An Open-Label Study to Evaluate the Long-Term Safety and Efficacy of ALXN2220 in Adults With Transthyretin Amyloid Cardiomyopathy

* Inclusion Criteria * Type of Participant: Participants who have completed the Blinded Treatment Period (including the PC visit) of Study 301. * Sex and Contraceptive/Barrier Requirements: Male and/or female (according to their reproductive organs and functions assigned by chromosomal complement). * Informed Consent: Participant, or legally authorized representative where relevant and allowed by law, is willing and able to comply with all study requirements and to provide signed informed consent. * Exclusion Criteria * Participants who permanently discontinued study intervention in Study 301 * Participants who withdrew full consent during Study 301. * Medical Conditions: Suspected or known intolerance/allergy to proteins or any components of ALXN2220. Has had a heart transplant or permanent CMAD implantation. Has any new or worsening of existing medical or psychological condition or risk factor that in the opinion of the Investigator or Sponsor might jeopardize participant's safety or compliance with the protocol, or pose any additional risk for the participant, or confound the assessment of the participant or outcome of the study. * Prior/Concurrent/Future Clinical Study Experience: Current or future participation in another investigational clinical study or intake of investigational drug within 30 calendar days or 5 half-lives of the study intervention, whichever is longer, before signing the ICF, except for study intervention used in Study 301.