Quantitative assessment of coronary arterial diameter before and after coronary artery bypass grafting.

Because coronary artery bypass graft patency is related to the size of the artery, a preoperative assessment of arterial diameter is important. However, the relation between coronary arterial diameter (assessed by angiography) and true luminal size of arteries that are occluded and filled by collaterals has not been completely characterized. This study was done to measure the luminal diameter of coronary arteries before and after bypass grafting. Twenty-six patients (20 men and 6 women, aged 34 to 72 years) had coronary angiography before and from 1 to 35 months after bypass surgery. Coronary arterial luminal diameter was similar before and after operation for the 18 insignificantly narrowed arteries and the 24 arteries with narrowings that filled by anterograde flow before operation and were bypassed. In contrast, in the 21 arteries that were occluded and filled by collateral flow, coronary arterial diameter was significantly larger (p less than 0.001) after operation. Thus, when a coronary artery is occluded and filled by collaterals, its true luminal size is consistently underestimated by the angiogram.