Assessment of percutaneous transluminal coronary angioplasty by quantitative coronary angiography: diameter versus densitometric area measurements.

Cineangiograms of 138 patients who underwent percutaneous transluminal coronary angioplasty (PTCA) were analyzed with a computer-based coronary angiography analysis system. The results before and after dilatation are presented. In a first study group (120 patients), the severity of the obstructive lesions derived from the automatically detected contours was evaluated in absolute terms and in percent-diameter reduction. In a second group of patients, 18 coronary lesions were selected for their extreme severity and symmetric aspect before angioplasty as assessed from multiple views. In the second group, the densitometric percent-area stenosis was used to assess the changes in cross-sectional area after PTCA and was compared with the circular percent-area stenosis computed from the diameter measurements. Before PTCA, a good agreement exists between the densitometric percent-area stenosis and the circular percent-area stenosis. After PTCA, important discrepancies between these 2 types of measurements are observed. It is suggested that these discrepancies in results after PTCA can be accounted for by asymmetric morphologic changes in luminal cross section, which cannot be assessed accurately from diameter measurements in a single-plane view.