MATERIALS AND METHODS

An intention-to-treat single-center cohort (n = 592) was re-evaluated for all patients in whom no reperfusion could be achieved (n = 63). Baseline characteristics of patients were compared between patients with and without reperfusion failures. After qualitative review of all cases with reperfusion failures, a classification system was proposed and relative frequencies were reported. In a second step, occurrence of delayed recanalization at 24 hours after reperfusion failure and dependency on IV-tPA were evaluated.

RESULTS

In 63/592 patients with an intention to perform stent-retriever thrombectomy, no reperfusion was achieved (TICI 0/1, 10.6%, 95% CI, 8.2%–13.1%). Older patients (adjusted OR per yr = 1.03; 95% CI, 1.01–1.05) and patients with M2 occlusion (adjusted OR = 3.36; 95% CI, 1.82–6.21) were at higher risk for reperfusion failure. In most cases, no reperfusion was a consequence of technical difficulties (56/63, 88.9%). In one-third of these cases, reperfusion failures were due to the inability to reach the target occlusion (20/63, 31.7%), while “stent-retriever failure” occurred in 39.7% (25/63) of patients. Delayed recanalization was very rare (18.2%), without dependence on IV-tPA pretreatment status.

CONCLUSIONS

Reasons for reperfusion failure in stent-retriever thrombectomy are heterogeneous. The failure to establish intracranial or cervical access is almost as common as stent-retriever failure after establishing intracranial access. Systematic reporting standards of reasons may help to further estimate relative frequencies and thereby guide priorities for technical development and scientific effort.

The technical success of endovascular stroke therapy is one of the most important modifiable predictors of therapy benefit in patients presenting with large-vessel-occlusion acute ischemic stroke.1,2 The American Stroke Association/American Heart Association guidelines continue to support stent retrievers as the dominant technical platform for thrombectomy; however, this may change with the final publication of A Comparison of Direct Aspiration Versus Stent Retriever as a First Approach (COMPASS) trial.3⇓–5 Recently published large-cohort registries of patients treated with stent retrievers have shown that contemporary endovascular interventions in acute ischemic stroke are angiographically successful in up to 80%–90% of cases (Thrombolysis in Cerebral Infarction 2b/3).6,7 While unsuccessful reperfusion (≤TICI 2a) often results from incomplete retrieval due to distal embolization and/or clot fragmentation (TICI 2a), in some patients, no reperfusion (TICI 0/1) can be achieved (“reperfusion failure”). Reasons for such reperfusion failures may range from difficulty establishing cervical or intracranial access to the inability to dislocate and retrieve the clot despite having reached the target location and having established intracranial access.8,9 Further conceivable explanations for failures to reestablish flow are underlying nonembolic vessel diseases (eg, vasculitis, intracranial atherosclerosis)10,11 or thrombi of nonthrombotic origin and extraordinary composition, such as calcified or neoplastic thrombi.12,13

The aim of this analysis was to provide estimates of the relative frequencies of underlying causes of reperfusion failure in patients with acute ischemic stroke who underwent angiography with an intention to perform stent-retriever-based thrombectomy.