812-21 Angiographic Progression of Inactive Unstable Plaque versus Stable Plaque in Patients with Stable Angina

The angiographic progression of ischemia-related stenoses (IRS) and non-IRS stenoses was prospectively assessed in 256 patients (pts) with stable angina (stable symptoms for at least 3 months) using computerized angiography. IRS were categorized as inactive unstable plaque (IRS which was responsible for a previous (g3 months) episode of unstable angina) in 76 pts (Group 1) and stable plaque (IRS which was not associated with a previous acute episode) in the remaining 180 pts (Group 2.). Following diagnostic angiography, pts were put on a waiting list for PTCA and restudied (8 ± 3 months after first angiogram) immediately preceding PTCA (230 pts) or soon after occurrence of coronary events (MI in 9 pts, unstable angina in 17 pts). IRS were complex (irregular borders, overhanging edges or introcoronary thrombus) in 40 of 76 (55%) inactive unstable plaques and 25 of 180 (21%1 stable plaques (p l 0.001). Stenosis progression (g20% diameter reduction or new total occlusion) and coronary events occurred more frequently in Group 1 than in Group 2 (26% vs. 11%, p = 0.01 and 17% vs. 7%, p = 0.02, respectively). IRS progressed in 14 pts of Group 1 and 9 pts of Group 2 (18% vs. 5%, p = 0.001). Progression of non-IRS (15 of 404 (4%)) was similar in Groups 1 and 2 (5% vs. 5%). Pts of Group 1 were younger than patients of Group 2 (55 ± 8 vs. 59 ± 10 (years). p = 0.002). Pts gender, risk factors, multivessel disease, baseline severity of IRS were not associated with IRS progression. Multiple regression analysis showed that inactive unstable plaque, angiographic complex morphology, and coronary events independently predicted IRS progression (p = 0.03, p = 0.02, and p = 0.0001, respectively). Change of percent stenosis (%) and minimal stenosis diameter (mm) in different subgroups were as following: 1st angio (%) 2nd angio (%) Δ (%) 1st angio (mm) 2nd angio (mm) Δ (mm) IRS in G1 66.3 ± 6.9 72.3 ± 15.3 * 6.0 ± 14.7 1.14 ± 0.26 0.88 ± 0.49* 0.26 ± 0.46 IRS in G2 65.6 ± 17.5 66.6 ± 11.0 † 1.0 ± 9.4 § 1.14 ± 0.28 1.10 ± 0.37 * 0.04 ± 0.28§ non-IRS in Gl 44.3 ± 12.2 46.6 ± 13.8 * 2.3 ± 95 1.69 ± 045 1.59 ± 0.48 * 0.10 ± 0.32 non-IRS in G2 44.1 ± 13.2 46.3 ± 12.6 * 2.2 ± 10.1 1.71 ± 0.45 1.63 ± 0.50 * 0.08 ± 0.31 Data are mean ± SD. G = Group, Angio = angiogram * p l 0.01 † p l 0.05 vs 1st angio by paired t-test § p l 0.001 vs IRS in Gl by unpaired t-test In pts with stable angina, inactive unstable plaques, and stenoses with complex morphology are predictors of rapid progression. Our results may be of clinical and pathophysiological relevance.