Relevance of persistent perfusion deficits on clinical outcome after successful endovascular treatment: a prospective serial magnetic resonance study

Adrián Valls Carbó ¹ Alicia Palomar ² Carlos Laredo ³ Mariano Werner ⁴ Laura Dorado ¹ Sebastià Remollo ¹ Josep Munuera ⁵ Josep Puig ¹ Yolanda Silva ⁶ Natalia Pérez De La Ossa ¹ Meritxell Gomis ¹ Alejandro Bustamante ¹ Carlos Castaño ¹ Lucia Muñoz ¹ Sira Domenech ¹ Mikel Terceño ⁶ Monica Millan ¹ Maria Hernandez-Perez ^1*

• ¹ Department of Neurosciences, Hospital Germans Trias i Pujol, Barcelona, Spain
• ² Canon Medical Research Europe Ltd., Edinburgh, United Kingdom
• ³ August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Catalonia, Spain
• ⁴ Hospital Clinic of Barcelona, Barcelona, Catalonia, Spain
• ⁵ Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Catalonia, Spain
• ⁶ Doctor Josep Trueta Girona University Hospital, Girona, Catalonia, Spain

Background: Half of patients achieving successful recanalization after endovascular treatment (EVT) have poor clinical outcomes. Impaired microvascular reperfusion (IMR) may explain this lack of improvement, but its frequency and clinical significance remain unclear. The aim of the study is to describe the frequency and associated factors to the IMR.We conducted a study on a cohort of patients with anterior large artery occlusion treated with EVT at a single center achieving mTICI ≥2C. Perfusion MRI was obtained at arrival, up to 2 hrs after EVT (post-EVT MRI) and at 5 days. IMR was identified only on the post-EVT rCBV maps as the voxels within the follow-up ischemic lesion, that displayed a >15% asymmetry compared to a mirror homolog in the absence of internal carotid occlusion, haemorrhagic transformation and arterial reocclusion. Patients with an IMR volume greater than 5 mL were defined as having significant IMR. IMR was analysed as a binary variable (presence/absence using the 5 mL cut-off), and by total and relative volume.Results: IMR was present in 8/33 (24.2%) patients (4/11, 36.4% with mTICI 2C; 18.2%, 4/22 with mTICI 3). After adjustment by relevant variables, absolute and relative IMR volumes were associated with higher NIHSS at 5 days (adjusted beta =0.50 [0.05, 0.96], p=0.03) and at 24 h (adjusted beta=0.11 [0.02, 0.19], p=0.01). No independent associations were found between IMR and 90-day mRS.Conclusion: IMR is present in one quarter of patients and was associated with worse early neurological evolution.