Percutaneous patent foramen ovale closure for secondary stroke prevention: Network meta-analysis

Transcatheter PFO closure for cryptogenic stroke: current approaches and future considerations

Patent Foramen Ovale (PFO) is a common congenital atrial septal defect present in 20%-35% of the general population. Although generally considered a benign anatomic variant, a PFO may facilitate passage of a thrombus from the venous to arterial circulation, thereby resulting in cryptogenic stroke or systemic embolization. A PFO is detected in nearly one half of patients presenting with cryptogenic stroke and often considered the most likely etiology when other causes have been excluded. In this review, we discuss the contemporary role of transcatheter closure of PFO in the treatment of cryptogenic stroke, including devices currently available for commercial use in the United States (Amplatzer PFOTM Occluder and GoreTM Cardioform Septal Occluder) and a novel suture-mediated device (NobleStitchTM EL) under clinical investigation. To provide the best care for cryptogenic stroke patients, practitioners should be familiar with the indications for PFO closure and corresponding treatment options.

Management of patent foramen ovale; findings from a nationwide survey

OBJECTIVES

Several clinical trials have provided evidence supporting the transcatheter closure of patent foramen ovale (PFO) in selected patients following a cryptogenic stroke. However, it remains unknown to what extent these guidelines have been implemented in everyday clinical practice and the familiarity of physicians from different specialties with PFO closure. The aim of our nationwide survey is to explore the implementation of transcatheter PFO occlusion in Greek clinical practice.

MATERIALS AND METHODS

Attending level cardiologists, internal medicine physicians and neurologists involved in the management of PFO-related strokes working in Greece were invited to complete an online questionnaire. The questionnaire consisted of 19 questions and was designed to obtain comprehensive data on provider demographics, PFO characteristics, and specific clinical scenarios.

RESULTS

A total of 51 physicians (56.9 % cardiologists, 25.5 % neurologists and 17.6 % internal medicine physicians) completed the survey, resulting in a response rate of 53 %. Cardiologists, internal medicine physicians and neurologists agree on several issues regarding PFO closure, such as PFO closure as first line treatment, management of patients with DVT or prior decompression sickness, and post-closure antithrombotic treatment, but different approaches were reported regarding closure in patients with thrombophilia treated with oral anticoagulation (p=0.012) and implantable loop recorder placement for atrial fibrillation exclusion (p=0.029 and p=0.020).

CONCLUSIONS

Our findings show that cardiologists, internal medicine physicians and neurologists agree in numerous issues, but share different views in the management of patients with thrombophilia and rhythm monitoring duration. These results highlight the significance of collaboration among physicians from different medical specialties for achieving optimal results.

Efficacy of interventional closure therapy on cryptogenic stroke with coexisting patent foramen ovale in young patients and its impact on serum fibrinogen and D-dimer levels

OBJECTIVE

To explore the efficacy of interventional closure therapy in young patients with cryptogenic stroke and coexisting patent foramen ovale and analyze its impact on serum fibrinogen and D-dimer levels.

METHODS

All subjects in this study were young stroke patients with PFO. After excluding patients who did not meet the inclusion criteria, they were registered and divided into two groups based on the treatment method: the closure group and the medical group.

RESULTS

There were no significant differences in basic clinical data between the two groups, indicating comparability (p > 0.05). The closure group showed better heart function after treatment compared to the medical group, with significant differences (p < 0.05). Headache symptoms in the closure group were less severe than those in the medical group after treatment, with significant differences (p < 0.05). Laboratory indicators in the closure group were better than those in the medical group after treatment, with significant differences (p < 0.05). Serum fibrinogen and D-dimer levels in the closure group were lower than those in the medical group after treatment, with significant differences (p < 0.05).

CONCLUSION

Interventional closure therapy demonstrated positive effects on young patients with cryptogenic stroke and coexisting PFO, showing improvements in heart function, headache symptoms, and blood coagulation parameters. While the study suggests potential benefits, cautious interpretation is warranted, given the observational study design. Further research with a larger sample size and long-term follow-up is needed to validate these findings.

Heart-brain axis: Association of congenital heart abnormality and brain diseases

Brain diseases are a major burden on human health worldwide, and little is known about how most brain diseases develop. It is believed that cardiovascular diseases can affect the function of the brain, and many brain diseases are associated with heart dysfunction, which is called the heart-brain axis. Congenital heart abnormalities with anomalous hemodynamics are common treatable cardiovascular diseases. With the development of cardiovascular surgeries and interventions, the long-term survival of patients with congenital heart abnormalities continues to improve. However, physicians have reported that patients with congenital heart abnormalities have an increased risk of brain diseases in adulthood. To understand the complex association between congenital heart abnormalities and brain diseases, the paper reviews relevant clinical literature. Studies have shown that congenital heart abnormalities are associated with most brain diseases, including stroke, migraine, dementia, infection of the central nervous system, epilepsy, white matter lesions, and affective disorders. However, whether surgeries or other interventions could benefit patients with congenital heart abnormalities and brain diseases remains unclear because of limited evidence.

Recent progress in patent foramen ovale and related neurological diseases: A narrative review

Patent foramen ovale (PFO) is a common congenital cardiac abnormality when the opening of the interatrial septum is not closed in adulthood. This abnormality affects 25% of the general population. With the development of precision medicine, an increasing number of clinical studies have reported that PFO is closely related to various neurological diseases such as stroke, migraine, obstructive sleep apnea, and decompression syndrome. It has also been suggested that PFO closure could be effective for preventing and treating these neurological diseases. Therefore, increasing attention has been given to the prevention, diagnosis, and treatment of PFO-related neurological diseases. By reviewing existing literature, this article focuses on the pathogenesis, epidemiology, and clinical characteristics of PFO-related neurological diseases, as well as the prevention and treatment of different neurological diseases to discuss, and aims to provide current progress for this field and decision-making evidence for clinical practice.

Machine learning in a real-world PFO study: analysis of data from multi-centers in China

PURPOSE

The association of patent foreman ovale (PFO) and cryptogenic stroke has been studied for years. Although device closure overall decreases the risk for recurrent stroke, treatment effects varied across different studies. In this study, we aimed to detect sub-clusters in post-closure PFO patients and identify potential predictors for adverse outcomes.

METHODS

We analyzed patients with embolic stroke of undetermined sources and PFO from 7 centers in China. Machine learning and Cox regression analysis were used.

RESULTS

Using unsupervised hierarchical clustering on principal components, two main clusters were identified and a total of 196 patients were included. The average age was 42.7 (12.37) years and 64.80% (127/196) were female. During a median follow-up of 739 days, 12 (6.9%) adverse events happened, including 6 (3.45%) recurrent stroke, 5 (2.87%) transient ischemic attack (TIA) and one death (0.6%). Compared to cluster 1 (n = 77, 39.20%), patients in cluster 2 (n = 119, 60.71%) were more likely to be male, had higher systolic and diastolic blood pressure, higher body mass index, lower high-density lipoprotein cholesterol and increased proportion of presence of atrial septal aneurysm. Using random forest survival (RFS) analysis, eight top ranking features were selected and used for prediction model construction. As a result, the RFS model outperformed the traditional Cox regression model (C-index: 0.87 vs. 0.54).

CONCLUSIONS

There were 2 main clusters in post-closure PFO patients. Traditional cardiovascular profiles remain top ranking predictors for future recurrence of stroke or TIA. However, whether maximizing the management of these factors would provide extra benefits warrants further investigations.

Patent foramen ovale closure vs. medical therapy alone after cryptogenic stroke in China: A cost-effectiveness analysis

Background

In 2019, there were 28. 76 million patients with stroke in China, with ~25% of them suffering from cryptogenic stroke (CS). Patent foramen ovale (PFO) is related to CS, and PFO closure can reduce recurrent stroke. To date, no study has investigated the cost-effectiveness of PFO closure vs. medical therapy among such populations in China.

Methods

A Markov model with a cycle length of 3 months was established to compare the 30-year cost-effectiveness of PFO closure and medical therapy. The transition probability of recurrent stroke was derived from the RESPECT study, and the costs and utility were obtained from domestic data or studies conducted in China. The primary outcome of this study was the incremental cost-effectiveness ratio (ICER), which represents the incremental cost per quality-adjusted life year (QALY). PFO closure was considered cost-effective if the ICER obtained was lower than the willingness-to-pay (WTP) threshold of 37,654 USD/QALY; otherwise, PFO closure was regarded as not being cost-effective. One-way and probabilistic sensitivity analyses were performed to test the robustness of the results.

Results

After a simulation of a 30-year horizon, a cryptogenic stroke patient with PFO was expected to have QALY of 13.15 (15.26 LY) if he received PFO closure and a corresponding value of 11.74 QALY (15.14 LY) after medical therapy. The corresponding costs in both cohorts are US $8,131 and US $4,186, respectively. Thus, an ICER of 2783 USD/QALY and 31264 USD/LY was obtained, which is lower than the WTP threshold. One-way and probabilistic sensitivity analyses showed that the results were robust.

Conclusion

With respect to the WTP threshold of three times per capita GDP in China in 2021, PFO closure is a cost-effective method for Chinese cryptogenic stroke patients with PFO, as shown in the 30-year simulation.

Current Challenges and Future Directions in Handling Stroke Patients With Patent Foramen Ovale—A Brief Review

The role of patent foramen ovale (PFO) in stroke was debated for decades. Randomized clinical trials (RCTs) have shown fewer recurrent events after PFO closure in patients with cryptogenic stroke (CS). However, in clinical practice, treating stroke patients with coexisting PFO raises some questions. This brief review summarizes current knowledge and challenges in handling stroke patients with PFO and identifies issues for future research. The rationale for PFO closure was initially based on the concept of paradoxical embolism from deep vein thrombosis (DVT). However, RCTs did not consider such details, limiting their impact from a pathophysiological perspective. Only a few studies explored the coexistence of PFO and DVT in CS with varying results. Consequently, the PFO itself might play a role as a prothrombotic structure. Transesophageal echocardiography thus appears most appropriate for PFO detection, while a large shunt size or an associated atrial septum aneurysm qualify for a high-risk PFO. For drug-based treatment alone, studies did not find a definite superiority of oral anticoagulation over antiplatelet therapy. Remarkably, drug-based treatment in addition to PFO closure was not standardized in RCTs. The available literature rarely considers patients with transient ischemic attack (TIA), over 60 years of age, and competing etiologies like atrial fibrillation. In summary, RCTs suggest efficacy for closure of high-risk PFO only in a small subgroup of stroke patients. However, research is also needed to reevaluate the pathophysiological concept of PFO-related stroke and establish strategies for older and TIA patients and those with competing risk factors or low-risk PFO.

Atrial fibrillation after closure of patent foramen ovale in the REDUCE clinical study

OBJECTIVES

To describe the occurrence of postprocedural atrial fibrillation (AF) among patients with cryptogenic stroke undergoing patent foramen ovale (PFO) closure in the REDUCE clinical study and analyze for potential risk factors for the development of postprocedural AF.

BACKGROUND

AF is an adverse event that might potentially counterbalance the stroke prevention benefit from PFO closure. Data on AF after transcatheter PFO closure are sparse.

METHODS

We evaluated data from patients having PFO closure (Gore HELEX or Gore Cardioform Septal Occluder) in the REDUCE clinical trial (n = 408) in at post hoc explorative analysis. Median follow-up was 5.0 years.

RESULTS

AF occurred in 30 patients (7.4%) after PFO closure with a total of 34 AF events. Most were reported as non-serious (68%), detected within 45 days post-procedure (79%), and resolved within 2 weeks of onset (63%). One subject with AF had recurrent stroke. Postprocedural AF occurred more frequently among subjects with higher age and large device sizes. Male sex was the only independent predictor of postprocedural AF. We found no association between the type of occluder (HELEX or Gore Cardioform Septal Occluder) or PFO anatomical characteristics and post-procedural AF.

CONCLUSION

In the REDUCE clinical study, postprocedural atrial fibrillation was mostly early onset, transient and with no later recurrence. Postprocedural AF occurred more frequently among patients with higher age and larger devices. Male sex was the only independent predictor of postprocedural AF.

Patent foramen ovale closure in a patient with vena cava filter: a case report

Background

The presence of a patent foramen ovale (PFO) is associated with several medical conditions, including cryptogenic left circulation thromboembolism. PFO closure was demonstrated to reduce recurrent ischaemic stroke in patients with prior cryptogenic stroke. The presence of an inferior vena cava filter (IVCF), however, may impede a transfemoral PFO closure procedure.

Case summary

We describe the case of a 50-year-old man with a PFO suffering from ischaemic stroke from paradoxical thromboembolism originating from deep vein thrombosis and requiring an IVCF. After deep vein thrombosis resolution, due to the high risk of stroke recurrences, the patient was recommended PFO closure. IVCF retrieval by the interventional radiologist was first attempted but failed. A transfemoral PFO closure procedure was thus endeavoured with the IVCF in place and was successful. The patient was then discharged in good clinical status and no stroke recurrences were reported at 5 months follow-up.

Discussion

Albeit an IVCF provides benefit in patients with recurrent thromboembolic events despite adequate anticoagulation therapy, its presence may hinder interventional procedures necessitating delivery systems to advance through the inferior vena cava. We reported on a successful PFO closure procedure via a femoral venous access in a patient with an IVCF in place, thus demonstrating the feasibility of advancing delivery systems through an IVCF. As interventional procedures requiring the advancement of delivery systems through the inferior vena cava are becoming increasingly common, the feasibility of IVCF crossing with catheters and delivery systems alike paves the way for novel interventional possibilities.

Prevalence of patent foramen ovale in the Greek population is high and impacts on the interpretation of the risk of paradoxical embolism (RoPE) score

Background:

The risk of paradoxical embolism (RoPE) score calculates the probability that patent foramen ovale (PFO) is causally related to stroke (PFO attributable fraction, PFOAF), based on PFO prevalence in patients with cryptogenic stroke (CS) compared with that in the general population. The latter has been estimated at 25%; however, PFO prevalence in nonselected populations varies widely.

Methods:

Since PFO prevalence in Greece remains unknown, we evaluated it and we calculated PFOAF stratified by RoPE score in a cohort of patients with CS ⩽55 years old. PFO was detected according to the international consensus transcranial Doppler (TCD) criteria in 124 healthy subjects (H), in 102 patients with CS, and in 56 patients with stroke of known cause (nonCS). Each subject underwent unilateral middle cerebral artery recording after infusion of agitated saline, at rest, and after a controlled Valsalva maneuver. We characterized PFO as large (>20 microbubbles or curtain), moderate (11–20), and small (⩽10).

Results:

PFO was detected in 42.7% of H, 49% of CS, and 25% of nonCS (p = 0.013). Large PFOs were numerically higher in CS [28.4% (29/102)] compared with H [19.3% (24/124); p = 0.1] and to nonCS [7.1% (4/56), p = 0.04]. The median RoPE score in patients with CS and PFO was seven. Even patients with very high RoPE score (9–10) had moderate PFOAF (57%). For any individual stratum up to RopE score 8, PFOAF was <33%.

Conclusions:

PFO prevalence in the Greek population is much higher than the widely accepted 25%. PFO may be the cause of stroke in one out of nine Greek patients with CS. Among Greek CS patients who harbor a PFO, the latter is causal in one out of five. The established RoPE score cutoff of ⩾7 for having a probable PFO-associated stroke may overestimate the probability in patients deriving from populations with high PFO prevalence.

Patent Foramen Ovale in Cryptogenic Ischemic Stroke: Direct Cause, Risk Factor, or Incidental Finding?

Patent foramen ovale (PFO) has been associated with cryptogenic stroke. There is conflicting data and it remains uncertain whether PFO is the direct cause, a risk factor or an incidental finding. Potential stroke mechanisms include paradoxical embolism from a venous clot which traverses the PFO, in situ clot formation within the PFO, and atrial arrhythmias due to electrical signaling disruption. Main risk factors linked with PFO-attributable strokes are young age, PFO size, right-to-left shunt degree, PFO morphology, presence of atrial septal aneurysm, intrinsic coagulation-anticoagulation systems imbalance, and co-existence of other atrial abnormalities, such as right atrial septal pouch, Eustachian valve and Chiari's network. These may act independently or synergistically, multiplying the risk of embolic events. The RoPE score, a scale that includes factors such as young age, cortical infarct location and absence of traditional stroke risk factors, is associated with the probability of a PFO being pathogenic and stroke recurrence risk after the index stroke. Multiple investigators have attempted to correlate other PFO features with the risk of PFO-related stroke, but further investigation is needed before any robust conclusions are reached. PFO presence in young patients with cryptogenic stroke should be considered as etiologically suspect. Caution should be exercised in interpreting the relevance of other PFO features.

A Narrative and Critical Review of Randomized-Controlled Clinical Trials on Patent Foramen Ovale Closure for Reducing the Risk of Stroke Recurrence

Patent foramen ovale (PFO) is a common cardiac anatomic variant that has been increasingly found in young (<60 years) cryptogenic stroke patients. Despite initial neutral randomized-controlled clinical trials (RCTs), there have been four recent RCTs providing consistent data in favor of the efficacy and safety of PFO closure compared to medical therapy for secondary stroke prevention. However, taking into consideration the high prevalence of PFO, the low risk of stroke recurrence under medical treatment and the uncommon yet severe adverse events of the intervention, patient selection is crucial for attaining meaningful clinical benefits. Thorough workup to exclude alternative causes of stroke and identification of high-risk PFOs through clinical, neuroimaging and echocardiographic criteria are essential. Cost effectiveness of the procedure cannot be proven for the time being, since there are no robust data on clinical outcome after PFO-associated stroke but only limited anecdotal data suggesting low risk for long-term disability.

Epidemiology of Patent Foramen Ovale in General Population and in Stroke Patients: A Narrative Review

Introduction: Percutaneous closure of patent foramen ovale (PFO) in selected patients with cryptogenic cerebrovascular ischemic events (CEs) decreases the risk of recurrent stroke; however, optimal patient selection criteria are still under investigation. Candidates for PFO closure are usually selected from the pool of CE patients with a high risk of Paradoxical Embolism (RoPE) score. The RoPE score calculates the probability that PFO is causally related to stroke, based on PFO prevalence in patients with CE compared with that in healthy subjects. The latter has been set at 25% based on the average of autopsy and transesophageal echocardiography (TEE) studies.

Methods: We conducted a comprehensive review of studies investigating PFO prevalence in general population and in patients with CE and non-CE using autopsy, TEE, transcranial Doppler (TCD) or transthoracic echocardiography (TTE). Studies were excluded if they (1) reported data from referred subjects with underlying cerebrovascular disease or (2) did not specify etiologically the events.

Results: In healthy/control subjects, PFO prevalence was 24.2% (1,872/7,747) in autopsy studies, 23.7% (325/1,369) in TEE, 31.3% (111/355) in TCD, and 14.7% (186/1,267) in TTE studies. All diagnostic modalities included PFO prevalence was higher in CE compared with healthy/control population [odds ratio (OR) = 3.1, 95% confidence interval (CI) = 2.5–3.8] and compared with non-CE (OR = 2.3, 95% CI = 2.0–2.6). In patients with CE, PFO prevalence in the young compared to the old was higher when the diagnostic modality was TEE (48.9 vs. 27.3%, p < 0.0001, OR = 2.6 with 95% CI = 2.0–3.3) or TCD (58.1 vs. 41%, OR = 1.9, 95% CI = 1.6–2.5), but not TTE (53.3 vs. 37.5%, p = 0.16). Regarding non-CE, PFO prevalence in the young compared to the old was higher when the diagnostic modality was TEE (20 vs. 12.9%, OR = 1.7, 95% CI = 1.0–2.8) but not TTE (10.4 vs. 7.8%, p = 0.75) or TCD (22.8 vs. 20.1%, p = 0.56).

Conclusions: Given the limitations of autopsy and TEE studies, there is good reason not to take a fixed 25% PFO prevalence for granted. The estimation of degree of causality may be underestimated or overestimated in populations with PFO prevalence significantly lower or higher than the established. Given the high sensitivity, non-invasive nature, low cost, and repeatability of TCD, future large-scale TCD-based studies should investigate potential heterogeneity in PFO prevalence in different healthy racial/ethnic populations.

Efficacy and safety of percutaneous patent foramen ovale closure devices for recurrent stroke: A systemic review and network metaanalysis

Background:

Randomized controlled trials (RCTs) that directly compare the efficacy and safety of percutaneous patent foramen ovale (PFO) closure devices have not been conducted. Thus, we performed a network meta-analysis to identify the efficacy and safety of occluder devices.

Methods:

From 1st January, 2000 to 1st May, 2018, we searched Embase, PubMed, and Cochrane Library for RCTs about percutaneous closure devices (such as STARFlex, GORE, and Amplatzer) and medical therapy for cryptogenic cerebral ischemic patients with PFO. The occurrence rate of recurrent stroke, atrial fibrillation (AF), major vascular complication (MVC), headache, transient ischemic attack, and bleeding were compared with the frequentist and Bayesian methods using R statistics.

Results:

We included 3747 patients from six RCTs. The GORE and Amplatzer occluders were found to be significantly associated with a decreased risk of recurrent stroke [relative risk (RR): 0.37 and 0.49; 95% confidence interval (CI): 0.17–0.81, 0.29–0.83, respectively]. Moreover, STARFlex was correlated to an increased risk of postoperative AF and MVCs (RR: 11.66 and 7.63; 95% CI: 4.87–21.91, 2.34–24.88).

Conclusions:

Among the three devices, the GORE and Amplatzer occluders are found to be the most effective in preventing secondary stroke in patients with PFO. Meanwhile, STARFlex is the least recommended device because it cannot decrease the risk of recurrent stroke and is the most likely to cause adverse events.

Role of PFO Closure in Ischemic Stroke Prevention

PURPOSE OF REVIEW

To highlight recent advancements in the management of acute ischemic stroke patients with patent foramen ovale (PFO).

RECENT FINDINGS

One significant recent development was publication of long-term follow-up data from the RESPECT trial demonstrating evidence in favor of PFO closure over medical management. This data subsequently led to FDA approval for AMPLATZER™ septal occluder in the treatment of patients aged 18 to 60 years with both PFO and no other determined etiology for ischemic stroke, otherwise referred to as embolic stroke of undetermined source. Several subsequent closure trial results have recently been published, which also demonstrated benefit of PFO closure over medical management for ischemic stroke risk reduction in select patients. Based on the results of the more recently published REDUCE trial, the FDA granted approval for the GORE™ septal occluder. There is current, well-established evidence that PFO closure for secondary stroke prevention is effective in select cases.

Guidelines for the Early Management of Patients With Acute Ischemic Stroke: 2019 Update to the 2018 Guidelines for the Early Management of Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association

Background and Purpose- The purpose of these guidelines is to provide an up-to-date comprehensive set of recommendations in a single document for clinicians caring for adult patients with acute arterial ischemic stroke. The intended audiences are prehospital care providers, physicians, allied health professionals, and hospital administrators. These guidelines supersede the 2013 Acute Ischemic Stroke (AIS) Guidelines and are an update of the 2018 AIS Guidelines. Methods- Members of the writing group were appointed by the American Heart Association (AHA) Stroke Council's Scientific Statements Oversight Committee, representing various areas of medical expertise. Members were not allowed to participate in discussions or to vote on topics relevant to their relations with industry. An update of the 2013 AIS Guidelines was originally published in January 2018. This guideline was approved by the AHA Science Advisory and Coordinating Committee and the AHA Executive Committee. In April 2018, a revision to these guidelines, deleting some recommendations, was published online by the AHA. The writing group was asked review the original document and revise if appropriate. In June 2018, the writing group submitted a document with minor changes and with inclusion of important newly published randomized controlled trials with >100 participants and clinical outcomes at least 90 days after AIS. The document was sent to 14 peer reviewers. The writing group evaluated the peer reviewers' comments and revised when appropriate. The current final document was approved by all members of the writing group except when relationships with industry precluded members from voting and by the governing bodies of the AHA. These guidelines use the American College of Cardiology/AHA 2015 Class of Recommendations and Level of Evidence and the new AHA guidelines format. Results- These guidelines detail prehospital care, urgent and emergency evaluation and treatment with intravenous and intra-arterial therapies, and in-hospital management, including secondary prevention measures that are appropriately instituted within the first 2 weeks. The guidelines support the overarching concept of stroke systems of care in both the prehospital and hospital settings. Conclusions- These guidelines provide general recommendations based on the currently available evidence to guide clinicians caring for adult patients with acute arterial ischemic stroke. In many instances, however, only limited data exist demonstrating the urgent need for continued research on treatment of acute ischemic stroke.

Management of Patients with Patent Foramen Ovale and Cryptogenic Stroke: An Update

Patent foramen ovale (PFO) is a common benign finding in healthy subjects, but its prevalence is higher in patients with stroke of unclear cause (cryptogenic stroke). PFO is believed to be associated with stroke through paradoxical embolism, and certain clinical and anatomical criteria seem to increase the likelihood of a PFO to be pathological. Recent trials have shown that closure of PFO, especially if associated with an atrial septal aneurysm and/or a large interatrial shunt, may reduce the risk of recurrent stroke as compared to medical treatment. However, it remains challenging to risk stratify patients with suspected PFO-related stroke and to decide if device closure is indicated. We sought to review contemporary evidence and to conclude an evidence-based strategy to prevent recurrence of PFO-related stroke.

Embolic strokes of undetermined source: theoretical construct or useful clinical tool?

In 2014, the definition of embolic strokes of undetermined source (ESUS) emerged as a new clinical construct to characterize cryptogenic stroke (CS) patients with complete vascular workup to determine nonlacunar, nonatherosclerotic strokes of presumable embolic origin. NAVIGATE ESUS, the first phase III randomized-controlled, clinical trial (RCT) comparing rivaroxaban (15 mg daily) with aspirin (100 mg daily), was prematurely terminated for lack of efficacy after enrollment of 7213 patients. Except for the lack of efficacy in the primary outcome, rivaroxaban was associated with increased risk of major bleeding and hemorrhagic stroke compared with aspirin. RE-SPECT ESUS was the second phase III RCT that compared the efficacy and safety of dabigatran (110 or 150 mg, twice daily) to aspirin (100 mg daily). The results of this trial have been recently presented and showed similar efficacy and safety outcomes between dabigatran and aspirin. Indirect analyses of these trials suggest similar efficacy on the risk of ischemic stroke (IS) prevention, but higher intracranial hemorrhage risk in ESUS patients receiving rivaroxaban compared to those receiving dabigatran (indirect HR = 6.63, 95% CI: 1.38-31.76). ESUS constitute a heterogeneous group of patients with embolic cerebral infarction. Occult AF represents the underlying mechanism of cerebral ischemia in the minority of ESUS patients. Other embolic mechanisms (paradoxical embolism via patent foramen ovale, aortic plaque, nonstenosing unstable carotid plaque, etc.) may represent alternative mechanisms of cerebral embolism in ESUS, and may mandate different management than oral anticoagulation. The potential clinical utility of ESUS may be challenged since the concept failed to identify patients who would benefit from anticoagulation therapy. Compared with the former diagnosis of CS, ESUS patients required thorough investigations; more comprehensive diagnostic work-up than is requested in current ESUS diagnostic criteria may assist clinicians in uncovering the source of brain embolism in CS patients and individualize treatment approaches.

Microembolic signal detection by transcranial Doppler: Old method with a new indication

Transcranial Doppler (TCD) is useful for investigation of intracranial arterial blood flow and can be used to detect a real-time embolic signal. Unfortunately, artefacts can mimic the embolic signal, complicating interpretation and necessitating expert-level opinion to distinguish the two. Resolving this situation is critical to achieve improved accuracy and utility of TCD for patients with disrupted intracranial arterial blood flow, such as stroke victims. A common type of stroke encountered in the clinic is cryptogenic stroke (or stroke with undetermined etiology), and patent foramen ovale (PFO) has been associated with the condition. An early clinical trial of PFO closure effect on secondary stroke prevention failed to demonstrate any benefit for the therapy, and research into the PFO therapy generally diminished. However, the recent publication of large randomized control trials with demonstrated benefit of PFO closure for recurrent stroke prevention has rekindled the interest in PFO in patients with cryptogenic stroke. To confirm that emboli across the PFO can reach the brain, TCD should be applied to detect the air embolic signal after injection of agitated saline bubbles at the antecubital vein. In addition, the automated embolic signal detection method should further facilitate use of TCD for air embolic signal detection after the agitated saline bubbles injection in patients with cryptogenic stroke and PFO.