{"entity":{"id":"cardiac-amyloidosis-attr","kind":"indication","name":"Cardiac amyloidosis (transthyretin, ATTR-CM)","aka":[],"tldr":"A misfolded blood protein called transthyretin builds up as stiff deposits inside the heart muscle, making it thicken and stop relaxing properly. A bone-scanning tracer that also sticks to these deposits can diagnose it without a heart biopsy.","summary":"Transthyretin amyloid cardiomyopathy (ATTR-CM) is caused by misfolded transthyretin (wild-type or a hereditary variant) depositing as amyloid fibrils in the myocardium, producing a restrictive, thick-walled heart failure phenotype that mimics hypertensive heart disease on echocardiography. It is distinct from AL (light-chain) cardiac amyloidosis, which needs haematology-led treatment, so excluding a plasma cell clone (serum/urine immunofixation and free light chains) alongside imaging is mandatory.\n\nBone-avid Tc-99m bisphosphonate tracers (pyrophosphate, or DPD/HMDP outside the US) bind ATTR amyloid deposits, apparently via calcium co-deposition, and are read against rib (bone) uptake on a 0-3 visual grade. Gillmore et al. (2016, JAMA Cardiology, n=1,217) showed grade 2-3 uptake, combined with the absence of a monoclonal protein, had 100% specificity and positive predictive value for ATTR-CM, avoiding endomyocardial biopsy in most patients. Multisociety expert consensus (ASNC/AHA/ASE/EANM/HFSA/ISA/SCMR/SNMMI, with a 2021 addendum) now requires SPECT or SPECT/CT confirmation of myocardial uptake; planar grading or the heart-to-contralateral ratio alone is no longer sufficient for diagnosis.\n\nThe test matters clinically because ATTR-specific therapies (TTR stabilisers and gene-silencing agents) are now available, so a confident non-invasive diagnosis changes management; this is outside Nuclide's therapeutic scope but is the reason demand for pyrophosphate scanning has grown sharply since the mid-2010s.","asOf":"2026-09-22","links":[{"label":"Gillmore et al. 2016, JAMA Cardiology: Tc-99m PYP scintigraphy for ATTR cardiac amyloidosis","url":"https://jamanetwork.com/journals/jamacardiology/fullarticle/2546034"},{"label":"ASNC practice points: 99mTc-pyrophosphate imaging for cardiac amyloidosis","url":"https://www.asnc.org/wp-content/uploads/2024/05/ASNC-Practice-Point-99mTechnetium-Pyrophosphate.2016.pdf"}],"tags":[],"related":["tc-99m-pyrophosphate","tc-99m"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"group":"cardiology","subtypes":[],"biomarkers":[],"standardOfCare":[{"setting":"non-invasive diagnosis of ATTR-CM","approach":"Tc-99m pyrophosphate (or DPD/HMDP) SPECT/CT grade 2-3 myocardial uptake plus exclusion of a monoclonal light-chain clone","refs":["tc-99m-pyrophosphate"]}],"stateOfArt":[],"history":[],"pipeline":[],"openProblems":[]},"route":"/indications/cardiac-amyloidosis-attr/","neighbours":{"drug":[{"id":"tc-99m-pyrophosphate","kind":"drug","name":"Technetium Tc-99m pyrophosphate","route":"/drugs/tc-99m-pyrophosphate/"}],"isotope":[{"id":"tc-99m","kind":"isotope","name":"Technetium-99m","route":"/isotopes/tc-99m/"}],"institution":[{"id":"asnc","kind":"institution","name":"American Society of Nuclear Cardiology","route":"/institutions/asnc/"}]}}