1.This is a diagram of the coronary anatomy and 3 major coronary arteries.

2.It will be used to illustrate how there can be heterogeneity in how studies of the same research question are carried out.

3.Alderman EL, Stadius ML. The angiographic definitions of the Bypass Angioplasty Revascularization Investigation. Coronary Artery Disease; 1992;3:1189–207.