Background: Intravascular ultrasound (IVUS) is used to assess intermediate lesions in native coronary arteries; minimum lumen area (MLA) <4.0 mm(2) is accepted as a cutoff for a significant stenosis. We evaluated the IVUS in-stent MLA at 9-month follow-up that best predicted subsequent target lesion revascularization (TLR)-free survival in patients from the TAXUS IV, V, and VI studies.
Methods and results: In the combined TAXUS IV, V, and VI randomized trials, 9-month IVUS was available in 635 patients (331 treated with paclitaxel-eluting stents [PES] and 304 treated with bare-metal stents [BMS]) who did not require TLR in the first 9 months postintervention and who were followed for 3 years. The in-stent MLA that best predicted 3-year TLR-free survival was determined. At 9-months follow-up, IVUS-measured in-stent MLA was 5.7 + or -2.3 mm(2) in the PES group and 4.8 + or - 2.3 mm(2) in the BMS group. Between 9 months and 3 years, TLR was required in 4.9% of patients who were treated with PES and 6.7% of patients who were treated with BMS. Multivariate analysis identified MLA at 9 months as a significant predictor of late TLR (hazard ratio, 0.63 [0.43-0.93]; P = 0.02). The ability of MLA to predict late TLR was further assessed using receiver operating characteristic analysis. MLA was found to be an acceptable discriminator for both PES (c = 0.7448) and BMS (c = 0.7329). Finally, the optimal thresholds of MLA that best predicted subsequent TLR-free survival were determined to be 4.2 mm(2) for PES and 4.0 mm(2) for BMS.
Conclusions: In the combined IVUS analysis of TAXUS IV, V, and VI, patients who did not require TLR within the first 9 months had a high subsequent TLR-free survival rate whether treated with PES or BMS. MLA measured by IVUS at 9 months predicted subsequent TLR with a cutoff similar to intermediate, de novo lesions in native coronary arteries.