Discordant results of visual and quantitative estimates of stenosis severity before and after coronary angioplasty

The ability to accurately estimate the severity of epicardial coronary stenoses is critical in the assessment of the immediate and long-term results of percutaneous transluminal coronary angioplasty (PTCA). We prospectively compared visual estimates, performed by experienced interventional cardiologists, with computerized quantitative angiographic measurements of stenosis severity in a group of patients (n = 305) before, immediately after and 6 months after PTCA. Before PTCA the visual estimate of the mean (+/- SD) percentage stenosis severity, 80.6 (+/- 9.7)%, was significantly (P < 0.001) higher than the equivalent value, 73.4 (+/- 11.1)%, obtained with use of quantitative angiography. Immediately after PTCA the visual estimate of the mean residual stenosis, 18.8 (+/- 12.3)%, was significantly (P < 0.0001) lower than the equivalent quantitative estimate, 37.4 (+/- 14)%. Additionally, the residual stenosis was more frequently (18% vs. 3%) classified as significant (> 50%) by quantitative angiography. At follow-up, quantitative measurements of stenosis severity showed a Gaussian distribution with a mean of 54.8 (+/- 21)%, whereas visual estimates had a bimodal distribution with populations greater than 70% and less than 50%. Visual estimates provide an inaccurate assessment of the immediate and medium term results of PTCA. Quantitative measurements suggest that the immediate results of PTCA are frequently misclassified as successful by the operator. Conversely, restenosis rates are underestimated by the operators suggesting that a more objective method must be used in trials to assess the impact of new therapies on the rate of restenosis.