TTR and cardiac amyloidosis: Transthyretin cardiac amyloidosis (ATTR-CA) causes progressive, fatal, heart failure (HF), due to misfolding of transthyretin (TTR), forming insoluble amyloid fibrils, which are deposited within the myocardial extracellular space.1,2 Until recently, ATTR-CA was considered a rare, untreatable disease.