Normal angiographic tapering of the coronary arteries.

OBJECTIVE: Although the size of normal coronary arteries has been reported, the expected magnitude of angiographic tapering has not. Accordingly, the coronary angiograms of 13 men and 13 women with normal and right dominant coronary arteries were analyzed in detail to calculate the normal tapering of angiographic segments.
BACKGROUND: Coronary artery disease is a diffuse process that can lead to the underestimation of the extent of lumen narrowing by angiographic analysis. Knowledge about the expected size of the angiographic lumen may help to overcome this problem in quantitative angiographic studies. Similarly, the expected magnitude of tapering is potentially useful to identify segments with nonapparent disease if the propensity of atheroma to build up distally and at branch points induces greater than expected tapering.
METHODS: Lumen diameter was measured in 13 main segments. Two tapering indexes (T1 and T2) were defined. T1 was the difference between the proximal and distal segment diameter, divided by the proximal segment diameter, expressed as a percentage. T2 was the difference between the mean diameter of the proximal half of a segment and the distal diameter, divided by the mean of the proximal half of the segment, expressed as a percentage.
RESULTS: In women, for the proximal and distal left anterior descending artery, T1 was 18 14% and 29 9%, respectively, while T2 was 14 11% and 21 9%, respectively. The right coronary artery (RCA) demonstrated a lesser magnitude of T1 and T2 tapering. In women, T1 was 9 12% and 7 8% for the proximal and the distal RCA, respectively, while T2 was 4 10% and 2 9% for the proximal and the distal RCA, respectively. Similar tapering results were obtained in men.
CONCLUSIONS: The estimation of an expected magnitude of tapering of coronary arteries may identify diseased segments that are not angiographically stenotic.