TTR and restrictive cardiomyopathy: Hereditary ATTR with predominant cardiac involvement is called ATTRv-CA.52, 53The main features of ATTRv-CA are bundle branch, atrioventricular, and/or sinoatrial blocks, as well as increased thickness of ventricular walls, especially the interventricular septum.54The accumulation of amyloid in the heart can lead to restrictive cardiomyopathy, right-sided heart failure, or heart failure with preserved ejection fraction.