Embolic Stroke of Undetermined Source: A Population with Left Atrial Dysfunction

Altered left atrial metrics in patients with cryptogenic stroke: A systematic review and meta-analysis

BACKGROUND

There is no defined cause for cryptogenic stroke/embolic stroke of undetermined source (CS-ESUS). As atrial fibrillation (AF) develops in a significant proportion of these patients, it has been suggested that left atrial (LA) myopathy may predispose to CS-ESUS. We investigated alterations in echocardiographic measures of LA size and function in patients with CS-ESUS.

METHODS

A systematic literature review and meta-analysis was performed. PubMed, EMBASE, Cochrane Library, Web of Science and SCOPUS were searched for articles published between 1 January 1990 and 10 February 2023. All observational studies of adult CS-ESUS patients with LA volume or function measurements performed by transthoracic echocardiogram were included. Individual random effects meta-analyses were performed on LA measurements in the CS-ESUS patients using subgroup analysis of comparator groups.

RESULTS

We included 29 articles with 3927 CS-ESUS patients. Analysis of weighted mean differences showed CS-ESUS patients had altered LA structure and function parameters, with a larger maximum indexed LA volume, reduced LA emptying fraction and/or LA reservoir strain, compared to healthy controls and noncardioembolic stroke patients. Conversely, CS-ESUS patients had a smaller left atrium with better function, compared to cardioembolic stroke patients and CS-ESUS patients who subsequently developed atrial fibrillation.

CONCLUSIONS

LA volume and function are altered in CS-ESUS patients compared to healthy controls and other stroke aetiologies. An underlying atrial myopathy in a subset of CS-ESUS patients may be involved in both thrombogenesis and dysrhythmia (specifically AF). While LA functional assessment is not currently recommended following stroke, it may offer an opportunity for recurrent stroke risk stratification.

Arterial Hypertension and Its Consequences Are the Main Predictors of Embolic Stroke of Undetermined Source

Methods

We performed a hospital-based prospective cohort study with 1,317 enrolled participants. We compared patients and healthy volunteers according to the main demographic, anthropometric parameters, stroke risk factors, comorbidities, and data of clinical and instrumental examination. In order to balance the study and the control groups for age and sex, the propensity score matching was performed. In order to generate the overall predictive model, a multivariate analysis was performed using the binary logistic regression method.

Results

The following predictors of ESUS were identified in current study: arterial hypertension (AH); increased heart rate and pulmonary arterial systolic pressure (PASP); the presence of conduction disturbance; the enlargement of left, right atrium, and left ventricle end-systolic length; increased intima-media thickness (IMT) in right and left common carotid artery (CCA); lowered Montreal Cognitive Assessment (MoСA) cognitive scale score; the presence of subcortical microbleeds; central brain atrophy; the larger size of third ventricle; and the higher medial temporal lobe atrophy (MTA) score. The following risk factors were included in the final predictive model: the presence of AH (p < 0.0005; OR = 12.98 (95% CI: 4.53-37.21)) and PASP (p=0.018; OR = 1.13 (95% CI: 1.02-1.25)) and male sex (p=0.046; OR = 2.771 (95% CI: 1.017-7.555)). The Nagelkerke's pseudo-R-squared value was 0.404 and the significance of the Hosmer-Lemeshow test was 0.733, which indicate the goodness of the final logistic regression model.

Conclusions

We propose that AH and its consequences are the main predictors of ESUS. The results of this study emphasize the importance of AH control for primary and secondary prevention of ESUS.

Plasma FGF23 is associated with left atrial remodeling in children on hemodialysis

BACKGROUND

FGF23 mediates cardiac fibrosis through the activation of pro-fibrotic factors in in vitro models and is markedly elevated in kidney disease. Left atrial global longitudinal strain (LA GLS) derived by echocardiographic speckle-tracking measures longitudinal shortening of the LA walls, quantifies atrial performance and may enable detection of early LA remodeling in the setting of normal ventricular function. We hypothesized that LA GLS is abnormal in children on hemodialysis (HD) compared to healthy controls of comparable age/sex distribution and that, among HD patients, greater FGF23 levels are associated with abnormal LA GLS.

METHODS

Clinical and echocardiographic data from 29 children receiving HD and 13 healthy controls were collected in a cross-sectional single-center study. Plasma FGF23 concentrations were measured using ELISA. The primary outcome was LA GLS measured using 2D speckle-tracking strain analysis. Linear regression analysis was used to investigate predictors of LA GLS in HD.

RESULTS

Median dialysis vintage was 1.5 (IQR 0.5-4.3) years. Median intact FGF23 levels were substantially higher in the HD vs. control group (1206 [215, 4707] vs. 51 [43, 66.5] pg/ml; P = 0.0001), and LA GLS was 39.9% SD 11.6 vs. 32.8% SD 5.7 (P = 0.04). Among HD patients, higher FGF23 was associated with lower LA GLS (β per unit Ln-FGF23: - 2.7; 95% CI slope - 5.4, - 0.1; P = 0.04 after adjustment for age, body size, and HD vintage. FGF23 was not associated with LA phasic reservoir, conduit, or contractile strain.

CONCLUSIONS

In children on HD and preserved left ventricular ejection fraction, greater FGF23 is associated with lower LA GLS (indicative of impaired atrial performance). A higher resolution version of the Graphical abstract is available as Supplementary information.

Atrial cardiopathy in young adults with embolic stroke of undetermined source: a myocardial deformation imaging analysis

Background

Atrial cardiopathy (AC) has emerged as a potential pathological thrombogenic atrial substract of embolic stroke of undetermined source (ESUS), even in the absence of atrial fibrillation. Left atrium (LA) myocardial deformation analysis may be of value as a subclinical marker of AC and a predictor of ESUS.

Aims

To compare LA mechanical function between ESUS cases and age and sex-matched controls.

Methods

A single-center analytical study with case-control design was performed. Case group was composed by young patients admitted in the Neurology department from January 2017 to June 2021. Control group was composed by age and sex matched controls recruited from the community. All participants performed echocardiogram and a smaller sample underwent cardiac magnetic resonance.

Results

We recruited 31 ESUS patients aged between 18 and 65 years and 31 age and sex matched controls. ESUS patients had a significantly higher prevalence of cardiovascular risk factors and patent foramen ovale (PFO). The prevalence of AC was not different between groups. Echocardiogram parameters, including strain analysis, were similar between groups, except for LA appendage (LAA) ostium variation which was significantly lower in ESUS patients (absolute: 6.5vs8.7mm, p<0.001; relative: 44.5%vs53.4%, p=0.002). After exclusion of patients with PFO, all the results were statistically similar. Regarding cardiac magnetic resonance analysis, there were no statistically significant differences between groups.

Conclusion

This study shows that in our population atria cardiopathy and atrial function was not associated with ESUS.LAA structural and functional abnormalities may play a major role. The role of LAA in ESUS warrants further studies.

Prevention of Pathological Atrial Remodeling and Atrial Fibrillation: JACC State-of-the-Art Review

Atrial enlargement in response to pathological stimuli (e.g., hypertension, mitral valve disease) and physiological stimuli (exercise, pregnancy) can be comparable in magnitude, but the diseased enlarged atria is associated with complications such as atrial fibrillation (AF), whereas physiological atrial enlargement is not. Pathological atrial enlargement and AF is also observed in a small percentage of athletes undergoing extreme/intense endurance sport and pregnant women with preeclampsia. Differences between physiological and pathological atrial enlargement and underlying mechanisms are poorly understood. This review describes human and animal studies characterizing atrial enlargement under physiological and pathological conditions and highlights key knowledge gaps and clinical challenges, including: 1) the limited ability of atria to reverse remodel; and 2) distinguishing physiological and pathological enlargement via imaging/biomarkers. Finally, this review discusses how targeting distinct molecular mechanisms underlying physiological and pathological atrial enlargement could provide new therapeutic and diagnostic strategies for preventing or reversing atrial enlargement and AF.

Right atrium and cryptogenic ischaemic stroke in the young: a case-control study

Background

Recent studies suggest left atrial (LA) dysfunction in cryptogenic stroke. We studied the dynamics of right atrium (RA) and right atrial appendage (RAA) in young adults with cryptogenic stroke. We hypothesised that bi-atrial dysfunction and blood stagnation might contribute to thrombosis formation in patients with patent foramen ovale (PFO), as deep venous thrombosis is detected only in the minority of patients.

Methods

Thirty patients (aged 18–49) with a first-ever cryptogenic stroke and 30 age-matched and sex-matched stroke-free controls underwent cardiac magnetic resonance (CMR) imaging. An approach to estimate the RAA volume was developed, using crista terminalis and pectinate muscles as anatomical landmarks. Atrial expansion indices were calculated as (maximal volume – minimal volume) ×100%/minimal volume. Total pulmonary to systemic blood flow ratio (Qp/Qs) was based on phase contrast CMR. Right-to-left shunt (RLS) was evaluated with transoesophageal echocardiography in 29 patients and transcranial Doppler in 30 controls, moderate-to-severe RLS considered as clinically significant.

Results

We found that RA and RAA volumes were similar between patients and controls. Also, RA expansion index was similar, but RAA (95.6%±21.6% vs 108.7%±25.8%, p=0.026) and LA (126.2%±28% vs 144.9%±36.3%, p=0.023) expansion indices were lower in patients compared with controls. Seven (24%) of 29 patients had an RLS compared with 1 (3%) of 30 controls (p=0.012). Among 59 study subjects, RLS was associated with lower RA (81.9%±15.9% vs 98.5%±29.5%, p=0.030), RAA (84.7%±18% vs 105.6%±24.1%, p=0.022), LA (109.8%±18.6% vs 140.1%±33.7%, p=0.017) and LAA (median 102.9% (IQR 65.6%–121.7%) vs 229.1% (151.8%–337.5%], p=0.002) expansion indices and lower Qp/Qs ratio (0.91±0.06 vs 0.98±0.07, p=0.027).

Conclusions

This study suggests bi-atrial dysfunction in young adults with cryptogenic stroke, associated with moderate-to-severe RLS. Dysfunction of the atria and atrial appendages may be an additional mechanism for PFO-related stroke.

Trial registration number

NCT01934725.

Partitioning risk factors for embolic stroke of undetermined source using exploratory factor analysis

Background

Embolic stroke of undetermined source (ESUS) accounts for up to 25% of strokes. Understanding risk factors associated with ESUS is important in reducing stroke burden worldwide. However, ESUS patients are younger and present with fewer traditional risk factors. Significant global variation in ESUS populations also exists making the clinical picture of this type of stroke unclear.

Methods and results

ESUS patients were pair matched for age, sex, and ethnicity with a group of all other strokes (both n = 331). Exploratory factor analysis was applied in both groups to 14 risk and clinical factors to identify latent factors. In ESUS patients, two latent factors emerged consisting primarily of heart-related variables such as left ventricular wall motion abnormalities, reduced ejection fraction, and increased left atrial volume index, as well as aortic arch atherosclerosis. This is in comparison to the all other strokes group, which was dominated by traditional stroke risk factors.

Conclusions

Our findings support the existence of a unique pattern of risk factors specific to ESUS. We show that LVWMA and corresponding changes in left heart function are a potential source of emboli in these patients. In addition, the clustering of aortic arch atherosclerosis with left heart factors suggests a causal link. Through the application of exploratory factor analysis, this work contributes to a further understanding of stroke mechanisms in ESUS.

Association of Global Cardiac Calcification with Atrial Fibrillation and Recurrent Stroke in Patients with Embolic Stroke of Undetermined Source

BACKGROUND

Calcium deposits in the heart have been associated with cardiovascular events, mortality, stroke, and atrial fibrillation (AF). However, there is no accepted standard method for scoring cardiac calcifications. Existing methods have also not been validated for the assessment of patients with embolic stroke of undetermined source (ESUS). The aim of this study was to evaluate the association of various cardiac calcification scores with new-onset AF and stroke recurrence in a cohort of patients with ESUS.

METHODS

In this study, 181 consecutive patients with stroke diagnosed with ESUS were identified and evaluated. They were followed for new-onset AF and ischemic stroke recurrence for a median duration of 2.1 years. Various echocardiographic cardiac calcification scores were assessed on transthoracic echocardiography performed during the evaluation of ESUS and subsequently assessed for their relation to AF detection and recurrent stroke. The echocardiographic calcium scores assessed were the (1) global cardiac calcium score (GCCS), (2) echocardiographic calcium score (eCS), (3) echocardiographic calcification score, (4) echocardiographic composite cardiac calcium score, and (5) total heart calcification score. Only two of these scoring schemes, GCCS and eCS, quantified the cardiac calcium burden.

RESULTS

Higher calcium scores as measured by GCCS and eCS were found to be significantly associated with subsequent AF detection as well as recurrent ischemic stroke in patients with ESUS. The association with recurrent stroke remained significant even after adjustment for comorbidities and AF.

CONCLUSIONS

Higher cardiac calcification measured using the GCCS and eCS is independently associated with AF detection and recurrent ischemic stroke in patients with ESUS, and these scores can be useful markers for further risk stratification in patients with ESUS.

[Embolic stroke of undetermined source (ESUS) - Classification of a new stroke entity]

Embolic stroke of undetermined source (ESUS) represents a subpopulation of cryptogenic strokes defined by its embolic stroke pattern on imaging and if after a carefully performed diagnostic evaluation, a specific, well recognized cause of stroke has not been identified. This review article analyses the basics of the ESUS concept and provides an overview of the evidence from recent cohort studies. The definition, aetiology and diagnosis of ESUS are reassessed. Targeted diagnostics in ESUS patients can reduce the number of cryptogenic strokes by making a specific diagnosis.

Biomarkers of atrial cardiopathy in patients with different pathogenetic subtypes of ischemic stroke

Studies of the biomarkers of atrial cardiopathy seem to be promising for identifying patients with cryptogenic stroke (CS), in which an intensive search for atrial fibrillation is indicated. Nevertheless, the diagnostic value of these markers and their threshold values require clarification.

Objective: to present the characteristics of echocardiographic markers for atrial cardiopathy and the serum concentration of N-terminal pro-Btype natriuretic peptide (NT-proBNP) in embolic CS versus cardioembolic stroke (CES) and non-cardioembolic stroke (non-CES) to determine the threshold values of parameters with the highest sensitivity and specificity in differentiating CES and non-CES.

Patients and methods. A total of 259 patients with ischemic stroke were examined. The standard examination additionally involved calculation of the parameters that reflected left atrial LA) function (LAF): LA emptying fraction (LAEF), and LA functional index (LAFI). The serum NT-proBNP concentration was also determined in 75 patients.

Results and discussion. The patients with CES versus those with CS and non-CES were characterized by a considerable increase in LA diameter (4.3 [3.5; 4.5] cm vs 3.7 [3.4; 4.0] cm vs 3.7 [3.4; 3.9] cm; p=0.005 and p=0.009, respectively), LAVI (35.7 [30.5; 39.9] ml/m2 vs 28.5 [25.6; 34.6] ml/m2 vs 27.1 [24.5; 31.2] ml/m2 ; p< 0.001) and NT-proBNP level (559 [409; 1144] pg/ml vs 164 [65; 308] pg/ml vs 191 [63; 446] pg/ml; p=0.002 and p=0.019, respectively), as well as by a lower LAEF value [50.3 [48.5; 51.1]% vs 54.7 [51.6; 56.6]% vs 54.9 [52.5; 56.8]%; p< 0.001). The only parameter that showed significant differences between all the three groups (CES, CS, and nonCES) was LAFI (0.24 [0.2; 0.32] units vs 0.37 [0.3; 0.47] units vs 0.40 [0.34; 0.47] units; p<0.00 1), while maintaining the differences in the values for the two groups (CS and non-CES) (p=0.004). The following threshold values of biomarkers were obtained for CES and nonCES; these were a LA diameter of 41.5 mm (p< 0.001), a LAVI of 36.3 ml/m2 (p< 0.001), a LAEF of 51.8% (p< 0.001), a LAFI of 0.28 units (p< 0.001), and an NT-proBNP of 316 pg/ml (p< 0.001). Analysis of the ROC curves and the area under the curve (AUC) revealed that the most informative criteria for sensitivity and specificity were LAEF (79 and 88%, AUC 0.89), NT-proBNP (67 and 91%, AUC 0.89) and LAFI (93 and 72%, AUC 0.81).

Conclusion. The CS group and non-CES one are comparable in the echocardiographic manifestations of atrial cardiopathy and in serum NTproBNP values. LAEF and NT-proBNP concentrations are promising biomarkers to classify CS patients into potential arterio- and cardioembolic types.

Embolic Stroke of Undetermined Source: Gateway to a New Stroke Entity?

Embolic stroke of unknown source (ESUS) is currently thought to represent a subpopulation of cryptogenic strokes defined by its embolic stroke pattern on imaging, and if after a carefully performed diagnostic evaluation, a specific, well-recognized cause of stroke has not been identified. The concept was primarily established to justify and enable the conduct of the ESUS trials, such as Randomized, Double-Blind, Evaluation in Secondary Stroke Prevention Comparing the Efficacy and Safety of the Oral Thrombin Inhibitor Dabigatran Etexilate versus Acetylsalicylic Acid in Patients with Embolic Stroke of Undetermined Source (RESPECT-ESUS) and New Approach Rivaroxaban Inhibition of Factor Xa in a Global Trial versus aspirin to Prevent Embolism in Embolic Stroke of Undetermined Source (NAVIGATE-ESUS). With both studies having neutral results, the question arises if the ESUS concept is misleading or rather a gateway for a modern understanding of stroke etiology. This review will analyze the background of the ESUS concept, overview the results and the impact of the recent multicenter trials and cohort studies, and discuss the definition, etiology, and diagnosis of ESUS.

Left Atrial Dynamics Is Altered in Young Adults With Cryptogenic Ischemic Stroke: A Case-Control Study Utilizing Advanced Echocardiography

Background Ischemic stroke in young individuals often remains cryptogenic. Some of these strokes likely originate from the heart, and atrial fibrosis might be one of the etiological mechanisms. In this pilot study, we investigated whether advanced echocardiography findings of the left atrium (LA) of young cryptogenic stroke patients differ from those of stroke-free controls. Methods and Results We recruited 30 cryptogenic ischemic stroke patients aged 18 to 49 years and 30 age- and sex-matched stroke-free controls among participants of the SECRETO (Searching for Explanations for Cryptogenic Stroke in the Young: Revealing the Etiology, Triggers, and Outcome) study (NCT01934725). We measured basic left ventricular parameters and detailed measures of the LA, including 4-dimensional volumetry, speckle tracking epsilon, strain rate, and LA appendix orifice variation. Data were compared as continuous parameters and by tertiles. Compared with controls, stroke patients had smaller LA reservoir volumes (10.2 [interquartile range, 5.4] versus 13.2 [5.4] mL; P=0.030) and smaller positive epsilon values (17.8 [8.5] versus 20.8 [10.1]; P=0.023). In the tertile analysis, stroke patients had significantly lower left atrial appendage orifice variation (3.88 [0.75] versus 4.35 [0.90] mm; P=0.043), lower LA cyclic volume change (9.2 [2.8] versus 12.8 [3.5] mL; P=0.023), and lower LA contraction peak strain rate (-1.8 [0.6] versus -2.3 [0.6]; P=0.021). We found no statistically significant differences in left ventricular measures. Conclusions This preliminary comparison suggests altered LA dynamics in young patients with cryptogenic ischemic stroke, and thus that LA wall pathology might contribute to these strokes. Our results await confirmation in a larger sample.