Delayed Aneurysmal Rupture following Flow Diverter Placement despite Adjunctive Coiling: Case Report.

Introduction: Flow diverters significantly alter the inflow dynamics of an aneurysm, leading to both qualitative and quantitative changes in the intra-aneurysmal hemodynamic environment (AJNR Am J Neuroradiol. 2014 Aug 1;35(8):1567-73). Case Presentation: A 65-year-old woman with a giant left internal carotid artery aneurysm causing visual symptoms underwent treatment with coiling, Surpass Evolve flow diverter placement, and balloon angioplasty. Despite being on dual antiplatelet therapy, she developed in-stent thrombosis on postoperative day 4, leading to neurological symptoms. Intra-arterial thrombolysis with eptifibatide and tenecteplase achieved near total recanalization and initial clinical improvement. However, she subsequently developed a massive subarachnoid hemorrhage and was declared brain dead the next day. Conclusion: Delayed rupture of an aneurysm following Surpass Evolve flow diverter embolization is a rare complication associated with high morbidity and mortality. In our case, in-stent thrombosis occurred on postoperative day 4 and subsequently progressed to aneurysmal rupture, despite the presence of coils within the aneurysm sac. Rupture on the fourth day after Surpass Evolve flow diverter placement - despite initial coil embolization - along with aneurysmal thrombosis, partial recanalization, thrombus extension into the parent vessel, and subsequent treatment with intra-arterial eptifibatide and tenecteplase highlights the profound hemodynamic instability in giant aneurysms that can contribute to post-procedural rupture.