Background: The aim of this study was to assess the incidence and clinical outcome of the occlusion of major (> 1 mm) side branches following coronary stenting in patients undergoing percutaneous coronary intervention for acute ST-elevation myocardial infarction (STEMI).
Methods: Among 276 consecutive patients presenting with STEMI, we found 80 patients (29%) with 101 stent-covered side branches. Clinical data and quantitative angiographic analysis were evaluated. Angiographic follow-up was available in 56 (70%) patients, and clinical follow-up could be completed in all patients.
Results: Acute side branch occlusion after stent implantation (SBO) was observed in 10 (12.5%) patients involving 11 (10.9%) side branches. Predictors for SBO were: (1) reference side branch diameter at baseline < or = 1.4 mm; (2) ostial side branch stenosis > 50%; and (3) minimal side branch diameter at baseline < or = 0.6 mm. During hospitalization, in the SBO group, 2 patients died in cardiogenic shock and 1 underwent bypass surgery; no events were causally related to SBO. During long-term follow-up, 1 patient with SBO developed repeat MI as opposed to 7 patients in the non-SBO group who developed major adverse cardiac events (1 death, 6 repeat revascularizations).
Conclusions: The presence of a side branch originating from the target lesion in patients undergoing coronary stenting for acute STEMI is a frequent observation (29%) and is associated with a low incidence of side branch occlusion. Major predictors for SBO are the side branch size and the presence of an ostial side branch stenosis.