Order the following tests^1,2†

• Serum kappa/lambda free light chains
• Serum protein electrophoresis with immunofixation
• Urine protein electrophoresis with immunofixation

Order a PYP scan

• The ACC advises utilization of PYP cardiac imaging to diagnose ATTR cardiac amyloidosis²

Visual interpretation

• Both planar and SPECT imaging should be evaluated for diffuse uptake of PYP in the myocardium³

Multisocietal expert consensus recommendations highlight the importance of PYP cardiac imaging in diagnosing ATTR cardiac amyloidosis³

• ^99mTc-PYP radioactive tracer is a highly sensitive, noninvasive diagnostic imaging technique
  • Used as an adjunct to diagnosis after ruling out AL, though not FDA approved for the diagnosis of ATTR cardiac amyloidosis

SPECT imaging is necessary for studies that show planar myocardial uptake because it can help differentiate myocardial uptake from blood or overlying bone uptake³

^|| Illustrative representation.

• The recommended time between injection of ^99mTc-PYP and scan is 3 hours to maximize specificity^¶
• Both planar and SPECT imaging should be reviewed and interpreted, irrespective of the timing of acquisition

Visual interpretation

• Evaluate planar and SPECT images to confirm diffuse radiotracer uptake in the myocardium
• Differentiate myocardial radiotracer uptake from residual blood pool activity on SPECT images
• If myocardial tracer uptake is visually present on SPECT, proceed to Step 2, semi-quantitative visual grading. If no myocardial tracer uptake is present on SPECT, the visual grade is 0

Semi-quantitative grading to distinguish AL from ATTR cardiac amyloidosis (1- or 3-hour approach)^3#

Examine planar and SPECT images for tracer uptake in the myocardium relative to ribs and grade using the following scale:

PYP imaging is used as an adjunct to diagnosis after ruling out AL. AL is ruled out by testing for presence of monoclonal protein via serum and urine protein electrophoresis with immunofixation and serum free light chain assay.

Heart/contralateral lung (H/CL) uptake ratio assessment (when applicable)³

Circular target regions of interest (ROI) are drawn over the heart on the planar images and are mirrored over the contralateral chest to account for background and ribs.

• An H/CL ratio is calculated as the fraction of heart ROI mean counts to contralateral lung ROI mean counts. If discordant or the visual grade is equivocal, H/CL ratio may be helpful to classify equivocal visual Grade 1 vs 2 as positive or negative
• H/CL ratios of ≥1.5 at 1 hour can accurately identify ATTR cardiac amyloidosis if myocardial PYP uptake is visually confirmed on SPECT and systemic AL amyloidosis is excluded. An H/CL ratio of ≥1.3 at 3 hours can identify ATTR cardiac amyloidosis
• NOTE: Diagnosis of ATTR cardiac amyloidosis cannot be made solely based on H/CL ratio alone with PYP. H/CL ratio is not recommended if there is absence of myocardial uptake on SPECT