Agreement in Endovascular Thrombolysis Patient Selection Based on Interpretation of Presenting CT and CT-P Changes in Ischemic Stroke Patients

Intravenous thrombolysis and thrombectomy decisions in acute ischemic stroke: An interrater and intrarater agreement study

PURPOSE

We aimed to assess agreement on intravenous tissue-plasminogen activator (IV tPA) and mechanical thrombectomy (MT) management decisions in acute ischemic stroke (AIS) patients. Secondary objectives were to assess agreement on Diffusion-Weighted-Imaging-Alberta-Stroke-Program-EArly-CT-Score (DWI-ASPECTS), and clinicians' willingness to recruit patients in a randomized controlled trial (RCT) comparing medical management with or without MT.

MATERIALS AND METHODS

Studies assessing agreement of IV tPA and MT were systematically reviewed. An electronic portfolio of 41 AIS patients was sent to randomly selected providers at French stroke centers. Raters were asked 4 questions for each case: (1) What is the DWI-ASPECTS? (2) Would you perform IV tPA? (3) Would you perform MT? (4) Would you include the patient in a RCT comparing standard medical therapy with or without MT? Twenty responders were randomly selected to study intrarater agreement. Agreement was assessed using Fleiss' Kappa statistics.

RESULTS

The review yielded two single center studies involving 2-5 raters, with various results. The electronic survey was answered by 86 physicians (60 vascular neurologists and 26 interventional neuroradiologists). The interrater agreement was moderate for IV tPA treatment decisions (κ=0.565 [0.420-0.680]), but only fair for MT (κ=0.383 [0.289-0.491]) and for combined treatment decisions (κ=0.399 [0.320-0.486]). The intrarater agreement was at least substantial for the majority of raters. The interrater agreement for DWI-ASPECTS was fair (κ=0.325 [0.276-0.387]). Physicians were willing to include a mean of 14±9 patients (33.1%±21.7%) in a RCT.

CONCLUSION

Disagreements regarding the use of IVtPA or MT in the management of AIS patients remain frequent. Further trials are needed to resolve the numerous areas of uncertainty.

Prospective Endovascular Treatment in Acute Ischemic Stroke Evaluating Non-Contrast Head CT versus CT Perfusion (PLEASE No CTP)

Background

Studies have shown a lack of agreement of computed tomography perfusion (CTP) in the selection of acute ischemic stroke (AIS) patients for endovascular treatment.

Purpose

To demonstrate whether non-contrast computed tomography (CT) within 8 h of symptom onset is comparable to CTP imaging.

Methods

Prospective study of consecutive anterior circulation AIS patients with a National Institute of Health Stroke Scale (NIHSS) score > 7 presenting within 8 h of symptom onset with endovascular treatment. All patients had non-contrast CT, CT angiography, and CTP. The neuro-interventionalist was blinded to the results of the CTP and based the treatment decision using the Alberta Stroke Program Early CT score (ASPECTS). Baseline demographics, co-morbidities, and baseline NIHSS scores were collected. Outcomes were modified Rankin scale (mRS) score at discharge and in-hospital mortality. Good outcomes were defined as a mRS score of 0-2.

Results

283 AIS patients were screened for the trial, and 119 were enrolled. The remaining patients were excluded for: posterior circulation stroke, no CTP performed, could not obtain consent, and NIHSS score < 7. Mean -NIHSS score at admission was 16.8 ± 3, and mean ASPECTS was 8.4 ± 1.4. There was no statistically significant correlation with CTP penumbra and good outcomes: 50 versus 47.8% with no penumbra present (p = 0.85). In patients without evidence of CTP penumbra, there was 22.5% mortality compared to 22.1% mortality in patients with a CTP penumbra. If ASPECTS ≥7, 64.6% had good outcome versus 13.3% if ASPECTS < 7 (p < 0.001). Patients with an ASPECTS ≥7 had 10% mortality versus 51.4% in patients with an ASPECTS < 7 (p < 0.001).

Conclusions

CTP penumbra did not identify patients who would benefit from endovascular treatment when patients were selected with non-contrast CT ASPECTS ≥7. There is no correlation of CTP penumbra with good outcomes or mortality. Larger prospective trials are warranted to justify the use of CTP within 6 h of symptom onset.

Computed tomography perfusion and computed tomography angiography for prediction of clinical outcomes in ischemic stroke patients after thrombolysis

Cerebral blood perfusion and cerebrovascular lesions are important factors that can affect the therapeutic efficacy of thrombolysis. At present, the majority of studies focus on assessing the accuracy of lesion location using imaging methods before treatment, with less attention to predictions of outcomes after thrombolysis. Thus, in the present study, we assessed the efficacy of combined computed tomography (CT) perfusion and CT angiography in predicting clinical outcomes after thrombolysis in ischemic stroke patients. The study included 52 patients who received both CT perfusion and CT angiography. Patients were grouped based on the following criteria to compare clinical outcomes: (1) thrombolytic and non-thrombolytic patients, (2) thrombolytic patients with CT angiography showing the presence or absence of a vascular stenosis, (3) thrombolytic patients with CT perfusion showing the presence or absence of hemodynamic mismatch, and (4) different CT angiography and CT perfusion results. Short-term outcome was assessed by the 24-hour National Institution of Health Stroke Scale score change. Long-term outcome was assessed by the 3-month modified Rankin Scale score. Of 52 ischemic stroke patients, 29 were treated with thrombolysis and exhibited improved short-term outcomes compared with those without thrombolysis treatment (23 patients). Patients with both vascular stenosis and blood flow mismatch (13 patients) exhibited the best short-term outcome, while there was no correlation of long-term outcome with CT angiography or CT perfusion findings. These data suggest that combined CT perfusion and CT angiography are useful for predicting short-term outcome, but not long-term outcome, after thrombolysis.

CT perfusion-guided versus time-guided mechanical recanalization in acute ischemic stroke patients

OBJECTIVE

Perfusion studies are increasingly used to triage acute stroke patients for endovascular recanalization therapies. We compare the safety and efficacy of CT perfusion (CTP)-guided to time-guided mechanical recanalization in acute ischemic stroke (AIS) patients.

METHODS

A review was conducted on 132 patients, 94 undergoing CTP-guided and 38 undergoing time-guided (maximum 8h from symptom onset) mechanical recanalization at our institution.

RESULTS

The rate of partial-to-complete recanalization did not differ between the CTP and the non-CTP group (78.7% vs. 81.6%, respectively, p=0.71). ICH occurred respectively in 18.1% in the CTP group versus 31.6% in the non-CTP group (p=0.06). The overall in-hospital mortality rate was significantly lower in the CTP group (15.9% vs. 36.8%, p=0.04). In multivariable analysis, CTP-guided patient selection was an independent negative predictor of in-hospital mortality (OR=3.2; p=0.01). CTP-guided patient selection, however, was not a predictor of favorable outcome (Modified Rankin Scale 0-2 or 0-3).

CONCLUSIONS

CTP-based patient selection was associated with lower ICH and mortality rates. Favorable outcomes, however, did not differ between the 2 groups. These results may suggest a possible benefit in terms of in-hospital mortality with CTP-guided triage of AIS patients for endovascular treatment.

Eligibility determination for intravenous thrombolysis based on radiology interpretation report of the head CT scan in patients with acute ischemic stroke

OBJECTIVE

To evaluate the variability of determining eligibility for intravenous thrombolysis (IV t-PA) by a stroke team interpretation of computed tomographic (CT) scan of the head versus review of the radiology interpretation (presented in final report) in patients with acute ischemic stroke.

METHODS

We compiled a database of all IV t-PA-treated ischemic stroke patients at our academic institution based on the stroke team's CT scan interpretation. The CT scan reports of 171 patients were reviewed by an independent board-certified vascular neurologist who was blinded to clinical information except that all patients were being considered for IV t-PA to determine their eligibility for thrombolysis. The reviewer's responses were then compared with the treating team's decision to identify discrepancies, and the impact of the discrepant decisions on clinical outcome including 24-hour National Institute of Health stroke Scale (NIHSS) score and discharge modified Rankin scale (mRS), symptomatic hemorrhage (sICH), and asymptomatic hemorrhage (aICH). We compared the outcomes of patients who received IV t-PA despite cautionary neuroradiologist interpretation and placebo-treated patients from NINDS t-PA study.

RESULTS

The independent reviewer decided to treat with IV t-PA 123 patients (72%) after reviewing the radiology reports. The rate of NIHSS score improvement (52.0% vs. 62.5%, P = .22) was not different between patients in whom IV t-PA should or should not have been used based on radiology reports. Favorable clinical outcome defined by mRS of 0-2 at discharge (50.4% vs. 47.9%, P = .77) and in-hospital mortality (15.6% vs. 12.5%, P = .61) were similar between the 2 groups. Favorable outcome (discharge or day 7-10 mRS 0-2) was significantly higher in patients who received t-PA compared with placebo-treated patients (48% vs. 28%, P = .006).

CONCLUSION

Our study demonstrates that administering IV t-PA to patients based on the stroke team's interpretation of the CT scan versus review of the radiology interpretation does not lead to significant differences in clinical outcome, aICH, or sICH.

Advanced neuroimaging to guide acute stroke therapy

Traditionally non-contrast CT has been considered the first choice imaging modality for acute stroke. Acute ischemic stroke patients presenting to the hospital within 3-hours from symptom onset and without any visible hemorrhages or large lesions on CT images are considered optimum reperfusion therapy candidates. However, non-contrast CT alone has been unable to identify best reperfusion therapy candidates outside this window. New advanced imaging techniques are now being used successfully for this purpose. Non-invasive CT or MR angiography images can be obtained during initial imaging evaluation for identification and characterization of vascular lesions, including occlusions, aneurysms, and malformations. Either CT-based perfusion imaging or MRI-based diffusion and perfusion imaging performed immediately upon arrival of a patient to the hospital helps estimate the extent of fixed core and penumbra in ischemic lesions. Patients having occlusive lesions with small fixed cores and large penumbra are preferred reperfusion therapy candidates.

How well do blood flow imaging and collaterals on angiography predict brain at risk?

As endovascular therapy emerges as a principal approach to restore blood flow in the setting of acute stroke, better methods of patient selection need to be developed. Noninvasive studies of blood flow and angiographic results acquired prior to endovascular therapy may help determine areas of brain at risk of infarction and hemorrhagic transformation, both largely determined by the severity of cerebral ischemia. Pathophysiologic measures of collateral flow and perfusion that characterize ischemic severity prior to revascularization may optimize acute stroke decision-making, currently driven by arbitrary time parameters derived from population studies devoid of imaging.

Clinical use of computed tomographic perfusion for the diagnosis and prediction of lesion growth in acute ischemic stroke

BACKGROUND

Computed tomography perfusion (CTP) mapping in research centers correlates well with diffusion-weighted imaging (DWI) lesions and may accurately differentiate the infarct core from ischemic penumbra. The value of CTP in real-world clinical practice has not been fully established. We investigated the yield of CTP-derived cerebral blood volume (CBV) and mean transient time (MTT) for the detection of cerebral ischemia and ischemic penumbra in a sample of acute ischemic stroke (AIS) patients.

METHODS

We studied 165 patients with initial clinical symptoms suggestive of AIS. All patients had an initial noncontrast head CT, CTP, CT angiogram (CTA), and follow-up magnetic resonance imaging (MRI) of the brain. The obtained perfusion images were used for image processing. CBV, MTT, and DWI lesion volumes were visually estimated and manually traced. Statistical analysis was conducted using R and SAS software.

RESULTS

All normal DWI sequences had normal CBV and MTT studies (N = 89). Seventy-three patients had acute DWI lesions. CBV was abnormal in 23.3% and MTT was abnormal in 42.5% of these patients. There was a high specificity (91.8%) but poor sensitivity (40.0%) for MTT maps predicting positive DWI. The Spearman correlation was significant between MTT and DWI lesions (ρ = 0.66; P > .0001) only for abnormal MTT and DWI lesions >0 cc. CBV lesions did not correlate with final DWI.

CONCLUSIONS

In real-world use, acute imaging with CTP did not predict stroke or DWI lesions with sufficient accuracy. Our findings argue against the use of CTP for screening AIS patients until real-world implementations match the accuracy reported from specialized research centers.