Histologic Diagnosis of Coronary Amyloidosis Using Percutaneous Transluminal Directional Atherectomy

Cardiac amyloidosis (CA) is a cardiomyopathy that results from deposition of amyloid fibrils in cardiac tissue, causing progressive heart failure.' Two types of amyloid protein are major causes of CA: light chain amyloidosis and transthyretin amyloidosis (ATTR).' In ATTR amyloidosis, dissociation of transthyretin (TTR) tetramer into misfolded monomers leads to self-assembly and formation of insoluble cross -b-sheet-rich amyloid fibrils.' Ischemic heart disease is among the comorbidities associated with ATTR-CA. Amyloid accumulation in intramural coronary arterioles associated with microvascular dysfunction is known to occur,2 but amyloid vasculopathy in epicardial coronary primary arteries causing myocardial ischemia has not been reported.