A review of acute ischemic stroke triage protocol evidence: a context for discussion

Time from image acquisition to endovascular team notification: a new target for enhancing acute stroke workflow

OBJECTIVE

To quantify the time between initial image acquisition (CT angiography (CTA)) and notification of the neuroendovascular surgery (NES) team, a potentially high yield time window to target for optimization of endovascular thrombectomy (ET) treatment times.

METHODS

We reviewed our multihospital database for all patients with a stroke with emergent large vessel occlusion treated with ET between January 1, 2017 and August 5, 2020. We dichotomized patients into rapid (≤20 min) and delayed (>20 min) notification times and analyzed treatment characteristics and outcomes.

RESULTS

Of 367 patients with ELVO undergoing ET for whom notification data were available, the median time from CTA to NES team notification was 24 min (IQR 12-47). The median total treatment time was 180 min (IQR 129-252). The median times from CTA to NES team notification for rapid (n=163) and delayed (n=204) cohorts were 11 (IQR 6-15) and 43 (IQR 30-80) min, respectively (p<0.001). The median overall times to reperfusion were 134 min (IQR 103-179) and 213 min (IQR 172-291), respectively (p<0.001). The delayed patients had a significantly lower National Institutes of Health Stroke Scale (NIHSS) score on presentation (15 (IQR 9-20) vs 16 (IQR 11-22), p=0.03), were younger (70 (IQR 60-79) vs 77 (IQR 64-85), p<0.001), and more often presented with posterior circulation occlusion (16.7% vs 7.4%, p<0.01). The group with rapid notification time had a statistically larger median improvement in NIHSS score from admission to discharge (6 (IQR 0.5-14) vs 5 (IQR 0.5-10), p=0.04).

CONCLUSIONS

Time delays from initial CTA acquisition to NES team notification can prevent expedient treatment with ET. Process improvements and automated stroke detection on imaging with automated notification of the NES team may ultimately improve time to reperfusion.

Intrinsic hospital factors: overlooked cause for variations in delay to transfer for endovascular thrombectomy

BACKGROUND

Intrinsic hospital factors leading to time delay to inter-hospital transfer for endovascular thrombectomy (EVT) have not been adequately investigated, leading to uncertainty in generalizability of hub and spoke EVT services. We investigated the contribution of intrinsic hospital factors to variations in time delay in a multicenter, retrospective study.

METHODS

The setting was a hub and spoke EVT state-wide system for a population of 6.3 million and 34 spoke hospitals. We collected data on acute large vessel occlusion strokes transferred from spoke to hub for consideration of EVT between January 2016 and December 2018. The primary endpoint was the proportion of variability in delay-time in transfer cases contributed to by intrinsic hospital factors estimated through variance component analysis implemented as a mixed-effect linear regression model with hospitals as random effects.

RESULTS

We included 434 patients. The median age was 72 years (IQR 62-79), 44% were female, and the median baseline National Institutes of Health Stroke Scale (NIHSS) was 16 (IQR 11-20). The median onset to CT time was 100 mins (IQR 69-157) at the spoke hospitals and CT acquisition at the spoke hospital to time of transfer was 93 min (IQR 70-132). 53% of the observed variability in time from CT acquisition at the spoke hospital to transfer to the EVT center was explained by intrinsic hospital factors, as opposed to patient-related factors.

CONCLUSIONS

Intrinsic hospital factors explained more than half of the observed variability in time from CT acquisition at the spoke hospital to departure for transfer. We recommend that the design of hub and spoke EVT services should account for intrinsic hospital factors to minimize hospital transfer delay.

Prehospital Triage Strategies for the Transportation of Suspected Stroke Patients in the United States

Background and Purpose:

Ischemic stroke patients with large vessel occlusion (LVO) could benefit from direct transportation to an intervention center for endovascular treatment, but non-LVO patients need rapid IV thrombolysis in the nearest center. Our aim was to evaluate prehospital triage strategies for suspected stroke patients in the United States.

Methods:

We used a decision tree model and geographic information system to estimate outcome of suspected stroke patients transported by ambulance within 4.5 hours after symptom onset. We compared the following strategies: (1) Always to nearest center, (2) American Heart Association algorithm (ie, directly to intervention center if a prehospital stroke scale suggests LVO and total driving time from scene to intervention center is <30 minutes, provided that the delay would not exclude from thrombolysis), (3) modified algorithms with a maximum additional driving time to the intervention center of <30 minutes, <60 minutes, or without time limit, and (4) always to intervention center. Primary outcome was the annual number of good outcomes, defined as modified Rankin Scale score of 0–2. The preferred strategy was the one that resulted in the best outcomes with an incremental number needed to transport to intervention center (NNTI) <100 to prevent one death or severe disability (modified Rankin Scale score of >2).

Results:

Nationwide implementation of the American Heart Association algorithm increased the number of good outcomes by 594 (+1.0%) compared with transportation to the nearest center. The associated number of non-LVO patients transported to the intervention center was 16 714 (NNTI 28). The modified algorithms yielded an increase of 1013 (+1.8%) to 1369 (+2.4%) good outcomes, with a NNTI varying between 28 and 32. The algorithm without time limit was preferred in the majority of states (n=32 [65%]), followed by the algorithm with <60 minutes delay (n=10 [20%]). Tailoring policies at county-level slightly reduced the total number of transportations to the intervention center (NNTI 31).

Conclusions:

Prehospital triage strategies can greatly improve outcomes of the ischemic stroke population in the United States, but increase the number of non-LVO stroke patients transported to an intervention center. The current American Heart Association algorithm is suboptimal as a nationwide policy and should be modified to allow more delay when directly transporting LVO-suspected patients to an intervention center.

Redistributing medical resources for a bypass strategy for large vessel occlusion: a community-based study

BACKGROUND

A bypass strategy for large vessel occlusion (LVO) benefits patients receiving endovascular thrombectomy (EVT), but may delay some patients from receiving IV thrombolysis. However, patient centralization has been shown to improve outcomes.

OBJECTIVE

To understand the current coverage of medical services for patients with stroke, and to identify the best coverage under different medical resource redistribution to help balance medical equality and patient centralization.

METHODS

This 6-year geographic study of 7679 on-scene patients with suspected stroke with a positive Cincinnati Prehospital Stroke Scale (CPSS) score identified 4037 patients with all three CPSS items who were suspected as having an LVO. Geographic, population, and patient coverage rates for hospitals providing IV thrombolysis and those providing EVT were identified according to hospital service areas, defined as geographic districts with access to a hospital within a ≤15 min off-peak driving time estimated using Google Maps. Moreover, we estimated the effects on resource redistribution when implementing a bypass strategy.

RESULTS

Geographic coverage rates for hospitals providing IV thrombolysis and those providing EVT were 64.75% and 56.62%, respectively, and population coverage rates were 97.30% and 92.72%, respectively. The service areas of hospitals providing IV thrombolysis covered 93.77% of patients with suspected stroke, and those of hospitals providing EVT covered 87.89% of patients with suspected LVO. The number of hospitals providing IV thrombolysis and those providing EVT could be reduced to six and two hospitals, respectively, without affecting hospital arrival time when implementing a bypass strategy.

CONCLUSION

Hospitals providing IV thrombolysis and EVT could be reduced without reducing medical equality.

Technological innovation for prehospital stroke triage: ripe for disruption

Background

With the benefit of mechanical thrombectomy firmly established, the focus has shifted to improved delivery of care. Reducing time from symptom onset to reperfusion is a primary goal. Technology promises tremendous opportunities in the prehospital space to achieve this goal.

Methods

This review explores existing, fledgling, and potential future technologies for application in the prehospital space.

Results

The opportunity for technology to improve stroke care resides in the detection, evaluation, triage, and transport of patients to an appropriate healthcare facility. Most prehospital technology remains in the early stages of design and implementation.

Conclusion

The major challenges to tackle for future improvement in prehospital stroke care are that of public awareness, emergency medical service detection, and triage, and improved systems of stroke care. Thoughtfully applied technology will transform all these areas.

Comparative Evaluation of 10 Prehospital Triage Strategy Paradigms for Patients With Suspected Acute Ischemic Stroke

Background

The best strategy to identify patients with suspected acute ischemic stroke and unknown vessel status (large vessel occlusion) for direct transport to a comprehensive stroke center instead of a nearer primary stroke center is unknown.

Methods and Results

We used mathematical modeling to estimate the impact of 10 increasingly complex prehospital triage strategy paradigms on the reduction of population‐wide stroke‐related disability. The model was applied to suspected acute ischemic stroke patients in (1) abstract geographies, and (2) 3 real‐world urban and rural geographies in Germany. Transport times were estimated based on stroke center location and road infrastructure; spatial distribution of emergency medical services calls was derived from census data with high spatial granularity. Parameter uncertainty was quantified in sensitivity analyses. The mothership strategy was associated with a statistically significant population‐wide gain of 8 to 18 disability‐adjusted life years in the 3 real‐world geographies and in most simulated abstract geographies (net gain −4 to 66 disability‐adjusted life years). Of the more complex paradigms, transportation of patients with clinically suspected large vessel occlusion based on a dichotomous large vessel occlusion detection scale to the nearest comprehensive stroke center yielded an additional clinical benefit of up to 12 disability‐adjusted life years in some rural but not in urban geographies. Triage strategy paradigms based on probabilistic conditional modeling added an additional benefit of 0 to 4 disability‐adjusted life years over less complex strategies if based on variable cutoff scores.

Conclusions

Variable stroke severity cutoff scores were associated with the highest reduction in stroke‐related disability. The mothership strategy yielded better clinical outcome than the drip‐‘n'‐ship strategy in most geographies.