In quantitative coronary arteriography (QCA), the outer diameter of th
e contrast catheter is used almost exclusively as the calibration devi
ce, Since the true outer diameter of these catheters are smaller than
the French sizes listed by the manufacturer, it has been advocated to
measure the actual sizes with a precision micrometer. However, this re
presents a significant effort in the organizations of the QCA Angiogra
phic Core Laboratories and of the participating cardiac catheterizatio
n laboratories. In the Dutch REGRESS trial on regression/progression o
f coronary artery disease, we have measured a total of 2,104 catheters
from four different manufacturers. In 2,048 of the 2,104 catheters th
e variabilities in the measurements were 0.02-0.03 mm, which represent
s an error of only 1% of the average catheter sizes, In the remaining
56 catheter measurements, the variability was 0.04 mm, From these data
we may conclude that from now on the stated mean values can be used f
or calibration purposes. This has important practical consequences for
running clinical trials and QCA Core Laboratory operations. (C) 1994
Wiley-Liss, Inc.