We assessed the optimal intravascular ultrasound (IVUS) stent area to predict angiographic in-stent restenosis (ISR) after sirolimus-eluting stent implantation for unprotected left main coronary artery (LM) disease.

A total of 403 patients treated with single- or 2-stent strategies (crushing and T-stent) had immediate poststenting IVUS and 9-month follow-up angiography. Poststenting minimal stent area (MSA) was measured in each of 4 segments: ostial left anterior descending (LAD), ostial left circumflex (LCX) polygon of confluence (POC, confluence zone of LAD and LCX), and proximal LM above the POC. Overall, 46 (11.4%) showed angiographic restenosis at 9 months: 3 of 67 (4.5%) nonbifurcation lesions treated with a single-stent, 14 of 222 (6.3%) bifurcation lesions treated with single-stent crossover, and 29 of 114 (25.4%) of bifurcation lesions treated with 2 stents. The MSA cutoffs that best predicted ISR on a segmental basis were 5.0 mm² (ostial LCX ISR), 6.3 mm² (ostial LAD ISR), 7.2 mm² (ISR within the POC), and 8.2 mm² (ISR within the LM above the POC). Using these criteria, 133 (33.8%) had underexpansion of at least 1 segment. Angiographic ISR (at any location) was more frequent in lesions with underexpansion of at least 1 segment versus lesions with no underexpansion (24.1% versus 5.4%, P<0.001). Two-year major adverse coronary event–free survival rate was significantly lower in patients with underexpansion of at least 1 segment versus lesions with no underexpansion (90±3% versus 98±1%, log-rank P<0.001), and poststenting underexpansion was an independent predictor for major adverse cardiac events (adjusted hazard ratio, 5.56; 95% confidence interval, 1.99–15.49; P=0.001).

With these criteria, IVUS optimization during LMCA stenting procedures may improve clinical outcomes.