Transfer of stroke patients impairs eligibility for endovascular stroke treatment

Point-of-care ultrasound of the common carotid arteries for detection of large vessel occlusion stroke: Results of the POCUS-LVO study

INTRODUCTION

Distal arterial occlusions can cause measurable changes in the flow wave profile in proximal segments of the feeding artery. Our objective was to study the diagnostic accuracy of point-of-care ultrasound (POCUS) of the common carotid arteries (CCA) for detection of anterior circulation large vessel occlusion (ac-LVO) in patients with suspected stroke.

PATIENTS AND METHODS

We conducted a prospective, single-center, observational study of adult patients with suspected stroke admitted in the emergency department. Flow wave profiles of both CCAs were generated by non-specialists using POCUS as soon as possible after admission. ac-LVO was defined as an internal carotid artery or M1 occlusion in CT- or MR-angiography. The diagnostic performances for detection of ac-LVO using flow wave parameters were calculated.

RESULTS

Among 283 patients recruited during a 10-month period, 257 patients (91%) had CCA ultrasound images of sufficient quality and were included for analysis. The mean age was 75 years (IQR 62-83), 131 were female (51.0%), median baseline NIHSS was 2 (IQR 0-5). The most frequent final diagnosis was ischemic stroke (49.4%), ac-LVO was present in 30 patients (11.9%). The median duration of POCUS was 3 min (IQR 2-5). Among all flow wave parameters, the highest diagnostic accuracy for ac-LVO detection was found for end-diastolic velocity difference between sides (AUC = 0.90, 95%CI = 0.85-0.93), with a specificity of 83% (95%CI = 78-88%) at a predefined sensitivity threshold of 80%.

DISCUSSION AND CONCLUSION

POCUS of the CCA in patients with suspected stroke can predict the presence of ac-LVO. These results need to be replicated in a prehospital setting.

Neurological Improvement by One-Thirds Is Associated With Early Recanalization in Stroke With Large Vessel Occlusion

BACKGROUND

A proportion of large vessel occlusion strokes demonstrate early recanalization, obviating the initial intention to proceed to endovascular thrombectomy. Neurological improvement is a possible surrogate marker for reperfusion. We aimed to determine the optimal threshold of neurological improvement, as defined by the National Institutes of Health Stroke Scale (NIHSS), which best associates with early recanalization.

METHODS

We retrospectively analyzed consecutive patients with large vessel occlusion transferred from primary stroke centers to a tertiary comprehensive stroke center in Melbourne, Australia, for possible endovascular thrombectomy from January 2018 to December 2022. Absolute and percentage changes in NIHSS between transfer, as well as other definitions of neurological improvement, were compared using receiver operating characteristic curve analysis for association with recanalization as defined by the absence of occlusion in the internal carotid artery, middle cerebral artery (M1 or M2 segments), or basilar artery on repeat vascular imaging.

RESULTS

Six hundred and fifty-four transferred patients with large vessel occlusion were included in the analysis: mean age was 68.8±14.0 years, 301 (46.0%) were women, and 338 (52%) received intravenous thrombolytics. The proportion of extracranial internal carotid artery, intracranial internal carotid artery, M1, proximal M2, and basilar artery occlusion was 18.8%, 13.6%, 48.3%, 15.0%, and 4.3%, respectively, on initial computed tomography angiogram. Median NIHSSprimary stroke center and NIHSScomprehensive stroke center scores were 15 (interquartile range, 9-18) and 13 (interquartile range, 8-19), respectively. Early recanalization occurred in 82 (13%) patients. NIHSS reduction of ≥33% was the best tradeoff between sensitivity (64%) and specificity (83%) for identifying recanalization. NIHSS reduction of ≥33% had the highest discriminative ability to predict recanalization (area under the curve, 0.735) in comparison with other definitions of neurological improvement.

CONCLUSIONS

One-third neurological improvement between the primary hospital and tertiary center was the best predictor of early recanalization.

Effect of time delay in inter-hospital transfer on outcomes of endovascular treatment of acute ischemic stroke

Background

Endovascular treatment (EVT) with mechanical thrombectomy is the standard of care for large vessel occlusion (LVO) in acute ischemic stroke (AIS). The most common approach today is to perform EVT in a comprehensive stroke center (CSC) and transfer relevant patients for EVT from a primary stroke center (PSC). Rapid and efficient treatment of LVO is a key factor in achieving a good clinical outcome.

Methods

We present our retrospective cohort of patients who underwent EVT between 2018 and 2021, including direct admissions and patients transferred from PSC. Primary endpoints were time intervals (door-to-puncture, onset-to-puncture, door-to-door) and favorable outcome (mRS ≤ 2) at 90 days. Secondary outcomes were successful recanalization, mortality rate, and symptomatic intracranial hemorrhage (sICH). Additional analysis was performed for transferred patients not treated with EVT; endpoints were time intervals, favorable outcomes, and reason for exclusion of EVT.

Results

Among a total of 405 patients, 272 were admitted directly to our EVT center and 133 were transferred; there was no significant difference between groups in the occluded vascular territory, baseline NIHSS, wake-up strokes, or thrombolysis rate. Directly admitted patients had a shorter door-to-puncture time than transferred patients (190 min vs. 293 min, p < 0.001). The median door-to-door shift time was 204 min. We found no significant difference in functional independence, successful recanalization rates, or sICH rates. The most common reason to exclude transferred patients from EVT was clinical or angiographic improvement (55.6% of patients).

Conclusion

Our results show that transferring patients to the EVT center does not affect clinical outcomes, despite the expected delay in EVT. Reassessment of patients upon arrival at the CSC is crucial, and patient selection should be done based on both time and tissue window.

Point-of-Care Ultrasound to Detect Acute Large Vessel Occlusions in Stroke Patients: A Proof-of-Concept Study

BACKGROUND AND PURPOSE

A primary admission of patients with suspected acute ischemic stroke and large vessel occlusion (LVO) to centers capable of providing endovascular stroke therapy (EVT) may induce shorter time to treatment and better functional outcomes. One of the limitations in this strategy is the need for accurately identifying LVO patients in the prehospital setting. We aimed to study the feasibility and diagnostic performance of point-of-care ultrasound (POCUS) for the detection of LVO in patients with acute stroke.

METHODS

We conducted a proof-of-concept study and selected 15 acute ischemic stroke patients with angiographically confirmed LVO and 15 patients without LVO. Duplex ultrasonography (DUS) of the common carotid arteries was performed, and flow profiles compatible with LVO were scored independently by one experienced and one junior neurologist.

RESULTS

Among the 15 patients with LVO, 6 patients presented with an occlusion of the carotid-T and 9 patients presented with an M1 occlusion. Interobserver agreement between the junior and the experienced neurologist was excellent (kappa = 0.813, p < 0.001). Flow profiles of the CAA allowed the detection of LVO with a sensitivity of 73%, a positive predictive value of 92 and 100%, and a c-statistics of 0.83 (95%CI = 0.65-0.94) and 0.87 (95%CI = 0.69-0.94) (experienced neurologist and junior neurologist, respectively). In comparison with clinical stroke scales, DUS was associated with better trade-off between sensitivity and specificity.

CONCLUSION

POCUS in acute stroke setting is feasible, it may serve as a complementary tool for the detection of LVO and is potentially applicable in the prehospital phase.

The Maryland Acute Stroke Emergency Medical Services Routing Pilot: Expediting Access to Thrombectomy for Stroke

Background: Mechanical thrombectomy (MT) is the standard of care for acute ischemic stroke caused by large vessel occlusion, but is not available at all stroke centers. Transfers between hospitals lead to treatment delays. Transport directly to a facility capable of MT based on a prehospital stroke severity scale score has been recommended, if transportation time is less than 30 min.

Aims: We hypothesized that an Emergency Medical Services (EMS) routing algorithm for stroke, using the Los Angeles Motor Scale (LAMS) in the field, would improve time from last known well to MT, without causing patients to miss the IV Thrombolysis (IVT) window.

Methods: An EMS algorithm in the Baltimore metro area using the LAMS was implemented. Patients suspected of having an acute stroke were assessed by EMS using the LAMS. Patients scoring 4 or higher and within 20 h from last known well, were transported directly to a Thrombectomy Center, if transport could be completed within 30 min. The algorithm was evaluated retrospectively with prospectively collected data at the Thrombectomy Centers. The primary outcome variables were proportion of patients with suspected stroke rerouted by EMS, proportion of rerouted ischemic stroke patients receiving MT, time to treatment, and whether the IVT window was missed.

Results: A total of 303 patients were rerouted out of 2459 suspected stroke patients over a period of 6 months. Of diverted patients, 47% had acute ischemic stroke. Of these, 48% received an acute stroke treatment: 16.8% IVT, 17.5% MT, and 14% MT+IVT. Thrombectomy occurred 119 min earlier in diverted patients compared to patients transferred from other hospitals (P = 0.006). 55.3% of diverted patients undergoing MT and 38.2% of patients transferred from hospital to hospital were independent at 90 days (modified Rankin score 0–2) (P = 0.148). No patient missed the time window for IVT due to the extra travel time.

Conclusions: In this retrospective analysis of prospectively acquired data, implementation of a pre-hospital clinical screening score to detect patients with suspected acute ischemic stroke due to large vessel occlusion was feasible. Rerouting patients directly to a Thrombectomy Center, based on the EMS algorithm, led to a shorter time to thrombectomy.

Drip-and-ship versus mothership for endovascular treatment of acute stroke: A comparative effectiveness analysis

BACKGROUND

Triage for suspected acute stroke has two main options: (1) transport to the closest primary stroke center (PSC) and then to the nearest comprehensive stroke center (CSC) (Drip-and-Ship) or (2) transport the patient to the nearest CSC, bypassing a closer PSC (mothership). The purpose was to evaluate the effectiveness of drip-and-ship versus mothership models for acute stroke patients.

METHODS

A Markov decision-analytic model was constructed. All model parameters were derived from recent medical literature. Our target population was adult patient with sudden onset of acute stroke within 8 h of onset over a one-year horizon. The primary outcome was quantified in terms of quality-adjusted-life-years (QALYs).

RESULTS

The base case scenario show that the drip-and-ship strategy has a slightly higher expected health benefit, 0.591 QALY, as compared to 0.586 QALY in the mothership strategy when the time to PSC is 30 min and to CSC is 65 min, although the difference in health benefit becomes minimal as the time to PSC increases towards 60 min. Multiple sensitivity analyses show that when both PSC and CSC are far from place of onset (>1.5 h away), drip-and-ship becomes the better strategy. Mothership strategy is favored by smaller difference between distances to PSC and CSC, shorter transfer time from PSC to CSC, and longer delay in reperfusion in CSC for transferred patients. Drip-and-ship is favored by the reverse.

CONCLUSION

Drip-and-ship has a slightly higher utility than mothership. This study assesses the complex issue of prehospital triage of acute stroke patients and can provide a framework for real-world data input.

Outcomes following endovascular therapy for acute stroke by interventional cardiologists

OBJECTIVES

To summarize the outcomes of acute ischemic stroke (AIS) intervention by interventional cardiologists (IC) working on a stroke team.

BACKGROUND

There is a geographic maldistribution of dedicated neuro-interventionalists (NI) to treat large vessel occlusion (LVO) AIS.

METHODS

Results of 166 consecutive patients who received endovascular therapy (EVT) for AIS due to LVO by IC at three centers between 2009 and 2019 are reported. A modified Rankin score (mRs) of ≤ 2 at 90 days after EVT was used as the primary measurement of a good neurological outcome. Univariate logistic regression was used to evaluate predictors of the mRS > 2 and mortality. Those variables with significance of p < .2 from the univariate analysis were included in a multivariate analysis.

RESULTS

All-cause mortality at 30 days was 22%. A favorable clinical outcome, mRS ≤ 2 at 90 days, was 49%. After multivariate analysis and controlling for confounders, a higher baseline NIHSS was predictive of 30-day mortality (OR 1.20 [95% CI 1.09-1.32] p < .001) and unfavorable clinical outcome (mRS > 2) at 90 days (OR 1.16 [95% CI 1.07-1.25] p < .001).

CONCLUSION

Outcomes for carotid stent capable IC performing EVT for AIS are comparable to those achieved by NI physicians in major randomized clinical trials. Our data supports conducting a clinical trial of carotid stent capable IC working on multidisciplinary stroke teams to perform EVT for AIS due to LVO in communities and hospitals without timely access (<60 min by ground transport) to dedicated NI.

Delayed Thrombectomy Center Arrival is Associated with Decreased Treatment Probability

BACKGROUND

Endovascular thrombectomy (EVT) is effective in reducing disability in selected patients with stroke and large vessel occlusion (LVO), but access to this treatment is suboptimal.

AIM

We examined the proportion of patients with LVO who did not receive EVT, the reasons for non-treatment, and the association between time from onset and probability of treatment.

METHODS

We conducted a retrospective cohort study of consecutive patients with acute stroke and LVO presenting between January 2017 and June 2018. We used multivariable log-binomial models to determine the association between time and probability of treatment with and without adjustment for age, sex, dementia, active cancer, baseline disability, stroke severity, and evidence of ischemia on computerized tomography.

RESULTS

We identified 256 patients (51% female, median age 74 [interquartile range, IQR 63.5, 82.5]), of whom 59% did not receive EVT. The main reasons for not treating with EVT were related to occlusion characteristics or infarct size. The median time from onset to EVT center arrival was longer among non-treated patients (218 minutes [142, 302]) than those who were treated (180 minutes [104, 265], p = 0.03). Among patients presenting within 6 hours of onset, the relative risk (RR) of receiving EVT decreased by 3% with every 10-minute delay in arrival to EVT center (adjusted RR 0.97 CI95 [0.95, 0.99]). This association was not found in the overall cohort.

CONCLUSIONS

The proportion of patients with acute stroke and confirmed LVO who do not undergo EVT is substantial. Minimizing delays in arrival to EVT center may optimize the delivery of this treatment.

Safety of inter-hospital transfer of patients with acute ischemic stroke for evaluation of endovascular thrombectomy

Stroke networks facilitate access to endovascular treatment (EVT) for patients with ischemic stroke due to large vessel occlusion. In this study we aimed to determine the safety of inter-hospital transfer and included all patients with acute ischemic stroke who were transferred within our stroke network for evaluation of EVT between 06/2016 and 12/2018. Data were derived from our prospective EVT database and transfer protocols. We analyzed major complications and medical interventions associated with inter-hospital transfer. Among 615 transferred patients, 377 patients (61.3%) were transferred within our telestroke network and had transfer protocols available (median age 76 years [interquartile range, IQR 17], 190 [50.4%] male, median baseline NIHSS score 17 [IQR 8], 246 [65.3%] drip-and-ship i.v.-thrombolysis). No patient suffered from cardio-respiratory failure or required emergency intubation or cardiopulmonary resuscitation during the transfer. Among 343 patients who were not intubated prior departure, 35 patients (10.2%) required medical interventions during the transfer. The performance of medical interventions was associated with a lower EVT rate and higher mortality at three months. In conclusion, the transfer of acute stroke patients for evaluation of EVT was not associated with major complications and transfer-related medical interventions were required in a minority of patients.

Clinical Outcomes of Endovascular Thrombectomy in Tissue Plasminogen Activator versus Non-Tissue Plasminogen Activator Patients at Primary Stroke Care Centers

Background:

The effect of intravenous tissue plasminogen activator (IV tPA) administration before endovascular intervention as compared to without at thrombectomy-capable low-volume centers on procedural aspects and patient outcomes has not been investigated.

Methods:

Retrospective chart review was performed in all consecutive large vessel cerebrovascular accident patients treated with endovascular therapy at two select rural primary stroke centers between 2011 and 2015. Patients’ data regarding age, sex, and medical history, as well as thrombus location by catheter-based cerebral angiography, postprocedural reperfusion status, and clinical outcomes were reviewed. The primary outcome measure of the study was a comparison of modified Rankin scale (MRS) at 90 days in patients’ postendovascular thrombectomy with prior IV tPA administration versus those who underwent thrombectomy and did not qualify for preprocedural IV tPA.

Results:

After application of the set inclusion and exclusion criteria, data of 46 out of 65 patients were analyzed. Twenty-three patients (50%) received IV tPA before thrombectomy and 23 patients did not qualify for IV tPA (50%). Successful recanalization (thrombolysis in cerebral infarction 2b/3) was achieved in 86% (20/23 patients) of thrombectomy patients without preprocedural IV tPA and 82% (19/23) of patients who received it (odds ratio [OR]: 0.03, confidence interval [CI]: 95% 0.062–0.16, P < 0.0001). MRS of 2 or less at 90 days was 43.4% (10/23) in patients with no preprocedural IV tPA and 39.1% (9/23) in the combined therapy group (OR: 0.84, CI: 0.26–2.70, P = 0.8).

Conclusion:

Patients undergoing endovascular thrombectomy for large vessel occlusion at select low-volume rural centers showed benefit from this treatment regardless of IV tPA administration. Clinical outcomes and complications at select low-volume thrombectomy-proficient centers are comparable to large volume comprehensive stroke centers as well as the landmark studies proving the efficacy of endovascular treatment.

Futile inter-hospital transfer for mechanical thrombectomy in a semi-rural context: analysis of a 6-year prospective registry

Background and purpose

Inter-hospital transfer for mechanical thrombectomy (MT) might result in the transfer of patients who finally will not undergo MT (ie, futile transfers [FT]). This study evaluated FT frequency in a primary stroke center (PSC) in a semi-rural area and at 156 km from the comprehensive stroke center (CSC).

Methodology

Retrospective analysis of data collected in a 6-year prospective registry concerning patients admitted to our PSC within 4.5 hours of acute ischemic stroke (AIS) symptom onset, with MR angiography indicating the presence of large vessel occlusion (LVO) without large cerebral infarction (DWI-ASPECT ≥5), and selected for transfer to the CSC to undergo MT. Futile transfer rate and reasons were determined, and the relevant time measures recorded.

Results

Among the 529 patients screened for MT, 278 (52.6%) were transferred to the CSC. Futile transfer rate was 45% (n=125/278) and the three main reasons for FT were: clinical improvement and reperfusion on MRI on arrival at the CSC (58.4% of FT); clinical worsening and/or infarct growth (16.8%); and longer than expected inter-hospital transfer time (11.2%). Predictive factors of FT due to clinical improvement/reperfusion on MRI could not be identified. Baseline higher NIHSS (21 vs 17; P=0.01) and lower DWI-ASPECT score (5 vs 7; P=0.001) were associated with FT due to clinical worsening/infarct growth on MRI.

Conclusions

In our setting, 45% of transfers for MT were futile. None of the baseline factors could predict FT, but the initial symptom severity was associated with FT caused byclinical worsening/infarct growth.