A new digital electronic caliper for measurement of coronary arterial stenosis: Comparison with visual estimates and computer-assisted measurements

Abstract

Visual analysis of the severity of coronary stenosis is limited by observer variability. However, more complex techniques of proved accuracy are tedious and costly. Therefore, a new digital electronic caliper (DEC) was evaluated as a potentially more accurate, rapid and less costly alternative for measuring stenosis severity. Stenosis minimum diameter (D min) and percent diameter reduction ( %S) were measured from the screen of the cine projector using a DEC. These measurements were compared with visual estimates (VIS) by 4 experienced angiographers and with measurements made by a computer-assisted method (QCA) of proved accuracy. In routine cineangiograms from 7 patients, 10 lesions were significant (>50%S) and 8 were mild (<50%S). Variability, the standard deviation of multiple estimates of D min and %S, averaged 0.09 mm and 3.1 % for QCA; 0.18 mm and 5.9% for DEC; and 0.26 mm and 7.4% for VIS. Compared with QCA, the visual determination of %S significantly underestimates (−5%; p < 0.02) mild and overestimates (+11 %; p < 0.002) significant stenosis. VIS underestimates D min in significant lesions by 20 % (p < 0.04). In contrast, the mean error for DEC measurement of D min and %S was not significantly different from 0 in either lesion group. For the entire group of lesions, and particularly in significant lesions, the mean error for measurement of these 2 indexes of disease was significantly less with DEC than with VIS. Thus, variability and error with DEC are acceptably low for clinical use. DEC is superior to VIS in evaluating significant (>50%) coronary stenoses, and it may be applied with improved accuracy in the evaluation of cineangiograms.