Multimodality imaging characterization of Perugini scintigraphic grades in transthyretin amyloid cardiomyopathy: a single-center experience.

BACKGROUND

Transthyretin amyloid cardiomyopathy (ATTR-CM) has undergone a shift towards noninvasive diagnostics using bone tracer scintigraphy with Perugini grading. While both grades 2 and 3 are considered diagnostic, potential phenotypic differences between these groups remain uncertain. We aimed to evaluate the diagnostic yield of technetium-99 m pyrophosphate (99mTc-PYP) scintigraphy and to compare clinical and multimodality imaging characteristics across scintigraphic grades in a single-center cohort.

METHODS

We retrospectively reviewed all patients who underwent 99mTc-PYP scintigraphy for suspected cardiac amyloidosis between 2018 and 2025. Patients with confirmed ATTR-CM were stratified by Perugini grade (grade 2 vs. grade 3). Clinical features, biomarkers, electrocardiography, echocardiography, and cardiac magnetic resonance (CMR) parameters were compared. Correlations between scintigraphic grade, imaging markers, and biomarkers were assessed.

RESULTS

Among 302 scans, 103 (34.1%) had reported cardiac uptake on planar imaging. Fifty-three patients were diagnosed with ATTR-CM, including 8 (15.1%) with grade 2 and 45 (84.9%) with grade 3 uptake. Grade 3 patients exhibited worse functional status, shorter 6-min walk distance, and higher troponin I levels. Echocardiography showed greater maximal wall thickness, lower left ventricular ejection fraction, and worse global longitudinal strain. In the subset with CMR (n = 38), grade 3 patients (n = 30) had significantly higher left ventricular mass index, extracellular volume fraction, right ventricular free wall thickness, and more frequent right ventricular involvement. Perugini grade showed strong rank-based correlations with left ventricular mass index (ρ = 0.61, P < 0.01) and extracellular volume (ρ = 0.53, p < 0.01), and a moderate correlation with troponin I (ρ = 0.55, P < 0.01). A modest correlation with brain natriuretic peptide (BNP) was also observed (ρ = 0.36, P < 0.05), although BNP levels did not differ significantly between grade groups. Grade 1 uptake was not associated with subsequent ATTR-CM diagnosis on available follow-up.

CONCLUSIONS

Noninvasive scintigraphy provides effective detection of ATTR-CM in a referral population. Although grades 2 and 3 both meet diagnostic criteria, in this retrospective cohort, grade 3 uptake was associated with markers of more advanced structural remodeling, higher extracellular volume, greater right ventricular involvement, and worse functional impairment.