Detect Transthyretin Amyloid Cardiomyopathy (ATTR-CM)

 DISCOVER THE TOOLS TO DIAGNOSE ATTR-CM   

See how nuclear scintigraphy, endomyocardial biopsy (EMB), and genetic testing can be used to reach an ATTR-CM diagnosis.

*Should be combined with blood and urine testing to rule out AL.^1,2

Nuclear Scintigraphy

• A noninvasive diagnostic tool with high sensitivity and specificity for ATTR-CM when combined with testing to rule out AL amyloidosis¹
• A multicentre international study demonstrated 99% sensitivity for ATTR-CM (visual grade 1-3). A separate analysis within the study demonstrated 100% specificity for visual grade 2, 3 with concurrent testing to rule out AL¹*^†                       
• Uses a radioactive bone tracer, [^99mtechnetium-labeled pyrophosphate (^99mTc-PYP), ^99mtechnetium-labeled 3,3-diphosphono-1,2-propanodicarboxylic acid (^99mTc-DPD), for detection of ATTR¹

Endomyocardial Biopsy (EMB)

• Histology with positive Congo red staining with apple-green birefringence^1,3
• Additional tests to determine amyloid type are recommended following diagnosis of cardiac amyloidosis¹
• Risk of complications and the need for specialised centres and expertise may contribute to a diagnostic delay^1,3
   

Genetic Testing

• Used to determine if the disease is hereditary due to a mutation in the TTR gene⁴
• Genetic counseling and gene sequencing are recommended following confirmation of ATTR-CM⁴

MAKING AN ATTR-CM DIAGNOSIS

Watch a cardiologist diagnose ATTR-CM. In the previous videos, Dr. Detective had a patient referred to him. He suspected ATTR-CM based on certain signs and symptoms. See what happens next.

HOW NUCLEAR SCINTIGRAPHY IS USED TO DIAGNOSE ATTR-CM

Diagnosing ATTR-CM with nuclear scintigraphy requires quantifying uptake of the radioactive tracer [^99mTc-PYP/^99mTc-DPD] in the heart.^1,5

Quantifying Myocardial [^99mTc-PYP/^99mTc-DPD]^1,5

In clinical practice, [^99mTc-PYP/^99mTc-DPD] uptake can be quantified by a quantitative approach and a semiquantitative approach: 

• Semiquantitative: visual comparison to bone uptake at 3 hours
  • Cardiac uptake of [^99mTc-PYP/^99mTc-DPD] evaluated using a visual scoring method in relation to bone uptake
  • Images are then given a visual grading score of 0 to 3
    • Grade 0: no uptake and normal rib uptake
    • Grade 1: uptake less than rib uptake
    • Grade 2: uptake equal to rib uptake
    • Grade 3: uptake greater than rib uptake with mild/absent rib uptake

Reproduced/Adapted/or Referenced with permission from ASNC. © 2019 American Society of Nuclear Cardiology.

• Quantitative: myocardial to contralateral lung ratio of uptake at 1 hour

Reproduced/Adapted/or Referenced with permission from ASNC. © 2019 American Society of Nuclear Cardiology.

• Interpretation is based on results from the semiquantitative or the quantification approach
  • A ratio >1.5 or visual score of 2 or 3 is considered strongly suggestive of ATTR
  • A ratio <1 or visual score of 0 is considered not suggestive of ATTR
  • A ratio of 1-1.5 and a visual score of 1 is considered equivocal

Making a Reliable Diagnosis

A recent key study suggests that a reliable diagnosis of ATTR-CM can be made with nuclear scintigraphy when the following criteria are met¹:

• The patient has heart failure with evidence of cardiac amyloidosis via echocardiography or CMR
• AL cardiac amyloidosis has been ruled out via blood and urine tests
• Nuclear scintigraphy results fall within the parameters of the grading system (ie, grade 2 or 3)

Histological confirmation and typing should be pursued in cases of suspected cardiac amyloidosis when the above criteria are not satisfied.¹

If a patient is positive for ATTR-CM with nuclear scintigraphy, genotyping is recommended to determine if it’s wtATTR or hATTR.^1†

*Please consult individual labeling for risks.
^†Also known as variant ATTR.⁶