Differential effect of side branch intervention on long-term clinical outcomes according to side branch stenosis after main vessel stenting: Results from the COBIS (Coronary Bifurcation Stenting) Registry II

Background Indication of side branch (SB) intervention after main vessel (MV) stenting is not established for coronary bifurcation lesions. Methods We evaluated 2017 patients who were treated with 1-stent technique or MV stenting as a first strategy. Patients undergoing SB intervention after MV stenting (SB intervention group, n = 929) were compared to those treated with MV stenting only (no-SB intervention group, n = 1088). Results During a median follow-up of 37 months, cardiac death or myocardial infarction (MI) tended to occur less frequently in the SB intervention group than in the no-SB intervention group (1.8% versus 2.9%; adjusted hazard ratio [HR] 0.53; 95% confidence interval [CI] 0.25–1.11; P = 0.09). There was a significant interaction between SB intervention and SB stenosis after MV stenting (P for interaction < 0.01). Among 1077 patients with diameter stenosis of SB ≥ 50% after MV stenting, SB intervention was associated with a lower risk of cardiac death or MI (1.2% versus 4.2%; adjusted HR 0.22; 95% CI 0.09–0.52; P < 0.01). However, among 940 patients with diameter stenosis of SB < 50%, there was no significant difference in cardiac death or MI between the SB intervention group and the no-SB intervention group (3.5% versus 2.2%; adjusted HR 1.36; 95% CI 0.58–3.20; P = 0.48). Conclusions The effect of SB intervention differed according to SB stenosis after MV stenting. SB intervention may reduce cardiac death or MI in bifurcation lesions with diameter stenosis of SB ≥ 50% after MV stenting.