Factors Leading to Obstructive Granulation Tissue Formation after Ultraflex Stenting in Benign Tracheal Narrowing

Background: This retrospective study aimed to determine the factors leading to obstructive granulation tissue formation after the placement of a self-expandable metallic stent (SEMS) in patients with benign tracheal disease. Methods: From 2001 to 2007, a total of 67 patients (age: 62.1 +/- 15.4 years; range: 23-87 years) with benign tracheal disease received 75 ultraflex SEMS in our institution. Results: There were 35 SEMSs complicated by obstructive granulation tissue formation out of the 75 stents placed in patients with tracheal disease, giving an incidence of 47.8% (32/67 patients). The median time until developing granulation tissue was 106 days (IQR, 46-396). Structural airway obstruction prior to SEMS implantation independently predicted obstructive granulation tissue formation after SEMS implantation (odds ratio: 3.84; 95% CI: 1.01-8.7; p = 0.04). Time to granulation tissue detection was shorter in patients with structural airway obstruction before SEMS implantation (structural airway obstruction vs. dynamic collapse airway: median [IQR] 95 [38-224, n = 26] vs. 396 days [73-994, n = 9]; p = 0.02). Conclusions: Obstructive granulation tissue formation is not uncommon after SEMS implantation and structural airway obstruction prior to SEMS implantation is an independent predictor. Although SEMS implantation should be restricted to a select population, it may be placed in patients not suitable for surgical intervention or rigid bronchoscopy with anesthesia because of poor pulmonary function.