SPC365

Role of 99mTC-DPD Scintigraphy in Tracking Therapeutic Response to Tafamidis in hATTR-CM

Session: Sessão de Posters 15 - Prognóstico, estratificação de risco e comorbilidades na amiloidose cardíaca
Speaker: João Mendes Cravo

Congress: CPC 2026
Topic: F. Valvular, Myocardial, Pericardial, Pulmonary, Congenital Heart Disease
Theme: 17. Myocardial Disease
Subtheme: 17.3 Myocardial Disease – Diagnostic Methods
Session Type: Posters Eletrónicos
FP Number: ---
Authors: João Cravo; Marta Vilela; Catarina Campos; Isabel Conceição; Fausto Pinto; Dulce Brito; João Agostinho
<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong>Introduction:&nbsp;</strong></span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#333333">Transthyretin amyloid cardiomyopathy (ATTR-CM) is nowadays a major cause of heart failure worldwide, due to improved awareness of clinical red flags and use of non-invasive diagnostic tools like&nbsp;</span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><sup>99m</sup></span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">TC-DPD scintigraphy</span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#333333">. The emergence of disease-modifying therapies&nbsp;like tafamidis, have altered the natural history of ATTR-CM and highlighted the need for reliable methods to assess treatment response. However, the ability of imaging modalities to reflect changes in amyloid burden during therapy and track disease progression is not fully established.&nbsp;</span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong>Aims:</strong></span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">To evaluate disease progression in hATTR-CM patients treated with tafamidis and assess the utility of </span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><sup>99m</sup></span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">TC-DPD</span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#333333"><span style="background-color:#ffffff"> in monitoring treatment response.</span></span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong>Methods:</strong></span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">Single-center, retrospective observational study including patients diagnosed with hATTR-CM</span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="background-color:#ffffff"> between 2022-2025. </span></span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">Pre and post-treatment </span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><sup>99m</sup></span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">TC-DPD bone scintigraphy was performed and Perugini scores were compared and correlated with disease progression and clinical outcomes.&nbsp;</span></span></span></p>

<p><br />
<span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong>Results</strong></span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">:&nbsp;</span></span></span></p>

<p><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">48 patients with hATTR-CM were included (mean age 69 &plusmn; 1.7 years, 33 (83%) male). Genetic variants included: Val30Met in 41 (85%),&nbsp; G89L in 1 (2%) and V122L in 6 (13%). Hypertension was present in 28 (58%), followed by atrial fibrillation in 11 (23%). At baseline, 34 patients (71%) had positive </span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><sup>99m</sup></span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">TC-DPD bone scintigraphy. Patients with Perugin Score of 0-1 underwent endomyocardial biopsy for diagnostic confirmation. All patients were treated with tafamidis 61 mg.</span></span></span></p>

<p><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">Over a mean follow-up of 36 &plusmn; 3 months, 11 patients (23%) experienced heart failure decompensation, 5 (10%) required cardiovascular hospitalization and 4 (8%) died, including 1 cardiovascular death.&nbsp;</span></span></span></p>

<p><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">Echocardiographic parameters had no significant changes between baseline and follow-up. Serum transthyretin (sTTR) levels increased significantly (24 &plusmn; 2 to 29 &plusmn; 1 mg/dL; p=0.002). Ongoing disease progression despite tafamidis prompted treatment escalation to vutrisiran in 5 patients (10%), with a mean switch time of 27 &plusmn; 6 months.</span></span></span></p>

<p><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">23 patients underwent follow-up </span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><sup>99m</sup></span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">TC-DPD scintigraphy at 27 &plusmn; 2 months after treatment initiation: 13 (57%) showed reduced cardiac uptake, whereas 4 (17%) showed increased uptake. No significant differences were observed between these groups regarding functional class, laboratory values, echocardiographic parameters, or outcomes.</span></span></span></p>

<p><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong>Conclusion:&nbsp;</strong></span></span></span></p>

<p><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">Despite showing that the majority of patients with hATTR-CM treated with tafamidis 61mg had a reduction in </span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><sup>99m</sup></span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">TC-DPD scintigraphy myocardial uptake, our study shows a poor correlation between changes in uptake at follow-up and disease progression/clinical outcomes, possibly limited by the low number of follow-up&nbsp;</span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><sup>99m</sup></span></span></span><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">TC-DPD scintigraphy.&nbsp;The utility of bone scintigraphy in assessing treatment response, disease progression and clinical outcomes should be made with caution.</span></span></span></p>