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Background Prognostic staging systems in transthyretin amyloid (ATTR) cardiomyopathy were developed before the introduction of disease‐modifying treatment. We therefore evaluated contemporary risk stratification according to different staging systems in patients with ATTR cardiomyopathy. Methods All patients with newly diagnosed ATTR cardiomyopathy and baseline biomarker measurements from 2019 to 2023 were included from Mayo Clinic, Rochester, MN. Prognostic outcomes were calculated with Kaplan–Meier analysis for 3e staging systems in the main analysis: the National Amyloidosis Centre (NAC) staging system; a modified Mayo staging system using hsTNT (high‐sensitivity troponin T) cutoff >65 ng/L; the extended NAC model with a fourth stage (NT‐proBNP [N‐terminal pro‐B‐type natriuretic peptide] >10 000 ng/L). Results The study population consisted of 441 patients with a median age of 76 years, 93% were men, 85% were initiated on tafamidis, and 94% had wild‐type ATTR. Median follow‐up was 3.4 years, and 109 deaths occurred during follow‐up. The 3‐year survival for the Mayo stages were 92.3% (88.7–95.9) for stage I, 71.6% (63.0–81.3) for stage II, and 43.5% (32.4–58.5) for stage III. For the NAC system, 3‐year survival were 92.0% (89.0–95.7), 67.5% (59.0–77.3), and 47.0% (34.7–63.5) for stages I, II, and III, respectively. The 3‐year survival by the extended NAC system was 92.0 (69.0–79.2), 69.0% (60.1–79.2), 53.2% (39.9–70.8) and 34.4% (17.4–68.0) for stages I, II, III, and IV, respectively. Conclusions In a contemporary cohort of patients with ATTR cardiomyopathy, the NAC and modified Mayo staging systems remained equally effective in delineating clinically meaningful prognostic groups, whereas the extended NAC system identified a stage IV subgroup with high mortality.

Abstract Background AL amyloidosis and multiple myeloma are plasma cell dyscrasias characterized by excess light-chain production leading to cardiac amyloid deposition and organ dysfunction. While effective, proteasome inhibitor–based therapy and stem cell transplantation are often limited in advanced disease. Daratumumab provides durable and well-tolerated plasma cell suppression and enables assessment of long-term cardiac outcomes. Purpose To evaluate the long-term effects of daratumumab therapy on cardiac biomarkers and myocardial amyloid burden, assessed by artificial intelligence- based electrocardiographic (AI-ECG) and echocardiographic measures, in patients with AL amyloidosis and cardiac involvement. Methods Following IRB approval, we conducted a retrospective review of patients with AL amyloidosis and cardiac involvement treated with daratumumab at Mayo Clinic Rochester since 2015, with a minimum follow-up of 6 months. Demographic, clinical, cardiac biomarker, electrocardiographic, and echocardiographic data were collected at baseline and last follow-up. Paired comparisons were performed using the Wilcoxon signed-rank test. Results Overall, 67 patients with AL amyloidosis were included (mean age at diagnosis 59 ± 10 years; 47 [70%] male; concomitant multiple myeloma 13 (19%) patients, mean left ventricular ejection fraction 61 ± 7%), with a mean follow-up duration of 8.3 ± 5.4 years. At diagnosis, the most common organ involvements were renal and cardiac, affecting 78% and 67% of patients, respectively. Free light-chain isotype was λ in 52 patients (75%) and κ in 17 (25%) and immunoglobulin heavy-chain was identified in 26 patients. Among patients with available baseline staging data, Mayo Clinic revised cardiac staging (2012) classified 32% as stage I, 14% as stage II, 21% as stage III, and 32% as stage IV. Most patients were NYHA class II (62%), with 27% in class III–IV. Baseline creatinine clearance <60 ml/min was observed in 48% of patients. No significant changes were observed in conventional echocardiographic parameters during follow-up. In contrast, cardiac biomarkers improved significantly with high-sensitivity troponin T decreased from a baseline median of 59 [25, 104.5] ng/L to 30.5 [14.5, 58.75] ng/L at follow-up (p = 0.003), and NT-proBNP declined from 1,053 [423.5, 6,211.5] pg/mL to 729 [299, 2,328] pg/mL (p = 0.02). Interestingly, artificial intelligence–based electrocardiographic analysis demonstrated a marked reduction in the predicted likelihood of cardiac amyloidosis, decreasing from 55.8% [5.1, 99.6] at baseline to 19.3% [4.3, 68.4] at follow-up (p < 0.0001). Conclusions Long-term daratumumab therapy was associated with significant reductions in cardiac biomarkers and AI-ECG derived measures of myocardial amyloid burden. These findings support the hypothesis that sustained suppression of pathogenic light-chain production may permit gradual improvement in amyloid cardiomyopathy over time.

BACKGROUND: Technetium-based cardiac amyloid radionuclide imaging enables noninvasive diagnosis of transthyretin amyloid cardiomyopathy (ATTR-CM), but conventional planar and visual semiquantitative approaches have important limitations. We developed the quantitative 3-dimensional Mayo 3D Score, defined as the ratio of mean left ventricular myocardial radiotracer uptake to right atrial blood-pool uptake using computed tomography (CT)-fused single-photon emission CT (SPECT) volumes of interest, and sought to validate its diagnostic performance against myocardial pathology. METHODS: Consecutive patients who underwent 99m Tc-pyrophosphate SPECT/CT at Mayo Clinic for suspected ATTR-CM between June 2017 and January 2025 with archived myocardial tissue were included. Baseline characteristics, including demographics, echocardiogram, biomarkers, visual semiquantitative, and Mayo 3D Score metrics, were collected. Myocardial specimens underwent histopathologic confirmation of amyloid, with amyloid subtype determination and further semiquantitative grading of amyloid burden and deposition patterns. RESULTS: Among 230 patients (median age, 72 years; 78% male), 107 (47%) had ATTR-CM, of whom 9 had hereditary ATTR-CM. The Mayo 3D Score showed excellent discrimination against pathology (area under the receiver operating characteristic curve, 0.92 [0.88–0.96]), exceeding planar Perugini (0.87 [0.83–0.92]; P =0.006), and heart-to-contralateral lung ratio (0.86 [0.81–0.91]; P =0.004) and comparable to SPECT Perugini (0.90 [0.86–0.94]; P =0.12). A cutoff ≥1.0 yielded 86.0% sensitivity, 92.7% specificity, 91.1% positive predictive value, and 88.4% negative predictive value. Among ATTR-positive cases, the Mayo 3D Score correlated strongly with semiquantitative amyloid burden (Spearman ρ=0.69), was higher in pericellular than nodular deposition patterns ( P <0.001), and was not associated with vascular involvement ( P =0.42). CONCLUSIONS: In patients with suspected ATTR-CM undergoing 99m Tc-pyrophosphate SPECT/CT, the Mayo 3D Score demonstrated superior diagnostic performance compared with planar metrics and comparable to SPECT Perugini, while correlating with myocardial ATTR burden and deposition patterns on pathology. These findings support its integration as a quantitative adjunct within clinical diagnostic ATTR-CM workflows.

Abstract Background Tafamidis is a near-complete transthyretin kinetic stabiliser for the treatment of patients with transthyretin amyloid cardiomyopathy (ATTR-CM). It is administered orally, once daily, and has demonstrated a statistically significant reduction in mortality at 30 months vs placebo. Purpose Report findings from patients who received up to 7.5 years treatment with tafamidis in the phase 3 trial and its long-term extension (LTE) study. Methods In ATTR-ACT, patients were randomised (2:1:2) to blinded tafamidis meglumine 80 mg, 20 mg, or placebo for 30 months. Patients continued their blinded tafamidis dose into the up to 60-month LTE study, until commercial prescription availability, or study termination. Those who received placebo in ATTR-ACT were randomized (2:1) to blinded tafamidis meglumine 80 mg or 20 mg in the LTE study. All patients were subsequently switched to open label tafamidis free acid 61 mg (bioequivalent to meglumine 80 mg). Outcomes were assessed over the entire 90-month follow-up. Results Of the 264 patients randomised to tafamidis in ATTR-ACT, 173 completed the trial and 170 continued to receive tafamidis the LTE study (Taf/Taf group). Of 177 patients randomised to placebo in ATTR-ACT, 85 completed the trial and 82 initiated tafamidis in the LTE study (Pbo/Taf group). Over a median follow-up of 54.2 months in the Taf/Taf group and 30.5 months in the Pbo/Taf group, incidence of all-cause mortality (ACM) was 54.5% and 71.2%. Median time to ACM was 47.5 and 30.3 months, resulting in a hazard ratio of 0.62 (95% CI: 0.49-0.79; P=0.0001; Figure). Incidence of cardiovascular-related mortality (CVM) was 42.0% and 57.1% in the Taf/Taf and Pbo/Taf groups. Median time to CVM was 47.6 and 30.3 months, resulting in a hazard ratio of 0.61 (0.47-0.81; P=0.0005). The total annual rate of all-cause hospitalisation in the LTE study was 0.69 in the Taf/Taf group and 1.14 in the Pbo/Taf group, and the total annual rate of cardiovascular-related hospitalisation was 0.36 and 0.63. Among patients remaining at each LTE study visit and with available data, improvement in New York Heart Association functional classification was more commonly seen in the Taf/Taf vs Pbo/Taf group. Mean observed reduction from baseline in Kansas City Cardiomyopathy Questionnaire Overall Summary score was significantly smaller in the Taf/Taf vs Pbo/Taf group at most LTE study visits. Treatment-related adverse events occurred in 11.2% of the Taf/Taf and 23.2% of the Pbo/Taf groups during the LTE study and were consistent with the known safety profile of tafamidis. Conclusions With up to 7.5 years of follow-up data, this analysis of ATTR-ACT trial and its LTE study is the longest reported to date for an ATTR-CM population treated with disease-modifying therapy. Findings demonstrate better long-term outcomes including survival, hospitalisation rates, quality of life, and heart failure symptoms with long-term tafamidis treatment. For image description, please refer to the figure legend and surrounding text.

Abstract Background Age and sex influence the clinical expression of transthyretin (ATTR) amyloidosis, but limited evidence exists on their real-world impact across disease phenotypes. The prospective, multi-national MaesTTRo study, currently enrolling patients from the USA, Canada, the UK, Germany and Spain, provides a uniquely comprehensive opportunity to explore age- and sex-associated differences in routine practice. The aim of this analysis was to quantify the associations between these factors and diagnostic delay and cardiac findings. Methods Baseline data from 230 consecutively enrolled patients were analysed. Cohorts were stratified by age at diagnosis (&lt;60 y, n = 45; ≥60 y, n = 185) and separately by sex (female n = 70; male n = 161). Clinical characteristics, laboratory values, echocardiographic parameters and Kansas City Cardiomyopathy Questionnaire (KCCQ-23) scores were compared descriptively. Additional data will be included in the presentation as enrollment continues. Results Younger patients exclusively expressed a hereditary genotype (100% vs 63%), and experienced a longer mean (+SD) diagnostic delay than older patients (48 ± 61.5 vs 40.9 ± 64.4 months). Cardiac involvement was markedly age-dependent: median NT-proBNP was 91.5 pg ml⁻¹ (IQR 48.5–307) in the &lt;60 yrs group versus 1,393.5 pg ml⁻¹ (457–3,065) in the ≥60 yrs group. Older patients were more likely to experience New York Health Association (NYHA) class II–IV limitation than younger patients (88% vs 44%). Nonetheless, LV ejection fraction remained preserved in both cohorts (51 ± 14.8 vs 55.6 ± 9.3%). Older patients also reported a higher burden of cardiac symptoms (52% vs 33%). Patient-reported KCCQ scores were lower in the ≥60 yrs group vs &lt;60 years (68.4 ± 22.3 vs 73.3 ± 27.4). Females were more often diagnosed with ATTRv (84% vs 63%) after longer delays (51.3 ± 80.9 vs 38.3 ± 54.6 months), despite a stronger family history (61% vs 34%), and had lower biomarkers (NT-proBNP: 589 pg ml⁻¹ [111–2,509] vs 1,220 pg ml⁻¹ [386–2,941]) and wall thickness (LV wall thickness &gt;12 mm: 58% vs 73%), although there was no difference in LV mass index. Males reported better health status (KCCQ: 70.7 ± 22.2 vs 64.7 ± 24.4). Neurologic manifestations were common in both sexes (~70%), while musculoskeletal symptoms were more commonly reported in females (33% vs 23%). Conclusions Age and sex may independently modulate the diagnostic trajectory and cardiac presentation of ATTR amyloidosis. Advanced age and male sex are associated with more pronounced structural biomarker evidence of myocardial damage, whereas younger age and female sex are linked to delayed diagnosis of primarily hereditary ATTR amyloidosis with polyneuropathy and less cardiac involvement, especially when non-indexed echo measurements are used. These results underscore the need for age- and sex-specific approaches to prompt early clinical suspicion and diagnosis in order to enable treatment to mitigate disease progression.For image description, please refer to the figure legend and surrounding text.For image description, please refer to the figure legend and surrounding text.

Abstract Background 99mTc-labelled cardiac scintigraphy enables noninvasive diagnosis of transthyretin amyloid cardiomyopathy (ATTR-CM). Guidelines recommend using planar semiquantitative (heart to contralateral ratio, H/CL) and single photon emission computed tomography (SPECT) qualitative visual grading for diagnostic interpretation. However, planar imaging has inherent limitations, and visual grading is prone to interobserver variability, underscoring the need for standardized quantitative assessment. We developed a 3D volumetric quantitative score (3D Score) and assessed its diagnostic performance compared to myocardial tissue, the gold standard for ATTR-CM diagnosis. Methods At a single, tertiary referral center, we retrospectively identified consecutive patients from 06/2017 to 06/2024 who underwent 3-hour 99mTc-pyrophosphate or 99mTc-hydroxymethylene diphosphonate planar and SPECT/CT for suspected ATTR-CM and had archived myocardial tissue (biopsy or myectomy). On planar imaging, H/CL was calculated. On SPECT/CT, volumes of interest were drawn around the entire left ventricle (LV), avoiding calcifications, and within the right atrium (RA) blood pool. Mean uptake values were used to calculate the 3D Score (LVmean:RAmean), Fig 1A. Myocardial tissue was stained via sulfated Alcian blue and/or Congo red histochemistry. Once histologically confirmed, amyloid deposits were subtyped by liquid chromatography tandem mass spectrometry. The diagnostic performance of H/CL and 3D Score was assessed using receiver operating characteristic (ROC) curve analysis and predictive characteristics were defined. ROC areas under the curve (AUC) were compared using Delong test. Optimal cutoffs were determined using Youden’s J statistic. Baseline characteristics (demographics, echocardiogram, biomarkers) and H/CL were compared between patients above and below 3D Score cutoff. Results 239 patients were identified (median age 72 [65-78], 78% male, 46% ATTR positive). Median time between cardiac scintigraphy and myocardial tissue collection was 22 (6-65) days. Distribution of the 3D Score stratified by ATTR-CM status is illustrated in Fig 1B-C. The discriminative ability of the 3D Score was excellent (AUC 0.92) and superior to H/CL (0.87, p =0.006, Fig 1D-E). The optimal 3D Score cutoff for identifying ATTR-CM was ≥1.0 with sensitivity of 86%, specificity of 92%, positive predictive value (PPV) 90%, and negative predictive value (NPV) 89%. The optimal H/CL ratio cutoff for identifying ATTR-CM was ≥1.4 with sensitivity of 72%, specificity of 86%, PPV 81%, NPV 78%. Baseline characteristics of the overall cohort stratified by 3D Score are displayed in Table 1. Conclusions The 3D Score demonstrated excellent diagnostic performance for detecting ATTR-CM and was superior to current quantitative metrics. Future studies are needed to externally validate its performance across diverse patient cohorts and imaging centers and to investigate correlation with myocardial amyloid burden. Figure 1