Screening for atrial fibrillation to prevent stroke in elderly individuals with or without preexisting cardiovascular disease

Background

Previous research has showed that various cardiovascular diseases (CVD) are associated with increased risks of atrial fibrillation (AF) and stroke. However, data on the interaction between CVD and AF screening efficacy are lacking.

Purpose

To evaluate the influence of preexisting CVD on the effects of AF screening with long-term continuous monitoring.

Methods

The LOOP Study (Atrial Fibrillation detected by Continuous ECG Monitoring using Implantable Loop Recorder to prevent Stroke in High-risk Individuals) randomized AF-naïve individuals aged ≥70 years and with additional stroke risk factors to either long-term screening with implantable loop recorder (ILR) and subsequent anticoagulation initiation upon detection of AF episodes ≥6 minutes, or usual care (the control group). In the current study, all participants from the LOOP Study were divided into two risk groups according to the presence of CVD (defined as ischemic heart disease, heart failure, previous stroke, valvular heart disease, or peripheral artery disease). The relative risks of outcomes in groupwise comparisons, as indicated by hazard ratio (HR), were assessed in the cause-specific Cox proportional-hazards model with death as competing risk.

Results

Of 6004 participants included, 1997 (33.3%) had ≥1 CVD at baseline. Compared with no CVD, the presence of CVD was associated with increased risks of AF diagnosis in the ILR group (adjusted HR 1.32 [1.09–1.59]) and of stroke or systemic arterial embolism in the entire study cohort (adjusted HR 1.34 [1.06–1.69]). For ILR screening versus usual care, there was no decrease in stroke or systemic arterial embolism among participants with preexisting CVD (adjusted HR 1.13 [0.76–1.68]), whereas a significant risk reduction was obtained by screening among those without CVD (adjusted HR 0.64 [0.44–0.93]). The interaction was significant (adjusted p-value for interaction 0.041).

Conclusions

In an elderly, high-risk population, ILR screening did not prevent stroke significantly in individuals with preexisting CVD, but it was associated with an approximately 40% risk reduction among those without CVD.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The LOOP Study was funded by Innovation Fund Denmark [grant number 12-1352259], The Research Foundation for the Capital Region of Denmark, The Danish Heart Foundation [grant number 11-04-R83-A3363-22625], Aalborg University Talent Management Program, Arvid Nilssons Fond, Skibsreder Per Henriksen, R og Hustrus Fond, the European Union's Horizon 2020 program [grant number 847770], Læge Sophus Carl Emil Friis og hustru Olga Doris Friis' Legat, and an unrestricted grant from Medtronic.

Accidental diagnosis of bradyarrhythmia in patients monitored for atrial fibrillation

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): The study was supported by The Innovation Fund Denmark [12-135225], The Research Foundation for the Capital Region of Denmark [no grant number], The Danish Heart Foundation [11-04-R83-A3363-22625], Aalborg University Talent Management Programme [no grant number], Arvid Nilssons Fond [no grant number], Skibsreder Per Henriksen, R. og Hustrus Fond [no grant number], Medtronic [no grant number], and the AFFECT-EU consortium which has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 847770.

Background

The interest in heart rhythm monitoring and technologies to detect arrhythmia is increasing. The prevalence and prognostic significance of subclinical bradyarrhythmias is unknown.

Objectives

To assess the accidental diagnosis of bradyarrhythmia and its subsequent treatment and prognostic impact in persons screened for atrial fibrillation compared to unscreened persons.

Methods

We utilized a randomized trial of ≥70-year-olds with cardiovascular risk factors recruited outside the hospital setting to receive implantable loop recorder screening for atrial fibrillation (ILR group) vs. usual care (Control group). Time-to-event analyses were performed for bradyarrhythmia, pacemaker implantation, syncope, and sudden cardiovascular death.

Results

A total of 6004 participants were randomized (mean age 75 years, 47% women, 91% with hypertension, 20% with prior syncope), 4503 to Control and 1501 to ILR. The median follow-up period was 64.5 [59.3, 69.8] months. A total of 675 deaths occurred with an overall rate of 2.16 (2.00-2.33) per 100 person-years, and 67 sudden cardiovascular deaths occurred with a rate of 0.21 (0.15-0.28) for the Control group and 0.23 (0.14-0.37) for the ILR group (hazard ratio (HR) 1.11 (0.64-1.90), p=0.71)).

The overall rate of incident bradyarrhythmia was 1.63 (1.49-1.79) per 100 person-years, and bradyarrhythmia was diagnosed in 172 (3.82%) and 312 (20.8%) participants in the Control and ILR group, respectively (HR 6.21 (5.15-7.48), p<0.0001) (Figure 1). The most common bradyarrhythmia was sinus node dysfunction (SND) which was diagnosed in 68 participants in the Control group (1.51%) and 214 in the ILR group (14.26%). In the Control group, 57.35% of diagnoses of sinus node dysfunction resulted in pacemaker implantation, compared to 12.15% in the ILR group where the majority was treated conservatively (Figure 2). The second-most common type of bradyarrhythmia was high-grade atrioventricular block (AVB) which was diagnosed in 86 participants in the Control group (1.91%) and 54 in the ILR group (3.60%). In both groups, the majority of high-grade AVB was treated with pacemaker, although 29.63% in the ILR group were treated conservatively. Risk factors for bradyarrhythmia included higher age, male sex, and prior syncope.

Overall, a pacemaker was implanted in 132 (2.93%) and 66 (4.40%) participants (HR 1.53 (1.14-2.06), p<0.0001), syncope occurred in 120 (2.66%) and 33 (2.20%) participants (HR 0.83 (0.56-1.22), p=0.34), and sudden cardiovascular death occurred in 49 (1.09%) and 18 (1.20%) participants (HR 1.11 (0.64-1.90), p=0.71) in the Control and ILR group, respectively.

Conclusions

Bradyarrhythmias are highly common in ≥70-year-olds with cardiovascular risk factors. Compared to Control, ILR monitoring led to a six-fold increase in diagnosis of bradyarrhythmia and a significant increase in pacemaker implantations, but no change in the risk of syncope or sudden death.

Systolic blood pressure and effects of screening for atrial fibrillation with long-term continuous monitoring

Funding Acknowledgements

Type of funding sources: Other. Main funding source(s): The LOOP Study was supported by Innovation Fund Denmark [grant number 12-1352259], The Research Foundation for the Capital Region of Denmark, The Danish Heart Foundation [grant number 11-04-R83-A3363-22625], Aalborg University Talent Management Program, Arvid Nilssons Fond, Skibsreder Per Henriksen, R og Hustrus Fond, the European Union’s Horizon 2020 program [grant number 847770 to the AFFECT-EU consortium], Læge Sophus Carl Emil Friis og hustru Olga Doris Friis’ Legat, and an unrestricted grant from Medtronic.

Background

The recently published LOOP Study was a randomized controlled clinical trial to evaluate systematic atrial fibrillation (AF) screening with long-term continuous monitoring in an elderly population at risk and found no significant reduction in stroke. However, the screening effects seemed to differ across levels of systolic blood pressure (SBP). It is well-known that hypertension constitutes a prominent risk factor for clinical AF and stroke alike, but data on the impacts of SBP on subclinical AF and hereby AF screening efficacy are lacking.

Purpose

With this post hoc analysis of the LOOP Study, we aimed to provide insights into the interaction between SBP and benefits of systematic AF screening.

Methods

The LOOP Study randomized individuals aged 70-90 years with ≥1 stroke risk factor (hypertension, diabetes, heart failure, or previous stroke) and without prior AF to either monitoring with implantable loop recorder (ILR) and initiation of oral anticoagulation upon detection of new-onset AF episodes lasting ≥6 minutes, or usual care (control group). In total, 5997 participants with available SBP measurements at enrolment were included in the present analysis. The interaction between SBP and ILR screening efficacy on stroke or systemic arterial embolism (SAE), as indicated by hazard ratio (HR) for ILR versus control, was assessed with polynomial moving-average regression. The lowest SBP threshold with significant screening benefits was further determined and used to examine clinical outcomes and the occurrence of AF with respect to dichotomized SBP. Additionally, penalized spline models were employed to assess AF occurrence by SBP as a continuous variable.

Results

HR of stroke/SAE for ILR versus control decreased with increasing SBP and the lowest threshold for significant screening benefits was at SBP ≥150 mmHg. ILR screening of participants with SBP ≥150 mmHg yielded a 45% risk reduction of stroke/SAE (HR 0.55 [0.37-0.82]). Within the ILR group, SBP ≥150 mmHg was associated with an increased risk of AF episodes ≥24 hours as compared to lower SBP (HR 1.57 [1.01-2.45]), but not with the overall occurrence of AF (HR 1.14 [0.95-1.36]). No significant association between SBP and AF occurrence in the ILR group was reported in penalized spline models either (p-value: 0.73).

Conclusions

The benefits of ILR screening for AF on stroke/SAE increased with increasing blood pressure. SBP ≥150 mmHg was associated with a 1.5-fold increased risk of AF episodes ≥24 hours, along with an almost 50% risk reduction of stroke/SAE by ILR screening.

Left atrial remodeling and cerebrovascular disease assessed by magnetic resonance imaging in patients undergoing continuous heart rhythm monitoring

Background

Atrial remodeling and atrial fibrillation (AF) have both been associated with cerebrovascular lesions. We wished to investigate the possible direct association between atrial remodeling and cerebrovascular disease including white matter lesions and lacunar infarcts in patients with and without atrial fibrillation (AF) as documented by implantable loop recorder (ILR).

Methods

Cardiac and cerebral MRI scans were acquired in a cross-sectional study including participants ≥70 years of age with stroke risk factors (history of hypertension, diabetes mellitus, congestive heart failure and/or previous stroke) but without known AF. Cerebrovascular disease was visually rated using the Fazekas scale and number of lacunar strokes. Left atrial (LA) (see figure) and ventricular volumes and function were analyzed, and associations between atrial remodeling and cerebrovascular disease were assessed with logistic regression models. Multivariable models were adjusted for sex, age, diabetes, hypertension, heart failure and history of stroke/transient ischemic attack. The analyses were stratified according to sinus rhythm or any AF during three months of continuous ILR monitoring to account for subclinical AF.

Results

Of 200 participants investigated, 87% had a Fazekas score≥1 and 45% had ≥1 lacunar infarct. Within three months of ILR implantation, AF was detected in 28 (14%) participants, while 172 (86%) had sinus rhythm only. Results are summarized in table. For participants with sinus rhythm, lower LA passive emptying fraction was associated with Fazekas score after multivariable adjustment, while LA total emptying fraction was borderline significant, and increased LA maximum and minimum volumes were associated with lacunar infarcts. There were no significant associations in patients with AF.

Sensitivity analyses showed similar results with longer screening periods for AF.

Conclusions

In patients free from AF as documented by ILR monitoring, we found an independent association between LA passive emptying and Fazekas score, and between atrial volumes and lacunar infarcts. This supports that atrial remodeling alone without AF is associated with an increased risk of cerebrovascular lesions.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The Innovation Fund, DenmarkThe Research Foundation for the Capital Region of Denmark

Left atrial late gadolinium enhancement is associated with atrial fibrillation as detected by continuous monitoring

Background

Left atrial late gadolinium enhancement (LA LGE) measured with cardiac magnetic resonance (CMR) imaging is emerging as a marker of atrial fibrosis and has been associated with worse outcomes in AF ablation procedures. However, the prognostic value of LA LGE for incident AF remains unknown.

Methods

CMR including measurement of left ventricular (LV) and LA volumes and function, as well as LV extracellular volume fraction and LA LGE, was acquired in 68 patients aged at least 70 years with risk factors for stroke. All included patients received and implantable loop recorder and were continuously monitored for previously unknown AF. Incident AF was adjudicated by senior cardiologists.

Results

Patients were monitored for AF with implantable loop recorder during a median of 41 [36; 43] months. AF episodes lasting ≥6 minutes were detected in 32 patients (47%) and 16 patients (24%) experienced AF episodes lasting ≥5.5-hour. In Cox regression analyses adjusted for sex, age and comorbidities, we found that LA volumes and function and LA LGE were independently associated with incident AF. For LA LGE, the hazard ratio for time to AF episodes lasting ≥6 minutes and ≥5.5 hours were 1.40 (1.03, 1.89) per 10 cm2 increase (p=0.03) and 1.63 (1.11, 2.40) per 10 cm2 increase (p=0.01), respectively. LA LGE was significantly associated with high burden of AF. The addition of LA LGE to a multivariable risk prediction model for incident AF significantly increased the predictive value.

Conclusions

Extent of LA fibrosis measured by LA LGE was significantly associated with incident AF detected by implantable loop recorder.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): The Innovation Fund Denmark, The Research Foundation for the Capital Region of Denmark [no grant number]

Mechanical Thrombectomy with the Embolus Retriever with Interlinked Cages in Acute Ischemic Stroke: ERIC, the New Boy in the Class

BACKGROUND AND PURPOSE

The Embolus Retriever with Interlinked Cages (ERIC) device is a novel stent retriever for mechanical thrombectomy. It consists of interlinked cages and could improve procedural benchmarks and clinical outcome compared with classic stent retrievers. This study compares the rates of recanalization, favorable clinical outcome, procedural adverse events, and benchmarks between the ERIC device and classic stent retrievers.

MATERIALS AND METHODS

From 545 patients treated with thrombectomy between 2012 and 2015, 316 patients were included. The mean age was 69 ±13 years, the mean baseline NIHSS score was 17 ± 5, and 174 (55%) were men. The ERIC was used as the primary thrombectomy device in 59 (19%) patients. In a propensity score matched analysis including the NIHSS score, clot location, delay to groin puncture, neurointerventionalist, and anesthetic management, 57 matched pairs were identified.

RESULTS

Patients treated with the ERIC device compared with classic stent retrievers showed equal rates of recanalization (86% versus 81%, P = .61), equal favorable 3-month clinical outcome (mRS 0-2: 46% versus 40%, P = .71), and procedural adverse events (28% versus 30%, P = 1.00). However, in patients treated with the ERIC device, thrombectomy procedures were less time-consuming (67 versus 98 minutes, P = .009) and a rescue device was needed less often (18% versus 39%, P = .02) compared with classic stent retrievers.

CONCLUSIONS

Mechanical thrombectomy with the ERIC device is effective and safe. Rates of favorable procedural and clinical outcomes are at least as good as those with classic stent retrievers. Of note, the ERIC device might be time-saving and decrease the need for rescue devices. These promising results call for replication in larger prospective clinical trials.

Thrombolysis and thrombectomy in patients treated with dabigatran with acute ischemic stroke: Expert opinion

Systemic thrombolysis with rt-PA is contraindicated in patients with acute ischemic stroke anticoagulated with dabigatran. This expert opinion provides guidance on the use of the specific reversal agent idarucizumab followed by rt-PA and/or thrombectomy in patients with ischemic stroke pre-treated with dabigatran. The use of idarucizumab followed by rt-PA is covered by the label of both drugs.

Acute Cerebrovascular Disease in the Young

Background and Purpose—

Strokes have especially devastating implications if they occur early in life; however, only limited information exists on the characteristics of acute cerebrovascular disease in young adults. Although risk factors and manifestation of atherosclerosis are commonly associated with stroke in the elderly, recent data suggests different causes for stroke in the young. We initiated the prospective, multinational European study Stroke in Young Fabry Patients (sifap) to characterize a cohort of young stroke patients.

Methods—

Overall, 5023 patients aged 18 to 55 years with the diagnosis of ischemic stroke (3396), hemorrhagic stroke (271), transient ischemic attack (1071) were enrolled in 15 European countries and 47 centers between April 2007 and January 2010 undergoing a detailed, standardized, clinical, laboratory, and radiological protocol.

Results—

Median age in the overall cohort was 46 years. Definite Fabry disease was diagnosed in 0.5% (95% confidence interval, 0.4%–0.8%; n=27) of all patients; and probable Fabry disease in additional 18 patients. Males dominated the study population (2962/59%) whereas females outnumbered men (65.3%) among the youngest patients (18–24 years). About 80.5% of the patients had a first stroke. Silent infarcts on magnetic resonance imaging were seen in 20% of patients with a first-ever stroke, and in 11.4% of patients with transient ischemic attack and no history of a previous cerebrovascular event. The most common causes of ischemic stroke were large artery atherosclerosis (18.6%) and dissection (9.9%).

Conclusions—

Definite Fabry disease occurs in 0.5% and probable Fabry disease in further 0.4% of young stroke patients. Silent infarcts, white matter intensities, and classical risk factors were highly prevalent, emphasizing the need for new early preventive strategies.

Clinical Trial Registration Information—

URL: http://www.clinicaltrials.gov .Unique identifier: NCT00414583

Cooling for Acute Ischemic Brain Damage (COOL AID): a feasibility trial of endovascular cooling

OBJECTIVE

To report results of a randomized pilot clinical feasibility trial of endovascular cooling in patients with ischemic stroke.

METHODS

Forty patients with ischemic stroke presenting within 12 hours of symptom onset were enrolled in the study. An endovascular cooling device was inserted into the inferior vena cava of those randomized to hypothermia. A core body temperature of 33 degrees C was targeted for 24 hours. All patients underwent clinical assessment and MRI initially, at days 3 to 5 and days 30 to 37.

RESULTS

Eighteen patients were randomized to hypothermia and 22 to receive standard medical management. Thirteen patients reached target temperature in a mean of 77 +/- 44 minutes. Most tolerated hypothermia well. Clinical outcomes were similar in both groups. Mean diffusion-weighted imaging (DWI) lesion growth in the hypothermia group (n = 12) was 90.0 +/- 83.5% compared with 108.4 +/- 142.4% in the control group (n = 11) (NS). Mean DWI lesion growth in patients who cooled well (n = 8) was 72.9 +/- 95.2% (NS).

CONCLUSIONS

Induced moderate hypothermia is feasible using an endovascular cooling device in most patients with acute ischemic stroke. Further studies are needed to determine if hypothermia improves outcome.

An acute clinical trial evaluating the cardiovascular effects of an herbal ephedra-caffeine weight loss product in healthy overweight adults

OBJECTIVE

This study was undertaken to determine the acute effects of a commercial weight loss supplement containing herbal ephedrine and caffeine on cardiovascular function in healthy overweight adults.

DESIGN

Randomized double blind clinical trial evaluating the cardiovascular effects of an ephedra-caffeine (Xenadrine(TM); XEN) based herbal product vs placebo (PLA).

SUBJECTS

Twenty-seven healthy overweight adults (age 21-60 y; body mass index > or = 25 kg/m(2)).

MEASUREMENTS

Systolic and diastolic blood pressure, heart rate, serial electrocardiograms (EKG) and Doppler echocardiograms.

RESULTS

A comparison of means between the groups indicated no statistically significant differences at the start of the study for the variables above. There were no serious adverse events. When examining the effects of XEN vs PLA on cardiovascular health/function, there were no significant effects observed in heart rate, systolic blood pressure, diastolic blood pressure, left ventricular ejection fraction, heart valve function or in cardiovascular physiology within the parameters measured.

CONCLUSION

These findings indicate that, over a 14-day period, ingestion of the commercial weight loss supplement in a healthy overweight population did not produce any noticeable cardiovascular side effects.

Hypothermia after cardiac arrest: feasibility and safety of an external cooling protocol

BACKGROUND

No proven neuroprotective treatment exists for ischemic brain injury after cardiac arrest. Mild-to-moderate induced hypothermia (MIH) is effective in animal models.

METHODS AND RESULTS

A safety and feasibility trial was designed to evaluate mild-to-moderate induced hypothermia by use of external cooling blankets after cardiac arrest. Inclusion criteria were return of spontaneous circulation within 60 minutes of advanced cardiac life support, hypothermia initiated within 90 minutes, persistent coma, and lack of acute myocardial infarction or unstable dysrhythmia. Hypothermia to 33 degrees C was maintained for 24 hours followed by passive rewarming. Nine patients were prospectively enrolled. Mean time from advanced cardiac life support to return of spontaneous circulation was 11 minutes (range 3 to 30); advanced cardiac life support to initiation of hypothermia was 78 minutes (range 40 to 109); achieving 33 degrees C took 301 minutes (range 90 to 690). Three patients completely recovered, and 1 had partial neurological recovery. One patient developed unstable cardiac dysrhythmia. No other unexpected complications occurred.

CONCLUSIONS

Mild-to-moderate induced hypothermia after cardiac arrest is feasible and safe. However, external cooling is slow and imprecise. Efforts to speed the start of cooling and to improve the cooling process are needed.

Real-time intraoperative neurophysiological monitoring

We discuss the utilization of signal processing techniques during surgical procedures. These techniques are used to provide real-time monitoring of nervous system function. We describe the historical development of these techniques and the hardware and software that have been used to implement them.

Uncoupling and recoupling of autonomic regulation of the heart beat in pediatric septic shock

Healthy physiological systems exhibit marked signal variability and complexity, whereas diseased systems generally show a loss of variability, decreased complexity ("decomplexification"), and increased regularity. The goal of this study was to evaluate the uncoupling and recoupling phenomenon in children with septic shock by observing serial changes in heart rate variability metrics. Data were collected from 7 children with septic shock by using the computer system in the Complex Systems Laboratory at Oregon Health Sciences University. Heart rate time series were constructed and analyzed by using the Hales Research System at intervals of 6 h during pediatric intensive care unit (PICU) hospitalization. These power spectral values were then plotted vs. time. Six of seven patients showed an increase over time in low-frequency heart rate power and the low-/high-frequency ratio, whereas high-frequency heart rate power decreased. We also compared the change in mean heart rate, heart rate standard deviation, and power spectral values during the first 24 h of PICU hospitalization vs. the remainder of the PICU stay (for the 5 patients with a PICU length of stay > 48 h). Compared to the initial 24 h in the PICU, low-frequency power and the low-/high-frequency ratio increased, whereas high-frequency power decreased over the course of the illness. This report shows the potential value of monitoring the uncoupling and recoupling phenomenon in patients with septic shock. Our results are in agreement with other investigators who report evidence of decomplexification both in experimental models of sepsis and in clinical studies and provide direction for further work.

In vivo magnetic resonance imaging and surgical histopathology of intracardiac masses: distinct features of subacute thrombi

We evaluated intracardiac masses in vivo, in situ and histologically to determine tissue properties revealed by magnetic resonance (MR) imaging. In 15 consecutive patients scheduled for cardiotomy, the cardiac chambers were studied preoperatively with MR imaging and echocardiography. Visual examination of one or more chambers was performed during cardiotomy for mitral valve replacement, aneurysmectomy, atrial septal repair and atriotomy. Six thrombi (1 atrial appendage, 5 ventricular) and 2 atrial myxomas were removed and subjected to histological analysis. All masses were detected preoperatively by MR imaging. The smallest was a subacute 3-mm mural clot in the left ventricle and was undetected by transesophageal and transthoracic echocardiography. The 3 subacute clots had homogeneously low MR signals, did not enhance with gadolinium and exhibited magnetic susceptibility effects; histopathology confirmed these clots to be avascular and laden with dense iron deposition related to hemoglobin breakdown products. The 3 organized clots had intermediate and heterogeneous MR signals and multiple areas of gadolinium enhancement. The 2 myxomas had low MR signals and gadolinium enhancement in the core and septal attachment; these areas had dense neovascular channels. Subacute thrombi appear to have MR features that are distinct from organized thrombi and myxomas, and MR images of subacute thrombi contrast sharply with normal cardiac structures, enabling detection of thin mural clots that may be echographically occult. These findings may be of value, because a subacute clot may be more likely than an organized thrombus to give rise to an embolus.

Predictors of fatal brain edema in massive hemispheric ischemic stroke

BACKGROUND AND PURPOSE

Early identification of stroke patients at risk for fatal brain edema may be useful in selecting patients for aggressive interventions. Prior studies suggested that early nausea/vomiting and major hypodensity on baseline computed tomography (CT) were predictive of herniation.

METHODS

This study was a retrospective multicenter case-control study of patients with large middle cerebral artery (MCA) strokes admitted within 48 hours of symptom onset. Medical records, laboratory data, and CT scans were analyzed. Cases, defined as patients who died of massive brain swelling, were compared with all remaining patients as controls.

RESULTS

Two hundred one patients with large MCA strokes were identified: 94 (47%) died of brain swelling, 12 (6%) died of non-neurological causes, and 95 (47%) survived at day 30. Multivariable analysis, adjusted for age and clustered by center, identified the following predictors of fatal brain edema: history of hypertension (OR 3.0, 95% CI 1.2 to 7.6, P=0.02), history of heart failure (OR 2.1, 95% CI 1.5 to 3.0, P<0.001), elevated white blood cell count (OR 1.08 per 1000 white blood cells/microL, 95% CI 1.01 to 1.14, P=0.02), >50% MCA hypodensity (OR 6.3, 95% CI 3.5 to 11.6, P<0.001), and involvement of additional vascular territories (anterior cerebral artery, posterior cerebral artery, or anterior choroidal artery; OR 3.3, 95% CI 1.2 to 9.4, P=0.02). Initial level of consciousness, National Institutes of Health Stroke Scale score, early nausea/vomiting, and serum glucose were associated with neurological death in bivariable but not multivariable analyses.

CONCLUSIONS

Among patients with large MCA infarctions, an increased risk of fatal brain edema is associated with history of hypertension or heart failure, increased baseline white blood cell count, major early CT hypodensity involving >50% of the MCA territory, and involvement of additional vascular territories. These data confirm and expand on prior research with a broad-based patient population. The presence of these risk factors identifies those stroke patients who may require aggressive therapeutic approaches.

Cooling for acute ischemic brain damage (cool aid): an open pilot study of induced hypothermia in acute ischemic stroke

BACKGROUND AND PURPOSE

Hypothermia is effective in improving outcome in experimental models of brain infarction. We studied the feasibility and safety of hypothermia in patients with acute ischemic stroke treated with thrombolysis.

METHODS

An open study design was used. All patients presented with major ischemic stroke (National Institutes of Health Stroke Scale [NIHSS] score >15) within 6 hours of onset. After informed consent, patients with a persistent NIHSS score of >8 were treated with hypothermia to 32+/-1 degrees C for 12 to 72 hours depending on vessel patency. All patients were monitored in the neurocritical care unit for complications. A modified Rankin Scale was measured at 90 days and compared with concurrent controls.

RESULTS

Ten patients with a mean age of 71.1+/-14.3 years and an NIHSS score of 19.8+/-3.3 were treated with hypothermia. Nine patients served as concurrent controls. The mean time from symptom onset to thrombolysis was 3.1+/-1.4 hours and from symptom onset to initiation of hypothermia was 6.2+/-1.3 hours. The mean duration of hypothermia was 47.4+/-20.4 hours. Target temperature was achieved in 3.5+/-1.5 hours. Noncritical complications in hypothermia patients included bradycardia (n=5), ventricular ectopy (n=3), hypotension (n=3), melena (n=2), fever after rewarming (n=3), and infections (n=4). Four patients with chronic atrial fibrillation developed rapid ventricular rate, which was noncritical in 2 and critical in 2 patients. Three patients had myocardial infarctions without sequelae. There were 3 deaths in patients undergoing hypothermia. The mean modified Rankin Scale score at 3 months in hypothermia patients was 3.1+/-2.3.

CONCLUSION

Induced hypothermia appears feasible and safe in patients with acute ischemic stroke even after thrombolysis. Refinements of the cooling process, optimal target temperature, duration of therapy, and, most important, clinical efficacy, require further study.

A computed tomography score for assessment of mass effect in space-occupying cerebellar infarction

BACKGROUND AND PURPOSE

Patients with cerebellar infarction are threatened by infratentorial herniation and impaired circulation of cerebrospinal fluid if mass effect in posterior fossa develops. Clinical assessment is often impaired in patients with disturbances of consciousness. Therefore, computed tomography (CT) examination is essential in the diagnosis of complication and decision for operative treatment.

METHODS

Mass effect of cerebellar infarction was quantitatively assessed using a 3-item CT score: width of fourth ventricle, compression of quadrigeminal cistern, and width of lateral ventricle. Retest and interrater reliability was determined. Validity of assessment of mass effect was examined using 185 CT scans from a cerebellar infarction study, and the effect of operative treatment on CT score was determined.

RESULTS

The correlation coefficients for retest and interrater reliability were 0.94 and 0.75, respectively. The authors found a significant difference for the CT sum score and all CT items except "compression of the fourth ventricle" between patients with different levels of consciousness. Effect of operative treatment was documented by improvement of CT score.

CONCLUSIONS

The proposed CT score is of high interrater and retest reliability, supplements the clinical assessment of the patient, and is able to monitor the efficacy of decompressive treatment.

Masking of vertebral artery dissection by severe trauma to the cervical spine

STUDY DESIGN

A prospective case study was performed.

OBJECTIVES

To illustrate the association of cervical trauma with vertebral artery dissection, and to propose a diagnostic and therapeutic algorithm for suspected traumatic vertebral artery dissection.

SUMMARY OF BACKGROUND DATA

Vertebral artery dissection is a recognized but underdiagnosed complication of trauma to the cervical spine. Symptoms of spinal cord injury, however, may obscure those of vertebral artery dissection, presumably causing gross underdiagnosis of this complication.

METHODS

All patients with vertebral artery dissection admitted to the authors' facility between 1992 and 1997 were screened for cervical trauma.

RESULTS

This article presents four patients with severe trauma to the cervical spine, defined as luxation, subluxation, or fracture, in whom symptoms of vertebral artery dissection developed after a delay ranging from several hours to weeks. The traumatic vertebral artery dissection typically was located at the site of vertebral injury or cranial to it. One patient with fracture of the odontoid process survived symptom free without ischemic brain infarctions. Another patient survived with traumatic quadriplegia in addition to large cerebellar and posterior cerebral artery infarctions. Two patients died as a result of fulminant vertebrobasilar infarctions, both with only moderate impairment from the primary spinal cord injury.

CONCLUSIONS

Early signs of vertebral artery dissection include head and neck pain, often localized to the site of intimal disruption, which may be disguised by the signs of the spinal injury. Early Doppler ultrasound and duplex sonography as a noninvasive screening method should be performed for patients with severe trauma to the cervical spine. In cases of vertebral artery dissection, immediate anticoagulation should be initiated. Traumatologists should be aware of this complication in evaluating patients with severe trauma of the cervical spine, and also for a variety of forensic reasons.

Stent-assisted angioplasty of intracranial vertebrobasilar atherosclerosis: an initial experience

OBJECT

Patients with intracranial vertebrobasilar artery (VBA) atherosclerotic occlusive disease have few therapeutic options. Unfortunately, VBA transient ischemic attacks (TIAs) herald a lethal or devastating event within 5 years in 25 to 30% of patients. The authors report their initial experience with eight patients in whom medically refractory TIAs secondary to intracranial posterior circulation atherosclerotic occlusive lesions were treated with stent-assisted angioplasty.

METHODS

Eight patients (six men), ranging in age from 43 to 77 years, experienced signs and symptoms of VBA insufficiency despite combination therapy with warfarin and antiplatelet agents. Angiographic studies revealed severe distal vertebral (four patients), proximal basilar (one patient), or proximal and midbasilar stenoses (three patients). Aspirin and clopidogrel were administered for 3 days before primary angioplasty and stent placement, and this regimen was maintained by the patients on discharge. Patients underwent heparinization during the procedure and were given a bolus and 12-hour infusion of abciximab. A neurologist specializing in stroke evaluated all patients before and after the procedure. The VBAs in all patients were successfully revascularized with 7 to 28% residual stenosis. Six patients experienced no neurological complications. One patient died the evening of the procedure due to a massive subarachnoid hemorrhage. Two patients had groin hematomas, one developed congestive heart failure, and one had transient encephalopathy. All surviving patients are asymptomatic up to 8 months postoperatively.

CONCLUSIONS

Although primary intracranial VBA angioplasty with stent insertion is technically feasible, complications associated with the procedure can be life threatening. As experience is gained with this procedure, it may be offered routinely as an alternative therapy to patients with medically refractory posterior circulation occlusive disease that may develop into catastrophic VBA insufficiency.

Intracranial clot dissolution is associated with embolic signals on transcranial Doppler

Reperfusion of intracranial arteries can be detected by transcranial Doppler (TCD). The authors report microembolic signals (MES) on TCD as a sign of clot dissolution and recanalization. Microembolic signals were detected during routine diagnostic TCD examination performed in the emergency room in patients eligible for thrombolytic therapy. Microembolic signals were found at the site of M1 middle cerebral artery (MCA) high-grade stenosis or near-occlusion. Transcranial Doppler was performed before, during, and after thrombolytic therapy. Of 16 consecutive patients, 3 (19%) had MES on TCD. All three patients had a severe MCA syndrome at 2 hours after stroke onset scored using the National Institutes of Health Stroke Scale (NIHSS). In patient #1 (NIHSS 12), clusters of MES were detected distal to a high-grade M1 MCA stenosis preceding spontaneous clinical recovery by 2 minutes. Because of subsequent fluctuating clinical deficit, intraarterial thrombolysis was given with complete recovery. In patient #2 (NIHSS 20), TCD detected an M1 MCA near-occlusion. At 1.5 hours after intravenous tissue plasminogen activator, TCD showed minimal MCA flow signals followed by MES, increased velocities, and normal flow signals in just 2 minutes. She gradually recovered up to NIHSS 8 in 5 days. In patient #3 with NIHSS 22 and an M1 MCA near-occlusion, TCD detected MES 15 minutes after TPA bolus followed by MCA flow velocity improvement from 15 cm/sec to 30 cm/sec. The patient recovered completely by the end of tissue plasminogen activator infusion. The authors conclude that embolic signals detected by TCD at the site of arterial obstruction can indicate clot dissolution. Intracranial recanalization on TCD can be associated with MES and changes in flow waveform, pulsatility, and velocity if insonation is performed at the site of arterial obstruction.

Comparison of orthogonal search and canonical variate analysis for the identification of neurobiological systems

In this paper, we investigate two general methods of modeling and prediction which have been applied to neurobiological systems, the orthogonal search (OS) method and the canonical variate analysis (CVA) approach. In these methods, nonlinear autoregressive moving average with observed inputs (ARX) and state affine models are developed as one step predictors by minimizing the mean-squared-error. An unknown nonlinear time-invariant system is assumed to have the Markov property of finite order so that the one step predictors are finite dimensional. No special assumptions are made about model terms, model order or state dimensions. Three examples are presented. The first is a numerical example which demonstrates the differences between the two methods, while the last two examples are computer simulations for a bilinear system and the Lorenz attractor which can serve as a model for the EEG. These two methods produce comparable results in terms of minimizing the mean-square-error; however, the OS method produces an ARX model with fewer terms, while the CVA method produces a state model with fewer state dimensions.

Surgical and medical management of patients with massive cerebellar infarctions: results of the German-Austrian Cerebellar Infarction Study

Surgical intervention (ventricular drainage or decompressive craniotomy) may be necessary in patients with cerebellar infarction if mass effect develops. However, patient selection and timing of surgery remain controversial, and there are few data on clinical signs in the early course that are predictive for outcome. The clinical course and neuroradiological features of 84 patients (aged 22-78, mean 58.5 years) with massive cerebellar infarction confirmed by computed tomography were prospectively observed for 21 days after admission and at 3-month follow-up using a standardized protocol. Data were gathered from 1992 to 1996 in 17 centers. The patients were assigned to three treatment groups depending on the decision of the primary caretaker: 34 underwent craniotomy and evacuation, 14 received ventriculostomy, and 36 were treated medically. Treatment groups differed regarding the level of consciousness, signs of mass effect in computed tomography and signs of brainstem involvement. The overall risk for poor outcome depended on the level of consciousness after clinical deterioration (odds ratio = 2.8). Subgroup analysis of awake/drowsy or somnolent/stupor patients revealed no relationship to treatment. The vascular territory involved did not affect outcome. Surgical treatment for massive cerebellar infarctions was not found to be superior to medical treatment in awake/drowsy or somnolent/stupor patients. Half of all patients deteriorating to coma treated with ventricular drainage or decompressive craniotomy had a meaningful recovery. We were unable to compare surgical versus medical therapy in this subgroup due to lack of control group. This study supports the notion that the level of consciousness is the most powerful predictor of outcome, superior to any other clinical sign and treatment assignment. Deterioration of consciousness typically occurred between days 2 and 4, with a maximum on day 3.

Early clinical and radiological predictors of fatal brain swelling in ischemic stroke

BACKGROUND AND PURPOSE

Early identification of acute stroke patients at risk of fatal brain swelling is necessary to facilitate implementation of aggressive therapies. Initial clinical, laboratory, and CT characteristics that may be used as selection criteria were analyzed to determine predictors of herniation and neurological death.

METHODS

Data from the placebo arm of the Lubeluzole-International-9 trial were reviewed to identify patients with fatal brain edema. Early clinical, laboratory, and radiographic parameters were evaluated in a case-control design. Initial CT scans were analyzed for early ischemic abnormalities by 2 blinded investigators.

RESULTS

Twenty-three patients died from brain swelling, with minimum baseline National Institutes of Health Stroke Scale (NIHSS) scores of 20 (n=12; mean, 23.2+/-1.8) with left and 15 (n=11; mean, 17.6+/-2.2) with right hemispheric infarctions (P=0. 0001). A sample of 112 subjects with comparably severe strokes, but who did not die from brain swelling, was selected from the remaining population according to the same NIHSS scores. Among clinical and laboratory characteristics, nausea/vomiting within 24 hours after onset (odds ratio [OR], 5.1; 95% CI, 1.7 to 15.3; P=0.003) and 12-hour systolic blood pressure >/=180 mm Hg (OR, 4.2; 95% CI, 1.4 to 12.9; P=0.01) were independently associated with fatal brain swelling. Among radiographic factors, only hypodensity of >50% of the middle cerebral artery territory on initial CT scan was an independent predictor (OR, 6.1; 95% CI, 2.3 to 16.6; P=0.0004).

CONCLUSIONS

Patients with baseline NIHSS score >/=20 with left or >/=15 with right hemispheric infarctions within 6 hours of symptom onset who also have nausea/vomiting or >50% middle cerebral artery territory hypodensity are at high risk for developing fatal brain swelling.

Serum glucose level and diabetes predict tissue plasminogen activator-related intracerebral hemorrhage in acute ischemic stroke

BACKGROUND AND PURPOSE

Five pretreatment variables (P<0.1 univariate analysis), including serum glucose (>300 mg/dL), predicted symptomatic intracerebral hemorrhage (ICH) in the National Institute of Neurological Disorders and Stroke rtPA trial. We retrospectively studied stroke patients treated <3 hours from onset with intravenous rtPA at 2 institutions to evaluate the role of these variables in predicting ICH.

METHODS

Baseline characteristics, including 5 prespecified variables (age, baseline glucose, smoking status, National Institutes of Health Stroke Scale [NIHSS] score, and CT changes [>33% middle cerebral artery territory hypodensity]), were reviewed in 138 consecutive patients. Variables were evaluated by logistic regression as predictors of all hemorrhage (including hemorrhagic transformation) and symptomatic hemorrhage on follow-up CT scan. Variables significant at P<0.25 level were included in a multivariate analysis. Diabetes was substituted for glucose in a repeat analysis.

RESULTS

Symptomatic hemorrhage rate was 9% (13 of 138). Any hemorrhage rate was 30% (42 of 138). Baseline serum glucose (5.5-mmol/L increments) was the only independent predictor of both symptomatic hemorrhage [OR, 2.26 (CI, 1.05 to 4.83), P=0.03] and all hemorrhage [OR, 2.26 (CI, 1.07 to 4.69), P=0.04]. Serum glucose >11.1 mmol/L was associated with a 25% symptomatic hemorrhage rate. Baseline NIHSS (5-point increments) was an independent predictor of all hemorrhage only [OR, 12.42 (CI, 1.64 to 94.3), P=0.01]. Univariate analysis demonstrated a trend for nonsmoking as a predictor of all hemorrhage [OR, 0.45 (CI, 0.19 to 1. 08), P=0.07]. Diabetes was also an independent predictor of ICH when substituted for glucose in repeat analysis.

CONCLUSIONS

Serum glucose and diabetes were predictors of ICH in rtPA-treated patients. This novel association requires confirmation in a larger cohort.

Real time signal processing in the clinical setting

We routinely use a variety of real time signal acquisition, enhancement, and display techniques in the operating room to provide the surgeon with functional information. This enables reduction of surgical morbidity in cases which present a significant risk to the nervous system. Here we present regression based signal processing algorithms which produce considerable signal-to-noise-ratio enhancement with corresponding reduction in the time required to obtain an interpretable neurophysiological signal. We also present the approach we have applied to fault tolerance and distributed data display for our workstation cluster environment.

Hemicraniectomy for massive cerebral infarction: Evoked potentials as presurgical prognostic factors

In patients with massive hemispheric infarctions, mortality exceeds 80% with medical therapy alone. In certain conditions hemicraniectomy may result in meaningful survival. We studied presurgical clinical and electrophysiological parameters that may serve as prognostic factors to assess efficacy of decompressive surgery. We evaluated 26 consecutive patients with severe focal neurological deficit, deterioration of consciousness, and massive hemispheric infarction by cranial computerized tomography who underwent hemicraniectomy. Clinical examination included pupillary size and reaction, and determination of level of consciousness on an hourly basis. Median nerve somatosensory evoked potentials and brainstem auditory evoked potentials were obtained before and after hemicraniectomy. Outcome was assessed by using the Barthel Index. Clinical and evoked potential data were correlated with the outcome. Fisher's Exact Test was applied to establish statistical significance. With surgery 18 of 26 patients survived on an average intensive care treatment of 29.6 (+/-27.5) days. Barthel Index at discharge was 61.7 (+/-24.4) in survivors. Presurgical pupillary reaction, level of consciousness, and somatosensory evoked potentials were not found to correlate with outcome. In contrast, presurgical brainstem auditory evoked potentials showed a significant correlation with survival (P<.05). All patients with good outcomes (Barthel Index >/=60: n=12, 46.1%) had normal brainstem auditory evoked potentials before surgery. Clinical parameters did not reliably forecast prognosis in patients with massive cerebral infarction treated with hemicraniectomy.

Manganese augments nitric oxide synthesis in murine astrocytes: a new pathogenetic mechanism in manganism?

Since manganese (Mn2+) is known to be sequestered in glial cells, we investigated possible neurotoxic mechanisms involving astrocytes in vitro. Low concentrations of Mn2+ were toxic only in astrocyte-neuronal cocultures but not in pure astrocyte or neuronal cultures. As a possible mediator of manganese-derived neurotoxicity, we measured the production of nitric oxide in astrocytes. Manganese, but not other transition metals, dose dependently increased iNOS mRNA and protein levels and the release of nitric oxide in activated astrocytes. This effect was specific for astrocytes, since we observed no stimulation in microglial cells. The observations suggest that besides the known inhibition of mitochondrial function the neurotoxic effect of manganese in low concentrations might be mediated by the increased production of nitric oxide in astrocytes.

Intravenous tissue plasminogen activator for acute ischemic stroke: feasibility, safety, and efficacy in the first year of clinical practice

BACKGROUND AND PURPOSE

The feasibility, safety, and efficacy of intravenous tissue plasminogen activator (t-PA) for patients with acute ischemic stroke in clinical practice need to be assessed.

METHODS

We initiated a prospective open-label study at a university hospital and two community hospitals in Houston, Tex, immediately after the publication of the National Institute of Neurological Disorders and Stroke (NINDS) t-PA study. A total of 30 patients, age 32 to 90 years, were treated with 0.9 mg/kg of intravenous t-PA (maximum dose, 90 mg) within 3 hours of acute ischemic stroke between December 1995 and December 1996.

RESULTS

Six percent (6%) of all patients hospitalized with ischemic stroke received intravenous t-PA at the university hospital and 1.1% at the community hospitals. The rates of total, symptomatic, and fatal intracerebral hemorrhage were 10%, 7%, and 3%. Thirty-seven percent (37%) of patients recovered to fully independent function. The average time from stroke onset to emergency department arrival was 57 minutes; emergency department arrival to computed tomography scan 41 minutes; and computed tomography scan to administration of treatment 59 minutes.

CONCLUSIONS

When treatment guidelines are carefully followed in an urban hospital setting, intravenous t-PA for acute ischemic stroke is feasible and shows safety and efficacy comparable to the results of the NINDS study.