Paul E. Cotter

Incidence of atrial fibrillation detected by implantable loop recorders in unexplained stroke

Objectives: The usefulness of the implantable loop recorder (ILR) with improved atrial fibrillation (AF) detection capability (Reveal XT) and the factors associated with AF in the setting of unexplained stroke were investigated. Methods: A cohort study is reported of 51 patients in whom ILRs were implanted for the investigation of ischemic stroke for which no cause had been found (cryptogenic) following appropriate vascular and cardiac imaging and at least 24 hours of cardiac rhythm monitoring. Results: The patients were aged from 17 to 73 (median 52) years. Of the 30 patients with a shunt investigation, 22 had a patent foramen ovale (73.3%; 95% confidence interval [CI] 56.5%–90.1%). AF was identified in 13 (25.5%; 95% CI 13.1%–37.9%) cases. AF was associated with increasing age (p = 0.018), interatrial conduction block (p = 0.02), left atrial volume (p = 0.025), and the occurrence of atrial premature contractions on preceding external monitoring (p = 0.004). The median (range) of monitoring prior to AF detection was 48 (0–154) days. Conclusion: In patients with unexplained stroke, AF was detected by ILR in 25.5%. Predictors of AF were identified, which may help to target investigations. ILRs may have a central role in the future in the investigation of patients with unexplained stroke.

Predicting readmissions: poor performance of the LACE index in an older UK population

INTRODUCTION interventions to prevent hospital readmission depend on the identification of patients at risk. The LACE index predicts readmission (and death) and is in clinical use internationally. The LACE index was investigated in an older UK population. METHODS randomly selected alive-discharge episodes were reviewed. A LACE score was calculated for each patient and assessed using receiver operator characteristic (ROC) curves. A logistic regression model was constructed, compared with the LACE and validated in a separate population. RESULTS a total of 507 patients were included with a mean (SD) age of 85 (6.5) years; 17.8% were readmitted and 4.5% died within 30 days. The median LACE score of those readmitted compared with those who were not was 12.5 versus 12 (P = 0.13). The Lace index was only a fair predictor of both 30-day readmission and death with c-statistics of 0.55 and 0.70, respectively. Only the emergency department visit was an independent predictor of readmission, with a c-statistic of 0.61 for readmission. In a validation cohort of 507 cases, the c-statistic of the regression model was 0.57. CONCLUSION the LACE index is a poor tool for predicting 30-day readmission in older UK inpatients. The absence of a simple predictive model may limit the benefit of readmission avoidance strategies.

Does perfusion computed tomography facilitate clinical decision making for thrombolysis in unselected acute patients with suspected ischaemic stroke

Background: Despite use in clinical practice and major positive trials of thrombolysis, non-contrast computed tomography (NCCT) is not sensitive for identifying penumbral tissue in acute stroke. This study evaluated how physiological imaging using CT perfusion (CTP) could add to the diagnostic utility of an NCCT and inform clinical decisions regarding thrombolysis. Methods: Forty imaging datasets containing NCCT and CTP were retrospectively identified from a cohort of consecutive acute stroke patients. Two sets of observers (n = 6) and a neuroradiologist evaluated the images without knowledge of clinical symptoms. Inter-observer agreement was calculated using the ĸ statistic for identifying acute ischaemic change on NCCT: perfusion abnormalities (namely cerebral blood volume, cerebral blood flow and time to peak), and penumbral tissue on perfusion maps obtained by two image processing algorithms. Results: Inter-rater agreement was moderate (ĸ = 0.54) for early ischaemic change on NCCT. Perfusion maps improved this to substantial for cerebral blood volume (ĸ = 0.67) and to almost perfect for time to peak (ĸ = 0.87) and cerebral blood flow (ĸ = 0.87). The agreement for qualitative assessment of penumbral tissue was substantial to perfect for images obtained using the two different perfusion algorithms. Overall, there was a high rate of decision to thrombolyse based on NCCT (81.25%). CTP strengthened the decision to thrombolyse based on NCCT in 38.3% of cases. It negatively influenced the decision in 14.6% of cases, this being significantly more common in experienced observers (p = 0.02). Conclusions: We demonstrate that the qualitative evaluation of CTP produces near perfect inter-observer agreement, regardless of the post-processing method used. CTP is a reliable, accessible and practical imaging modality that improves confidence in reaching the appropriate diagnosis. It is particularly useful for less experienced clinicians, to arrive at a physiologically informed treatment decision.

Thrombolysis Delivery by a Regional Telestroke Network—Experience From the UK National Health Service

Background The majority of established telestroke services are based on “hub‐and‐spoke” models for providing acute clinical assessment and thrombolysis. We report results from the first year of the successful implementation of a locally based telemedicine network, without the need of 1 or more hub hospitals, across a largely rural landscape. Methods and Results Following a successful pilot phase that demonstrated safety and feasibility, the East of England telestroke project was rolled out across 7 regional hospitals, covering an area of 7500 square miles and a population of 5.6 million to enable out‐of‐hours access to thrombolysis. Between November 2010 and November 2011, 142 telemedicine consultations were recorded out‐of‐hours. Seventy‐four (52.11%) cases received thrombolysis. Median (IQR) onset‐to‐needle and door‐to‐needle times were 169 (141.5 to 201.5) minutes and 94 (72 to 113.5) minutes, respectively. Symptomatic hemorrhage rate was 7.3% and stroke mimic rate was 10.6%. Conclusions We demonstrate the safety and effectiveness of a horizontal networking approach for stroke telemedicine, which may be applicable to areas where traditional “hub‐and‐spoke” models may not be geographically feasible.

Towards Understanding the Cause of Stroke in Young Adults Utilising a New Stroke Classification System (A-S-C-O)

Background: Stroke in younger people is relatively common and frequently unexplained. While understanding of the causes of young stroke has improved, there remains uncertainty over the role of low-risk lesions such as a patent foramen ovale (PFO). The TOAST criteria are often used to describe stroke aetiology, but in younger people in whom PFOs are frequent, there is a very high proportion of cases attributed to cardiac embolism. The impact of using the newer A-S-C-O criteria on stroke aetiology was investigated. Methods: Consecutive patients with ischaemic stroke were investigated and categorised by the TOAST and ASCO1 criteria. Stroke aetiology was presented and compared by the different classification systems. Results: Of the 106 ischaemic stroke cases, by TOAST 6% were ‘large artery atheroma’, 11% ‘small vessel occlusion’, 28% ‘cardioembolic’, 22% ‘other determined cause’ and 33% ‘undetermined cause’. The vascular territory and associated causes are presented. With the ASCO1 criteria, there were more cases of unclassified stroke (51.9 vs. 34.0%; p < 0.001) and fewer cases of cardiac embolism. Kappa ranged from 0.5 for ‘undetermined aetiology’ to 1.0 for both ‘large artery atheroma’ and ‘other determined aetiology’. Younger cases (<45 years) were less likely to be either ‘large artery atheroma’ or ‘small vessel occlusion’. Conclusion: Using the ASCO criteria, more patients fall into the undetermined group which more accurately reflects our current uncertainty regarding the pathogenic relevance of PFOs in this age group.

Increased incidence of interatrial block in younger adults with cryptogenic stroke and patent foramen ovale.

Background: Stroke is often unexplained in younger adults, although it is often associated with a patent foramen ovale (PFO). The reason for the association is not fully explained, and mechanisms other than paradoxical embolism may be involved. Young stroke patients with PFO have more atrial vulnerability than those without PFO. It is plausible that stretching of the interatrial septum may disrupt the interatrial conduction pathways causing interatrial block (IAB). IAB is associated with atrial fibrillation, dysfunctional left atria and stroke. Methods: Electrocardiogram (ECG) characteristics of prospectively recruited young patients (≤55 years of age) with unexplained stroke (TOAST and A-S-C-O) were compared with control data. All stroke cases underwent bubble contrast transthoracic and transoesophageal echography. IAB was defined as a P-wave duration of ≧110 ms. ECG data were converted to electronic format and analysed in a blind manner. Results: Fifty-five patients and 23 datasets were analysed. Patients with unexplained stroke had longer P-wave duration (p = 0.013) and a greater prevalence of IAB (p = 0.02) than healthy controls. Case status was an independent predictor of P-wave duration in a significant multivariate model. There was a significant increase in the proportion of cases with a PFO with IAB compared with cases without PFO and with controls (p = 0.005). Conclusions: Young patients with unexplained stroke, particularly those with PFO, exhibit abnormal atrial electrical characteristics suggesting atrial arrhythmia or atrial dysfunction as a possible mechanism of stroke.

Stroke in younger patients: the heart of the matter.

Stroke in young adults is not a rare entity, and often provides difficult management decisions for neurologists. The knowledge gained from stroke in older adults does not transfer easily to this younger group given the different causes of stroke observed. Cardiac causes of stroke are common in this group, but often consist of low risk cardiac lesions such as a patent foramen ovale. Appropriate investigation should follow a stepwise approach to initially exclude higher risk pathology for recurrent stroke such as arterial dissection. Similarly, stepwise application of cardiac investigations will allow early identification of significant pathology, with investigation for abnormalities of the inter-atrial septum reserved for those with no other identified cause of stroke. Bubble contrast echo is now widely available, and with improved image quality may be performed with either transthoracic or transoesophageal echo, as well as with transcranial Doppler. Following this approach, patients can be best categorised by the expected rate of recurrent stroke, as informed by observational studies. Appropriate secondary prevention can then be tailored to the recurrence rate, with anticoagulation and possibly device closure reserved for those at highest risk of recurrence.

Toward understanding the atrial septum in cryptogenic stroke.

Ischemic stroke in younger people is common, and often remains unexplained. There is a well-documented association between unexplained stroke in younger people, and the presence of a patent foramen ovale. Therefore, in the absence of a clear cause of stroke, the heart is often assessed in detail for such lower risk causes of stroke. This usually involves imaging with a transesophageal echo, and investigation for a right-to-left shunt. An understanding of the anatomy of the atrial septum, and its associated abnormalities, is important for the stroke neurologist charged with decision making regarding appropriate secondary prevention. In this paper, we review the development and anatomy of the right heart with a focus on patent foramen ovale, and other associated abnormalities. We discuss how the heart can be imaged in the case of unexplained stroke, and provide examples. Finally, we suggest a method of investigation, in light of the recent European Association of Echocardiography guidance. Our aim is to provide the neurologist with an understanding on how the heart can be investigated in unexplained stroke, and the significance of abnormalities detected.

Etiologic investigation of ischemic stroke in young adults

# {#article-title-2} To the Editor: We read with interest the article by Larrue et al.1 We recently assessed the impact of newer stroke classification systems on stroke subtypes.2 We also agree with the conclusion regarding the contribution of atrial septal abnormalities to stroke in younger people. Despite the thorough cardiac investigation, Larrue et al. report a relatively low proportion of patients with unexplained stroke with patent foramen ovale (PFO). Of 160 cases investigated, 67 (41.2%) had a PFO (24 isolated, 43 with an atrial septal aneurysm [ASA]). In our institution, of those with …

219Use of Pre-Stroke Anticoagulation to Assess Changes in Anticoagulation Prescribing for Stroke Prevention in AF, since the Introduction of DOACs

Background: The prevalence of atrial fibrillation (AF) in ischaemic stroke is estimated at approximately 30%. Proportion of patients with ischaemic stroke and known AF who are prescribed anticoagulation is an accepted quality metric (NHS) for anticoagulation in the community. We aimed to quantify changes in the proportion of anticoagulated patients and those prescribed DOACs who presented with ischaemic stroke and previously known AF to our institution between 2013 and 2016. Methods: The National Stroke Register was used to identify all patients admitted to our institution between 2013–2016 with ischaemic stroke and AF. For each year, the proportion of patients on anticoagulation (overall) and DOACs was calculated. Primary endpoint was the change in proportion of patients prescribed anticoagulation prior to stroke. The secondary endpoint was proportion of ischaemic strokes attributable to AF. We performed a Chi Square test to assess statistical significance. Results: A total of 522 patients presented to our institution with ischaemic stroke, of which 22% were known to have AF. The proportion of patients anticoagulated increased from 50% in 2013 to 76% in 2016, (p = 0.043). The proportion of patients on DOACs increased from 8% to 58%, (p = 0.0069). There was a downward trend in proportion of ischaemic strokes attributable to AF (39% -2013, 37% -2014, 36% -2015 and 33% -2016) however this wasn’t significant (p = 0.84). Conclusion: The audit quantifies the paradigm shift in OAC prescribing since the introduction of DOACs which has led to an overall increase in the proportion of people with AF being anticoagulated. It may also be associated with a decrease in the proportion of ischaemic strokes attributable to AF which requires a larger sample to adequately test. In our opinion, the ease of anticoagulation with DOACs, along with the associated increased focus on stroke prevention with DOAC marketing have contributed.