Francisco Klein

Newly Diagnosed Atrial Fibrillation after Acute Ischemic Stroke and Transient Ischemic Attack: Importance of Immediate and Prolonged Continuous Cardiac Monitoring

Atrial fibrillation (AF) is the major cause of cardioembolic stroke. It often remains occult when asymptomatic and paroxysmal. We hypothesized that the detection of AF after acute ischemic stroke (AIS) or transient ischemic attack (TIA) could be improved by using continuous cardiac monitoring (CCM) immediately after admission. We sought to determine the detection rate of AF by immediate in-hospital CCM after cryptogenic and noncryptogenic AIS or TIA in patients without a previous diagnosis of AF. We retrospectively studied a cohort of 155 patients with cryptogenic and noncryptogenic AIS or TIA without known AF. We compared the detection rates of newly diagnosed AF (NDAF) in patients admitted to areas with CCM and those never admitted to these areas. We developed a multiple logistic regression model for identifying predictors of NDAF. We characterized NDAF episodes and analyzed how the availability of CCM data changed secondary prevention strategies. We detected NDAF in 21 patients (13.5%). Diagnostic rates of NDAF in patients who underwent CCM and those who did not undergo CCM were 18.2% and 2.2%, respectively (P = .005). The median time from admission to recognition of NDAF was 2.0 days. Most NDAFs were paroxysmal (95.2%) and lasted less than 1 hour (85.7%). Diabetes mellitus and infarct size were predictors of NDAF. Detection of NDAF prompted the initiation of anticoagulation therapy in 8.2% of the patients admitted to areas with CCM availability. Our findings suggest that immediate and prolonged CCM significantly improves the detection of NDAF after cryptogenic and noncryptogenic AIS or TIA, and that diabetes mellitus and infarct size are significantly associated with NDAF.

Feeling, learning from and being aware of inner states: interoceptive dimensions in neurodegeneration and stroke

Interoception is a complex process encompassing multiple dimensions, such as accuracy, learning and awareness. Here, we examined whether each of those dimensions relies on specialized neural regions distributed throughout the vast interoceptive network. To this end, we obtained relevant measures of cardiac interoception in healthy subjects and patients offering contrastive lesion models of neurodegeneration and focal brain damage: behavioural variant fronto-temporal dementia (bvFTD), Alzheimers disease (AD) and fronto-insular stroke. Neural correlates of the three dimensions were examined through structural and functional resting-state imaging, and online measurements of the heart-evoked potential (HEP). The three patient groups presented deficits in interoceptive accuracy, associated with insular damage, connectivity alterations and abnormal HEP modulations. Interoceptive learning was differentially impaired in AD patients, evidencing a key role of memory networks in this skill. Interoceptive awareness results showed that bvFTD and AD patients overestimated their performance; this pattern was related to abnormalities in anterior regions and associated networks sub-serving metacognitive processes, and probably linked to well-established insight deficits in dementia. Our findings indicate how damage to specific hubs in a broad fronto-temporo-insular network differentially compromises interoceptive dimensions, and how such disturbances affect widespread connections beyond those critical hubs. This is the first study in which a multiple lesion model reveals fine-grained alterations of body sensing, offering new theoretical insights into neuroanatomical foundations of interoceptive dimensions. This article is part of the themed issue ‘Interoception beyond homeostasis: affect, cognition and mental health’.

Atrial Fibrillation Detected after Acute Ischemic Stroke: Evidence Supporting the Neurogenic Hypothesis

BACKGROUND It is unknown whether atrial fibrillation (AF) detected after acute ischemic stroke is caused by neurogenic or cardiogenic mechanisms. Based on the potential damage to the autonomic nervous system, neurogenic mechanisms could be implicated in the pathophysiology of newly diagnosed AF. To test this hypothesis, we developed a mechanistic approach by comparing a prespecified set of indicators in acute ischemic stroke patients with newly diagnosed AF, known AF, and sinus rhythm. METHODS We prospectively assessed every acute ischemic stroke patient undergoing continuous electrocardiographic monitoring from 2008 through 2011. We compared newly diagnosed AF, known AF, and sinus rhythm patients by using 20 indicators grouped in 4 domains: vascular risk factors, underlying cardiac disease, burden of neurological injury, and in-hospital outcome. RESULTS We studied 275 acute ischemic stroke patients, 23 with newly diagnosed AF, 64 with known AF, and 188 with sinus rhythm. Patients with newly diagnosed AF had a lower proportion of left atrial enlargement (60.9% versus 91.2%, P=.001), a smaller left atrial area (22.0 versus 26.0 cm2, P=.021), and a higher frequency of insular involvement (30.4% versus 9.5%, P=.017) than participants with known AF. Compared with patients in sinus rhythm, those with newly diagnosed AF had a higher proportion of brain infarcts of 15 mm or more (60.9% versus 37.2%, P=.029) and a higher frequency of insular involvement (30.4% versus 7.3%, P<.001). CONCLUSIONS The low frequency of underlying cardiac disease and the strikingly high proportion of concurrent strategic insular infarctions in patients with newly diagnosed AF provide additional evidence supporting the role of neurogenic mechanisms in a subset of AF detected after acute ischemic stroke.

Improvement in executive function after unilateral carotid artery stenting for severe asymptomatic stenosis

OBJECT Executive functions are crucial for organizing and integrating cognitive processes. While some studies have assessed the effect of carotid artery stenting (CAS) on cognitive functioning, results have been conflicting. The object of this study was to assess the effect of CAS on cognitive status, with special interest on executive functions, among patients with severe asymptomatic internal carotid artery (ICA) stenosis. METHODS The authors prospectively assessed the neuropsychological status of 20 patients with unilateral asymptomatic extracranial ICA stenosis of 60% or more by using a comprehensive assessment battery focused on executive functions before and after CAS. Individual raw scores on neuropsychological tests were converted into z scores by normalizing for age, sex, and years of education. The authors compared baseline and 3-month postoperative neuropsychological scores by using Wilcoxon signed-rank tests. RESULTS The mean preoperative cognitive performance was within normal ranges on all variables. All patients underwent a successful CAS procedure. Executive function scores improved after CAS, relative to baseline performance as follows: set shifting (Trail-Making Test Part B: -0.75 ± 1.43 vs -1.2 ± 1.48, p = 0.003) and processing speed (digit symbol coding: -0.66 ± 0.85 vs -0.97 ± 0.82, p = 0.035; and symbol search: -0.24 ± 1.32 vs -0.56 ± 0.77, p = 0.049). The benefit of CAS for working memory was marginally significant (digit span backward: -0.41 ± 0.61 vs -0.58 ± 0.76, p = 0.052). Both verbal (immediate Rey Auditory Verbal Learning Test: 0.35 ± 1.04 vs -0.22 ± 0.82, p = 0.011) and visual (delayed Rey-Osterrieth Complex Figure: 0.27 ± 1.26 vs -0.22 ± 1.01, p = 0.024) memory improved after CAS. CONCLUSIONS The authors found a beneficial effect on executive function and memory 3 months after CAS among their prospective cohort of consecutive patients with unilateral and asymptomatic ICA stenosis of 60% or more.

Newly diagnosed atrial fibrillation linked to wake-up stroke and TIA: Hypothetical implications

Background: Based on the higher frequency of paroxysmal atrial fibrillation during night and early morning hours, we sought to analyze the association between newly diagnosed atrial fibrillation and wake-up ischemic cerebrovascular events. Methods: We prospectively assessed every acute ischemic stroke and TIA patient admitted to our hospital between 2008 and 2011. We used a forward step-by-step multiple logistic regression analysis to assess the relationship between newly diagnosed atrial fibrillation and wake-up ischemic stroke or TIA, after adjusting for significant covariates. Results: The study population comprised 356 patients, 274 (77.0%) with a diagnosis of acute ischemic stroke and 82 (23.0%) with TIA. A total of 41 (11.5%) of these events occurred during night sleep. A newly diagnosed atrial fibrillation was detected in 27 patients of 272 without known atrial fibrillation (9.9%). We found an independent association between newly diagnosed atrial fibrillation and wake-up ischemic stroke and TIA (odds ratio 3.6, 95% confidence interval 1.2–7.7, p = 0.019). Conclusions: The odds of detecting a newly diagnosed atrial fibrillation were 3-fold higher among wake-up cerebrovascular events than among non–wake-up events. The significance of this independent association between newly diagnosed atrial fibrillation and wake-up ischemic stroke and TIA and the role of other comorbidities should be investigated in future studies.

Intraoperative hypotension, new onset atrial fibrillation, and adverse outcome after carotid endarterectomy

BACKGROUND Information regarding predisposing factors, frequency, and prognostic implications of new onset atrial fibrillation (NOAF) after carotid endarterectomy (CEA) is scarce. We assessed the frequency, risk factors, and the prognostic impact of NOAF after CEA. METHODS We assessed every patient undergoing CEA (n = 186) at our academic hospital between 2006 and 2009. Patients underwent continuous electrocardiographic monitoring during surgery and during the rest of hospital stay. We performed univariate and multivariate analyses for identifying variables associated with NOAF and for individualizing variables related to four perioperative adverse outcome measures: a) ischemic stroke; b) ischemic stroke and myocardial infarction, c) ischemic stroke and death, and d) ischemic stroke, myocardial infarction, and death. RESULTS The study cohort comprised 186 patients. Overall, NOAF was detected in 7 cases (3.8%). The only variable associated with NOAF was intraoperative hypotension (OR 9.6, 95% CI 1.9-47.4, P = .006). There were no perioperative deaths. NOAF was associated with perioperative ischemic stroke and with the combined outcome of ischemic stroke and myocardial infarction. CONCLUSIONS We found a low frequency of NOAF after CEA. Intraoperative hypotension was associated to a higher risk of NOAF. In turn, NOAF was related to adverse postoperative outcome. Further research is needed to clarify the pathophysiological relation between intraoperative hypotension, NOAF, and adverse CEA outcome.

Status and perspectives of liver transplantation in Argentina.

The first liver transplantation (LTx) was performed in Argentina in 1988, and through September 2005, a total of 1896 liver transplants have been performed. During the past 10 years there has been a significant increase in the number of patients listed for LTx. There are (to May, 2005), 15 authorized centers for LTx (7 of them in Buenos Aires). The rise in organ demands are far beyond the supply, resulting in longer waiting periods and higher mortality rates on the waitlists (Table 1). Organ donor shortage represents a major obstacle to LTx development in Argentina, with a current rate of 10.76 organ donors pmp (per million population), far below the Spanish or US figures (34.6 pmp and 24.34 pmp, respectively) and the mean European rate (18 pmp). Although there was a decrease in LTx that followed a national economic crisis in 2001, economic recovery has been associated with increasing numbers of LTxs. In 2004, the Argentinian LTx figures rose to a historical peak of 660 LTx per million inhabitants, which still compares rather modestly with the rates reported by Spain or the United States (Spain: 24.1 pmp; United States: 21.04 pmp). Although the majority of LTxs are from cadaveric donors, the imbalance between the organ donation and procurement rates and the increasing size of the waiting lists has led to a rise in the proportion of living donor transplantations (LDTx). During the 2000 to 2004 period LDTx represented 25% to 53% of the total procedures performed. Argentina has a Transplant Law that regulates and defines brain death criteria, informed consent procedures, organ allocation, and living donor restrictions and that emphasizes the lack of economic benefits from organ donation. A central national administration

Stroke Severity Score based on Six Signs and Symptoms The 6S Score: A Simple Tool for Assessing Stroke Severity and In-hospital Mortality.

Background and Purpose Ascertaining stroke severity and predicting risk of in-hospital mortality is crucial to advise patients and families about medical decisions. We developed and tested the validity of a new stroke score, the 6S Score (Stroke Severity Score based on Six Signs and Symptoms), for quantifying ischemic stroke severity and predicting in-hospital mortality. Methods We prospectively assessed 210 consecutive acute ischemic stroke patients. The cohort was further divided into a derivation (n=120) and a validation (n=90) sample. From a total of 10 stroke signs and symptoms, we selected those with likelihood ratios P<0.005. We tested the validity of the score for predicting in-hospital mortality by using receiver operating characteristic curves. We used a scatterplot and the Spearmans test to evaluate the correlation between the 6S Score and the National Institutes of Health Stroke Scale as a marker of stroke severity. We used principal component and exploratory factor analyses for assessing qualitative aspects of the 6S Score. Results The C statistic for in-hospital mortality was 0.82 for the 6S Score and 0.86 for the National Institutes of health Stroke Scale, respectively, with no significant differences between each other (P=0.79). The correlation between both scores was strong (Spearmans rho 0.68, P<0.001). The factor analyses showed a good balance between left/right hemispheres and anterior/posterior circulations. Conclusions The 6S Score may constitute a tool for easily assessing stroke severity and predicting stroke mortality. Further research is needed for further assessing its external validity.

Presumed perinatal ischemic stroke. A review

The risk of stroke is actually highest during the perinatal period. However, some newborn infants may have no signs indicative of the need of brain imaging, or brain images taken may not be sensitive enough to diagnose ischemic injuries; so, the diagnosis of stroke may be delayed several months or years. The neurological picture in patients with perinatal stroke detected through neuroimaging months or years after the neonatal period is called presumed perinatal ischemic stroke. Although a presumed perinatal ischemic stroke is just a confirmation of the existence of an important level of underdiagnosis in relation to perinatal stroke, establishing the extent of this condition has allowed to improve knowledge on perinatal ischemic vascular disease.