Variation in measurement of coronary lesions on 35 and 70 mm angiograms.

Inter- and intraobserver variability in the measurement of coronary artery stenosis using 35 mm cine and 70 mm spot film angiography was examined. Three experienced observers measured 52 lesions on two occasions. The 35 mm cine was evaluated visually, and a single 70 mm frame demonstrating the stenosis was assessed both visually and with a calibrated magnifying device (jeweler's eyepiece). Higher correlation coefficients within and between observers were obtained using the cine method compared to the 70 mm visual and eyepiece techniques. Observer variability was decreased further by using an average of several readings from the 35 mm cine to assess the degree of stenosis. The data suggest that neither higher resolution film (70 mm) nor calibrated magnifying devices diminish observer variability in the measurement of coronary artery lesions.