The ENDOSTROKE Study

Singer et al in a study that was conducted at six centers and published in Radiology assessed the significance and role of collateral circulation in160 patients with proximal middle cerebral artery (MCA) occlusion; The ENDOSTROKE study.

Collateral vessel status was assessed at angiography by using the American Society of Interventional and Therapeutic Neuroradiology (ASITN) Society of Interventional Radiology (SIR) collateral vessel grading system, while using the Thrombolysis in Cerebral Infarction (TICI) scale assessed reperfusion. Good outcome was defined as a modified Rankin Scale score of 0–2 at follow-up.

Good clinical outcome was attained in 62 (39%) of the 160 patients, and TICI 2b–3 reperfusion was achieved in 94 (59%) patients. Nineteen patients had ASITN/SIR collateral vessel grades of 0 or 1, 63 patients had a grade of 2, and 78 patients had grades of 3 or 4.

Better collateral vessels were associated with higher reperfusion rates (21%, 48%, and 77% for ASITN/SIR grades of 0 or 1, 2, and 3 or 4, respectively; P < .001), a higher proportion of infarcts smaller than one-third of the MCA territory (32%, 48%, and 69% for ASITN/SIR grades of 0 or 1, 2, and 3 or 4, respectively; P < .001), and a higher proportion of good clinical outcome (11%, 35%, and 49% for ASITN/SIR grades of 0 or 1, 2, and 3 or 4, respectively; P = .007). At multivariable analysis, collateral vessel status independently predicted reperfusion, final infarct size, and clinical outcome. Within an onset-to-treatment time (OTT) of 0–3 hours, collateral vessel status predicted final infarct size and reperfusion. Within an OTT of 3–6 hours, it additionally predicted clinical outcome, with 53% of patients with ASITN/SIR grades of 3 or 4 having a good outcome, as compared with 0% of patients with grades of 0 or 1 and 27% of patients with a grade of 2 (P = .008).

The researchers concluded that collateral circulation independently predicted parameters such as reperfusion, infarct size, and clinical outcome.