Implementation of Standardized Early Identification and Diagnosis for Transthyretin Amyloidosis (ATTR) in High-Risk Populations

Inclusion Criteria: 1. Age ≥ 60 years, at the time of signing the informed consent (ICF). 2. Documented diagnosis of symptomatic heart failure (NYHA class I-III) at enrolment, and current diagnosis or a medical history of HF 3. Documented Elevated N-terminal pro-B-type natriuretic peptide (NT-proBNP) \> 300 pg/mL at enrolment. 4. Documented LVEF ≥40% at enrolment. 5. Documented LVH defined as end-diastolic wall thickness of ≥12 mm (IVS or PWT) on transthoracic Echocardiogram (TTE) at enrolment. 6. Patients who are willing and able to comply with all scheduled visits, laboratory tests, and other study procedures. 7. Willing and able to undergo 99mTc-PYP scintigraphy. 8. Capable of giving signed ICF as described in Appendix A which includes compliance with the requirements and restrictions listed in the ICF and in this protocol. Exclusion Criteria: 1. Known etiology of myocardial disease: A confirmed diagnosis of amyloidosis (e.g., amyloid A amyloidosis, primary \[light chain\] amyloidosis), a non-amyloid infiltrative cardiomyopathy (i.e., cardiac sarcoidosis, hemochromatosis), muscular dystrophies, cardiomyopathy with reversible causes, hypertensive heart disease, pheochromocytoma, hypertrophic obstructive cardiomyopathy with known geneticetiology, or known pericardial constriction, etc. These diagnoses of myocardial disease could be further validated by the Investigator at Screening if the prior diagnosis is considered suspect. 2. Known serum free light chain (sFLC), serum immunofixation electrophoresis (sIFE), or urine immunofixation electrophoresis (uIFE) anomalies. 3. Prior clinical history of Coronary Artery Bypass Grafting (CABG) or multi-vessel obstructive coronary disease (\>50% stenosis of \>2 epicardial coronary arteries). 4. Acute Myocardial Infarction (AMI) within 6 months before Screening. 5. Unable to undergo 99mTc-PYP examination, such as: 1)Previously documented hypersensitivity reaction to 99mTc; 2)Severe renal insufficiency (eGFR \<30 mL/min/1.73m²); 3)Severe myelosuppression (leukocytes \<3.5×10⁹/L or platelets \<80×10⁹/L). 6.Other medical or psychiatric condition including recent (within the past year) active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the patient inappropriate for the study.