Thromboembolism in the Absence of Atrial Fibrillation

Risk of cardioembolic ischemic events and relation to atrial fibrillation/flutter in patients with arrhythmogenic cardiomyopathy during a long-term follow-up

BACKGROUND

Arrhythmogenic cardiomyopathy (ACM) is an inherited heart disease characterized by fibro-fatty replacement of myocardium. Limited data is available concerning cardioembolic stroke. This study sought to determine the occurrence of cardioembolic ischemic events (CIEs) in ACM patients and to identify clinical and imaging predictors of CIEs.

METHODS

Every consecutive ACM patient was enrolled. ECG, Holter monitoring or implantable cardiac devices were used to detect atrial arrhythmias (AAs). CIEs were defined according to TOAST classification.

RESULTS

In our cohort of 111 patients, CIEs were observed in eleven (10%) over a 12.9-year median follow-up, with an incidence of 7.9 event/1000 patient-year (HR 4.12 compared to general population). Mean age at the event was 42 ± 9 years. Female sex (p = 0.03), T-wave inversion (p = 0.03), RVOT dilatation (p = 0.006) and lower LVEF (p = 0.006) were associated with CIEs. Among patients with AAs (23/111, 20.7%), 5 (21.7%) experienced CIEs. CHA2DS2-VASc did not prove useful to define patients at higher risk of CIEs (p = 0.098). 60% of stroke suffering patients had a pre-event score between 0 and 1 (if female).

CONCLUSIONS

In ACM patients, CIEs are much more common than in general population and present a high burden at younger age. AAs relate to less than half of these events. In AAs patients, CHA2DS2-VASc is not useful to stratify those requiring oral anticoagulation. As a hypothesis-generating study, our research proposes the role of atrial myopathy, irrespective of AAs, as a pivotal factor in thrombogenesis risk, pointing out a definite unmet need in ACM therapeutic algorithm.

Left atrial reservoir strain predicts ischaemic stroke after coronary artery bypass grafting independent of postoperative atrial fibrillation

Aims

Measures of left atrial (LA) function are known to predict both ischaemic stroke and atrial fibrillation in specific patient groups. The aim of this study was to investigate the value of LA reservoir strain for predicting ischaemic stroke in patients undergoing coronary artery bypass grafting (CABG) and investigate whether the presence of postoperative atrial fibrillation (POAF) modified this relationship.

Methods and results

Patients undergoing isolated CABG were included. The primary endpoint was ischaemic stroke. The association between LA reservoir strain and ischaemic stroke was investigated in uni- and multivariable Cox proportional hazards regression models including adjustment for POAF.We included 542 patients (mean age 67.3±8.9 years, 16.4% female). During a median follow-up period of 3.9 years, 21 patients (3.9%) experienced an ischaemic stroke. In total, 96 patients (17.7%) developed POAF during the index hospitalization. In a multivariable-adjusted Cox proportional hazards regression model, LA reservoir strain was significantly associated with the development of ischaemic stroke [HR (hazard ratio) 1.09 (95% CI 1.02-1.17) per 1% decrease, P = 0.011]. The presence of POAF did not modify this association (p for interaction = 0.07). The predictive value of the LA reservoir strain persisted in multiple sensitivity analyses including restricting the analysis to patients with normal left atrial volumes (LAV<34 ml/m²), patients without POAF, patients without prior stroke, and when excluding patients who developed atrial fibrillation at any time during follow-up.

Conclusion

LA reservoir strain was independently associated with ischaemic stroke in CABG patients. The predictive value of LA reservoir strain was unaffected by the presence of POAF. Prospective studies are warranted to validate the potential usefulness of LA reservoir strain to predict postoperative ischaemic stroke in the setting of CABG.

Atrial Fibrillation, thromboembolic risk, and the potential role of the natriuretic peptides, a focus on BNP and NT-proBNP - A narrative review

Atrial fibrillation (AF) is one of the most commonly encountered arrythmia in clinical practice. AF itself can be driven by genetic predisposition, ectopic electrical activity, and abnormal atrial tissue substrates. Often there is no single etiological mechanism, but rather a combination of factors that feed back to remodel and worsen tissue substrate, "AF begets AF". The clinical consequences of AF can often include emboli, heart failure, and early mortality. The classical AF cardioembolic (CE) concept requires thrombus formation in the left atrial appendage, with subsequent embolization. The temporal dissociation between AF occurrence and CE events has thrown doubt on AF as the driver of this mechanism. Instead, there has been a resurgence of the "atrial cardiomyopathy" (ACM) concept. An ACM is proposed as a potential mechanism of embolic disease through promotion of prothrombotic mechanisms, with AF instead reflecting atrial disease severity. Regardless, AF has been implicated in 25% to 30% of cryptogenic strokes. Natriuretic peptide(NP)s have been shown to be elevated in AF, with higher levels of both NT-proBNP and BNP being predictive of incidental AF. NPs potentially reflect the atrial environment and could be used to identify an underlying ACM. Therefore, this narrative review examines this evidence and mechanisms that may underpin the role of NPs in identifying atrial dysfunction, with focus on both, BNP and NTproBNP. We explore their potential role in the prediction and screening for both, ACM and AF. Moreover, we compare both NPs directly to ascertain a superior biomarker.

Left Atrial Volumes and Function, and Long-Term Incidence of Ischemic Stroke in the General Population

Background Left atrial (LA) volumes and emptying fraction in the general population may address structural and functional aspects of atrial cardiomyopathy associated with long-term risk of ischemic stroke in the absence of atrial fibrillation or prior stroke. We investigated the association between LA volumes and function and ischemic stroke. Methods and Results In a community-based cohort, we measured LA minimal volume, LA maximal volume, and LA emptying fraction by transthoracic echocardiography. The primary end point was ischemic stroke. Participants with known atrial fibrillation or prior ischemic stroke were excluded, which resulted in 1866 participants. The mean age was 58±16 years, and 57% were women. During a median follow-up of 16.5 years (interquartile range: 11.4-16.8 years), 176 (9.4%) ischemic strokes occurred. In multivariable cause-specific regression models and competing risk models with death as a competing risk, LA emptying fraction was associated with ischemic stroke (hazard ratio [HR], 1.14 per 10% decrease [95% CI, 1.02-1.28]) and (subdistribution HR, 1.14 [95% CI, 1.01-1.29]). This association remained when adjusting for participants who developed atrial fibrillation during follow-up (HR, 1.12 per 10% decrease [95% CI, 1.00-1.26]). Indexed LA volumes were not associated with ischemic stroke in the same models. LA emptying fraction and indexed LA volumes were not associated with all-cause mortality. Conclusions Lower LA emptying fraction measured by transthoracic echocardiography was associated with future ischemic stroke independently of incident atrial fibrillation. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02993172.

Comprehensive metabolomic characterization of atrial fibrillation

Background

Using human humoral metabolomic profiling, we can discover the diagnostic biomarkers and pathogenesis of disease. The specific characterization of atrial fibrillation (AF) subtypes with metabolomics may facilitate effective and targeted treatment, especially in early stages.

Objectives

By investigating disturbed metabolic pathways, we could evaluate the diagnostic value of biomarkers based on metabolomics for different types of AF.

Methods

A cohort of 363 patients was enrolled and divided into a discovery and validation set. Patients underwent an electrocardiogram (ECG) for suspected AF. Groups were divided as follows: healthy individuals (Control), suspected AF (Sus-AF), first diagnosed AF (Fir-AF), paroxysmal AF (Par-AF), persistent AF (Per-AF), and AF causing a cardiogenic ischemic stroke (Car-AF). Serum metabolomic profiles were determined by gas chromatography–mass spectrometry (GC-MS) and liquid chromatography–quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). Metabolomic variables were analyzed with clinical information to identify relevant diagnostic biomarkers.

Results

The metabolic disorders were characterized by 16 cross-comparisons. We focused on comparing all of the types of AF (All-AFs) plus Car-AF vs. Control, All-AFs vs. Car-AF, Par-AF vs. Control, and Par-AF vs. Per-AF. Then, 117 and 94 metabolites were identified by GC/MS and LC-QTOF-MS, respectively. The essential altered metabolic pathways during AF progression included D-glutamine and D-glutamate metabolism, glycerophospholipid metabolism, etc. For differential diagnosis, the area under the curve (AUC) of specific metabolomic biomarkers ranged from 0.8237 to 0.9890 during the discovery phase, and the predictive values in the validation cohort were 78.8–90.2%.

Conclusions

Serum metabolomics is a powerful way to identify metabolic disturbances. Differences in small–molecule metabolites may serve as biomarkers for AF onset, progression, and differential diagnosis.

Could echocardiographic left atrial characterization have additive value for detecting risks of atrial arrhythmias and stroke in patients with hypertrophic cardiomyopathy?

AIMS

Atrial arrhythmia (AA) is considered a turning point for prognosis in patients with hypertrophic cardiomyopathy (HCM). We sought to assess whether the occurrence of AA and stroke could be estimated by an echocardiographic evaluation.

METHODS AND RESULTS

A total of 216 patients with HCM (52 ± 16 years old) were analysed. All patients underwent transthoracic echocardiography for the evaluation of left atrial volume (LAV), peak left atrial strain (PLAS), and peak atrial contraction strain. The patients were followed for 2.9 years for the occurrence of a composite endpoint including AA and/or stroke and peripheral embolism. Among the 216 patients, 78 (36%) met the composite endpoint. These patients were older (57.1 ± 14.4 vs. 50.3 ± 16.7 years; P = 0.0035), had a higher prevalence of arterial hypertension (62.3 vs. 42.3%; P = 0.005), and had higher NT-proBNP. The LAV (47 ± 20 vs. 37.2 ± 15.7 mL/m²; P = 0.0001) was significantly higher in patients who met the composite endpoint, whereas PLAS was significantly impaired (19.3 ± 9.54 vs. 26.6 ± 9.12%; P < 0.0001). After adjustment, PLAS was independently associated with events with an odds ratio of 0.42 (95% confidence interval 0.29-0.61; P < 0.0001). Stroke occurred in 67% of the patients without any clinical AA. The PLAS with a cut-off of under 15.5% provided event prediction with 91% specificity. Using a 15% cut-off, PLAS also demonstrated a predictive value for new-onset of AA.

CONCLUSION

The decrease in PLAS was strongly associated with the risk of stroke, even in patients without any documented AA. Its value for guiding the management of patients with HCM requires further investigation.

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.

The Importance of Atrial Fibrillation's Associated Comorbidities as Clinical Presentation and Outcome Contributors

Atrial fibrillation (AF) has a heterogeneous clinical presentation. It can occur: (a) in the presence or absence of detectable heart disease, and, (b) with or without relatedsymptoms. Its prognosis in terms of thromboembolismand mortality is most benign when applied to young individuals (aged less than 60 years) without clinical orechocardiographic evidence of cardiopulmonary disease [termed "lone AF"]. However, by virtue of aging or because of the development of concomitant cardiovascular disorders, patientsmove out of the lone AF category over time, accompanied by increased risks for thromboembolism and mortality. Thus, underlying and/or associated comorbidities must play an important role in the presentation and consequences of patients with AF. While, no doubt, most clinicians likely appreciate that the majority of the AF patients they see have associated cardiovascular, pulmonary, metabolic, endocrinologic, genetic, and/or other disorders, it is not clear how much they appreciate that these disorders directly relate to the presenting symptoms and to the risks from AF in addition to their role as risk factors (or markers) for AF. This issue is the subject of this review manuscript.

Atrial cardiopathy predicts detection of atrial fibrillation in embolic stroke of undetermined source: real-life data

OBJECTIVES

Atrial cardiopathy (AC) is more frequent in patients with embolic stroke of undetermined source (ESUS) than in patients with non-cardioembolic stroke. The aim of this work was to describe AC in patients with ESUS and to study its impact on detection of atrial fibrillation (AF) during follow-up.

METHODS

This is an observational study of 123 consecutive ESUS patients and 55 ESUS patients from a previous cohort. AC was defined according to the presence of one or more of the following criteria: severe left atrial enlargement, p-wave terminal force in lead V₁ > 5000 μVxms, and excessive premature atrial complexes. Unadjusted and adjusted survival analyses for the occurrence of AF and stroke or transient ischemic attack (TIA) were performed. Diagnostic performance of AC for the detection of AF was analyzed.

RESULTS

Among 178 patients with ESUS, those with AC (42.7%) were older (p < 0.001), and more frequently had hypertension (p = 0.001) and lower total cholesterol levels (p = 0.001) than patients without AC. The detection of AF during follow-up (median 34 months, interquartile range = 12.8-64) was higher in patients with AC (hazard ratio = 7.00, 95% confidence interval = 2.01-24.39, p = 0.002). This association persisted after adjusting for age, arterial hypertension, and other vascular risk factors. The c-statistic for detection of AF during follow-up for AC was 0.719. There were no differences in stroke or TIA recurrence between groups with and without AC.

DISCUSSION

ESUS patients with AC have different baseline clinical characteristics than patients without AC and have a higher detection of AF during follow-up.

Cardiac mechanics and incident ischemic stroke: the Cardiovascular Health Study

Recent evidence indicates that our understanding of the relationship between cardiac function and ischemic stroke remains incomplete. The Cardiovascular Health Study enrolled community-dwelling adults ≥ 65 years old. We included participants with speckle-tracking data from digitized baseline study echocardiograms. Exposures were left atrial reservoir strain (primary), left ventricular longitudinal strain, left ventricular early diastolic strain rate, septal e’ velocity, and lateral e’ velocity. The primary outcome was incident ischemic stroke. Cox proportional hazards models were adjusted for demographics, image quality, and risk factors including left ventricular ejection fraction and incident atrial fibrillation. Among 4,000 participants in our analysis, lower (worse) left atrial reservoir strain was associated with incident ischemic stroke (HR per SD absolute decrease, 1.14; 95% CI 1.04–25). All secondary exposure variables were significantly associated with the outcome. Left atrial reservoir strain was associated with cardioembolic stroke (HR per SD absolute decrease, 1.42; 95% CI 1.21–1.67) and cardioembolic stroke related to incident atrial fibrillation (HR per SD absolute decrease, 1.60; 1.32–1.95). Myocardial dysfunction that can ultimately lead to stroke may be identifiable at an early stage. This highlights opportunities to identify cerebrovascular risk earlier and improve stroke prevention via therapies for early myocardial dysfunction.

Long-term implications of left atrial appendage thrombus identified incidentally by pre-procedural cardiac computed tomography angiography in patients undergoing transcatheter aortic valve replacement

AIMS

The prevalence and prognostic implications of left atrial appendage (LAA) thrombus (LAAT) in patients considered for transcatheter aortic valve replacement (TAVR) are incompletely defined. We, therefore, studied pre-procedural cardiac computed tomography angiography (CCTA) scans of TAVR candidates to determine the prevalence of LAAT and its association with late outcomes.

METHODS AND RESULTS

Baseline clinical variables and CCTA findings from a prospective TAVR registry were analysed for the prevalence of pre-procedural LAAT and its impact on in-hospital outcomes and late mortality. LAAT was differentiated from LAA filling defects (LAAFD) reflecting stasis without clot. Patients (n = 561) with complete in-hospital and late mortality data were included in the study (median follow-up 31.6 months). LAAT and LAAFD were evidenced on pre-procedural CCTA in 24 (4.3%) and 26 (4.6%) patients, respectively. One hundred fourteen (20.3%) patients died during the study period. Though in-hospital adverse event rates (including stroke) did not differ among groups, mortality at long-term follow-up was higher among LAAT patients compared with those with or without LAAFD (58.3% vs. 11.5% vs. 19.0%, respectively; P < 0.003). By multivariable analysis, LAAT (but not LAAFD) was independently associated with all-cause mortality [hazard ratio (HR) = 3.33 (1.83-6.00), P < 0.001]. In patients with LAAT, oral anticoagulation at discharge was associated with lower mortality risk, independently of atrial fibrillation status.

CONCLUSIONS

LAAT visualized by pre-procedural CCTA is an independent predictor of late mortality following TAVR, but not peri-procedural stroke. When reporting TAVR-CCTA, particular note should be made of LAA features and presence of LAAT which may have prognostic and management implications.

Atrial Cardiopathy Biomarkers and MRI-Based Infarct Patterns in Patients with Embolic Strokes of Undetermined Source

OBJECTIVES

The study aimed to investigate whether N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration and/or left atrial volume index (LAVI), as atrial cardiopathy biomarkers, were associated with infarct patterns on diffusion-weighted imaging in patients with embolic strokes of undetermined source (ESUS).

MATERIALS AND METHOD

We retrospectively evaluated patient with ESUS from our stroke registry between January 2018 and November 2019. Cut-off values for atrial cardiopathy biomarkers were defined as >250 pg/mL for NT-proBNP and >34 mL/m² for LAVI. Eligible patients were then assigned to 3 groups and infarct patterns were compared according to their atrial cardiopathy markers: Group 1 (no atrial cardiopathy markers), Group 2 (one marker), and Group 3 (both markers).

RESULTS

Among 194 eligible patients with ESUS (76 women; mean age, 69.2 years), simultaneous increases of NT-proBNP concentration and LAVI were identified in 39 (20.1%). Group 3 had a significantly larger infarct volume, relative to Group 1 and Group 2 (P=0.043) Multivariable logistic regression analyses revealed that these patients (Group 3) were significantly more likely to have multi-territorial infarcts (adjusted odds ratio [aOR]: 3.03, 95% confidence interval [CI]: 1.05-8.72; P=0.04), a maximal lesion diameter >15mm (aOR: 4.51, 95% CI: 1.70-11.93; P=0.001), and large cortical infarctions (aOR: 4.17, 95% CI: 1.75-9.96; P=0.001).

CONCLUSION

We found that simultaneously increased values for NT-proBNP concentration and LAVI were independently associated with multi-territorial and large cortical infarct patterns in patients with ESUS. These findings suggest that NT-proBNP and LAVI may be useful biomarkers for identifying cardioembolic subtypes and guiding treatment selection in patients with ESUS.

Left atrial dimension and ischemic stroke in patients with and without atrial fibrillation

The incidence of ischemic stroke (IS) increases in patients with enlarged left atrium (LA) irrespective of whether or not the existence of atrial fibrillation (AF). In such situation, it is unclear whether the impact of LA on incidence of IS still significant in young, non-AF patients with enlarged LA who are primarily unconcerned on anticoagulation therapy. The study population consisted of 18,511 consecutive patients not receiving oral anticoagulants and undergoing echocardiography with measurement of LAD at baseline. The incidence rate of ischemic stroke was calculated in 3 groups according to left atrial dimension (LAD; < 30, 30-45 and ≥ 45 mm) in AF and non-AF patients. Further subgroup analysis was performed in stratification by elderly and young (aged ≥ 65 and < 65 years, respectively). The incidences of IS (per 100 patient-years) were 0.11 and 0.71 in non-AF and AF patients with LAD < 30 mm, respectively, which increased to 0.58 and 1.35 in LAD ≥ 45 mm (adjusted hazard ratios [HRs]; 1.95 [95% confidence intervals, CIs: 0.76-5.01] and 1.22 [95% CIs: 0.27-5.58], interaction P was 0.246). In non-AF patients, the incidences of IS were 0.30 and 0.04 in elderly and young patients with LAD < 30 mm, which increased to 0.67 and 0.48 in LAD ≥ 45 mm (adjusted HRs; 1.34 [95% CIs: 0.43-4.15] and 4.21 [95% CIs: 0.77-23.12], interaction P was 0.158). The incidence of IS significantly increased with increase of LAD in non-AF, especially in non-AF and young patients, although the difference was not independent of other clinical factors. The impact of LAD on IS was numerically larger in non-AF than in AF, and larger in young and non-AF than in elderly counterpart, although a significant interaction was not observed in this small population. Further studies with large population are necessary to judge whether these population with enlarged LA need antithrombotic therapy.

The Link Between CHA2DS2-VASc Score and Thromboembolic Risk in Patients Without Known Atrial Fibrillation: Are We Missing a Silent Culprit?

Stroke is a leading cause of morbidity and mortality. The majority of strokes are ischemic and a subset of these are due to atrial fibrillation (AF). Other etiologies include a variety of cardiovascular disorders. The CHA₂DS₂-VASc score is a validated stroke prediction tool for patients with non-valvular AF. However, it has also been shown to predict increased risk for stroke or thromboembolism in the absence of AF. Given how common subclinical AF (SCAF) is when looked for in patients with elevated CHA₂DS₂-VaSc scores who are not known to have AF, (especially when implanted monitors are used), the stroke/thromboembolism risk that has been associated with CHA₂DS₂-VASc scores absent known AF may be an overestimate of the true risk due to the likely presence of SCAF in some of the subjects included. This has not yet been adequately addressed in the literature. Finally, the risk of a left atrial thromboembolic event is a consequence of the altered atrial anatomy and physiology (atrial cardiomyopathy) that may result from comorbid disorders and AF itself, or, additively from both - whether or not the AF has been already recognized clinically.