Prognostic utility of the Perugini grading of ^99mTc-DPD scintigraphy in transthyretin (ATTR) amyloidosis and its relationship with skeletal muscle and soft tissue amyloid

High-grade (Perugini grade 2 or 3) cardiac uptake on bone scintigraphy with ^99mTechnetium labelled 3,3-diphosphono-1,2-propanodicarboxylic acid (^99mTc-DPD) has lately been confirmed to have high diagnostic sensitivity and specificity for cardiac transthyretin (ATTR) amyloidosis. We sought to determine whether patient stratification by Perugini grade on ^99mTc-DPD scintigraphy has prognostic significance in ATTR amyloidosis.

Patient survival from time of ^99mTc-DPD scintigraphy was determined in 602 patients with ATTR amyloidosis, including 377 with wild-type ATTR (ATTRwt) and 225 with mutant ATTR (ATTRm) amyloidosis. Patients were stratified according to Perugini grade (0-3) on ^99mTc-DPD scan. The prognostic significance of additional patient and disease-related factors at baseline were determined. In the whole cohort, the finding of a Perugini grade 0 ^99mTc-DPD scan (n = 28) was invariably associated with absence of cardiac amyloid according to consensus criteria as well as significantly better patient survival compared to a Perugini grade 1 (n = 28), 2 (n = 436) or 3 (n = 110) ^99mTc-DPD scan (P < 0.005). There were no differences in survival between patients with a grade 1, grade 2 or grade 3 ^99mTc-DPD scan in ATTRwt (n = 369), V122I-associated ATTRm (n = 92) or T60A–associated ATTRm (n = 59) amyloidosis. Cardiac amyloid burden, determined by equilibrium contrast cardiac magnetic resonance imaging, was similar between patients with Perugini grade 2 and Perugini grade 3 ^99mTc-DPD scans but skeletal muscle/soft tissue to femur ratio was substantially higher in the latter group (P < 0.001).

^99mTc-DPD scintigraphy is exquisitely sensitive for identification of cardiac ATTR amyloid, but stratification by Perugini grade of positivity at diagnosis has no prognostic significance.