Iatrogenic vertebral artery injury during surgery can cause pseudoaneurysm, hemorrhage, thrombosis, ischemia, or death. Strategies to prevent cerebrovascular embolic complications include surgical ligation, endovascular stenting, and/or antiplatelet therapy. A 73-year-old female with a known right vertebral artery occlusion underwent a C2-3 laminectomy, complicated by left vertebral artery injury and occlusion with subsequent posterior circulation ischemia. She underwent immediate angioplasty and stenting of the injured artery with undersized drug-eluting stents. Dual antiplatelet therapy of aspirin 81 mg daily and ticagrelor 90 mg twice daily was initiated. On two occasions, more than 6 months after stenting, holding a single ticagrelor dose led to in-stent thrombosis and embolic stroke within hours of the missed dose. Lifelong therapy with ticagrelor was favored over further procedural intervention. It is recommended to prioritize optimal wall stent apposition with oversized stents in patients without collateral circulation. The risk of thromboembolism due to poorly apposed stents is very high, even in delayed (> 6 months) settings. Stent construct revision or bypass grafting may not be feasible or desirable options. For patients without wall apposition, endothelialization may not occur, necessitating lifelong P2Y12 inhibitor therapy to prevent recurrent thromboembolic events. https://thejns.org/doi/10.3171/CASE24296.