Hemodynamic and Geometric Risk Factors for In-Stent Restenosis in Patients with Intracranial Atherosclerotic Stenosis

Abstract

Problem. Investigating the importance of vessel geometry and hemodynamics in intracranial atherosclerotic stenosis (ICAS) might provide a more profound understanding about the underlying mechanisms of in-stent restenosis (ISR). Methods. Severe ICAS patients managed with percutaneous transluminal angioplasty and stenting (PTAS) were included in the retrospective cohort study and were divided into two groups according to whether ISR occurred at follow-up (ISR group and no-ISR group). Computational fluid dynamics models were built based on digital subtraction angiography before and after PTAS to simulate blood flow and quantify hemodynamic parameters. The associations between vessel geometry, hemodynamics, and ISR in ICAS patients were investigated. Results. Among 39 patients, ISR occurred in seven patients (17.95%) after a mean follow-up period of $6.69\pm 3.24$ months. Stenting decreased vessel angulation (51.11° [40.07°–67.27°] vs. 15.97° [0.00°–36.16°], $P=0.000$ ) and vessel tortuosity (0.09 [0.06–0.13] vs. 0.01 [0.00–0.03], $P=0.000$ ). Meanwhile, the translational pressure ratio (PR) dramatically increased (0.07 [0.00–0.31] vs. 0.62 [0.41–0.82], $P=0.000$ ) with the wall shear stress ratio decreased (13.93 [8.37–40.30] vs. 2.90 [1.69–4.48], $P=0.000$ ). In the multivariate analysis, smaller $\Delta$ tortuosity ( $P=0.038$ ) was independently associated with the occurrence of ISR, and smaller post-PTAS translesional PR was also a predictive factor of marginal significance ( $P=0.059$ ). Conclusion. PTAS decreased vessel angulation, vessel tortuosity, and translesional wall shear stress ratio while it increased translesional pressure ratio (PR) dramatically in ICAS patients. Smaller $\Delta$ tortuosity was found to be a risk factor for ISR, and smaller post-PTAS translesional PR was also a predictive factor of marginal significance, indicating that both geometric and hemodynamic parameters played important roles in the occurrence of ISR after PTAS.