrophosphate (PYP) scintigraphy in ATTR-CA patients.

Methods
This is a prospective, observational, longitudinal study to evaluate clinical, laboratory and data obtained from non-invasive imaging methods for a period of 24 months. Only patients with a diagnosis of ATTR-CA suggested by scintigraphy and after ruling out monoclonal gammopathies were selected. Patients underwent 99mTc-PYP-scintigraphy and myocardial uptake was confirmed on planar images and SPECT/CT according to Perugini visual score.
The primary outcome was a composite of cardiovascular death due to worsening of heart failure or fatal arrhythmia, atrial fibrillation and stroke.

Results
Ten subjects were included from August 2020 to October 2022. Median age of 72 years, all male and 5 (50%) African American. 8 (80%) patients had hereditary ATTR-CA and 2 (20%) ATTR-CA wild type. 5 (50%) had mild renal dysfunction and NYHA Class II or III was observed in 90% of the patients. Median levels of NT-pro-BNP and troponin were 1688,77 pg/ml (100–4545) and 0,084 ng/ml (0,064–0,123), respectively. Median Left Ventricle Ejection Fraction was 39,5 ± 7,86 (Simpson's) and median interventricular septum thickness was 16,1 ± 2,56 mm.
Regarding scintigraphy results bi-ventricular (BIV) uptake was observed in 7 patients (70%). All patients had a grade 3 of Perugini score on left ventricle (LV) and the most common pattern of uptake was homogeneous and diffuse (70%). In patients with BIV the grade of Perugini score observed in RV was 57% (grade 3), 29% (grade 2) and 14% (grade 1) and the most common pattern of uptake was also homogeneous and diffuse (57%). Apex and mid-apex uptake was observed in 14% and 29% of patients, respectively. Three patients died during follow-up due to worsening of heart failure and cardiogenic shock: two in the group with BIV uptake and one in the group without right ventricle uptake at 99m-Tc-PYP scintigraphy. No statically significant difference was observed in the survival curve during follow up.

Conclusions
The prevalence of bi-ventriclular uptake on 99m-Tc-PYP- scintigraphy was high but was not related to a poor outcome of patients with ATTR-CA in our study.