Frequency and risk of in-stent stenosis following pulmonary artery stenting

Peripheral and central pulmonary artery (PA) stenoses can result in right ventricular hypertension, dysfunction, and death. Percutaneous PA angioplasty and stent placement relieve obstruction acutely, but patients frequently require reintervention. Within a heterogeneous patient population with PA stents referred for catheterization because of noninvasive signs of PA obstruction, we have observed that in-stent stenosis (ISS) occurs commonly in some groups, challenging previous reports that this phenomenon occurs infrequently. We set out to evaluate the incidence and demographics of patients with previous PA stent placement who develop ISS. Consecutive patients with previously placed stents presenting for catheterization and undergoing PA angiography were reviewed (104 patients, 124 cases). We defined ISS angiographically, as a 25% narrowing of the contrast-filled lumen relative to the fluoroscopically apparent stent diameter at any site along the length of the stent. For inclusion, we required that the stenotic segment be narrower or equal in size to the distal vessel. ISS was diagnosed in 24% of patients, with the highest incidence among patients with tetralogy of Fallot and multiple aortopulmonary collaterals, Williams syndrome, or Alagille syndrome. In conclusion, ISS after PA stent placement is a more frequent problem than previously reported, and patients with inherently abnormal PAs are disproportionately affected. Increased clinical surveillance after stent placement and investigation of innovative preventive strategies may be indicated.