BACKGROUND: Bifurcation percutaneous coronary intervention (PCI) is associated with higher procedural failure and worse outcomes compared with PCI of non-bifurcated lesions. Based on recent randomized trials, the strategy of stenting main vessel with provisional side branch (SB) stenting is currently favored. Nonetheless, more frequent re-intervention rate in two stents strategy might be due to so-called oculostenotic reflex. So, we compared the angiographic outcome in SB ostium between two strategies in coronary bifurcation. METHODS AND RESULTS: One hundred and forty five patients with bifurcation lesion who underwent PCI were identified from SNUH-DES cohort(03.5-06.6) and analyzed. The patients were divided into one stent group (n = 125) and two stents group (n = 20). Between two groups, there was no difference in baseline clinical characteristics. Prior to intervention, SB ostium minimal luminal diameter (MLD) was wider in one stent group with marginal significance (1.38mm vs. 1.04mm; p=0.08). Nevertheless, following intervention, SB MLD of one stent group became smaller than two stents group (1.28mm vs. 2.19mm; p < 0.01). Six to nine months later after intervention, this angiographic superiority in SB MLD of two stents group persisted (one vs. two stents, 1.20mm vs. 1.70mm; p < 0.01), although there was higher late loss in two stents group (-0.08mm vs. 0.50mm; p < 0.01). At 1 year, there was no significant difference in the rates of clinical events including death of any cause, nonfatal myocardial infarction, stent thrombosis and cerebrovascular accident. However, target lesion revascularization (TLR) rates were higher in two stents group (one vs. two stent, 7.7% vs 25%; p= 0.03). The final results including more patients data will be presented at the meeting. CONCLUSION: There is no significant difference of clinical hard end points between one stent versus two stents strategy for PCI of bifurcation lesions, except for TLR that was higher in two stent group and may be related with oculostenotic reflex. In terms of angiographic outcomes of SB ostium, however, two stents group provided the long-term larger ostium. Accordingly, the strategy to use two stents would be actively adopted in coronary intervention of bifurcation lesion whose anatomic features require two stents.