Pathology of ostial right coronary artery

Abstract Background Clinical outcomes after percutaneous coronary intervention (PCI) for patients with severely calcified coronary artery disease have improved with advancements in treatment devices such as drug-eluting stents (DES), drug-coated balloons (DCB), and atherectomy devices. However, PCI outcomes for ostial right coronary artery (RCA) lesions remain suboptimal. Purpose This study aims to characterize the angiographic and pathological features of the ostial RCA in detail and compare them with those of the ostial left main trunk (LMT). Methods A total of 197 arteries from 125 hearts in our coronary pathology registry were analyzed. The arteries were sectioned sequentially at 3- to 4-mm intervals, yielding 5,384 sections stained with H&E and Movat Pentachrome. Ostial RCA and LMT lesions were examined and compared for plaque morphology, including calcification patterns. Additionally, we assessed the length of elastic fibers extending from the ascending aorta into the ostial RCA and LMT lesions and measured the delta angle of systolic and diastolic cardiac motion in these regions. Results The cohort had a mean age of 74 years, with 105 males (78%). Elastic fibers in the ostial LMT were significantly longer than those in the ostial RCA (8.8±4.4 mm vs. 5.1±4.5 mm, p=0.02), highlighting structural differences between these regions. The delta angle of systolic and diastolic cardiac motion was significantly larger in the ostial RCA than in the ostial LMT (18.0° IQR: 8.5°–88.5° vs. 5.5° IQR: 3.3°–12.8°, p=0.04). Nodular calcification, which likely represents fractures of sheet calcification due to hinge motion, was more frequently observed in the ostial RCA than in the ostial LMT (p=0.06). This may be attributed to greater cardiac motion and reduced stiffness due to shorter elastic fibers in the ostial RCA. Conclusion The shorter length of elastic fibers extending from the ascending aorta into the ostial RCA, combined with a higher prevalence of nodular calcification, may contribute to the poorer PCI outcomes observed in this region. Further studies are warranted to validate these findings in real-world clinical settings.Characteristics of Ostial RCA and LMT