Advancements in diagnostic and interventional radiology for stroke treatment: the path from trial to bedside through the pre-MR CLEAN, MR CLEAN, and MR CLEAN II eras

The stroke field is inevitably connected with imaging in which radiologists fulfill a central role. Our landmark MR CLEAN trial led to the implementation of baseline computed tomography angiography or magnetic resonance angiography in the acute stroke workup and subsequent endovascular treatment (EVT) for ischemic stroke patients with a large vessel occlusion in the anterior circulation, resulting in numerous patients worldwide currently being treated often successfully. A reversal of the pathophysiologic process behind an acute cerebrovascular event was made possible. Subsequently, in the MR CLEAN II trials, the clinical impact of both diagnostic and interventional radiologists remained a cornerstone of our research, which means value-based radiology. Within these MR CLEAN II trials, we proved that aspirin and heparin during EVT should be avoided due to increased symptomatic intracranial hemorrhage risk (MR CLEAN-MED). We concluded there is additional benefit of EVT in the 6-to-24-h window after stroke in the presence of good collaterals on baseline CTA (MR CLEAN-LATE). The impactful success of our stroke trials that changed many guidelines was mainly attributable to (1) the societal burden of the disease, with two thirds of patients dying or being independent at 3 months; (2) the fact that stroke is a common disease, (3) the relatively simple and pragmatic approach of the trials resembling real-world setting; (4) the acceleration of implementation in clinical practice facilitated by a structured approach to guideline development and conditional funding; and foremost (5) the excellent collaboration on a professional level between-disciplines, i.e., diagnostic radiologists, interventionalists, and neurologists.Critical relevance statement The MR CLEAN and MR CLEAN II trials have had tremendous impact on clinical practice, directly by more patients being treated with an effective intervention and indirectly through adoption of evidence-based guidelines. It is in this setting of stroke treatment that diagnostic and interventional radiologists have played a crucial role and created clinical impact.

Cost-effectiveness of Direct Transfer to Angiography Suite of Patients With Suspected Large Vessel Occlusion

BACKGROUND AND OBJECTIVES

Patients with acute ischemic stroke due to large vessel occlusion (LVO) deemed eligible for endovascular thrombectomy (EVT) are transferred from the emergency room to the angiography suite to undergo the procedure. Recently, the strategy of direct transfer of patients with suspected LVO to the angiography suite (DTAS) has been shown to improve functional outcomes. This study aims to evaluate the cost-effectiveness of the DTAS strategy vs initial transfer of patients with suspected LVO (Rapid Arterial Occlusion Evaluation score >4 and NIH Stroke Scale >10) to the emergency room (ITER).

METHODS

A decision-analytic Markov model was developed to estimate the cost-effectiveness of the DTAS strategy vs the ITER strategy from a Dutch health care perspective with a 10-year time horizon. The primary outcome was the incremental cost-effectiveness ratio (ICER) using Dutch thresholds of $59,135 (€50,000) and $94,616 (€80,000) per quality-adjusted life year (QALY). Uncertainty of input parameters was assessed using 1-way sensitivity analysis, scenario analysis, and probabilistic sensitivity analysis.

RESULTS

The DTAS strategy yielded 0.65 additional QALYs at an additional $16,089, resulting in an ICER of $24,925/QALY compared with the ITER strategy. The ICER varied from $27,169 to $38,325/QALY across different scenarios. The probabilistic sensitivity analysis showed that the DTAS strategy had a 91.8% and 97.0% likelihood of being cost-effective at a decision threshold of $59,135/QALY and $94,616/QALY, respectively.

DISCUSSION

The cost-effectiveness of the DTAS strategy over ITER is robust for patients with suspected LVO. Together with recently published clinical results, this means that implementation of the DTAS strategy may be considered to improve the workflow and outcome of EVT.

Tranexamic Acid After Aneurysmal Subarachnoid Hemorrhage: Post Hoc Analysis of the ULTRA Trial

BACKGROUND AND OBJECTIVES

The ULTRA trial showed that ultra-early and short-term tranexamic acid treatment after subarachnoid hemorrhage did not improve clinical outcome at 6 months. An expected proportion of the included patients experienced nonaneurysmal subarachnoid hemorrhage. In this post hoc study, we will investigate whether ultra-early and short-term tranexamic acid treatment in patients with aneurysmal subarachnoid hemorrhage improves clinical outcome at 6 months.

METHODS

The ULTRA trial is a multicenter, prospective, randomized, controlled, open-label trial with blinded outcome assessment, conducted between July 24, 2013, and January 20, 2020. After confirmation of subarachnoid hemorrhage on noncontrast CT, patients were allocated to either ultra-early and short-term tranexamic acid treatment with usual care or usual care only. In this post hoc analysis, we included all ULTRA participants with a confirmed aneurysm on CT angiography and/or digital subtraction angiography. The primary endpoint was clinical outcome at 6 months, assessed by the modified Rankin scale (mRS), dichotomized into good (0-3) and poor (4-6) outcomes.

RESULTS

Of the 813 ULTRA trial patients who experienced an aneurysmal subarachnoid hemorrhage, 409 (50%) were assigned to the tranexamic acid group and 404 (50%) to the control group. In the intention-to-treat analysis, 233 of 405 (58%) patients in the tranexamic acid group and 238 of 399 (60%) patients in the control group had a good clinical outcome (adjusted odds ratio [aOR] 0.92; 95% CI 0.69-1.24). None of the secondary outcomes showed significant differences between the treatment groups: excellent clinical outcome (mRS 0-2) (aOR 0.76; 95% CI 0.57-1.03), all-cause mortality at 30 days (aOR 0.91; 95% CI 0.65-1.28), and all-cause mortality at 6 months (aOR 1.10; 95% CI 0.80-1.52).

DISCUSSION

Ultra-early and short-term tranexamic acid treatment did not improve clinical outcomes at 6 months in patients with aneurysmal subarachnoid hemorrhage and therefore cannot be recommended.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov (NCT02684812; submission date February 18, 2016, first patient enrollment on July 24, 2013).

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that tranexamic acid does not improve outcomes in patients presenting with aneurysmal subarachnoid hemorrhage.

Time Since Stroke Onset, Quantitative Collateral Score and Functional Outcome After Endovascular Treatment for Acute Ischemic Stroke

BACKGROUND

In patients with ischemic stroke undergoing endovascular treatment (EVT), time to treatment and collateral status are important prognostic factors and may be correlated. We aimed to assess the relation between time to CT angiography (CTA) and a quantitatively determined collateral score and to assess whether the collateral score modified the relation between time to recanalization and functional outcome.

METHODS

We analysed data from patients with acute ischemic stroke included in the MR CLEAN Registry between 2014 and 2017, who had a carotid terminus or M1 occlusion and were treated with EVT within 6.5 hours of symptom onset. A quantitative collateral score (qCS) was determined from baseline CTA using a validated automated image analysis algorithm. We also determined a 4-point visual collateral score (vCS). Multivariable regression models were used to assess the relations between time to imaging and the qCS, and between the time to recanalization and functional outcome (90-day modified Rankin Scale score). An interaction term (time to recanalization * qCS) was entered in the latter model to test whether the qCS modifies this relation. Sensitivity analyses were performed using the vCS.

RESULTS

We analyzed 1813 patients. Median time from symptom onset to CTA was 91 minutes [IQR:65-150] and the median qCS was 49% [IQR:25-78]. Longer time to CTA was not associated with the log-transformed qCS (adjusted β per 30 minutes, 0.002, 95%CI: -0.006 - 0.011). Both a higher qCS (acOR per 10% increase: 1.06, 95%CI: 1.03-1.09) and shorter time to recanalization (acOR per 30 minutes: 1.17, 95%CI: 1.13-1.22) were independently associated with a shift towards better functional outcome. The qCS did not modify the relation between time to recanalization and functional outcome (p for interaction: 0.28). Results from sensitivity analyses using the vCS were similar.

CONCLUSIONS

In the first 6.5 hours of ischemic stroke caused by carotid-terminus or M1 occlusion, the collateral status is unaffected by time to imaging and the benefit of a shorter time to recanalization is independent of baseline collateral status.

Diagnostic Yield of ECG-gated Cardiac CT in the Acute Phase of Ischemic Stroke vs Transthoracic Echocardiography

BACKGROUND

Guidelines recommend echocardiography to screen for structural sources of cardioembolism in patients with ischemic stroke. Cardiac CT is a promising alternative as a first-line screening method. We aimed to determine whether cardiac CT, acquired during the initial stroke imaging protocol, has a higher yield for detecting high-risk cardio-aortic sources of embolism than transthoracic echocardiography (TTE).

METHODS

We performed a prospective, single center, observational cohort study and included consecutive adult patients with acute ischemic stroke who underwent ECG-gated cardiac CT during the initial stroke imaging protocol. Patients also underwent routine stroke work-up, including TTE. The main outcome was the proportion of patients with a predefined high-risk cardio-aortic source of embolism on cardiac CT versus TTE in patients undergoing both investigations.

RESULTS

Between May 2018 and November 2020, 774 patients with a suspected ischemic stroke underwent hyperacute cardiac CT. We excluded 228 patients with a diagnosis other than ischemic stroke and 94 because they did not provide informed consent. Therefore, 452 patients (59.3% male, median age 72) were included. The median additional scan time of cardiac CT was 6 (interquartile range 5-7) minutes with poor scan quality in only 3%.In total, 350/452 (77.4%) patients underwent TTE, 99 of which were performed in an outpatient setting. Reasons for not undergoing TTE were: death (33, 7.3%) and TTE being too burdensome to perform in the outpatient setting (69, 15.3%). A high-risk cardio-aortic source of embolism was detected in 40/350 (11.4%) patients on CT, compared to 17/350 (4.9%) on TTE (odds ratio 5.60, 95%CI: 2.28-16.33). Cardiac thrombus was the most frequent finding (7.1% vs 0.6%). The diagnostic yield of cardiac CT in the full study population was 54/452 (12.2%). Among 175 patients with cryptogenic stroke after routine work-up, cardiac CT identified a cause of the stroke in 11 (6.3%).

DISCUSSION

Cardiac CT acquired in the acute phase of ischemic stroke is technically feasible and has a superior diagnostic yield compared to TTE for the detection of high-risk sources of embolism. Cardiac CT may be considered as an alternative to TTE to screen for cardioembolism.

Clinical Outcome After Endovascular Treatment in Patients With Active Cancer and Ischemic Stroke: A MR CLEAN Registry Substudy

OBJECTIVE

To explore clinical and safety outcomes of patients with acute ischemic stroke (AIS) and active cancer after endovascular treatment (EVT).

METHODS

Using data from the MR CLEAN Registry, we compared patients with active cancer (defined as cancer diagnosed within 12 months prior to stroke, metastatic disease, or current cancer treatment) to patients without cancer. Outcomes were 90-day modified Rankin Scale (mRS) score, mortality, successful reperfusion (eTICI scores≥2b), symptomatic intracranial hemorrhage (sICH), and recurrent stroke. Subgroup analyses were performed in patients with a pre-stroke mRS score of 0 or 1 and according to treatment setting (curative or palliative). Analyses were adjusted for prognostic variables.

RESULTS

Of 2583 patients who underwent EVT, 124 (4.8%) had active cancer. They more often had pre-stroke disability (mRS≥2: 34.1% vs. 16.6%). The treatment setting was palliative in 25.3% of the patients. There was a shift towards worse functional outcome at 90 days in patients with active cancer (adjusted common OR 2.2, 95% CI 1.5-3.2). At 90 days, patients with active cancer were less often independent (mRS 0-2: 22.6% vs. 42.0%, aOR 0.5, 95% CI 0.3-0.8), and more often dead (52.2% vs. 26.5%, aOR 3.2, 95% CI 2.1-4.9). Successful reperfusion (67.8% vs. 60.5%, aOR 1.4, 95% CI 1.0-2.1) and sICH rates (6.5% vs. 5.9%, aOR 1.1, 95 %CI 0.5-2.3) did not differ. Recurrent stroke within 90 days was more common in patients with active cancer (4.0% vs. 1.3%, aOR 3.1, 95% CI 1.2-8.1). The sensitivity analysis of patients with a pre-stroke mRS of 0 or 1 showed that patients with active cancer still had a worse outcome at 90 days (acOR 1.9, 95% CI 1.2-3.0). Patients with active cancer in a palliative treatment setting regained functional independence less often compared to patients in a curative setting (18.2% vs. 32.1%) and mortality was also higher (81.8% vs. 39.3%).

CONCLUSIONS

Despite similar technical success, patients with active cancer had significantly worse outcomes after EVT for AIS. Moreover, they had an increased risk of recurrent stroke. Nevertheless, about a quarter of the patients regained functional independence and the risk of other complications, most notably sICH, was not increased.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that patients with active cancer undergoing EVT for AIS have worse functional outcomes at 90 days compared to those without active cancer.