Transthyretin Amyloidosis with Cardiomyopathy (ATTR-CM) means a protein called transthyretin builds up in the heart, causing problems. This study is testing a new drug, nucresiran, to see if it helps patients with this disease by reducing deaths and heart-related issues. A placebo is a fake treatment used to compare results in research.

Eligibility: Participants should have been diagnosed with ATTR-CM and have a history of heart failure. They can be on certain heart failure medications and must meet specific heart health criteria. However, severe heart failure or advanced disease stages, severe nerve problems, and poor kidney function disqualify participation.

• The study compares nucresiran to a placebo to see if it helps people live longer or have fewer heart issues.
• Participants should have documented heart failure history and are allowed certain heart medications.
• People with severe heart or nerve problems, or on specific treatments, cannot join.