A tool to identify patients with embolic stroke of undetermined source at high recurrence risk

Independent external validation of a stroke recurrence score in patients with embolic stroke of undetermined source

BACKGROUND

Embolic stroke of undetermined source (ESUS) accounts for a substantial proportion of ischaemic strokes. A stroke recurrence score has been shown to predict the risk of recurrent stroke in patients with ESUS based on a combination of clinical and imaging features. This study aimed to externally validate the performance of the ESUS recurrence score using data from a randomized controlled trial.

METHODS

The validation dataset consisted of eligible stroke patients with available magnetic resonance imaging (MRI) data enrolled in the PreDAFIS sub-study of the MonDAFIS study. The score was calculated using three variables: age (1 point per decade after 35 years), presence of white matter hyperintensities (2 points), and multiterritorial ischaemic stroke (3 points). Patients were assigned to risk groups as described in the original publication. The model was evaluated using standard discrimination and calibration methods.

RESULTS

Of the 1054 patients, 241 (22.9%) were classified as ESUS. Owing to insufficient MRI quality, three patients were excluded, leaving 238 patients (median age 65.5 years [IQR 20.75], 39% female) for analysis. Of these, 30 (13%) patients experienced recurrent ischaemic stroke or transient ischemic attack (TIA) during a follow-up period of 383 patient-years, corresponding to an incidence rate of 7.8 per 100 patient-years (95% CI 5.3-11.2). Patients with an ESUS recurrence score value of ≥ 7 had a 2.46 (hazard ratio (HR), 95% CI 1.02-5.93) times higher risk of stroke recurrence than patients with a score of 0-4. The cumulative probability of stroke recurrence in the low-(0-4), intermediate-(5-6), and high-risk group (≥ 7) was 9%, 13%, and 23%, respectively (log-rank test, χ2 = 4.2, p = 0.1).

CONCLUSIONS

This external validation of a published scoring system supports a threshold of ≥ 7 for identifying ESUS patients at high-risk of stroke recurrence. However, further adjustments may be required to improve the model's performance in independent cohorts. The use of risk scores may be helpful in guiding extended diagnostics and further trials on secondary prevention in patients with ESUS.

TRIAL REGISTRATION

Clinical Trials, NCT02204267. Registered 30 July 2014, https://clinicaltrials.gov/ct2/show/NCT02204267 .

MRI-based risk stratification for recurrent ischemic stroke in embolic stroke of undetermined source

OBJECTIVE

Leukoaraiosis and other brain MRI-assessed parameters were shown to be associated with recurrent stroke in this population. We aimed to develop an MRI-based predictive tool for risk stratification of ESUS patients.

METHODS

We retrospectively assessed consecutive patients who were diagnosed with ESUS and underwent brain MRI and performed a multivariable analysis with the outcome of recurrent stroke/TIA. Based on the coefficient of each covariate, we generated an integer-based point scoring system. The discrimination and calibration of the score were assessed using the area under the receiver operator characteristic curve, net reclassification improvement, integrated discrimination improvement, calibration curve, and decision curve analysis. Also, we compared the new score with a previously published score (ALM score).

RESULTS

Among 176 patients followed for an overall period of 902.3 patient-years (median of 74 months), there were 39 recurrent ischemic stroke/TIAs (4.32 per 100 patient-years). Fazekas score (HR: 1.26, 95% CI: 1.03-1.54), enlarged perivascular space (EPVS) (HR: 2.76, 95% CI: 1.12-6.17), NIHSS at admission (HR: 1.11, 95% CI: 1.02-1.18), and infarct subtypes (HR: 2.88, 95% CI: 1.34-6.17) were associated with recurrent stroke/TIA. Accordingly, a score (FENS score) was developed with AUC-ROC values of 0.863, 0.788, and 0.858 for 1, 3, and 5 years, respectively. These were significantly better than the AUC-ROC of ALM score (0.635, 0.695, and 0.705, respectively). The FENS score exhibited better calibration and discrimination ability than the ALM score (Hosmer-Lemeshow test χ2 : 4.402, p = 0.819).

CONCLUSION

The MRI-based FENS score can provide excellent predictive performance for recurrent stroke/TIA and may assist in risk stratification of ESUS patients.

ADAMTS-13 activity in stroke of known and unknown cause: Relation to vascular risk factor burden

Background

The identification of the underlying mechanism in ischemic stroke has important implications for secondary prevention. A disintegrin and metalloprotease with a thrombospondin type 1 motif, member 13 (ADAMTS-13) has antithrombotic properties and was repeatedly implicated in the pathophysiology of stroke. In this study, we, therefore, aimed to investigate whether ADAMTS-13 is associated with stroke etiology and the burden of vascular risk factors.

Methods

We determined ADAMTS-13 activity in two prospectively recruited stroke cohorts in the long-term course after the event. Cohort 1 (n = 88) consisted of patients who suffered a stroke due to embolic stroke of undetermined source (ESUS), cardioembolic stroke due to atrial fibrillation (AF), large-artery atherosclerosis, or small vessel disease. In cohort 2, patients with cryptogenic stroke and patent foramen ovale (PFO) scheduled for PFO closure (n = 38) were enrolled. As measures of vascular risk factor burden, the CHA₂DS₂VASC score, the Essen Stroke Risk Score (ESRS), and the Risk of Paradoxical Embolism (RoPE) score were calculated, as appropriate.

Results

ADAMTS-13 activity was lower in patients with AF-related stroke compared to patients with ESUS (p = 0.0227), which was, however, due to confounding by vascular risk factors. ADAMTS-13 activity inversely correlated with the ESRS (r = -0.452, p < 0.001) and CHA₂DS₂VASC (r = -0.375, p < 0.001) in cohort 1. In accordance with these findings, we found a positive correlation between ADAMTS-13 activity and the RoPE score in cohort 2 (r = 0.413, p = 0.010).

Conclusion

ADAMTS-13 activity is inversely correlated with the number of vascular risk factors across different stroke etiologies. Further study is warranted to establish ADAMTS-13 as a mediator of cerebrovascular risk.

A score to predict the stroke recurrence of patients with embolic stroke of undetermined source

AIM

We aimed to develop a score and validate it in a prospective cohort to identify the patients with ESUS at high risk for stroke recurrence.

METHODS

We assessed the stroke recurrence in ESUS patients of the Third China National Stroke Registry. We performed multivariable logistic regression analysis to identify predictors of stroke recurrence in the derivation cohort. Based on the coefficient of each covariate of the fitted multivariable model, we generated an integer-based point scoring system. We validated the score in the validation cohort assessing its discrimination and calibration.

RESULTS

2415 patients were included: 1611 in the derivation and 804 in the validation sample. We developed a scoring system (0-15 points) by assigning 2 points for hypertension, 3 points for diabetes mellitus, 4 points for multiple stage infarction, 2 points for watershed involved infarction, 1 points for left atrial diameter index (per increasing 2.5 mm/m2) and 3 points for without statin at discharge. The rate of stroke recurrence was 5.9% per year (95% CI 4.2-7.6%) in patients with low risk(a score of 0-5), 9.4% (7.3-11.5%) in patients with intermediate risk (6-10), and 26.8% (16.5-37.1%) in patients with high risk (11-15). The AUC (area under curve of receiver operator characteristic curve) of the score in the derivation cohort and validation cohort was, respectively, 0.60 (0.55-0.65) and 0.63 (0.56-0.70). The score was well calibrated both in the derivation cohort (p = 0.36) and validation cohort (p = 0.26) with the Hosmer-Lemeshow test.

CONCLUSION

The developed score can improve risk stratification after ESUS in secondary care settings.

Predictors of Recurrent Stroke After Embolic Stroke of Undetermined Source in the RE-SPECT ESUS Trial

Background

We sought to determine recurrent stroke predictors among patients with embolic strokes of undetermined source (ESUS).

Methods and Results

We applied Cox proportional hazards models to identify clinical features associated with recurrent stroke among participants enrolled in RE‐SPECT ESUS (Randomized, Double‐Blind, Evaluation in Secondary Stroke Prevention Comparing the Efficacy and Safety of the Oral Thrombin Inhibitor Dabigatran Etexilate Versus Acetylsalicylic Acid in Patients With Embolic Stroke of Undetermined Source) trial, an international clinical trial evaluating dabigatran versus aspirin for patients with ESUS. During a median follow‐up of 19 months, 384 of 5390 participants had recurrent stroke (annual rate, 4.5%). Multivariable models revealed that stroke or transient ischemic attack before the index event (hazard ratio [HR], 2.27 [95% CI, 1.83–2.82]), creatinine clearance <50 mL/min (HR, 1.69 [95% CI, 1.23–2.32]), male sex (HR, 1.60 [95% CI, 1.27–2.02]), and CHA₂DS₂‐VASc ≥4 (HR, 1.55 [95% CI, 1.15–2.08] and HR, 1.66 [95% CI, 1.21–2.26] for scores of 4 and ≥5, respectively) versus CHA₂DS₂‐VASc of 2 to 3, were independent predictors for recurrent stroke.

Conclusions

In RE‐SPECT ESUS trial, expected risk factors previously linked to other common stroke causes were associated with stroke recurrence. These data help define high‐risk groups for subsequent stroke that may be useful for clinicians and for researchers designing trials among patients with ESUS.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02239120.

Characteristics and prognosis of patients with embolic stroke of undetermined source in China

BACKGROUND AND PURPOSE

We aimed to explore the frequencies, risk factors, and natural history of embolic stroke of undetermined source (ESUS) through a national prospective registry in China.

METHODS

Between August 2015 and March 2018, the Third China National Stroke Registry recruited consecutive patients with ischemic stroke or transient ischemic attack in China. The baseline characteristics, risks of stroke, and prognosis in patients with embolic stroke of undetermined source were described and compared with that in patients with other causative subtypes.

RESULTS

A total of 15,166 transient ischemic attack and ischemic stroke patients were enrolled in the Third China National Stroke Registry. Among 8528 ischemic stroke with standard diagnostic work-up, 2415 (28.3%) patients were diagnosed with embolic stroke of undetermined source. The mean age was 61 years and 70% of them were male. Compared to patients with cardioembolic strokes and small vessel disease, patients with embolic stroke of undetermined source had higher prevalence of nonstenosing large artery atherosclerosis (37.93% vs. 31.26%, P = 0.008 and 37.93% vs. 34.40%, P = 0.044 respectively). The cumulative probability of stroke recurrence in patients with embolic stroke of undetermined source at three months and one year was 5.59% and 8.74%. Compared with embolic stroke of undetermined source patients (0.70% and 1.99%), patients with the large artery atherosclerosis and cardioembolic strokes had higher cumulative probability of death at three months (1.94% and 3.22%) and one year (4.17% and 7.39%).

CONCLUSIONS

Embolic stroke of undetermined source is a common cause of ischemic stroke in Chinese population with a higher stroke recurrence than previously reported. It was more likely to have nonstenosing large artery atherosclerosis in patients with embolic stroke of undetermined source than with cardioembolic strokes and small vessel disease.

[Embolic stroke of undetermined source (ESUS) - Classification of a new stroke entity]

Embolic stroke of undetermined source (ESUS) represents a subpopulation of cryptogenic strokes defined by its embolic stroke pattern on imaging and if after a carefully performed diagnostic evaluation, a specific, well recognized cause of stroke has not been identified. This review article analyses the basics of the ESUS concept and provides an overview of the evidence from recent cohort studies. The definition, aetiology and diagnosis of ESUS are reassessed. Targeted diagnostics in ESUS patients can reduce the number of cryptogenic strokes by making a specific diagnosis.

A score to predict one-year risk of recurrence after acute ischemic stroke

BACKGROUND

An acute ischemic stroke carries a substantial risk of further recurrences. We aimed at developing and validating a prognostic tool to predict one-year stroke recurrence after acute ischemic stroke.

METHODS

An integer score was derived by Cox regression analysis on a hospital-referred cohort of 3246 acute ischemic stroke patients from Switzerland, and tested for external validity in three similar independent cohorts from Athens (n = 2495), Milan (n = 1279), and Helsinki (n = 714) by means of calibration and discrimination.

RESULTS

In the derivation cohort, the recurrence rate was 7% (n = 228/3246). We developed a nine-point score comprising: previous stroke or transient ischemic attack (1-point), stroke mechanism (small vessel disease and unknown mechanism: 0-points; rare stroke mechanism: 3-points; other mechanisms: 1-point), pre-stroke antiplatelets (1-point), active malignancy (2-points), chronic cerebrovascular lesions on imaging (1-point) and absence of early ischemic changes on first imaging (1-point). In the derivation cohort, the one-year risk of re-stroke was 3.0% (95%CI 1.9-4.1) in 932 (29%) patients with a score 0-1, 7.2% (6.1-8.3) in 2038 (63%) with a score 2-4, and 19.2% (14.6-23.9) in 276 (8%) with a score ≥ 5. The score calibrated well in the Athens (recurrences = 208/2495), but not in the Helsinki (recurrences = 15/714) or Milan (recurrences = 65/1279) cohorts. The AUC was 0.67 in the derivation cohort, and 0.56, 0.70, and 0.63 in the Athens, Helsinki, and Milan cohorts, respectively.

CONCLUSION

We developed a score to predict one-year stroke recurrence risk in patients with acute ischemic stroke. Since the score was not completely validated when applied to external datasets where it displayed poor to fair calibration and discrimination, additional efforts are required to ameliorate our accuracy for predicting stroke recurrence, by better refining this prognostic tool or developing new ones. Clinical and radiological markers of established cerebrovascular disease and stroke etiology were better predictors than the usual demographic vascular risk factors.

Embolic Stroke of Undetermined Source: Gateway to a New Stroke Entity?

Embolic stroke of unknown source (ESUS) is currently thought to represent a subpopulation of cryptogenic strokes defined by its embolic stroke pattern on imaging, and if after a carefully performed diagnostic evaluation, a specific, well-recognized cause of stroke has not been identified. The concept was primarily established to justify and enable the conduct of the ESUS trials, such as Randomized, Double-Blind, Evaluation in Secondary Stroke Prevention Comparing the Efficacy and Safety of the Oral Thrombin Inhibitor Dabigatran Etexilate versus Acetylsalicylic Acid in Patients with Embolic Stroke of Undetermined Source (RESPECT-ESUS) and New Approach Rivaroxaban Inhibition of Factor Xa in a Global Trial versus aspirin to Prevent Embolism in Embolic Stroke of Undetermined Source (NAVIGATE-ESUS). With both studies having neutral results, the question arises if the ESUS concept is misleading or rather a gateway for a modern understanding of stroke etiology. This review will analyze the background of the ESUS concept, overview the results and the impact of the recent multicenter trials and cohort studies, and discuss the definition, etiology, and diagnosis of ESUS.