The coronary arteries arise from the aortic root via the coronary ostia. Ostial morphology and spatial orientation influences catheter engagement and cannulation stability during percutaneous coronary intervention. Detailed anatomic characterization of coronary ostial dimensions and geometric relationships within the aortic root may clarify access-related variability. Sixteen formalin-fixed human hearts were examined. Number and shape of coronary ostia were documented. Ostial diameter and height were measured using digital calipers, and cross-sectional area was calculated to account for noncircular morphology. Circumference of the sinuses of Valsalva (SoV) was measured with a flexible tape and converted to diameter. Three rater pairs independently obtained measurements and inter-rater reliability was assessed. Associations between ostial measurements, SoV diameter, and heart weight were evaluated. Median donor age was 81.5. Inter-rater reliability across measurements was moderate to excellent (ICC range 0.67–0.90). Left coronary ostial area was significantly larger than right (median 11.4 vs 4.9 mm²; p < 0.001). Right ostial height exceeded left (median difference 1.6 mm; p = 0.002). High takeoff occurred in 84.4% of ostia; no low-lying ostia were observed. Ostial area did not scale with heart weight. Left ostial area correlated with SoV diameter (Ï• = 0.60, p = 0.015), whereas right did not. We conclude that coronary ostial morphology demonstrates consistent left–right asymmetry. The left ostium is larger and associated with aortic root geometry, while the right is smaller and positioned higher within the aortic root. These findings enhance anatomical understanding of coronary origins and may inform variability encountered during coronary cannulation.
