Diagram reproduced from Austen, et al.


Segment Description Notes
1 Proximal Right From ostium to ½ distance to the acute margin. Gives rise to the conus branch and Sinus node branch
2 Mid Right Up to the acute margin
3 Distal Right Up to the RPD origin
4 Right Posterior Descending May be absent if left dominant
5 Left Main Ostium to bifurcation
6 Proximal Left Anterior Descending Up to origin of first septal perforator
7 Mid Left Anterior Descending Up to half the distance from the first septal perforator to the cardiac apex
8 Distal Left Anterior Descending
9 First Diagonal May include ramus intermedius
10 Second Diagonal
11 Proximal Circumflex Up to and including marginal branch origin
12 Obtuse Marginal Largest branch
13 Distal Circumflex Distal to marginal origin
14 Posterolateral May be small
15 Left Posterior Descending Present in left dominant system



Austen, W. G., et al. (1975). “A reporting system on patients evaluated for coronary artery disease. Report of the Ad Hoc Committee for Grading of Coronary Artery Disease, Council on Cardiovascular Surgery, American Heart Association.” Circulation 51(4 Suppl): 5-40.


Young, P. M., et al. (2011). “Cardiac imaging: Part 2, normal, variant, and anomalous configurations of the coronary vasculature.” AJR Am J Roentgenol 197(4): 816-826.