Subclinical Transthyretin Cardiac Amyloidosis in V122I TTR Carriers

(V122I TTR carriers and carriers of other pathogenic TTR alleles (or matched non-carriers)) Inclusion Criteria: * Men and women ages 30-80 who are carriers of pathogenic TTR alleles (or matched non-carriers) without history of HF (this will be assessed by study personnel) and defined as: a) No history of hospitalization within the previous 12 months for management of HF; b) Without an elevated B-type natriuretic peptide level ≥100 pg/mL or NT-proBNP ≥360 pg/mL within the previous 12 months; or c) No clinical diagnosis of HF from a treating clinician * Signed informed consent Exclusion Criteria: * A self-reported history or clinical history of HF * Other known causes of cardiomyopathy * History of light-chain cardiac amyloidosis * Prior type 1 myocardial infarction (non-ST segment elevation myocardial Infarction {NSTEMI} or ST-elevation myocardial infarction {STEMI}) * Cardiac transplantation * Body weight \>250 lbs * Estimated glomerular filtration rate ≤30 mL/min/1.73 m2 * Inability to safely undergo CMRI (For participants with symptomatic hATTR-CA, we will enroll probands with HF from Aim 1 or patients with suspected symptomatic hATTR-CA from the three study sites.) Inclusion Criteria: * Men and women ages 30-80 who have symptomatic hATTR-CA as determined by a history of HF (this will be assessed by study personnel) and defined as: a) History of hospitalization within the previous 12 months for management of HF; b) An elevated B-type natriuretic peptide level ≥100 pg/mL or NT-proBNP ≥360 pg/mL within the previous 12 months; or c) A clinical diagnosis of HF from a treating clinician. * Have an established or suspected diagnosis of hATTR-CA based on either a) Biopsy confirmed by Congo red (or equivalent) staining with tissue typing with immunohistochemistry or mass spectrometric analysis or immunoelectron microscopy, OR b) positive technetium-99m (99mTc)-pyrophosphate or -bisphosphonate scan, combined with accepted laboratory criteria without abnormal M-protein. * TTR gene sequencing that is pending or that is confirming the pathogenic TTR variant * Signed informed consent Exclusion Criteria: * Other known causes of cardiomyopathy * History of light-chain cardiac amyloidosis * Cardiac transplantation * Liver transplantation * Previous treatment with a TTR stabilizer (tafamidis, acoramidis) within the prior 14 days or TTR any silencer (inotersen, patisiran, eplontersen) * Estimated glomerular filtration rate ≤30 mL/min/1.73 m2