935-32 Differing Mechanisms of Late Arterial Responses to Transcatheter Therapy: A Serial Quantitative Angiographic and Intravascular Ultrasound Study

Abstract

To evaluate the mechanisms of late arterial response to transcatheter therapy, we analyzed serial quantitative angiographic minimum lumen diameter (MLD) and diameter stenosis (DS) and intravascular ultrasound external elastic membrane (EEM), lumen, and plaque area in 137 lesions treated with various devices (31 PTCA, 57 directional and 26 rotational atherectomy, and 23 excimer laser angioplasty). From serial angiography (post-intervention and at follow-up 4.7 ± 2.8 mos later), lesions were divided into 3 groups based on Δ MLD and follow-up %DS. From serial intravascular ultrasound, late lumen loss (Δlumen area), geometric remodeling (ΔEEM area). and tissue growth (Δplaque area) were calculated for each group: ↑MLD (N = 14) ↓MLD, but DS < 0.5 (N = 44) ↓MLD and DS ≥ 05 p (N = 79) Post-intervention EEM (mm 2 ) 20.1 ± 3.7 20.7 ± 7.0 20.2 ± 6.5 NS Lumen (mm 2 ) 7.4 ± 2.0 7.0 ± 2.3 5.4 ± 2.2 < 0.0001 Plaque (mm 2 ) 12.7 ± 3.7 13.7 ± 5.9 14.8 ± 5.8 NS Follow-up EEM (mm 2 ) 21.3 ± 8.0 20.0 ± 6.6 18.0 ± 5.8 0.0849 Lumen (mm 2 ) 8.7 ± 6.7 5.6 ± 30 1.8 ± 1.5 < 0.0001 Plaque (mm 2 ) 12.6 ± 4.0 13.9 ± 5.0 16.2 ± 6.0 0.0169 Late lumen loss (mm 2 ) -1.3 ± 6.3 1.4 ± 2.6 3.5 ± 2.4 < 0.0001 Remodeling (mm 2 ) -1.2 ± 7.6 0.7 ± 2.9 2.3 ± 2.7 0.0014 Tissue growth (mm 2 ) -0.1 ± 4.0 0.7 ± 1.5 1.3 ± 2.4 0.0831 Geometric remodeling correlated with tissue growth (r = 0.426, p < 0.0001), but was independent of device used. We conclude: Patterns of the late arterial response following coronary intervention are determined less by tissue growth than by the direction and magnitude of geometric remodeling. Late lumen gain is the result of “overcompensation” with an increase in EEM area and minimal tissue growth. Late lumen loss without angiographic restenosis is the result of modest tissue growth with no decrease in EEM area. Angiographic restenosis is associated with moderate tissue growth, but is predominantly the result of geometric remodeling; a decrease in EEM area accounts for 66% of late lumen area loss