Angiographic Predictors and Clinical Outcome of Acute Side Branch Occlusion after Coronary Artery Stent Implantation

Objective- The aim of this study was to identify the incidence, angiographic and procedural predictors, and clinical outcome of acute side branch occlusion (SBO) following coronary stent implantation. Methods- In total, 138 patients who underwent coronary artery stenting were included. The stents had covered 185 side branches with a luminal diameter greater than 1 mm and less than 2 mm. All the procedures were performed according to the current standards. The data on the clinical events and angiographic characteristics were analyzed. The side branch size and the ostium involvement and its location within the stent were evaluated. SBO was defined as a (thrombolysis in myocardial infarction) TIMI flow ≤1. Results- Acute SBO after stent implantation occurred in 24 (12.9%) side branches. A significant side branch ostial stenosis (≥50%) and side branch diameter at base line ≤1.5 mm were predictors of SBO. Non Q-wave myocardial infarction (MI) was observed in 16.6% of the patients with acute SBO and in 4% of the cases without SBO (P=0.001). However, during hospital stay and long-term follow-up, the incidence of major adverse cardiac events (MACE) comprising death, need for target vessel revascularization, and Q-wave MI was almost similar in the patients with and in those without acute SBO. No MACE related to SBO was seen in these patients. Conclusion- The incidence of acute SBO after coronary stent implantation is relatively frequent. Major predictors of SBO are side branch diameter <1.5 mm and the presence of an ostial side branch stenosis (≥50%). These data yield support to the assumption that the occlusion of small and medium-sized branches during coronary artery stent implantation is not associated with an adverse clinical outcome and should not hinder an optimal interventional therapy of the target lesion (Iranian Heart Journal 2008; 9 (3):18 -24).