Determinants of declining kidney function are multifactorial and depend on the underlying genotype, comorbidities, and cardiac disease severity—hence, there is a need to define the disease course and stratify progression at an individual patient level. Nevertheless, the rate of eGFR decline observed in this cohort appears greater than that observed in the general heart failure population, possibly reflecting the more severe and rapidly advancing nature of ATTR-CM, which is potentially compounded by the direct impact of kidney ATTR fibril deposition. This evidence concerns the gene TTR and heart failure.