The limitations of coronary angiography: identification of a critical coronary stenosis using intravascular ultrasound.

Coronary angiography is considered the gold standard method of imaging coronary stenoses. Quantitative coronary angiography (QCA) has helped to provide information about the degree of stenosis which is used as a surrogate to indicate impaired flow in a coronary bed. QCA however can underestimate disease severity. In this case intravascular ultrasound identifies a critical coronary stenosis not seen on angiography.