TTR and cardiac amyloidosis: Her brain natriuretic peptide (BNP) level was elevated to 892.9 pg/mL, ^99mTc-pyrophosphate scintigraphy demonstrated myocardial tracer uptake, and gastrointestinal endoscopic biopsy demonstrated transthyretin amyloid deposition, confirming transthyretin cardiac amyloidosis (ATTR).