Incidence and angiographic predictors of side branch occlusion following high-pressure intracoronary stenting.

We evaluated the incidence, angiographic predictors, and clinical outcome of side branch occlusion (SBO) following high-pressure intracoronary stenting in 175 patients. All stent implants during a 7-month period were reviewed for the incidence of major (>1 mm) SBO. Side branches were further characterized based on side branch and index lesion morphology. Clinical events (death, myocardial infarction, and target vessel revascularization rates) were determined at 9 months. A total of 175 patients (182 lesions) had 224 major side branches covered by intracoronary stents. Of these, 43 (19%) occluded. Most SBOs (29 of 43 [67%]) occurred after poststent dilation using high-pressure inflations (15.3 +/- 3.3 atmospheres). No clinical characteristics correlated with SBO. By multivariate analysis, those side branches with >50% ostial narrowing that arose from within or just beyond the diseased portion of the parent vessel (threatened side branch morphologies) were a powerful angiographic predictor of SBO (odds ratio 40, 95% confidence interval, 14 to 130, p <0.0001). At 9-month follow-up there was no difference in combined clinical events between those patients with and without SBO. These data demonstrate that side branches with ostial stenoses in continuity with diseased parent lesions were at risk of occlusion following stenting. SBO, however, was not associated with adverse clinical outcome. These findings lend support to plaque shift ("snow plow effect") as the mechanism behind SBO following stent placement.