High frequency of occult transthyretin and apolipoprotein AI-type amyloid in aortic valves removed by valve replacement for aortic stenosis.

Background: A high incidence of valvular involvement of amyloid in the setting of aortic stenosis (AS) has been reported. Amyloid derived from ApoAI (AApoAI) can form local amyloid deposits in the aortic valve. Although a high prevalence of concomitant severe AS and cardiac transthyretin-type amyloidosis (ATTR) has been reported, the prevalence of valvular involvement by ATTR and AApoAI is unclear.

Methods: Using immunostaining and mass spectrometry, we analysed amyloid proteins in 97 aortic valves removed for valve replacement due to AS at Kyoto Prefectural University of Medicine between 2014 and 2021. Clinical information was also reviewed.

Results: Amyloid deposits were found in 44 cases (45%), of which 30 cases (68%) involved ATTR and 33 cases (75%) AApoAI. Statistical analysis showed significantly lower age and E/e' among amyloid-positive cases compared with amyloid-negative cases and significantly lower brain natriuretic peptide, higher fractional shortening, and higher left ventricular ejection fraction among ATTR-positive cases compared with ATTR-negative cases. Seven recent patients underwent bone scintigraphy and ATTR cardiomyopathy was observed in only one case.

Conclusions: AS symptoms can manifest earlier in patients with amyloid or ATTR deposition in the aortic valve than in patients without such deposition, even though left ventricular function is preserved.