Although we do not have tissue for mass spectroscopy or genotyping to prove our patient had ATTR, it is the likely culprit based on 99mTc-PYP uptake, cardiomyopathy phenotype without extracardiac involvement, negative protein electrophoresis, and free light chain workup, and no other underlying inflammatory conditions, plasma cell dyscrasias, or chronic renal failure. This evidence concerns the gene TTR and cardiomyopathy.