A Study to Learn More About the Change in the Blood Levels of Transthyretin When Participants With Transthyretin Amyloidosis With Cardiomyopathy Switch From Tafamidis to Acoramidis

Inclusion Criteria: * Participants must be 18 to 90 years of age inclusive, at the time of signing the informed consent. * Diagnosis of ATTR-CM; disease defining examination, i.e., Single Photon Emission Computed Tomography (SPECT) or SPECT/Computed Tomography (CT) or biopsy, within 24 months prior to Visit 1 (V1). * Participants must currently be treated with tafamidis and have used tafamidis for at least the previous 3 months prior to V1 and have adhered to tafamidis therapy. * New York Heart Association (NYHA) class ≤ II at V1. * Estimate glomerular filtration rate (eGFR) ≥ 30 mL/min/1.73m\^2 at V1. * N-terminal pro-B-type Natriuretic Peptide (NT-proBNP) \> 300 and ≤ 7000 pg/mL at V1. Exclusion Criteria: * Prior liver or heart transplantation or planned within the next 12 months. * Current or planned use of ventricular assist device. * Active cancer or other disease that decreases the life expectancy to less than one year. * Heart failure due to ischemic heart disease. * Myocardial infarction, cardiovascular (CV) surgery, or unstable angina within the last 90 days prior to V1. * Confirmed diagnosis of light-chain amyloidosis. * Dialysis or severe renal impairment as reflected by Urinary Albumin Creatinine Ratio (UACR) \> 300 mg/g at V1. * Major surgery within 90 days prior to V1. * Recent initiation of Sodium-Glucose-Cotransporter-2 inhibitors (SGLT2i) within 3 months before V1. * Initiation of treatment with a diuretic or increase in diuretic dose within 3 months before V1. * Treatment with calcium channel blockers (e.g., verapamil, diltiazem) or digitalis. * Recent CV hospitalization within 3 months before V1. * Known hypersensitivity to acoramidis or to any of the excipients. * A condition that, as judged by the investigator, would preclude compliance with the study protocol, such as a history of substance abuse, alcoholism, or a psychiatric condition. * Known or suspected liver disorder and bile secretion/flow (cholestasis, also history of it). * Abnormal liver function tests at V1, defined as ALT (GPT) or AST (GOT) ≥ 3 x ULN or total bilirubin ≥ 3 x ULN at V1.