Mechanism-specific acute silent ischaemic lesions and ischaemic periprocedural stroke after PTAS for severe symptomatic intracranial atherosclerotic stenosis

Background Preprocedural acute silent ischaemic lesions (ASILs) may reflect distinct ischaemic mechanisms in symptomatic intracranial atherosclerotic stenosis. We examined whether mechanism-specific ASIL phenotypes were associated with ischaemic periprocedural stroke after percutaneous transluminal angioplasty and stenting (PTAS).Methods This secondary mechanistic analysis included 1427 patients undergoing PTAS. Candidate lesions in 185 examinations were re-adjudicated against the index-event or baseline MRI. Final phenotypes were no definite ASIL, other definite ASIL patterns and isolated perforator-pattern definite ASIL. Firth-penalised logistic regression adjusted for prespecified covariates. Supportive analyses compared definite ASILs with and without a perforator component and used a global 2 df penalised likelihood-ratio test of the three-level phenotype for ischaemic periprocedural stroke; sensitivity analysis excluded non-retained examinations.Results Re-adjudication retained 138/185 examinations as definite ASILs; 47/185 were not retained. Final groups were no definite ASIL (n=1289), other definite ASIL patterns (n=117) and isolated perforator-pattern definite ASIL (n=21), with ischaemic periprocedural stroke in 26 (2.0%), 6 (5.1%) and 6 (28.6%), respectively. Compared with no definite ASIL, isolated perforator-pattern definite ASIL was associated with ischaemic periprocedural stroke (adjusted OR, 16.52; 95% CI 5.03 to 48.51; p<0.001), whereas the association for other definite ASIL patterns did not reach statistical significance (adjusted OR, 2.58; 95% CI 0.97 to 6.01; p=0.058). ASILs with a perforator component had higher odds than those without one (adjusted OR, 6.20; 1.66 to 22.89; p=0.008); the global test was significant (χ²=19.34; df=2; p<0.001). After excluding the 47 non-retained examinations, isolated perforator-pattern definite ASIL remained associated with ischaemic periprocedural stroke versus no definite ASIL (adjusted OR, 15.64; 4.75 to 46.05; p<0.001).Conclusion Isolated perforator-pattern definite ASIL was associated with ischaemic periprocedural stroke after PTAS; external validation is required.