Diagnostic Yield of Pelvic Magnetic Resonance Venography in Patients With Cryptogenic Stroke and Patent Foramen Ovale

MRI in the Evaluation of Cryptogenic Stroke and Embolic Stroke of Undetermined Source

Cryptogenic stroke refers to a stroke of undetermined etiology. It accounts for approximately one-fifth of ischemic strokes and has a higher prevalence in younger patients. Embolic stroke of undetermined source (ESUS) refers to a subgroup of patients with nonlacunar cryptogenic strokes in whom embolism is the suspected stroke mechanism. Under the classifications of cryptogenic stroke or ESUS, there is wide heterogeneity in possible stroke mechanisms. In the absence of a confirmed stroke etiology, there is no established treatment for secondary prevention of stroke in patients experiencing cryptogenic stroke or ESUS, despite several clinical trials, leaving physicians with a clinical dilemma. Both conventional and advanced MRI techniques are available in clinical practice to identify differentiating features and stroke patterns and to determine or infer the underlying etiologic cause, such as atherosclerotic plaques and cardiogenic or paradoxical embolism due to occult pelvic venous thrombi. The aim of this review is to highlight the diagnostic utility of various MRI techniques in patients with cryptogenic stroke or ESUS. Future trends in technological advancement for promoting the adoption of MRI in such a special clinical application are also discussed.

Patent Foramen Ovale Percutaneous Closure: Evolution and Ongoing Challenges

Patent foramen ovale (PFO) concerns nearly a quarter of the general population and incidence may reach up to 50% in patients with cryptogenic stroke. Recent randomized clinical trials confirmed that percutaneous closure of PFO-related stroke reduces the risk of embolic event recurrence. PFO also comes into play in other pathogenic conditions, such as migraine, decompression sickness or platypnea-orthodeoxia syndrome, where the heterogeneity of patients is high and evidence for closure is less well-documented. In this review, we describe the current indications for PFO percutaneous closure and the remaining challenges, and try to provide future directions regarding the technique and its indications.

Gadofosveset-Trinatrium-Enhanced MR Angiography and MR Venography in the Diagnosis of Venous Thromboembolic Disease: A Single-Center Cohort Study

BACKGROUND

The aim of this single-center combined prospective/retrospective cohort study was to analyze Gadolinium (Gd)-enhanced MRA (magnetic resonance angiography) and MRV (MR venography) for the diagnosis of pulmonary artery embolism and deep venous thrombosis. The gold standard methods result in major exposure to radiation and a high amount of nephrotoxic iodinated contrast media. This is the first larger contrast-enhanced MR imaging study of acute and chronic venous thromboembolic disease of various stages.

METHODS

We prospectively examined 88 patients presenting clinical signs of deep vein thrombosis and/or pulmonary artery embolism. A single-session, one-stop shop Gd-enhanced MRA/MRV at 1.5 Tesla, using gradient echo sequences with very short repetition and echo times as well as low flip angles with subtraction and three-dimensional reconstruction, was performed. A diagnosis was made with the consensus of two experienced radiologists.

RESULTS

We observed excellent MRA image quality in 87% and even higher diagnostic image quality of MRV in 90% of our examinations. Pulmonary artery embolism occurred with deep vein thrombosis in 22%.

CONCLUSIONS

Gd-enhanced MRA/MRV provided excellent image quality for the diagnosis of venous thromboembolic disease in the majority of cases. It may be particularly useful to plan and follow-up filter implantation and retrieval in the inferior caval vein.

From cryptogenic to ESUS: Toward precision medicine?

Cryptogenic infarctions are infarctions without a defined cause, despite a complete work-up. They differ from infarctions of undetermined causes, which may involve overlapping causes or an incomplete investigation. It is also different from uncommon heritable and non-heritable causes. The term embolic stroke of undetermined source (ESUS) proposed in 2014 is defined as a non-lacunar brain infarct without proximal arterial stenosis or cardioembolic sources. The major advantage of this definition compared to cryptogenic definition is the proposition of a specific work-up. In a general population, frequent potential sources of embolism in patients with ESUS have been suggested since a long time and include: patent foramen ovale (PFO), covert atrial fibrillation (AF), complex aortic arch atheroma, large vessel atheroma with stenosis<50%, carotid web, atrial cardiomyopathy, thrombophilia associated with cancer. It took almost 30 years to show, in patients under 60 with a cryptogenic stroke and a PFO, that PFO occlusion was superior to medical treatment alone for recurrent stroke. PFO under 60 is therefore no longer a cryptogenic cause of infarction. The concept of cryptogenic stroke and its refinement in ESUS have been fruitful for the identification of PFO associated as a cause. Covert AF can be detected by different techniques but its risk significance for recurrent stroke might be different from the simple electrocardiographic detection of AF. With the development of direct oral anticoagulants (DOAs), randomized studies in patients with ESUS, were run for stroke prevention but no difference was observed between patients treated by DOA compared to aspirin. These studies showed however the heterogeneity of ESUS patients. Further ESUS classification should be considered as a tool to identify homogeneous groups. We propose to further split the ESUS group into different subgroups: ESU-PFO>60-year-old, ESUS-ATH with stenosis<50%, ESUS-AF (covert AF & atrial cardiomyopathy), ESUS-cancer and others. Precision medicine is the ability to make targeted healthcare decisions based on the specific risks of individual patients. One preliminary stage is therefore to identify homogeneous groups suitable in the future for new therapeutic trials and, at the end, for new specific treatments.

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.

Endovascular Intervention for May-Thurner Syndrome in a Pregnant Patient with a Patent Foramen Ovale and Paradoxical Embolism

May-Thurner syndrome (MTS) is a known structural risk factor for deep vein thrombosis (DVT) and embolism. In patients with a patent foramen ovale (PFO), emboli originating from the deep veins are able to paradoxically reach the systemic circulation via the PFO, consequently resulting in transient ischemic attacks (TIA) or stroke.We report the case of a 31-year-old pregnant woman, with a recent history of TIA, who presented with chronic bilateral numbness, pain, and swelling in the lower extremities. On imaging, she was found to have a PFO and MTS. Her pregnancy was subsequently terminated. This decision was made independently by the patient. Her care team did not advise her to terminate her pregnancy as there was no specific medical reason to do so. However, the patient was in significant physical pain and distress and ultimately was not comfortable continuing with the pregnancy. This highlights the complex, multifactorial decision-making process that pregnant patients with comorbid health conditions undertake. The patient then underwent transcatheter PFO closure and stents were placed bilaterally in the left and right common iliac veins. Following the stent procedure, lower extremity symptoms swiftly resolved, allowing the patient to significantly improve her ability to ambulate. There have been no signs of TIA since her procedures, and her venous symptoms have been stable.In patients with TIA or stroke from a paradoxical embolism, MTS should be considered as a potential etiology. Endovascular intervention to treat the underlying MTS should also be considered to decrease the risk of recurrent DVT and embolism.

Uncertainties and Controversies in the Management of Ischemic Stroke and Transient Ischemic Attack Patients With Patent Foramen Ovale

Multiple randomized clinical trials have demonstrated the benefit of patent foramen ovale closure over medical therapy alone for patients who have had a stroke that has been attributed to the patent foramen ovale. Nevertheless, there are many areas of uncertainty and controversy related to patient selection, pathophysiology, diagnosis, and treatment. We summarize the available data on these challenging topics and attempt to provide some clarity and future directions for clinicians and investigators.

Investigation of echocardiographic characteristics and predictors for persistent defects of patent foramen ovale or patent ductus arteriosus in Chinese newborns

Background

Persistent patent foramen ovale (PFO) and patent ductus arteriosus (PDA) increase the adult risk of cryptogenic embolic stroke and chronic pulmonary hypertension. To understand the characteristics of PFO and PDA in newborns, we investigated the spontaneous closure rate and derived the determinants for residual defects.

Methods

We utilized the database of congenital heart disease (CHD) in Xiamen ChangGung Memorial Hospital from 2015 to 2017 and allocated 2523 eligible newborns into four groups according to PDA, PFO, both or neither at birth. A total of 574, 1229, 202 and 518 newborns were assigned into the group of PFO and PDA, PFO alone, PDA alone and non-PFO/non-PDA, respectively. Regular echocardiographic follow-ups at baseline, 6, 12 and 24 months after birth were performed for evaluating the spontaneous closure rate in the subjects. Regression analysis was carried out to study the risk factors of residual congenital defects.

Results

Newborns with PFO alone had the youngest birth age and lowest birth weight among the four groups. About one in four PDA-alone newborns had concomitant small ASD, i.e., <5 mm in diameter. Echocardiographic study showed that 71.3% and 30.8% of CHD newborns had PFO and PDA, respectively, compared to less than 10% of them having ASD or VSD. However, more than 95% of newborns with PFO or PDA closed spontaneously at 6 months, in contrast to about 30% of newborns with ASD or VSD had persistent existence of the intracardiac defects. Complex CHD significantly linked to persistent PFO or PDA at 6 and 12 months, with an adjusted hazard ratio of 9.03 (95% CI 1.97–41.46) and 12.11 (95% CI 2.11–69.72), respectively.

Conclusions

Chinese newborns with PFO or PDA expressed differences in characteristics and concomitant congenital defects. Additionally, persistent PFO or PDA is strongly associated with complex CHD and requires long-term regular monitoring for future associated complications.

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.

Deep Vein Thrombosis and Pulmonary Embolism Among Patients With a Cryptogenic Stroke Linked to Patent Foramen Ovale-A Review of the Literature

Background: Venous thromboembolism (VTE) can occur simultaneously with a cryptogenic stroke (CS) linked to patent foramen ovale (PFO), given paradox thromboembolism as potential stroke cause. However, little is known on the frequency of concomitant VTE and CS. We aimed to review the literature on the frequency of VTE in patients with CS linked to PFO (primary aim) and of ischemic stroke (IS) among patients with pulmonary embolism (PE) (secondary aim).

Methods: We performed a Medline search for cohort studies, written in English, with the following characteristics: (a) enrolling patients hospitalized for an acute ischemic stroke undergoing a work-up for deep venous thrombosis (DVT) and/or PE. To be included in this review, a study had to have at least a subgroup of patients with PFO; (b) the time interval between the index stroke and the work-up had to be within 40 days and the studies had to differentiate between DVT and PE. For the secondary aim, studies had to include patients with acute PE, known PFO-status and routine brain imaging on admission or within 1 year.

Results: We found eight studies reporting on the frequency of VTE after an acute CS linked to PFO. Concerning DVT, the reported frequency ranged between 7 and 27%; concerning PE, it lied between 4.4 and 37%. Six studies assessed the frequency of ischemic brain lesions among patients with an acute PE. In all studies, the presence of PFO was associated with ischemic brain lesions, both at baseline and follow-up.

Conclusion: VTE can be detected in patients with CS linked to PFO. While –based on the presented literature–routine screening for VTE in patients with CS linked to PFO does not appear justified, history taking, and clinical exam should consider concomitant VTE. Whenever clinically suspected, the threshold to trigger ancillary testing for VTE should be low. Among patients with an acute PE and PFO, vigilance for new neurologic deficits should be increased, with a low threshold for brain imaging.

Diagnostic Yield of Early Examination for Venous Thrombosis in Patients with Cryptogenic Stroke and a Right-to-left Shunt

Objective The presence of deep venous thrombosis (DVT) in a cryptogenic stroke (CS) patient with a right-to-left shunt (RLS) may lead to the development of paradoxical embolism. The aim of the present was to investigate the prevalence of DVT and pulmonary embolism (PE) in CS patients and the clinical features of CS in relation to DVT location and the presence of PE. Methods The medical records of 903 patients with cerebral infarction were retrospectively reviewed. For patients with a diagnosis of CS, contrast saline transcranial color-coded sonography was performed to identify an RLS. DVT and PE were assessed by duplex ultrasonography and/or contrast-enhanced computed tomography. Proximal DVT (P-DVT) was defined as DVT in the popliteal, femoral, or iliac veins, and distal DVT (D-DVT) was defined as DVT at other locations. The patients were divided into three groups: CS with P-DVT and/or PE (P-DVT/PE) group; CS with D-DVT (D-DVT) group; and CS without DVT (no DVT) group. Results Seventy-two (37%) of 194 patients with CS had an RLS. The median time to first DVT examination from stroke onset was three days. Twenty-nine percent of CS patients with an RLS had DVT. The P-DVT/PE group comprised 8.3% of the CS patients with an RLS and included a larger number of patients with multi-territory infarction than the D-DVT group. The D-DVT and P-DVT/PE groups tended to be female and older, while the P-DVT/PE group tended to have pre-stroke disability. Conclusion CS patients, especially those with multi-territory lesions, should be immediately examined for DVT and PE.

Patent foramen ovale and embolic cryptogenic stroke

The paper considers the actual problem of cryptogenic stroke and patent foramen ovale (PFO). It highlights the issues of pathogenesis and role of paradoxical embolism in the development of cerebral circulation disorders. The features of clinical manifestations and neuroimaging pattern of stroke in the presence of PFO are described. Ultrasound diagnostic techniques used to verify a cardiac anomaly are characterized. Approaches to establishing a cause-and-effect relationship between the presence of PFO and the development of stroke are presented. The current possibilities of secondary prevention in this category of patients, in particular the results of studies of percutaneous PFO occlusion, are discussed.

[Ten key messages regarding embolic stroke of undetermined source and cryptogenic stroke]

Cryptogenic stroke is a cerebral infarction where no source of cardioembolic events, no microangiopathy with lacunar infarcts, and no macroangiopathy with high-grade stenosis of the cerebral arteries can be detected. However, cryptogenic stroke is not operationally defined. The new concept of the embolic stroke of undetermined source (ESUS) is defined as a nonlacunar stroke in cerebral imaging and exclusion of significant stenosis of the cerebral arteries by angiographic or ultrasound techniques. Cardiac embolic sources must be excluded by ECG monitoring and echocardiography. At the moment, secondary prevention in patients with ESUS is performed with acetylsalicylic acid. The question of whether non-vitamin K oral anticoagulants (NOAK) are effective in these patients for secondary prevention is currently being investigated in randomized trials. The acute treatment of cryptogenic stroke/ESUS does not differ from other stroke subtypes because the stroke etiology is often not known initially, but can be identified during the course of treatment in the stroke unit.

Patent foramen ovale and stroke

A patent foramen ovale (PFO) is a highly prevalent finding in cryptogenic ischaemic stroke, particularly in young adults. A common challenge in clinical practice is to distinguish between incidental and pathogenic PFO. Some clinical features and tools such as the Risk of Paradoxical Embolism score may help determining the probability of a stroke-related PFO. Nonetheless, the best therapeutic option to reduce stroke recurrence after a cryptogenic stroke with PFO has been a matter of debate for a long time. We review the mechanisms of stroke-related PFO, together with its clinical features and diagnostic criteria. In addition, we focus on the methodological details and results from new studies in the field of secondary prevention. In contrast to prior evidence, the data from three recent clinical trials and an updated meta-analysis favour PFO closure over medical treatment after cryptogenic stroke/TIA for the prevention of stroke recurrence. The PFO closure device procedure is not associated with higher mortality or cardiovascular events, except for a small increase in the occurrence of transient atrial fibrillation. Furthermore, the benefit of PFO closure was higher among those with atrial septal aneurysm and PFO with large right-to-left shunt. Future studies should address pending issues such as the option for anticoagulants or antiplatelet in patients not undergoing closure, the duration of antiplatelet treatment after PFO closure and the role of PFO closure in patients older than 60.

Cryptogenic Stroke: Research and Practice

BACKGROUND

Cryptogenic stroke accounts for 30% to 40% of ischemic stroke. It is essential to determine the possible culprit because this will improve secondary stroke prevention strategies.

METHODS

We performed a narrative nonsystematic review of the literature that included randomized trials, exploratory comparative studies, and case series on cryptogenic stroke.

RESULTS

There are several possible mechanisms implicated in cryptogenic stroke, including occult paroxysmal atrial fibrillation, patent foramen ovale, aortic arch atherosclerosis, atrial cardiopathy, and substenotic atherosclerosis. The heterogeneity of these mechanisms leads to differences in stroke prevention strategies among cryptogenic stroke patients.

CONCLUSIONS

A thorough diagnostic evaluation is essential to determine the pathogenesis in cryptogenic stroke. This approach, in addition to risk factor management and lifestyle modifications, will lead to improved stroke prevention strategies in patients with cryptogenic stroke. This will allow for targeted clinical trials to improve stroke prevention strategies in this patient population.

Patent Foramen Ovale and Stroke

A patent foramen ovale (PFO) is common and found in nearly 25% of healthy individuals. The majority of patients with PFO remain asymptomatic and they are not at increased risk for developing a stroke. The presence of PFO, however, has been found to be higher in patients with cryptogenic stroke, suggesting there may be a subset of patients with PFO who are indeed at risk for stroke. Paradoxical embolization of venous thrombi through the PFO, which then enter the arterial circulation, is hypothesized to account for this relationship. Although aerated-saline transesophageal echocardiography is the gold standard for diagnosis, aerated-saline transthoracic echocardiography and transcranial Doppler are often used as the initial diagnostic tests for detecting PFO. Patients with cryptogenic stroke and PFO are generally treated with antiplatelet therapy in the absence of another condition for which anticoagulation is necessary. Based on the findings of 3 large randomized clinical trials, current consensus guidelines do not recommend percutaneous closure, though this is an area of controversy. The following review discusses the relationship of PFO and cryptogenic stroke, focusing on the epidemiology, pathophysiological mechanisms, diagnostic tools, associated clinical/anatomic factors and treatment. (Circ J 2016; 80: 1665-1673).

Embolic Strokes of Unknown Source and Cryptogenic Stroke: Implications in Clinical Practice

Up to a third of strokes are rendered cryptogenic or of undetermined etiology. This number is specifically higher in younger patients. At times, inadequate diagnostic workups, multiple causes, or an under-recognized etiology contributes to this statistic. Embolic stroke of undetermined source, a new clinical entity particularly refers to patients with embolic stroke for whom the etiology of embolism remains unidentified despite through investigations ruling out established cardiac and vascular sources. In this article, we review current classification and discuss important clinical considerations in these patients; highlighting cardiac arrhythmias and structural abnormalities, patent foramen ovale, paradoxical sources, and potentially under-recognized, vascular, inflammatory, autoimmune, and hematologic sources in relation to clinical practice.

Ischemic stroke in the young: Current perspectives on incidence, risk factors, and cardiovascular prognosis

About one-fourth of ischemic strokes occur in working-aged individuals in the high-income countries, with worldwide increasing incidence in this age group from 1980s to present. Recent evidence suggests that traditional vascular risk factors are more prevalent than previously suggested in young adult stroke patients and they accumulate with age particularly in men. Accordingly, relatively high rates of atherosclerotic changes have been detected in these patients. The strength of association of vascular risk factors has gone poorly studied, however. Many young patients with ischemic stroke have, in turn, no traditional risk factors, while they may harbor other conditions with weak or uncertain association with the stroke alone. These individual conditions often represent a risk factor that may be strictly young-age specific, more prevalent in younger than older stroke patients (e.g. patent foramen ovale), or more prevalent among the young in the population. Despite high rates of vascular risk factors and atherosclerotic changes, these findings do not translate to higher frequencies of identified classical stroke mechanisms. In fact, cryptogenic causes are markedly common and even more frequent among the very young patients. Limited randomized trial evidence exists to support secondary prevention decision-making in patients, yet they face an increased risk of death and future vascular events for years to come-dependent on risk factor profile and cause of the stroke. This review provides an overview of recent data on epidemiology, risk factors, and their strength of association in ischemic stroke in the young. Furthermore, the relationship between with the risk factors and cardiovascular outcomes and key features on the evidence related to secondary prevention will be discussed.

Patent foramen ovale

Patent foramen ovale (PFO) is the most common congenital heart abnormality of fetal origin and is present in approximately ∼25% of the worldwide adult population. PFO is the consequence of failed closure of the foramen ovale, a normal structure that exists in the fetus to direct blood flow directly from the right to the left atrium, bypassing the pulmonary circulation. PFO has historically been associated with an increased risk of stroke, the mechanism of which has been attributed to the paradoxical embolism of venous thrombi that shunt through the PFO directly to the left atrium. However, several studies have failed to show an increased risk of stroke in asymptomatic patients with a PFO, and the risk of stroke recurrence is low in patients who have had a stroke that may be attributed to a PFO. With the advent of transoesophageal and transthoracic echocardiography, as well as transcranial Doppler, a PFO can be routinely detected in clinical practice. Medical treatment with either antiplatelet or anticoagulation therapy is recommended. At the current time, closure of the PFO by percutaneous interventional techniques does not appear to reduce the risk of stroke compared to conventional medical treatment, as shown by three large clinical trials. Considerable controversy remains regarding the optimal treatment strategy for patients with both cryptogenic stroke and PFO. This Primer discusses the epidemiology, mechanisms, pathophysiology, diagnosis, screening, management and effects on quality of life of PFO.

RP, Henninger N. Prevalence of Pelvic Vein Pathology in Patients with Cryptogenic Stroke and Patent Foramen Ovale Undergoing MRV Pelvis

Background: A substantial proportion of ischemic strokes has no any identified underlying cause. Notably, the prevalence of a patent foramen ovale (PFO) is increased in cryptogenic stroke (CS) populations, which may serve as a conduit for paradoxical emboli originating from deep vein thrombosis (DVT) including the pelvic veins. Yet, there are no published guidelines for the assessment of pelvic veins as part of the stroke workup and few studies have systematically investigated pelvic veins as a potential source for paradoxical emboli in CS patients. Further, there is a relative paucity of data regarding pelvic DVT in CS and results have been conflicting. Hence, we sought to determine the prevalence of pelvic DVT in select CS patients with PFO who underwent magnetic resonance venography (MRV). Methods: We retrospectively identified patients (n = 50) who underwent contrast-enhanced pelvic MRV at the discretion of the treating physician for the evaluation of CS in the presence of a PFO during hospitalization at a single academic stroke center between January 2011 through December 2013. Multivariable logistic regression analyses were used to assess for factors independently associated with the presence of an abnormal MRV pelvis. Results: Patients (47 ± 13 years of age) had MRV performed 4 ± 3 days after their incident stroke. Nine patients had an abnormal MRV (18%). Of these, four (8%) had pelvic vein thrombosis and 5 (10%) a May-Thurner anatomic variant. All patients with pelvic DVT were subsequently anticoagulated with warfarin (none had abnormal hypercoagulability testing). Clinical clues suggesting paradoxical embolism were present in as many as 40% of patients. On multivariable logistic regression, a history of any risk factors predisposing to DVT (OR 6.7; coefficient 1.9; BCa 95% CI 0.08-20.2; p = 0.014) as well as the number of predisposing risk factors (OR 3.9; coefficient 1.4; BCa 95% CI 0.25-4.2; p = 0.005) predicted the presence of pelvic vein pathology on MRV. Conclusion: We demonstrate a relatively high prevalence of pelvic DVT among select CS patients emphasizing the importance of considering the pelvic veins as a potential source for emboli particularly in the presence of risk factors known to predispose DVT. Because patients were included at the treating physician's discretion, our results reflect ‘real-life' practice. Our results may be of clinical importance as inclusion of pelvic vein imaging in CS patients with PFO had impactful therapeutic and nosologic implications. Further study is needed to define patients most likely to benefit from pelvic vein imaging.

Cryptogenic stroke

In about a quarter of ischaemic strokes the cause is undetermined, because the investigation is incomplete or delayed, because there are multiple causes or because the stroke is truly cryptogenic. Cryptogenic stroke can be further classified as non-embolic or embolic. Embolic stroke of undetermined source can be due to paroxysmal atrial fibrillation, minor emboligenic cardiac conditions, atheroembolism, cancer associated and paradoxical embolism through a patent foramen ovale (PFO) or less often a pulmonary fistula. Currently, risk factor control, statins and antiplatelets are the main therapeutic measures to prevent recurrent stroke. There is no evidence to implement routine closure of PFO in patients with cryptogenic stroke. Direct anticoagulants are being evaluated in randomized controlled trials including embolic stroke of undetermined source patients. Advances in high resolution ultrasound or magnetic resonance imaging of extracranial and intracranial vessels and of the heart and prolonged heart rhythm monitoring will be instrumental techniques to identify arterial and cardiac hidden causes of stroke.