Non-interventional Study of Patients With Transthyretin (ATTR) Amyloidosis

Demographic characteristics (overall and in patients initiating a treatment with eplontersen)

* Age * Sex as determined by the investigator (male/female) * Race and ethnicity, where allowed

Treatment patterns (overall and in patients initiating a treatment with eplontersen)

In order to address this objective, the following treatments will be assessed: * ATTR amyloidosis treatment: Tafamidis, Diflunisal, Acoramidis, Vutrisiran, Patisiran, Inotersen, Eplontersen, Doxycycline and taurodesoxycholic acid, Liver transplant * Heart failure/arrhythmia-related treatment: Diuretics, Angiotensin converting enzyme inhibitor, Angiotensin receptor blocker, Angiotensin receptor-neprilysin inhibitor, Anticoagulation, Beta-blockers, Sodium-glucose co-transporter-2 inhibitor, Mineralocorticoid receptor antagonist, Digoxin, Pacemaker use, Implantable cardioverter-defibrillator, Left ventricular assist device, Cardiac transplant, Transcatheter aortic valve replacement, Surgical aortic valve replacement * Polyneuropathy-related treatment: Antiepileptics (gabapentin, pregabalin, carbamazepine, phenytoin), Antidepressants, Topical pain treatments, Opioids, Tetrahydrocannabinol * Other: Medications for gastrointestinal symptoms, Vitamin A supplementation, Dialysis

Clinical characteristics (overall and in patients initiating a treatment with eplontersen)

In order to address this objective, the following clinical characteristics will be assessed: * Modified body mass index (mBMI) * Medical history * TTR genetic test results * Family history of ATTR * Time period between the first symptoms to date of diagnosis of ATTR * Time since diagnosis of ATTR

Findings from biopsy (overall and in patients initiating a treatment with eplontersen)

In order to address this objective, the following biopsy information will be collected: * Type of biopsy * Amyloid identification result (Positive, Negative, Inconclusive for amyloid) * Method of amyloid typing * Result of the biopsy (Normal/Abnormal) * Reason for considering the biopsy result abnormal

Comparison of demographic and clinical characteristics of patients prescribed eplontersen at any time during the observation period to patients on other ATTR treatments

The following outcomes will be compared between patients treated with eplontersen and patients on other ATTR treatments: * Demographics * mBMI * Medical history * Family history of ATTR amyloidosis * Time period between the first symptoms to date of diagnosis of ATTR amyloidosis * Time since diagnosis of ATTR amyloidosis

Comparison of findings from biopsy in patients prescribed eplontersen at any time during the observation period to patients on other ATTR treatments

The following outcomes will be compared between patients treated with eplontersen and patients on other ATTR treatments: * Type of biopsy * Amyloid identification result (Positive, Negative, Inconclusive for amyloid) * Method of amyloid typing * Result of the biopsy (Normal/Abnormal) * Reason for considering the biopsy result abnormal

Comparison of findings from Cardiovascular magnetic resonance imaging (CMR) in patients prescribed eplontersen at any time during the observation period to patients on other ATTR treatments

The following outcomes will be compared between patients treated with eplontersen and patients on other ATTR treatments: extracellular volume (ECV), contrast use, left ventricular (LV) end-diastolic volume, LV end-systolic volume, LV ejection fraction, LV Mass Index, interventricular wall thickness, right ventricular Free Wall Thickness, LV Free Wall Thickness, left Atrial Volume Index, native T1 mapping, CMR result (Normal/Abnormal), reason for considering the result abnormal.

Comparison of findings from Echocardiography in patients prescribed eplontersen at any time during the observation period to patients on other ATTR treatments

The following outcomes will be compared between patients treated with eplontersen and patients on other ATTR treatments: LV ejection fraction, LV End Diastolic Volume, LV End Systolic Volume LV End Diastolic Dimension, LV End Systolic Dimension, Interventricular Septal, Thickness Diastole, Posterial Wall Thickness Diastole, Left Ventricular Mass Index, Left Atrial Volume, Left Atrial Volume Index, Mitral valve regurgitation, Aortic valve regurgitation, Tricuspid valve regurgitation, Pulmonic valve regurgitation, LV Outflow Gradient, Stroke Volume, Lateral early diastolic myocardial velocity (e' lateral), Medial early diastolic myocardial velocity (e' medial), Mitral E/e' Ratio, Early diastolic mitral inflow velocity (E), Late diastolic mitral inflow velocity (A), Mitral Peak E/A Ratio, Global LV longitudinal strain, Pulmonary artery systolic pressure, RV Free Wall Thickness Severity of Aortic stenosis, Severity of Mitral stenosis.

Risk factors for worsening ATTR progression

Factors associated with changes in clinical manifestations of ATTR amyloidosis, NYHA classification, NAC ATTR staging or Mayo staging, FAP (Coutinho) staging, PND score, LVEF, CCI and CCI components, and other comorbidities of interest will be identified.

Healthcare costs in patients with ATTR amyloidosis

Average annual costs will be calculated based on available data in the different countries.

Serious adverse events in patients treated with ATTR amyloidosis treatments

Serious adverse events in patients treated with ATTR amyloidosis treatments will be measured