CT Scans Linked to Increased Risk of Futile Recanalization in Stroke

September 3, 2020

The researchers noted that future studies should examine the cost-effectiveness of CT compared with MRI as the best initial imaging modality for mechanical thrombectomy.

Results from the multicenter, retrospective observational registry BEYOND-SWIFT (NCT03496064) suggest that computed tomography (CT) selection for mechanical thrombectomy (MT) is associated with an increased risk of futile recanalizations (FRs) compared to magnetic resonance imaging (MRI) selection.

Senior author Jan Gralla, MD, neuroradiology specialist, University Hospital Bern, and colleagues used FR as the primary end point of the analysis, which was defined as a modified Rankin Scale (mRS) score of 4 to 6 at 90 days despite successful endovascular recanalization. Secondary outcomes included a sensitivity analysis defining FR as mRS score of 5 to 6 at 90 days, all-cause mortality at 90 days, and symptomatic intracranial hemorrhage (sICH)

Using univariate and multivariate analyses, they found that CT-based selection (44%; interquartile range [IQR], 41–47) was associated with increased rates of FRs compared to MRI (29%; IQR, 25–32; P <.001) for an adjusted odds ratio (aOR) of 1.77 (95% CI, 1.25–2.51). This finding was consistent when using an ordinal shift analysis (aOR for the association of MRI with mRS, 0.689; 95% CI, 0.556–0.854). Additionally, the point estimate was “very similar” in the sensitivity analysis considering patients with mRS score 5–6 as futile (aOR, 1.758; 95% CI, 1.197–2.583).

Researchers also documented higher rates of sICH in patients selected with CT (7.0% vs 4.4%; P = .018), although this was non-significant after adjustments (aOR, 1.087; 95% CI, 0.552–2.141). Rates of good functional outcome, defined as mRS score 0–2, were lower on univariate (39.5% vs 50.1%; P <.001) and multivariate analysis (aOR, 0.539; 95% CI 0.395–0.735) in patients selected with CT as compared to MRI.

Gralla and colleagues noted, “Efforts are still needed to shorten workflow delays in MRI patients. Further research is needed to clarify the role of the initial imaging modality on FR occurrence and to develop a reliable FR prediction algorithm.”

Investigators found that MRI, as compared to CT, resulted in similar rates of subsequent MT (aOR, 1.048; 95% CI, 0.677–1.624). A total of 1489 futile and non-futile recanalizations were recorded, 571 (38%) of FR had an mRS score 4–6 and 393 (26%) had an mRS score 5–6. In total, 1213 of 1489 (81.5%) patients were included in the primary multivariable analysis.

Secondary analysis that examined mortality rates at 3 months also noted that rates were higher in patients selected with CT on univariate (28.1% vs 20.5%; P <.001) and multivariate analysis (aOR, 1.613; 95% CI, 1.153–2.257) compared to MRI.

Of the baseline factors, National Institutes of Health Stroke Scale (NIHSS; aOR, 1.198; 95% CI, 1.156–1.241 per 1 point increase), posterior circulation large vessel occlusion (aOR, 0.352; 95% CI, 0.228–0.542), preceding oral anticoagulation (aOR, 2.610; 95% CI, 1.062–6.418) and treatment with intravenous thrombolysis (aOR, 0.296; 95% CI, 0.203–0.432) were significantly associated with subsequent MT.

The increased risk of FR in patients selected by CT was robust in patients presenting 0–6 hours after known symptom onset (aOR, 1.757; 95% CI, 1.168–2.644). Additionally, the point estimate suggested an even more pronounced association for patients presenting beyond 6 hours (aOR, 24.6; 95% CI, 0.557–1087), without reaching significance in this small subgroup.

“If confirmed in upcoming RCTs, cost-effectiveness analyses comparing CT with MR as the best initial imaging modality for MT seem warranted due to the ambivalence between MR-related costs and those associated with futile recanalization,” Gralla and colleagues concluded.

REFERENCE
Meinel TR, Kaesmacher J, Mosimann PJ, et al. Association of initial imaging modality and futile recanalization after thrombectomy. Neurology. Published online August 26, 2020. doi: 10.1212/WNL.0000000000010614