Cardiac scintigraphy and echocardiography assessment in the diagnosis of transthyretin cardiac amyloidosis

The aim is to evaluate the diagnostic yield of echocardiography and [⁹⁹mTc]Tc-DPD scintigraphy in the detection of amyloid cardiomyopathy (CM) and define potential prognostic echocardiographic parameters. 133 patients were retrospectively studied, from 2016 to 2021, with a mean age of 80.2 ± 7.5 years. The final diagnosis was established according to international consensus. Patients had a transthoracic echocardiogram (TTE) and [⁹⁹mTc]Tc-DPD scintigraphy; RWT, E/e, LS, TAPSE, SAB, and IWT scores were calculated. All patients with ATTR-CM were classified into 3 prognostic stages and were compared with Perugini grades and echocardiographic parameters. CM was confirmed in 85 cases (63.9%), 76 (57.1%) ATTR-CM, and 9 (6.8%) AL-CM. The diagnostic yield of [⁹⁹mTc]Tc-DPD scintigraphy and echocardiography were calculated, with a sensitivity of 90.7%, specificity of 100%, PPV of 100%, and NPV of 87.2% in myocardial scintigraphy, versus 74.6%, 62.5%, 75.6%, 61.2% in the echocardiogram. According to the IWT score, most patients were classified in the intermediate group; 33 presented with grade 2–3 uptakes. Significant results were obtained when comparing Perugini score with IWT (p: 0.02) and SAB (p: 0.03); and between biomarkers stages and LVEF (p: 0.028), E/e´ (p: 0.001), and GLS% (p: 0.022). [⁹⁹mTc]Tc-DPD scintigraphy is superior in diagnosing CA. SAB could be the most reliable parameter in an early diagnostic phase, showing a strong correlation with Perugini grades 2 and 3.