Right Ventricular Bone-Avid Tracer Uptake: A Novel Risk Marker in Transthyretin Amyloid Cardiomyopathy
Key result
Diffuse right ventricular uptake on bone-avid tracer SPECT was present in 66% (936/1,422) of ATTR-CM patients and independently predicted mortality over a median 34-month follow-up (34.7% deaths).
Why the study?
Does diffuse right ventricular uptake on 99mTc-PYP/DPD/HMDP SPECT predict mortality in patients with transthyretin amyloid cardiomyopathy (ATTR-CM)?
Structured PICO
Does diffuse right ventricular uptake on 99mTc-PYP/DPD/HMDP SPECT predict mortality in patients with transthyretin amyloid cardiomyopathy (ATTR-CM)?
P
Population
1,422 patients with transthyretin amyloid cardiomyopathy (ATTR-CM) from 5 centers in the UK and Italy undergoing bone-avid tracer SPECT imaging, followed for a median of 34 months.
E
Exposure
Evaluation of right ventricular (RV) uptake (classified as diffuse, extending beyond the basal RV free wall) on 99mTc-PYP/DPD/HMDP SPECT images
C
Comparator
Focal RV uptake (limited to the basal RV free wall) on 99mTc-PYP/DPD/HMDP SPECT images
O
Outcome
Mortality at a median follow-up of 34 months (censored at time of death, initiation of disease-modifying therapy with stabilizers or silencers, or enrollment in a therapeutic clinical trial)hard clinical
Limitations
- Retrospective analysis
- Right ventricular longitudinal strain, a previously validated prognostic marker, was not included in multivariable models
- Challenges related to partial volume averaging for measurement of RV uptake in a thin-walled structure on relative SPECT images
- RV longitudinal strain, a previously validated prognostic marker, was not included in the univariable and multivariable models
- Challenges related to partial volume averaging for the measurement of RV uptake of 99mTc-PYP/DPD/HMDP SPECT due to the thin-walled structure of the normal right ventricle
Key expert perspectives
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“This simpler and novel metric could be routinely evaluated and reported in clinical practice.”
Implication
This editorial highlights that diffuse right ventricular uptake on bone-avid tracer SPECT imaging is a novel, simple, and independent predictor of mortality in patients with transthyretin amyloid cardiomyopathy that can be routinely reported in clinical practice.
Abstract
Single photon emission computed tomography (SPECT) using bone-avid tracers such as technetium-99m-labeled pyrophosphate (PYP), 99mTc-3,3-diphosphono-1,2-pyrophosphate (DPD), or 99mTc-hydroxymethylene diphosphonate (HMDP) is a well-established noninvasive method for diagnosing transthyretin amyloid cardiomyopathy (ATTR-CM).Extensive data from thousands of patients confirms its high accuracy in diagnosing ATTR-CM in those who are symptomatic.1 Recent studies also indicate its utility in screening for amyloidosis in individuals at risk, such as those with carpal tunnel syndrome.The prognostic value of 99mTc-PYP/DPD/HMDP myocardial uptake in ATTR-CM has been summarized in a prior review article. 2 Many of these studies evaluated visual grade as well as semiquantitative measures on planar images. 2 Patients with negative scans (no myocardial uptake, grade 0) have shown significantly better survival rates compared to those with positive scans (myocardial uptake less than bone, equal to bone or greater than bone uptake, grades 1, 2, or 3, respectively). 2 However, among patients with positive scans, there is no difference in survival rates between those with grades 1, 2, or 3 uptake.2 Semi-quantitative measures, such as the heart to contralateral lung ratio (H:CL ratio > 1.6) and heart to whole body ratio (H:WB > 7.5) derived from planar imaging, have also been shown to be poor prognostic markers. 2 Data evaluating right ventricular (RV) uptake on 99mTc-PYP/DPD/HMDP SPECT are limited.Distinction between left ventricular (LV) and right ventricular (RV) myocardial uptake is not feasible on planar images and SPECT is needed.In this issue, the study conducted by Porcari A et al. 3 evaluated RV uptake on 99mTc-PYP/DPD/HMDP SPECT images of patients diagnosed with ATTR-CM, and determined its prognostic significance.This retrospective analysis involved 1422 patients diagnosed with ATTR-CM based on standard criteria from five centers, including the National Amyloidosis Center (NAC) in the UK and four Italian centers.TTR genotyping was performed in all patients.RV uptake was classified on SPECT images as either focal, limited to the basal RV
Discussion
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Cite This Study
Sharmila Dorbala (2024) conducted an editorial in Transthyretin amyloid cardiomyopathy (ATTR-CM) (n=1,422). Diffuse right ventricular (RV) uptake on 99mTc-PYP/DPD/HMDP SPECT vs. Focal right ventricular uptake (limited to the basal RV free wall) was evaluated on All-cause mortality. Diffuse right ventricular uptake on bone-avid tracer SPECT was present in 66% (936/1,422) of ATTR-CM patients and independently predicted mortality over a median 34-month follow-up (34.7% deaths).