Assessment of coronary angioplasty by an automated digital angiographic method

Digital subtraction coronary angiograms (DSA) of 63 patients who had undergone coronary angioplasty (PTCA) for a total of 73 lesions were analyzed with an automated border-detecting computer program capable of simultaneous geometric and densitometric cross-sectional area estimation. The computer measurements were compared with visual interpretation of the 35 mm cineangiograms. The results indicated that visual reports of cineangiograms tend to overestimate the pre-PTCA diameter percent stenosis and to underestimate the post-PTCA residual stenosis in comparison with the computer (p less than 0.001 in bot cases). There was good agreement between geometric and densitometric area percent stenoses calculated by the program on the pre-PTCA digital angiograms (r = 0.82, p less than 0.001, mean of their differences = -0.2 with standard deviation = 6.1). Following PTCA, however, important discrepancies between the two methods existed (r = 0.71, p less than 0.001, mean of their differences = 1.0 with standard deviation = 18.6). Following PTCA (but not pre-PTCA), densitometric evaluation demonstrated a significantly greater mean coefficient of variation between different views (69%) than did the geometric evaluation on the same views (24%). We conclude (1) that visual interpretation of cine coronary angiograms compares poorly with quantitative methods for both the selection of PTCA candidates and the assessment of the results; (2) that the geometric and densitometric characteristics do not agree in describing the degree of post-PTCA residual stenosis; and (3) that after angioplasty, important discrepancies between densitometric evaluation in different views are observed.