Aging of the Tricuspid Valvular Annulus detected using photon-counting detector computed tomography.

Background: The aortic root (Ao) compresses the heart in elderly patients, potentially influencing the conduction system and causing atrial tachyarrhythmias (ATAs). However, actual anatomical alterations in the right side of the heart because of Ao compression have not yet been fully evaluated.

Objective: This study aimed to elucidate the alterations in the tricuspid valvular annulus (TVA) caused by Ao compression using a 3-dimensional endoscopic view of the heart constructed by photon-counting detector computed tomography (PCD-CT), an emerging medical technology.

Methods: We analyzed 135 consecutive patients who underwent PCD-CT at our institute after excluding those with diseases that directly influenced the right heart.

Results: Ao-compression caused significant TVA deformation. We defined severe TVA compression as the length of the TVA compressed by the aortic root ≥80% of the major axis of the TVA. Severe compression was more prevalent in elderly patients (age ≥ 75 years, 42%; p<0.01). The distance between the membranous septum and ostium of the coronary sinus was shortened, whereas the cavotricuspid isthmus (CTI) was elongated in older patients. The regression analysis identified aging as a significant contributor to TVA compression. The short minor and long major axes of the TVA, incidence of ATAs (70% vs. 45%, p<0.01), and atrioventricular conduction disturbances (38% vs. 15%, p<0.01) were more frequently observed in patients with severe compression.

Conclusions: Ao-compression deforms the TVA and alters the anatomical relationship between the atrioventricular conduction system and the CTI. Therefore, Ao-compression may contribute to the occurrence of ATAs and conduction disturbances in older patients.