The purpose of this study is to confirm that the treatment with acoramidis prevents the deterioration of the ATTR-CM disease progression index and that these indexes are surrogate markers of disease progression.

Inclusion Criteria:

• Treatment history of ATTR-CM is one of the following:

• Naive participants: newly diagnosed with ATTR-CM and no prior treatment with drugs for ATTR-CM

• Switch participants: Participants who are using tafamidis, a TTR stabilizer, as treatment for ATTR-CM and who, in the judgment of the post-marketing clinical trial investigator (co-principal investigator), can be expected to benefit from switching to acoramidis.

• Naive participants must meet the following requirements:

  1. History of hospitalization for heart failure or heart failure symptoms requiring treatment, including diuretics

  2. Echocardiographic end-diastolic ventricular septal thickness greater than 12 millimeters (mm)

  3. Confirmed diagnosis of ATTR-CM (wild type or mutant) by one of the following diagnostic methods

     1. Tissue biopsy shows amyloid deposition and TTR precursor protein is identified by immunohistochemistry or mass spectrometry.
     2. Bone scintigraphy showing strong accumulation ** (Perugini score ≥ 2) consistent with myocardium and no M protein, negating the possibility of AL amyloidosis

Exclusion Criteria:

• Have confirmed diagnosis of AL amyloidosis
• Switch participants: prior treatment with gene silencing agents (pachysilane sodium, butrisilane sodium) as treatment for ATTR-CM (including when specifically scheduled to start treatment with a gene silencing agent)
• Likelihood of receiving a heart transplant within 1 year from the time screening begins
• Hypersensitivity to acoramidis, its metabolites, or additives in the formulation has been confirmed.
• Pregnant or lactating women
• Has a clinically significant medical condition, an abnormal laboratory test result, or a condition that may jeopardize the safety of the study participant, increase the risk of participation in the post-marketing clinical trial, or affect the study
• Participating in an interventional study other than this study, including a clinical trial
• In the opinion of the responsible (sub)physician for the post-marketing clinical trial, has a history of drug abuse, alcoholism, or psychiatric disorder that would preclude compliance with this Post-Marketing Clinical Study Protocol

Alexion has a public commitment to allow requests for access to study data and will be supplying a protocol, CSR, and plain language summaries.