Background Follow-up infarct volume (FIV) is used as surrogate for treatment efficiency in mechanical thrombectomy (MT). However, previous works suggest that MT-related FIV reduction has only limited association with outcome comparing MT independently of recanalization success versus medical care. It remains unclear to what extent the relationship between successful recanalization versus persistent occlusion and functional outcome is explained by FIV reduction.
Objective To determine whether FIV mediates the relationship between successful recanalization and functional outcome.
Methods All patients from our institution enrolled in the German Stroke Registry (May 2015–December 2019) with anterior circulation stroke; availability of the relevant clinical data, and follow-up-CT were analyzed. The effect of FIV reduction on functional outcome (90-day modified Rankin Scale (mRS) score ≤2) after successful recanalization (Thrombolysis in Cerebral Infarction ≥2b) was quantified using mediation analysis.
Results 429 patients were included, of whom, 309 (72 %) had successful recanalization and 127 (39%) had good functional outcome. Good outcome was associated with age (OR=0.89, P<0.001), pre-stroke mRS score (OR=0.38, P<0.001), FIV (OR=0.98, P<0.001), hypertension (OR=2.08, P<0.05), and successful recanalization (OR=3.57, P<0.01). Using linear regression in the mediator pathway, FIV was associated with Alberta Stroke program Early CT Score (coefficient (Co)=−26.13, P<0.001), admission National Institutes of Health Stroke Scale score (Co=3.69, P<0.001), age (Co=−1.18, P<0.05), and successful recanalization (Co=−85.22, P<0.001). Successful recanalization increased the probability of good outcome by 23 percentage points (pp) (95% CI 16pp to 29pp). 56% (95% CI 38% to 78%) of the improvement in good outcome was explained by FIV reduction.
Conclusion 56% (95% CI 38% to 78%) of outcome improvement after successful recanalization was explained by FIV reduction. Results corroborate pathophysiological assumptions and confirm the value of FIV as an imaging endpoint in clinical trials. 44% (95% CI 22% to 62%) of the improvement in outcome was not explained by FIV reduction and reflects the remaining mismatch between radiological and clinical outcome measures.
Data availability statement
Data may be obtained from a third party and are not publicly available.
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Contributors Conception/design of the work: HK, SG. Data acquisition: LM, GB, MB, FA, RVM, CB, FF, AA, MD-C, UH, GT, JF. Data analysis: LM, GB, JF. Interpretation of data: HK, SG, LM, JF. Drafting the work: HK, SG. Revising the work critically for important intellectual content: LM, GB, MB, FA, RVM, CB, FF, AA, MD-C, UH, GT, JF, SG. Final approval of the version to be published: HK, LM, GB, MB, FA, RVM, CB, FF, AA, MD-C, UH, GT, JF, SG. Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved: HK, LM, GB, MB, FA, RVM, CB, FF, AA, MD-C, UH, GT, JF, SG. Accepts full responsibility for the finished work and/or the conduct of the study, had access to the data, and controlled the decision to publish: HK, SG.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests HK and FF are consultants for Eppdata GmbH. HK has financial interest in Eppdata GmbH. MD-C has received research grants from the Werner Otto Stiftung and serves on the advisory board of the PRECIOUS Trial. GT received fees as consultant from Acandis, Boehringer Ingelheim, Bayer, and Portola, and fees as lecturer from Acandis, Alexion, Amarin, Bayer, Boehringer-Ingelheim, BMS/Pfizer, Daiichii Sankyo, and Portola. He serves on the board of the TEA Stroke Study and of ESO. JF is consultant for Cerenovus, Medtronic, Microvention, Penumbra, Phenox, Roche, and Tonbridge. He serves on the advisory board of Stryker and Phenox. He is stock holder of Tegus Medical, Eppdata, and Vastrax. He is associate editor at JNIS.
Provenance and peer review Not commissioned; externally peer reviewed.