Cryptogenic stroke: time to determine aetiology

Translational molecular imaging: Thrombosis imaging with positron emission tomography

A key focus of cardiovascular medicine is the detection, treatment, and prevention of disease, with a move towards more personalized and patient-centred treatments. To achieve this goal, novel imaging approaches that allow for early and accurate detection of disease and risk stratification are needed. At present, the diagnosis, monitoring, and prognostication of thrombotic cardiovascular diseases are based on imaging techniques that measure changes in structural anatomy and biological function. Molecular imaging is emerging as a new tool for the non-invasive detection of biological processes, such as thrombosis, that can improve identification of these events above and beyond current imaging modalities. At the forefront of these evolving techniques is the use of high-sensitivity radiotracers in conjunction with positron emission tomography imaging that could revolutionise current diagnostic paradigms by improving our understanding of the role and origin of thrombosis in a range of cardiovascular diseases.

Recurrent Multifocal Embolic Strokes in a 50-Year-Old Male: Unmasking Occult Squamous Cell Carcinoma

Recurrent cryptogenic embolic strokes pose a diagnostic challenge, often necessitating an extensive evaluation to determine the underlying cause. Cancer-related stroke is a frequently overlooked etiology, accounting for a substantial proportion of cryptogenic strokes. This case study underscores the importance of considering occult malignancies in patients with recurrent strokes of unknown origin and emphasizes the need for a comprehensive diagnostic workup to detect hidden malignancies. A 50-year-old male with a complex medical history presented with expressive aphasia and blurred vision resembling previous stroke episodes. Neurological examinations revealed right hemianopsia, paraphasia, and abnormal coordination. Neuroimaging studies showed multiple chronic infarctions, a large hemorrhagic infarction in the left posterior cerebral artery territory, and a small acute-to-subacute left parietal infarction. Due to the time of presentation and the presence of hemorrhagic transformation, the patient did not meet the criteria for intravenous tissue plasminogen activator administration. Given the recurrent nature of the strokes, an extensive evaluation was initiated to determine the underlying cause. Vascular imaging, including magnetic resonance angiography (MRA) of the head and neck and a CT angiogram, showed no significant stenosis. Vasculitis workup and cardiac evaluation yielded negative results. The blood workup was notable for elevated D-dimer levels. The involvement of multiple vascular territories and recurrent stroke despite adequate treatment and the absence of traditional risk factors for stroke raised a high clinical suspicion of occult malignancy. Further investigations led to the diagnosis of locally advanced squamous cell carcinoma (P16+), metastatic to the right neck lymph nodes (cTxN3M0). Although the primary source of cancer could not be identified, the P16+ status suggests the right tonsil or base of the tongue as the probable origin. Anticoagulation therapy was initiated, and the patient was scheduled for chemoradiation therapy. Although routine cancer investigation is not justified in ischemic strokes, the possibility of an occult malignancy should be considered in the presence of multifocal infarctions across different vascular territories with elevated D-dimer levels, particularly when traditional risk factors have been ruled out. A detailed physical exam can help localize the malignancy and early identification of occult malignancies can guide appropriate management strategies and help prevent future strokes. Further clinical trials are needed to establish optimal therapeutic approaches for preventing stroke recurrence in cancer-related strokes.

Clinical and echocardiographic outcomes after percutaneous closure of patent foramen ovale: a single center experience

BACKGROUND

Patent foramen ovale (PFO) has a high estimated prevalence (25% of the general population) and has been implicated in the pathogenesis of cryptogenic stroke and transient ischemic attack (TIA), as well as in the pathogenesis of migraine headache. This study evaluated the effectiveness of percutaneous transcatheter PFO closure with Amplatzer™ (Abbott Laboratories, Abbott Park, IL, USA) devices, from a large single-center experience.

METHODS

From January 1998 to December 2014, 577 patients (243 males and 334 females, mean age 50 years, range 11-82 years) with documented PFO and history of at least one episode of cryptogenic stroke/TIA (N.=356) or occasional finding of previous ischemic lesions on MRI (N.=221) underwent percutaneous transcatheter closure of PFO using an Amplatzer™ Occluder (Abbott Laboratories). All the procedures were performed under general anesthesia or mild sedation and were assisted by transesophageal or intracardiac echocardiography.

RESULTS

Procedural success was 100%. After a median follow-up period of 2.7 years with echocardiographic evaluations, the rate of recurrent adverse cerebral events was 0.4%. Two patients (0.4%) required a secondary procedure for significant residual shunt. Of 36 patients with minor residual shunt, 30 (83%) showed spontaneous shunt regression at follow-up. There was a consistent decrease after procedure in headache migraine, platypnea-orthodeoxia, fainting episodes, syncope, and coenesthesia phenomena.

CONCLUSIONS

Transcatheter PFO closure is an effective and safe therapy for the prevention of thromboembolic events in the patients with cryptogenic stroke/TIA or an occasional finding of a positive cerebral MRI. Late follow-up shows device stability and clinical improvement in the majority of patients.

Impact of D-dimer for pathologic differentiation on transesophageal echocardiography in embolic stroke of undetermined source: a single-center experience

Background

Embolic stroke of undetermined source (ESUS) encompasses diverse embologenic mechanisms, which transesophageal echocardiography (TEE) is critical to detect. Specific markers related to each embolic source in ESUS is not fully studied. We focused on D-dimer levels, and explored the association of D-dimer with potential embolic sources (PES) identified on TEE in ESUS.

Methods

Consecutive patients with ESUS were included in this study. Clinical characteristics including D-dimer levels were compared between ESUS patients with and without TEE, and among none of, one, and at least two PES in ESUS patients undergoing TEE. Factors related to elevation of D-dimer were analyzed.

Results

A total of 211 patients (age, 69.3 ± 13.2 years; 149 males) with ESUS were enrolled. Of these, 115 received TEE, displaying significantly younger age and lower D-dimer levels than patients without TEE (P < 0.05), and 20 (17%), 61 (53%), and 34 (30%) patients were classified into none of, one, and ≥ two PES, respectively. On multiple logistic regression analysis, D-dimer levels were related to one PES (odds ratio [OR]: 9.01; 95% confidence interval [CI]: 1.00–81.51; P = 0.050) and PES ≥ two (OR: 9.76; 95% CI: 1.07–88.97; P = 0.043). Right-to-left shunt (RLS) with deep venous thrombosis (DVT)(OR: 13.94; 95% CI: 1.77–109.99; P = 0.012) and without DVT (OR: 3.90; 95% CI: 1.20–12.70; P = 0.024) were associated with elevation of D-dimer.

Conclusions

D-dimer levels were higher in patients with PES. Among PES, RLS, with and without DVT, were associated with increase of D-dimer in ESUS.

Effect of ASA on the risk of cerebrovascular ischemic events in patients with PFO

Background

Whether atrial septal aneurysm (ASA) increases the risk of cerebrovascular ischemic events in patients with patent foramen ovale (PFO) remains controversial.

Objective

We constructed a detailed meta‐analysis to assess the effect of ASA on risk of cerebrovascular ischemic events in patients with PFO.

Methods

Randomized controlled trials (RCTs) and observational studies (cohort studies and case‐control studies) that compared PFO‐ASA against PFO alone were included. Pooled odds ratios (OR) estimates and 95% CI were calculated using the fixed‐effect and random‐effect models.

Results

Four RCTs and twelve observational studies (five cohort studies and seven case‐control studies) contributed to the meta‐analysis. The pooled results of case‐control studies showed that ASA increased the risk of cerebrovascular ischemic events in patients with PFO (fixed‐effect model: OR = 3.69; 95% CI: 2.67–5.09; p < 0.01, random‐effect model: OR = 3.63; 95% CI: 2.51–5.24; p < 0.01). However, poole results from RCTs (fixed‐effect model: OR = 1.24; 95% CI: 0.78–1.95; p = 0.36, random‐effect model: OR = 1.27; 95% CI: 0.78–2.08; p = 0.34) and cohort studies (fixed‐effect model: OR = 1.35; 95% CI: 0.81–2.23; p = 0.25, random‐effect model: OR = 1.40; 95% CI: 0.84–2.33; p = 0.20) found no evidence. Overall analysis showed that ASA increased the risk of cerebrovascular ischemic events (fixed‐effect model: OR = 2.30; 95% CI: 1.84–2.87; p < 0.01, random‐effect model: OR = 2.11; 95% CI: 1.48–3.01; p < 0.01). The sensitivity analysis confirmed the stability of all results.

Conclusions

Although case‐control studies support ASA to increase the risk of cerebrovascular ischemic events in patients with PFO, RCTs and cohort studies challenged the credibility. Further prospective studies are needed to confirm the effect of ASA on patients with PFO.

Efficacy of mechanical thrombectomy in stroke patients with large vessel involvement

Ischemic stroke is a common disease worldwide and leads to a significant rate of mortality and disability in patients every year, and imposes high costs on the health care system. The aim of this study was to evaluate the efficacy of the invasive method of mechanical thrombectomy for rapid intervention in ischemic stroke patients with large vessel involvement. Patients suspected of having a stroke, who were referred to Imam Hossein Hospital, were examined, and the diagnosis of stroke was confirmed. In the next stage, patients' MRS index was measured and the possibility of emergency thrombectomy was evaluated in patients. Patients who underwent thrombectomy were considered as the case group and the other patients were contemplated as the control group; then, the cases of the two groups were evaluated and compared. The mean age of patients was 66.63 ± 12.26 years. the use of emergency thrombectomy in the study group significantly reduced the MRS index of patients after 90 days (p <0.001), while a significant increase in the mean scores of the MRS index was seen in patients receiving pharmacological treatments. Also, there was no significant difference in terms of gender between the group of patients undergoing thrombectomy and the group receiving other treatments (p = 0.375). Emergency mechanical thrombectomy significantly reduces disability in stroke patients in the long term and can be a good alternative to conventional drug treatments..

Atrial cardiomyopathy in patients with ischaemic stroke: a cross-sectional and prospective cohort study-the COAST study

INTRODUCTION

Despite workup for the aetiology of ischaemic stroke, about 25% of cases remain unexplained. Paroxysmal atrial fibrillation is typically suspected but often not detected. Even if atrial fibrillation (AF) is detected, the quantitative threshold of clinically relevant AF remains unclear. Emerging evidence suggests that left atrial (LA) functional and structural abnormalities may convey a risk of ischaemic stroke in which AF is only one of several features. These abnormalities have been termed 'atrial cardiomyopathy'. This study uses cardiac magnetic resonance (CMR) to evaluate atrial cardiomyopathy among patients with stroke of undetermined aetiology compared with those with an attributable mechanism and controls without established cardiovascular disease.

METHODS AND ANALYSIS

This cross-sectional and prospective cohort study included 100 patients with recent ischaemic stroke and 50 controls with no established cardiovascular disease. The study will assess LA structural and functional abnormalities with CMR. Inclusion began in March 2019, and follow-up is planned to be complete in January 2023. There are two scheduled follow-ups: (1) 18 months after individual inclusion, counting from the index diagnostic MRI of the brain, (2) end of study follow-up at 18 months after inclusion of the last patient, assessing the incidence of recurrent ischaemic stroke, AF and cardiovascular death. The primary endpoint is the extent of CMR-assessed atrial fibrosis in the LA at baseline. The study is powered to detect a difference of 6% fibrosis between stroke of undetermined aetiology and stroke of known mechanism with a SD of 9%, a significance level of 0.05, and power of 80%.

ETHICS AND DISSEMINATION

This study has been approved by the Danish National Committee on Health Research Ethics (H-18055313). All participants in the study signed informed consent. Results from the study will be published in peer-reviewed journals regardless of the outcome.

TRIAL REGISTRATION NUMBER

NCT03830983.

Investigation of Aortic Wall Thickness, Stiffness and Flow Reversal in Patients With Cryptogenic Stroke: A 4D Flow MRI Study

BACKGROUND

Stroke etiology is undetermined in approximately one-sixth to one-third of patients. The presence of aortic flow reversal and plaques in the descending aorta (DAo) has been identified as a potential retrograde embolic mechanism.

PURPOSE

To assess the relationships between aortic stiffness, wall thickness, and flow reversal in patients with cryptogenic stroke and healthy controls.

STUDY TYPE

Prospective.

POPULATION

Twenty one patients with cryptogenic stroke and proven DAo plaques (69 ± 9 years, 43% female), 18 age-matched controls (age: 65 ± 8 years, 61% female), and 14 younger controls (36 ± 9 years, 57% female).

FIELD STRENGTH/SEQUENCE

1.5T; 4D flow MRI and 3D dark blood T1 -weighted turbo spin echo MRI of the aorta.

ASSESSMENT

Noncontrast aortic 4D flow MRI to measure 3D flow dynamics and 3D dark blood aortic wall MRI to assess wall thickness. 4D flow MRI analysis included automated quantification of aortic stiffness by pulse wave velocity (PWV) and voxelwise mapping of the flow reversal fraction (FRF).

STATISTICAL TESTS

Analysis of variance (ANOVA) or Kruskal-Wallis tests, Student's unpaired t-tests or Wilcoxon rank-sum tests, regression analysis.

RESULTS

Aortic PWV and FRF were statistically higher in patients (8.9 ± 1.7 m/s, 18.4 ± 7.7%) than younger controls (5.3 ± 0.8 m/s, P < 0.0167; 8.5 ± 2.9%, P < 0.0167), but not age-matched controls (8.2 ± 1.6 m/s, P = 0.22; 15.6 ± 5.8%, P = 0.22). Maximum aortic wall thickness was higher in patients (3.1 ± 0.7 mm) than younger controls (2.2 ± 0.2 mm, P < 0.0167) and age-matched controls (2.7 ± 0.5 mm) (P < 0.0167). For all subjects, positive relationships were found between PWV and age (R2 = 0.71, P < 0.05), aortic wall thickness (R2 = 0.20, P < 0.05), and FRF (R2 = 0.47, P < 0.05). Patients demonstrated relationships between PWV and FRF in the ascending aorta (R2 = 0.32, P < 0.05) and arch (R2 = 0.24, P < 0.05).

DATA CONCLUSION

This study showed the utility of 4D flow MRI for evaluating aortic PWV and voxelwise flow reversal. Positive relationships between aortic PWV, wall thickness, and flow reversal support the hypothesis that aortic stiffness is involved in this retrograde embolic mechanism.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 1.

A case of multifocal stroke-the first presentation of underlying ovarian malignancy

Ischaemic stroke is a rare manifestation of hypercoagulability induced by underlying malignancy. It is proposed that paraneoplastic non-bacterial thrombotic endocarditis (NBTE) is the most common cause, predisposing to the formation of friable valvular lesions composed of platelets and fibrin that embolize commonly. Pancreas, gallbladder, stomach, colon and gynaecological malignancies have all been associated with NBTE. We describe a female patient who presented to our facility with syncope and limb weakness. Magnetic resonance imaging of the brain revealed ischaemic strokes in both the anterior and posterior circulation. Further investigation revealed a pelvic mass that was biopsy proven to be ovarian malignancy. Prognosis is heavily reliant on disease stage, thus diagnostic clues suggesting the possibility of underlying malignancy in the presentation of stroke should prompt a thorough investigation to exclude malignancy.

Trends in prevalence of acute stroke impairments: A population-based cohort study using the South London Stroke Register

BACKGROUND

Acute stroke impairments often result in poor long-term outcome for stroke survivors. The aim of this study was to estimate the trends over time in the prevalence of these acute stroke impairments.

METHODS AND FINDINGS

All first-ever stroke patients recorded in the South London Stroke Register (SLSR) between 2001 and 2018 were included in this cohort study. Multivariable Poisson regression models with robust error variance were used to estimate the adjusted prevalence of 8 acute impairments, across six 3-year time cohorts. Prevalence ratios comparing impairments over time were also calculated, stratified by age, sex, ethnicity, and aetiological classification (Trial of Org 10172 in Acute Stroke Treatment [TOAST]). A total of 4,683 patients had a stroke between 2001 and 2018. Mean age was 68.9 years, 48% were female, and 64% were White. After adjustment for demographic factors, pre-stroke risk factors, and stroke subtype, the prevalence of 3 out of the 8 acute impairments declined during the 18-year period, including limb motor deficit (from 77% [95% CI 74%-81%] to 62% [56%-68%], p < 0.001), dysphagia (37% [33%-41%] to 15% [12%-20%], p < 0.001), and urinary incontinence (43% [39%-47%) to 29% [24%-35%], p < 0.001). Declines in limb impairment over time were 2 times greater in men than women (prevalence ratio 0.73 [95% CI 0.64-0.84] and 0.87 [95% CI 0.77-0.98], respectively). Declines also tended to be greater in younger patients. Stratified by TOAST classification, the prevalence of all impairments was high for large artery atherosclerosis (LAA), cardioembolism (CE), and stroke of undetermined aetiology. Conversely, small vessel occlusions (SVOs) had low levels of all impairments except for limb motor impairment and dysarthria. While we have assessed 8 key acute stroke impairments, this study is limited by a focus on physical impairments, although cognitive impairments are equally important to understand. In addition, this is an inner-city cohort, which has unique characteristics compared to other populations.

CONCLUSIONS

In this study, we found that stroke patients in the SLSR had a complexity of acute impairments, of which limb motor deficit, dysphagia, and incontinence have declined between 2001 and 2018. These reductions have not been uniform across all patient groups, with women and the older population, in particular, seeing fewer reductions.

Prevalence and risk factors of ischaemic stroke in the young: a regional Australian perspective

BACKGROUND

There is no universally accepted age cut-off for defining young strokes.

AIMS

We aimed to determine, based on the profile of young stroke patients in our regional centre, an appropriate age cut-off for young strokes.

METHODS

A retrospective analysis of all ischaemic stroke patients admitted to our centre from 2015 to 2017. We identified 391 ischaemic stroke patients; 30 patients between the ages of ≤50, 40 between 51-60 inclusive and 321 ≥ 61 years of age. We collected data on demographic profiles, risk factors and stroke classification using the Trial of Org 10 172 in Acute Stroke Treatment criteria.

RESULTS

We found significant differences between the ≤50 and ≥61 age groups for most of the risk factors and similarities between the 51-60 inclusive and ≥ 61 age groups. At least one of the six risk factors assessed in the study was present in 86.7% of the youngest group, 97.5% of the intermediate age group and 97.2% in the oldest group. In terms of the mechanisms of stroke, the youngest and oldest age groups in our study differed in the prevalence of cryptogenic, cardioembolic and other causes of stroke. The middle and older age groups had similar mechanisms of stroke.

CONCLUSIONS

The prevalence of vascular risk factors and mechanisms of stroke likewise differed significantly across age groups. This study suggests that 50 years is an appropriate age cut-off for defining young strokes and reinforces the importance of primary prevention in all age groups.

Are we there yet with patent foramen ovale closure for secondary prevention in cryptogenic stroke? A systematic review and meta-analysis of randomized trials

Background:

We performed a meta-analysis to evaluate the benefit of patent foramen ovale closure in stroke prevention.

Methods:

We searched Medline/PubMed, EMBASE, Web of Science and Cochrane central database for randomized control trials assessing the incidence of recurrent stroke after patent foramen ovale closure when compared to medical therapy. Pooled odds ratio and 95% confidence intervals were calculated using a random effects model. The heterogeneity among studies was tested using the χ² test and inconsistency was quantified using the I² statistic.

Results:

Our search strategy yielded 71 articles. We included five studies with a total of 3440 patients. Median age in the device group was 45 (43, 5.5) years and in the medical group was 45 (44.5, 46) years; 52% were male, 27.7% of patients had an atrial septal aneurysm, 25% had hypertension, and 20.5% had diabetes mellitus. The median follow-up time was 44 (34.5–50) months. The pooled odds ratio of recurrent stroke, transient ischemic attack and composite end point of stroke + transient ischemic attack + peripheral embolism in the patent foramen ovale closure versus medical therapy group were 0.4 (95% confidence interval 0.25–0.63, I² = 57.5%), 0.93 (95% confidence interval 0.61–1.42, I² = 0%), and 0.6 (95% confidence interval 0.44–0.82, I² = 0%), respectively. The incidence of atrial fibrillation was found to be significantly higher in the patent foramen ovale closure group with odds ratio of 6 (95% confidence interval 3.13–11.4, I² = 33.5%). On subgroup analysis, patent foramen ovale closure appeared to benefit males and patients with a large shunt. Number needed to treat to prevent one recurrent stroke with patent foramen ovale closure is 42. Number needed to harm to cause one atrial fibrillation with patent foramen ovale closure is 39.

Conclusion:

This meta-analysis of randomized trials concludes that percutaneous patent foramen ovale closure is effective in recurrent stroke prevention especially in males and in those with a large shunt.

Fibrinolysis: strategies to enhance the treatment of acute ischemic stroke

Stroke is a major cause of disability worldwide, and is the second leading cause of death after ischemic heart disease. Until recently, tissue-type plasminogen activator (t-PA) was the only treatment for acute ischemic stroke. If administered within 4.5 h of symptom onset, t-PA improves the outcome in stroke patients. Mechanical thrombectomy is now the preferred treatment for patients with acute ischemic stroke resulting from a large-artery occlusion in the anterior circulation. However, the widespread use of mechanical thrombectomy is limited by two factors. First, only ⁓ 10% of patients with acute ischemic stroke have a proximal large-artery occlusion in the anterior circulation and present early enough to undergo mechanical thrombectomy within 6 h; an additional 9-10% of patients presenting within the 6-24-h time window may also qualify for the procedure. Second, not all stroke centers have the resources or expertise to perform mechanical thrombectomy. Nonetheless, patients who present to hospitals where thrombectomy is not an option can receive intravenous t-PA, and those with qualifying anterior circulation strokes can then be transferred to tertiary stroke centers where thrombectomy is available. Therefore, despite the advances afforded by mechanical thrombectomy, there remains a need for treatments that improve the efficacy and safety of thrombolytic therapy. In this review, we discuss: (i) current treatment options for acute ischemic stroke; (ii) the mechanism of action of fibrinolytic agents; and (iii) potential strategies to manipulate the fibrinolytic system to promote endogenous fibrinolysis or to enhance the efficacy of fibrinolytic therapy.

Traditional Mongolian medicine Eerdun Wurile improves stroke recovery through regulation of gene expression in rat brain

ETHNOPHARMACOLOGICAL RELEVANCE

Eerdun Wurile (EW) is one of the key Mongolian medicines for treatment of neurological and cardiological disorders. EW is ranked most regularly used Mongolian medicine in clinic. Components of EW which mainly originate from natural products are well defined and are unique to Mongolian medicine.

AIM OF THE STUDY

Although the recipe of EW contains known neuroactive chemicals originated from plants, its mechanism of action has never been elucidated at molecular level. The objective of the present study is to explore the mechanism of neuroregenerative activity of EW by focusing on the regulation of gene expression in the brain of rat model of stroke.

MATERIALS AND METHODS

Rat middle cerebral artery occlusion (MCAO) models were treated with EW for 15 days. Then, total RNAs from the cerebral cortex of rat MCAO models treated with either EW or control (saline) were extracted and analyzed by transcriptome sequencing. Differentially expressed genes were analyzed for their functions during the recovery of ischemic stroke. The expression level of significantly differentially expressed genes such as growth factors, microglia markers and secretive enzymes in the lesion was further validated by RT-qPCR and immunohistochemistry.

RESULTS

Previously identified neuroactive compounds, such as geniposide (Yu et al., 2009), myristicin (Shin et al., 1988), costunolide (Okugawa et al., 1996), toosendanin (Shi and Chen, 1999) were detected in EW formulation. Bederson scale indicated that the treatment of rat MCAO models with EW showed significantly lowered neurological deficits (p < 0.01). The regional cerebral blood circulation was also remarkably higher in rat MCAO models treated with EW compared to the control group. A total of 186 genes were upregulated in the lesion of rat MCAO models treated with EW compared to control group. Among them, growth factors such as Igf1 (p < 0.05), Igf2 (p < 0.01), Grn (p < 0.01) were significantly upregulated in brain after treatment of rat MCAO models with EW. Meanwhile, greatly enhanced expression of microglia markers, as well as complementary components and secretive proteases were also detected.

CONCLUSION

Our data collectively indicated that EW enhances expression of growth factors including Igf1 and Igf2 in neurons and microglia, and may stimulate microglia polarization in the brain. The consequences of such activity include stimulation of neuron growth, hydrolysis and clearance of cell debris at the lesion, as well as the angiogenesis.

Patent foramen ovale closure vs. medical therapy for cryptogenic stroke: a meta-analysis of randomized controlled trials

Aims

The efficacy of patent foramen ovale (PFO) closure for cryptogenic stroke has been controversial. We undertook a meta-analysis of randomized controlled trials (RCTs) comparing device closure with medical therapy to prevent recurrent stroke for patients with PFO.

Methods and results

We systematically identified all RCTs comparing device closure to medical therapy for cryptogenic stroke in patients with PFO. The primary efficacy endpoint was recurrent stroke, analysed on an intention-to-treat basis. The primary safety endpoint was new onset atrial fibrillation (AF). Five studies (3440 patients) were included. In all, 1829 patients were randomized to device closure and 1611 to medical therapy. Across all patients, PFO closure was superior to medical therapy for prevention of stroke [hazard ratio (HR) 0.32, 95% confidence interval (95% CI) 0.13-0.82; P = 0.018, I2 = 73.4%]. The risk of AF was significantly increased with device closure [risk ratio (RR) 4.68, 95% CI 2.19-10.00, P<0.001, heterogeneity I2 = 27.5%)]. In patients with large shunts, PFO closure was associated with a significant reduction in stroke (HR 0.33, 95% CI 0.16-0.72; P = 0.005), whilst there was no significant reduction in stroke in patients with a small shunt (HR 0.90, 95% CI 0.50-1.60; P = 0.712). There was no effect from the presence or absence of an atrial septal aneurysm on outcomes (P = 0.994).

Conclusion

In selected patients with cryptogenic stroke, PFO closure is superior to medical therapy for the prevention of further stroke: this is particularly true for patients with moderate-to-large shunts. Guidelines should be updated to reflect this.

Thrombophilia screening in young patients with cryptogenic stroke

The clinical relevance of thrombophilia screening in stroke patients is still a matter of debate, and descriptions of larger patterns of genetic variability are rare. We assessed the frequency of hereditary hypercoagulability in young patients with cryptogenic stroke (n = 44) and in healthy blood donors (n = 282) without prior cardiovascular event. Furthermore, we focused on the impact of thrombophilia screening on secondary stroke prevention. Results: Compared to the control group (19–67 years; median 38.5 years; 64% women), there was a lower prevalence of the FVII-R353Q mutation (p = 0.033) in stroke patients (17–52 years; median 36 years; 59.1% women). Of note, the FVII-R353Q mutation lowers FVII plasma levels, probably reducing the risk of cardiovascular events. The prevalence of the remaining 13 gene polymorphisms did not differ significantly. However, the prevalence of FV Leiden mutation tended to be higher among stroke patients. Conclusion: Overall, extended screening for inherited thrombophilia had an impact on medical stroke prevention in every sixth patient with cryptogenic stroke.

Peptide-based fibrin-targeting probes for thrombus imaging

The development of new methods to image the onset and progression of thrombosis is an unmet need. Non-invasive molecular imaging techniques targeting specific key structures involved in the formation of thrombosis have demonstrated the ability to detect thrombus in different disease state models and in patients. Due to its high concentration in the thrombus and its essential role in thrombus formation, the detection of fibrin is an attractive strategy for identification of thrombosis. Herein we provide an overview of recent and selected fibrin-targeted probes for molecular imaging of thrombosis by magnetic resonance imaging (MRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), and optical techniques. Emphasis is placed on work that our lab has explored over the last 15 years that has resulted in the progression of the fibrin-binding PET probe [64Cu]FBP8 from preclinical studies into human trials.

ECTOPIC BEATS: HOW MANY COUNT?

Premature atrial and ventricular contractions, or ectopic beats, are frequently detected on routine electrocardiogram monitoring. They are often considered to be benign with no pathological significance; however, the literature suggests that higher ectopic burdens may have clinical importance. This paper reviews the current literature and provides the treating physician with an understanding of when ectopic beats should be deemed significant and when treatment may be appropriate.

Importance of variants in cerebrovascular anatomy for potential retrograde embolization in cryptogenic stroke

OBJECTIVES

To test the hypothesis that variants in cerebrovascular anatomy will affect the number of patients demonstrating a plausible retrograde embolization mechanism from plaques in the descending aorta (DAo).

METHODS

Thirty-five patients (aged 63 ± 17 years) with cryptogenic stroke underwent 4D flow MRI for the assessment of aortic 3D blood flow and MR angiography for the evaluation of circle of Willis, posterior circulation, and aortic arch architecture. In patients with proven DAo plaque, retrograde embolization was considered a potential mechanism if retrograde flow extended from the DAo to a supra-aortic vessel supplying the cerebral infarct territory.

RESULTS

Retrograde embolization with matching cerebral infarct territory was detected in six (17%) patients. Circle of Willis and aortic arch variant anatomy was found in 60% of patients, leading to reclassification of retrograde embolization risk as present in three (9%) additional patients, for a total 26% of cryptogenic stroke patients.

CONCLUSION

4D flow MRI demonstrated 26% concordance with infarct location on imaging with retrograde diastolic flow into the feeding vessels of the affected cerebral area, identifying a potential etiology for cryptogenic stroke. Our findings further demonstrate the importance of cerebrovascular anatomy when determining concordance of retrograde flow pathways with vascular stroke territory from DAo plaques.

KEY POINTS

• Retrograde embolization from descending aortic plaques constitutes a plausible etiology in cryptogenic stroke. • Common variants of cerebrovascular anatomy are important in determining retrograde embolization mechanism. • Variant cerebrovascular anatomy can link retrograde flow pathways with vascular stroke territory.

Cryptogenic ischemic stroke and prevalence of asymptomatic atrial fibrillation: a prospective study

BACKGROUND

Atrial fibrillation is responsible for up to one-third of ischemic strokes, and is also associated with silent cerebral infarctions and transient ischemic attacks (TIAs). The self-terminating and often asymptomatic nature of paroxysmal atrial fibrillation (PAF) may lead to its underdiagnosis. A continuous and long-term heart rhythm monitoring can be useful in unmasking PAF episodes.

OBJECTIVE

Prevalence of asymptomatic PAF in patients suffering a cryptogenic stroke, at risk for atrial fibrillation but without any history of arrhythmia or palpitations, using a continuous electrocardiographic monitoring.

METHODS

One hundred and forty-two consecutive patients were admitted to the Stroke Unit of 'Città della Salute e della Scienza' Hospital of Turin between June 2010 and March 2013 and discharged with the diagnosis of ischemic cryptogenic stroke. Sixty fulfilled predefined inclusion criteria. Follow-up was carried on and completed for the 54 patients who consented to implantable loop recorder (ILR) implantation. After ILR implantation, trans-telephonic data were collected monthly.

RESULTS

Atrial fibrillation episodes lasting more than 5 min were recorded in 25 patients (46%), median detection time was 5.4 months (range 1-18) and median duration of atrial fibrillation episodes was 20 h (range 7 min-8 days) with 19 patients (76%) remaining asymptomatic and the others experiencing weakness and dyspnoea but not palpitations.

CONCLUSION

Long-term heart rhythm monitoring is successful in unmasking silent atrial fibrillation in 46% of patients suffering a cryptogenic stroke with concomitant atrial fibrillation risk factors, but without history of arrhythmia or palpitations.

Use of Magnetic Resonance Venography in Screening Patients With Cryptogenic Stroke for May-Thurner Syndrome

The purpose of this study was to determine the prevalence of May-Thurner syndrome (MTS) in patients with cryptogenic stroke and to determine the incidence of patent foramen ovale. Magnetic resonance venography of 214 patients with cryptogenic stroke and 50 control patients with abdominopelvic computed tomography scans were evaluated for MTS. Incidence of patent foramen ovale and MTS in the stroke group were significantly greater than the control group (P = 0.0001, P = 0.0023, respectively). In addition, there was significantly greater compression of the left common iliac vein in the stroke group (32%) compared with the control group (13%) (P < 0.00001). In conclusion, there is a significantly higher prevalence of MTS and left common iliac vein compression in patients with cryptogenic stroke. These results indicate that magnetic resonance venography of the pelvis may be appropriate in the evaluation of stroke.

Neurogenesis in Stroke Recovery

Stroke, resulting from limited blood flow to the brain, is one of the most important causes of morbidity and mortality worldwide. Stroke is classified as ischemic, due to lack of blood flow, or hemorrhagic, due to bleeding. Because 87 % of strokes are classified as ischemic, this type will be the predominant focus of this review. Except for thrombolytic therapy, there is no established treatment to reduce the neurological deficits caused by ischemic stroke. Therefore, it is necessary to develop new therapeutic strategies designed to improve neurological functions after ischemic stroke. Recently, therapies to enhance neurogenesis after ischemic stroke have been investigated. However, these approaches have not led to successful clinical outcomes. This review addresses the pathophysiology of stroke, neurogenesis after stroke, and how to stimulate these processes based on the current literature. Finally, ongoing clinical trials to improve neurological functions after stroke by enhancing neurogenesis are discussed in this review.

Insertable cardiac monitors in the diagnosis of syncope and the detection of atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Insertable or implantable cardiac monitors (ICMs) continuously monitor the heart rhythm and record irregularities over 3 years, enabling the diagnosis of infrequent rhythm abnormalities associated with syncope and stroke. The enhanced recognition capabilities of recent ICM models are able to accurately detect atrial fibrillation (AF) and have led to new applications of ICMs for the detection and monitoring of AF.

METHODS AND RESULTS

Based on a systematic literature search, two indications were identified for ICMs for which considerable evidence, including randomized studies, exists: diagnosing the underlying cardiac cause of unexplained recurrent syncope and detecting AF in patients after cryptogenic stroke (CS). Three randomized controlled trials (RCTs) were identified that compared the effectiveness of ICMs in diagnosing patients with unexplained syncope (n = 556) to standard of care. A meta-analysis was conducted in order to generate an overall effect size and confidence interval of the diagnostic yield of ICMs versus conventional monitoring. In the indication CS, one RCT and five observational studies were included in order to assess the performance of ICMs in diagnosing patients with AF (n = 1129). Based on these studies, there is strong evidence that ICMs provide a higher diagnostic yield for detecting arrhythmias in patients with unexplained syncope and for detection of AF in patients after CS compared to conventional monitoring.

CONCLUSIONS

Prolonged monitoring with ICMs is an effective tool for diagnosing the underlying cardiac cause of unexplained syncope and for detecting AF in patients with CS. In all RCTs, ICMs have a superior diagnostic yield compared to conventional monitoring.

Impact of BNP on cryptogenic stroke without potential embolic sources on transesophageal echocardiography

BACKGROUND

Clinical characteristics are important for determining the etiologies of embolic stroke, including patent foramen ovale and complex aortic plaques demonstrated on transesophageal echocardiography (TEE). This study sought to analyze the clinical signs of cryptogenic stroke (CS) without such embolic etiologies and to examine the association between CS and brain natriuretic peptide (BNP), which is currently unknown.

METHODS

Patients with CS after routine examinations who underwent TEE were included in this single-center observational study. Patients were classified into the potential embolic sources (PES) group (patients having PES on TEE) and the no potential embolic source (NPES) group. Patients were also categorized according to the tertile of BNP.

RESULTS

A total of 158 patients (age, 64.0 ± 13.9 years; 119 males) with CS were enrolled. The PES group had 108 (68%) patients, and the NPES group had 50 (32%). Hypertension was more common, and glucose, D-dimer, and BNP were higher in the NPES than in the PES group (p<0.05). NPES was independently associated with high-BNP tertile (OR: 5.61; 95% CI: 1.91 to 16.44; p=0.002).

CONCLUSIONS

BNP, an indicator of cardioembolism, was closely associated with NPES. Cardiogenic mechanisms may be implicated in the etiology of CS without potential embolic etiologies on TEE.

Detection of occult paroxysmal atrial fibrilation by implantable long-term electrocardiographic monitoring in cryptogenic stroke and transient ischemic attack population: a study protocol for prospective matched cohort study

BACKGROUND

Cardio-embolic etiology is the most frequently predicted cause of cryptogenic stroke/TIA. Detection of occult paroxysmal atrial fibrillation is crucial for selection of appropriate medication.

METHODS

Enrolment of eligible cryptogenic stroke and TIA patients began in 2014 and will continue until 2018. The patients undergo long-term (12 months) ECG monitoring (implantable loop recorder) and testing for PITX2 (chromosome 4q25) and ZFHX3 (chromosome 16q22) gene mutations. There will be an appropriate control group of age- and sex-matched healthy volunteers. To analyse the results descriptive statistics, statistical tests for group differences, and correlation analyses will be used.

DISCUSSION

In our study we are focusing on a possible correlation between detection of atrial fibrillation by an implantable ECG recorder, and PITX2 and/or ZFHX3 gene mutations in cryptogenic stroke/TIA patients. A correlation could lead to implementation of this genomic approach to cryptogenic stroke/TIA diagnostics and management. The results will be published in 2018.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02216370 .

Multisite Thrombus Imaging and Fibrin Content Estimation With a Single Whole-Body PET Scan in Rats

OBJECTIVE

Thrombosis is a leading cause of morbidity and mortality worldwide. Current diagnostic strategies rely on imaging modalities that are specific for distinct vascular territories, but a thrombus-specific whole-body imaging approach is still missing. Moreover, imaging techniques to assess thrombus composition are underdeveloped, although therapeutic strategies may benefit from such technology. Therefore, our goal was to test whether positron emission tomography (PET) with the fibrin-binding probe (64)Cu-FBP8 allows multisite thrombus detection and fibrin content estimation.

APPROACH AND RESULTS

Thrombosis was induced in Sprague-Dawley rats (n=32) by ferric chloride application on both carotid artery and femoral vein. (64)Cu-FBP8-PET/CT imaging was performed 1, 3, or 7 days after thrombosis to detect thrombus location and to evaluate age-dependent changes in target uptake. Ex vivo biodistribution, autoradiography, and histopathology were performed to validate imaging results. Arterial and venous thrombi were localized on fused PET/CT images with high accuracy (97.6%; 95% confidence interval, 92-100). A single whole-body PET/MR imaging session was sufficient to reveal the location of both arterial and venous thrombi after (64)Cu-FBP8 administration. PET imaging showed that probe uptake was greater in younger clots than in older ones for both arterial and venous thrombosis (P<0.0001). Quantitative histopathology revealed an age-dependent reduction of thrombus fibrin content (P<0.001), consistent with PET results. Biodistribution and autoradiography further confirmed the imaging findings.

CONCLUSIONS

We demonstrated that (64)Cu-FBP8-PET is a feasible approach for whole-body thrombus detection and that molecular imaging of fibrin can provide, noninvasively, insight into clot composition.

Hypercoagulability Is a Stronger Risk Factor for Ischaemic Stroke than for Myocardial Infarction: A Systematic Review

Background and Purpose

Hypercoagulability increases the risk of arterial thrombosis; however, this effect may differ between various manifestations of arterial disease.

Methods

In this study, we compared the effect of coagulation factors as measures of hypercoagulability on the risk of ischaemic stroke (IS) and myocardial infarction (MI) by performing a systematic review of the literature. The effect of a risk factor on IS (relative risk for IS, RR_IS) was compared with the effect on MI (RR_MI) by calculating their ratio (RRR = RR_IS/RR_MI). A relevant differential effect was considered when RRR was >1+ its own standard error (SE) or <1−SE.

Results

We identified 70 publications, describing results from 31 study populations, accounting for 351 markers of hypercoagulability. The majority (203/351, 58%) had an RRR greater than 1. A larger effect on IS risk than MI risk (RRE>1+1SE) was found in 49/343 (14%) markers. Of these, 18/49 (37%) had an RRR greater than 1+2SE. On the opposite side, a larger effect on MI risk (RRR<1-1SE) was found in only 17/343 (5%) markers.

Conclusions

These results suggest that hypercoagulability has a more pronounced effect on the risk of IS than that of MI.

B-Type Natriuretic Peptides Help in Cardioembolic Stroke Diagnosis

Background and Purpose—

Determining the underlying cause of stroke is important to optimize secondary prevention treatment. Increased blood levels of natriuretic peptides (B-type natriuretic peptide/N-terminal pro-BNP [BNP/NT-proBNP]) have been repeatedly associated with cardioembolic stroke. Here, we evaluate their clinical value as pathogenic biomarkers for stroke through a literature systematic review and individual participants’ data meta-analysis.

Methods—

We searched publications in PubMed database until November 2013 that compared BNP and NT-proBNP circulating levels among stroke causes. Standardized individual participants’ data were collected to estimate predictive values of BNP/NT-proBNP for cardioembolic stroke. Dichotomized BNP/NT-proBNP levels were included in logistic regression models together with clinical variables to assess the sensitivity and specificity to identify cardioembolic strokes and the additional value of biomarkers using area under the curve and integrated discrimination improvement index.

Results—

From 23 selected articles, we collected information of 2834 patients with a defined cause. BNP/NT-proBNP levels were significantly elevated in cardioembolic stroke until 72 hours from symptoms onset. Predictive models showed a sensitivity >90% and specificity >80% when BNP/NT-proBNP were added considering the lowest and the highest quartile, respectively. Both peptides also increased significantly the area under the curve and integrated discrimination improvement index compared with clinical models. Sensitivity, specificity, and precision of the models were validated in 197 patients with initially undetermined stroke with final pathogenic diagnosis after ancillary follow-up.

Conclusions—

Natriuretic peptides are strongly increased in cardioembolic strokes. Future multicentre prospective studies comparing BNP and NT-proBNP might aid in finding the optimal biomarker, the best time point, and the optimal cutoff points for cardioembolic stroke identification.

Increased visceral adipose tissue as a potential risk factor in patients with embolic stroke of undetermined source (ESUS)

PURPOSE

The etiology of an ischemic stroke remains undetermined in 20-35% of cases and many patients do not have any of the conventional risk factors. Increased visceral adipose tissue (VAT) is a suggested new risk factor for both carotid artery atherosclerosis (CAA) and atrial fibrillation (AF), but its role in the remaining stroke population is unknown. We assessed the amount of VAT in patients with embolic stroke of undetermined source (ESUS) after excluding major-risk cardioembolic sources, occlusive atherosclerosis, and lacunar stroke.

METHODS

Altogether 58 patients (mean age 57.7 ± 10.2 years, 44 men) with ischemic stroke of unknown etiology but without CAA, known AF or small vessel disease underwent computed tomography angiography and assessment of VAT. For comparison VAT values from three different reference populations were used. Conventional risk factors (smoking, hypertension, diabetes, increased total and LDL-cholesterol, decreased HDL-cholesterol) were also registered.

RESULTS

Mean VAT area was significantly higher in stroke patients (205 ± 103 cm2 for men and 168 ± 99 cm2 for women) compared to all reference populations (P < 0.01). 50% of male and 57% of female patients had an increased VAT area. In male patients, VAT was significantly higher despite similar body mass index (BMI). Increased VAT was more common than any of the conventional risk factors.

CONCLUSION

Increased VAT was found in over half of our patients with ESUS suggesting it may have a role in the pathogenesis of thromboembolism in this selected group of patients.

Transesophageal echocardiography in patients with cryptogenic ischemic stroke: a systematic review

BACKGROUND

The clinical utility of routine transesophageal echocardiography (TEE) for patients with unexplained ischemic stroke is controversial. We performed a systematic review to determine the frequency of detection of new cardiac findings in patients with cryptogenic ischemic stroke (IS) undergoing transesophageal echocardiography (TEE).

METHODS

Systematic review and meta-analysis of cohort studies of consecutive patients with "cryptogenic" IS undergoing TEE after routine etiologic workup. Patients were categorized into 2 groups: A (< 55 years) and B (≥ 55 years). Outcomes included proportion of patients with new TEE-detected cardiac findings and proportion of patients commenced on oral anticoagulation after TEE.

RESULTS

Twenty-seven studies were included (n = 5,653). We identified significant heterogeneity among studies and report a range of prevalence rates and I2 statistic as our primary analysis. Prevalence of individual cardiac findings on TEE varied significantly among studies; patent foramen ovale (A: 12.0%-57.8%, I2 = 89.9%; B: 3.9%-43.5%, I2 = 86.7%), atrial septal aneurysm (A: 0-48.9%, I2 = 91.9%; B: 3.5%-25.0%, I2 = 84.5%), left atrial thrombus (A: 0-10.9%, I2 = 61.1%; B: 0-21.2%, I2 = 91.7%), spontaneous echo contrast (A: 0-11.9%, I2 = 57.2%; B: 0-21.3%, I2 = 89.8%), and aortic atheroma (A: 0-9.6%, I2 = 53.8%; B: 2.8%-44.4%, I2 = 89.7%). Definitions of common findings were not provided for many studies. Five studies (n = 591) reported on the proportion of patients who were commenced on anticoagulant therapy after TEE (range 0-30.7%).

CONCLUSIONS

Routine TEE in patients with cryptogenic IS identifies cardiac findings in a large proportion. However, there is marked interstudy variation in the definition and prevalence of common findings. Transesophageal echocardiography-detected findings prompted the introduction of anticoagulant therapy in up to one-third of patients. However, these were mostly not for established guideline-based indications based on randomized controlled trial evidence. It is unclear if routine use of TEE in patients with cryptogenic IS is indicated.

Silent Atrial Fibrillation: A Critical Review

Atrial fibrillation (AF) in the most common cardiac arrhythmia, and is associated with an increased risk of thromboembolic events. Silent AF is an asymptomatic form of AF incidentally diagnosed during a routine test or manifesting as an arrhythmia-related complication. Although recent trials have clearly demonstrated that patients with sub-clinical AF are at increased risk of stroke, the real incidence of this form of AF is still unknown. In fact, studies about silent AF had been performed only in specific subgroups of patients such as those with implantable cardiac devices, with recent cryptogenic stroke or transient ischemic attack, and recently undergoing AF ablation. Continuous ECG-monitoring in patients without implantable cardiac devices may improve silent AF detection but its cost-effectiveness actually is not well established in all kind of patients. Moreover, recent data have revealed that only a small number of these patients may have sub-clinical AF within the month prior to their stroke suggesting a lack of temporal relationship between the stroke and the AF episode. This paper will review available data on different diagnostic tools for silent AF detection with a focus on their cost-effectiveness, analyzing the direct correlation between the arrhythmia and embolic events, and discussing areas of uncertainty where further research is required.

Red blood cell distribution width in patients with cryptogenic stroke

BACKGROUND

There is no information about a possible association of red blood cell distribution width (RDW) with cryptogenic stroke (CS). We aimed to analyze the association of RDW with CS.

PATIENTS AND METHODS

One hundred and sixty-three patients with CS were included along with 186 healthy controls. Fibrinogen, leukocytes, hemoglobin, and erythrocyte indices were evaluated.

RESULTS

Patients showed higher RDW, leukocyte count, and body mass index (BMI) than controls (P < .05). No differences were observed in the erythrocyte indices or in glucose, cholesterol, and triglycerides levels (P > .05). When patients with anemia were excluded from the study (6 controls and 5 cases), the differences between cases and controls persisted (P = .005). Multivariate logistic regression revealed that, after adjusting for potential confounders (anemia, age > 40 years, gender, and fibrinogen >382 mg/dL, total cholesterol >240 mg/dL, and BMI > 28.7 kg/m(2)), RDW >14% was the only parameter that independently increased the risk of CS.

CONCLUSION

The RDW >14% increased the risk of CS by 2.5-fold, irrespectively of anemia, inflammation, and lipidic profile.

Implication of left ventricular diastolic dysfunction in cryptogenic ischemic stroke

BACKGROUND AND PURPOSE

Left ventricular diastolic dysfunction (LVDD) is a predictor for atrial fibrillation (AF). This study was aimed to investigate whether LVDD in cryptogenic ischemic stroke (CS) could be a clue to stroke mechanism.

METHODS

The clinical and echocardiographic findings of 1589 consecutive patients with acute ischemic stroke or transient ischemic attack between 2004 and 2013 were reviewed. LVDDs among stroke subtypes were graded by transthoracic echocardiography into 4 groups by severity: normal, abnormal relaxation (grade I), pseudonormal (grade II), and restrictive diastolic filling (grade III), whereas severe LVDD was defined as grade III. We classified the lesion pattern of CS into cardioembolism-mimic or non-cardioembolism-mimic and determined whether cardioembolism-mimic lesions were associated with severe LVDD.

RESULTS

The fraction of severe LVDD in CS was not different from that of stroke with AF (27.3% versus 37.1%; P=0.173) but was significantly higher than that of stroke without AF (27.3% versus 13.4%; P=0.008). Cardioembolism-mimic CS had more severe LVDD than non-cardioembolism-mimic CS (41.4% versus 11.5%; P=0.013). LVDD of grade II (odds ratio, 4.37; 95% confidence interval, 2.99-6.41) and grade III (odds ratio, 5.60; 95% confidence interval, 3.42-9.17) were independently related to stroke with AF after adjusting covariates.

CONCLUSIONS

The severe LVDD could be a predictor of stroke with AF, and its frequency was similar between CS and stroke with AF. Cardioembolism-mimic CS had significantly more severe LVDD than non-cardioembolism-mimic CS. LVDD could be helpful to discriminate the stroke mechanism in the patients with acute CS.

Clinical significance of intraluminal atheroma in patients with ascending and arch aneurysm

BACKGROUND

Little is known about the clinical significance of intraluminal atheroma (ILA) in ascending and arch aneurysm (Asc-ArcA) regarding aneurysm expansion and associated cardiovascular events.

METHODS

We retrospectively investigated 70 consecutive patients with Asc-ArcA who underwent serial multidetector computed tomography between 2004 and 2011. We evaluated the diameter of the aneurysm, as well as the presence and characteristics of ILA. We also evaluated the characteristics of atheroma in terms of the presence of high-risk plaque (>4 mm in plaque thickness), vulnerable plaque (<60 HU in density), ulcerated plaque (extension of the contrast medium beyond the vascular lumen into the surrounding plaque with >3 mm orifice), and complex plaque (having all three characteristics). The annual expansion rate of Asc-ArcA and factors associated with cardiovascular events were evaluated.

RESULTS

During a median of 47 months of follow-up, cryptogenic stroke occurred in 13 patients (18.6%). Univariate and multivariate logistic regression analyses revealed the presence of ILA as an independent predictor for cryptogenic stroke. Cryptogenic stroke occurred in all 5 patients with complex atheroma. The annual expansion rate of Asc-ArcA was not significantly associated with the occurrence of cryptogenic stroke.

CONCLUSIONS

In patients with low to intermediate risk sized Asc-ArcA, ILA, especially complex atheroma, is strongly associated with cryptogenic stroke. Thus, the presence and characteristics of ILA within Asc-ArcA should be carefully evaluated for the prevention of adverse events.

In vivo molecular imaging of thrombosis and thrombolysis using a fibrin-binding positron emission tomographic probe

BACKGROUND

Fibrin is a major component of arterial and venous thrombi and represents an ideal candidate for molecular imaging of thrombosis. Here, we describe imaging properties and target uptake of a new fibrin-specific positron emission tomographic probe for thrombus detection and therapy monitoring in 2 rat thrombosis models.

METHODS AND RESULTS

The fibrin-binding probe FBP7 was synthesized by conjugation of a known short cyclic peptide to a cross-bridged chelator (CB-TE2A), followed by labeling with copper-64. Adult male Wistar rats (n=26) underwent either carotid crush injury (mural thrombosis model) or embolic stroke (occlusive thrombosis model) followed by recombinant tissue-type plasminogen activator treatment (10 mg/kg, IV). FBP7 detected thrombus location in both animal models with a high positron emission tomographic target-to-background ratio that increased over time (>5-fold at 30-90 minutes, >15-fold at 240-285 minutes). In the carotid crush injury animals, biodistribution analysis confirmed high probe uptake in the thrombotic artery (≈0.5%ID/g; >5-fold greater than blood and other tissues of the head and thorax). Similar results were obtained from ex vivo autoradiography of the ipsilateral versus contralateral carotid arteries. In embolic stroke animals, positron emission tomographic-computed tomographic imaging localized the clot in the internal carotid/middle cerebral artery segment of all rats. Time-dependent reduction of activity at the level of the thrombus was detected in recombinant tissue-type plasminogen activator-treated rats but not in vehicle-injected animals. Brain autoradiography confirmed clot dissolution in recombinant tissue-type plasminogen activator-treated animals, but enduring high thrombus activity in control rats.

CONCLUSIONS

We demonstrated that FBP7 is suitable for molecular imaging of thrombosis and thrombolysis in vivo and represents a promising candidate for bench-to-bedside translation.

96 hours ECG monitoring for patients with ischemic cryptogenic stroke or transient ischaemic attack

Atrial fibrillation (AF) is intermittent in 30% of patients with cardioembolic stroke and, therefore, might not be seen in a single standard ECG recording. The aim of this study was to evaluate if prolonged ECG monitoring (96 h) finds episodes of intermittent AF beyond the 24 h ECG monitoring in patients with cryptogenic stroke or transient ischemic attack (TIA). We prospectively evaluated consecutive patients affected by cryptogenic stroke or TIA who had sinus rhythm on a 12-lead ECG on admission, and during ECG monitoring performed in the acute phase (for at least 24 h). Patients had continuous 96 h Holter ECG monitoring within 30 days from stroke onset. 114 patients were included in the study (mean age 63.1 ± 15.1, 59 males). AF was found in 29 patients (24.3%). In 20 patients, AF was found in the first 24 h of recording, and in nine patients after 24 h. In addition, several other dysrhythmias such as supraventricular ectopic activity (33), ventricular tachycardia (10), sinus pause (4) and sinus-atrial block (1) were found. In patients with cryptogenic stroke or TIA, 96 h ECG monitoring detected a high rate of AF. One-third of AF was seen beyond 24 h of ECG monitoring.

Fibrin-targeted PET probes for the detection of thrombi

There is an ongoing effort to develop better methods for noninvasive detection and characterization of thrombi. Here we describe the synthesis and evaluation of three new fibrin-targeted positron emission tomography (PET) probes (FBP1, FBP2, FBP3). Three fibrin-specific peptides were conjugated as 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-monoamides at the C- and N-termini and chelated with (64)CuCl2. Probes were prepared with a specific activity ranging from 10 to 130 μCi/nmol. Both the peptides and the probes exhibited nanomolar dissociation constants (Kd) for the soluble fibrin fragment DD(E), although the Cu-DOTA derivatization resulted in a 2-3 fold loss in affinity relative to the parent peptide. Biodistribution and imaging studies were performed in a rat model of carotid artery thrombosis. For FBP1 and FBP2 at 120 min post injection, the vessel containing the thrombus showed the highest concentration of radioactivity after the excretory organs, that is, the liver and kidneys. This was confirmed ex vivo by autoradiography, which showed >4-fold activity in the thrombus-containing artery compared to the contralateral artery. FBP3 showed much lower thrombus uptake, and the difference was traced to greater metabolism of this probe. Hybrid MR-PET imaging with FBP1 or FBP2 confirmed that these probes were effective for the detection of an arterial thrombus in this rat model. A thrombus was visible on PET images as a region of high activity that corresponded to a region of arterial occlusion identified by simultaneous MR angiography. FBP1 and FBP2 represent promising new probes for the molecular imaging of thrombi.