State-of-the-art radionuclide imaging in cardiac transthyretin amyloidosis

Abstract

Cardiac amyloidosis, once considered untreatable, is now gaining well-deserved attention due to advances in imaging and the recent approval of targeted breakthrough therapies. In this paper, we discuss the role of radionuclide imaging in the evaluation and management of patients with the most common form of amyloidosis-cardiac transthyretin amyloidosis (ATTR). We provide a comprehensive summary of the literature interspersed with our institutional experience as appropriate, to deliver our perspective.

Clinical practice update on heart failure 2019: pharmacotherapy, procedures, devices and patient management. An expert consensus meeting report of the Heart Failure Association of the European Society of Cardiology

“…ATTR affects 20–30% of people aged >80 years and is more common in patients with HFpEF and/or degenerative aortic stenosis . Novel single photon emission computed tomography cardiac imaging with bone‐avid tracers (99mTc pyrophosphate, 3,3‐diphosphono1,2‐propanedicarboxylic acid, and hydroxymethylene diphosphonate (HMDP) help identify cases with high specificity, non‐invasively, obviating the need for endomyocardial biopsy. Similarly, the myocardial radiotracer uptake during bone scintigraphy could be used in clinical practice, as this was >99% specific and 86% sensitive to detect cardiac ATTR amyloid …”

“…ATTR affects 20-30% of people aged >80 years and is Table 2 Exclusion criteria of the ATTR-ACT trial 58 1 They had, in the opinion of the investigator, heart failure that was not due to transthyretin amyloid cardiomyopathy 2 New York Heart Association class IV heart failure 3 The presence of light-chain amyloidosis 4 A history of liver or heart transplantation 5 An implanted cardiac device 6 Previous treatment with tafamidis 7 An estimated glomerular filtration rate <25 mL/min/1.73 m 2 of body surface area 8 Liver transaminase levels exceeding two times the upper limit of the normal range 9 Severe malnutrition as defined by a modified body mass index of <600 calculated as the serum albumin level in g/L multiplied by the conventional body mass index (the weight in kg/m 2 ) 10 Concurrent treatment with non-steroidal anti-inflammatory drugs, tauroursodeoxycholate, doxycycline, calcium channel blockers, or digitalis more common in patients with HFpEF and/or degenerative aortic stenosis. [51][52][53][54][55] Novel single photon emission computed tomography cardiac imaging with bone-avid tracers (99mTc pyrophosphate, 3,3-diphosphono1,2-propanedicarboxylic acid, and hydroxymethylene diphosphonate (HMDP) help identify cases with high specificity, non-invasively, 56 obviating the need for endomyocardial biopsy. Similarly, the myocardial radiotracer uptake during bone scintigraphy could be used in clinical practice, as this was >99% specific and 86% sensitive to detect cardiac ATTR amyloid.…”

The current status of quantitative SPECT/CT in the assessment of transthyretin cardiac amyloidosis

“…21 In wtATTR, unlike in AL, specific renal involvement with amyloid is uncommon. 22 Hepatic uptake can occur in mATTR 23 but is not a common feature of bone scans in wtATTR (personal observation).…”

“…The mechanism by which bone scan radiopharmaceuticals are taken up and retained by the myocardium remains incompletely understood, 23 but it remains a reasonable hypothesis that more cardiac amyloid deposition will be associated with more bone scan uptake, that a greater amount of amyloid deposition is associated with a worse prognosis, and that changes in the amyloid burden can be assessed by changes in the amount of radiopharmaceutical uptake. The fact that that there is no difference in prognosis between visual grades 2 and 3 is disappointing, but is likely to be because the differentiation between these scores is determined by the amount of extracardiac ATTR deposition (which does not significantly affect prognosis) as well as by the amount of cardiac ATTR.…”

Scintigraphic non-invasive diagnosis of amyloid cardiomyopathy

“…Amyloidosis encompasses a heterogeneous group of disorders, characterized by extracellular deposition of insoluble abnormal amyloid aggregates, due to a failure in protein quality control. Cardiac amyloidosis is a disorder in which proteins misfold and deposit as amyloid fibrils that infiltrate the myocardial extracellular space [1].…”