Left atrial strain, embolic stroke of undetermined source, and atrial fibrillation detection

BACKGROUND

Atrial cardiopathy is a proposed mechanism of embolic stroke of undetermined source (ESUS). Left atrial (LA) strain may identify early atrial cardiopathy prior to structural changes. We aim to study the associations between LA strain, ESUS, and atrial fibrillation (AF) detection in ESUS.

METHODS

The study population included patients with ESUS and noncardioembolic (NCE) stroke presenting to the Rhode Island Hospital Stroke Center between January 2016 and June 2017 who underwent transthoracic echocardiography. Speckle tracking echocardiography (STE) was used to measure the three phases of LA strain (reservoir, conduit, and contractile). Binary logistic regression analysis was performed to determine the associations between LA strain and stroke subtype (ESUS vs. NCE) as well as follow-up detection of AF in ESUS patients.

RESULTS

We identified 656 patients, 307 with ESUS and 349 with NCE. In binary logistic regression, the lowest tertiles of LA reservoir (adjusted OR 1.944, 95% CI 1.266-2.986, p = .002), contractile (aOR 1.568, 95% CI 1.035-2.374, p = .034), and conduit strain (aOR 2.288, 95% CI 1.448-3.613, p = .001) were more likely to be significantly associated with ESUS compared to NCE stroke. Among all ESUS patients, the lowest tertiles of LA reservoir strain (OR 2.534, 95% CI 1.029-6.236, p = .043), contractile strain (OR 2.828, 95% CI 1.158-6.903, p = .022), and conduit strain (OR 2.614, 95% CI 1.003-6.815, p = .049) were significantly associated with subsequent detection of AF.

CONCLUSION

Reduced LA strain is associated with ESUS occurrence and AF detection in ESUS patients. Therefore, quantification of LA strain in ESUS patients may improve risk stratification and guide secondary prevention strategies.

Predicting risk of AF in ischaemic stroke using sinus rhythm ECG abnormalities: A meta-analysis

OBJECTIVE

To identify ECG changes in sinus rhythm that may be used to predict subsequent development of new AF.

METHOD

We identified prospective and retrospective cohort or case control studies evaluating ECG patterns from a 12-lead ECG in sinus rhythm taken in hospital or community predicting subsequent development of new AF. For each identified ECG predictor, we then identify absolute event rates and pooled risk ratios (RR) using an aggregate level random effects meta-analysis.

RESULTS

We identified 609,496 patients from 22 studies. ECG patterns included P wave terminal force V1 (PTFV1), interatrial block (IAB) and advanced interatrial block (aIAB), abnormal P wave axis (aPWA), PR prolongation and atrial premature complexes (APCs). Pooled risk ratios reached significance for each of these; PTFV1 RR 1.48 (95% CI 1.04-2.10), IAB 2.54 (95% CI 1.64-3.93), aIAB 4.05 (95% CI 2.64-6.22), aPWA 1.89 (95% CI 1.25-2.85), PR prolongation 2.22 (95% CI 1.27-3.87) and APCs 3.71 (95% CI 2.23-6.16). Diabetes reduced the predictive value of PR prolongation.

CONCLUSION

APC and aIAB were most predictive of AF, while IAB, PR prolongation, PTFV1 and aPWA were also significantly associated with development of AF. These support their use in a screening tool to identify at risk cohorts who may benefit from further investigation, or following stroke, with empirical anticoagulation.

Tricuspid regurgitation: a hidden risk factor for atrial fibrillation related stroke?

Background and purpose

Tricuspid regurgitation (TR) is a common but overlooked valvular disease, and its association with the etiologic subtypes of ischemic stroke is unclear. We explored the relationship between TR and atrial fibrillation (AF) in patients with acute ischemic stroke.

Methods

This retrospective analysis of ongoing stroke registry assessed 6,886 consecutive acute ischemic stroke patients who underwent transthoracic echocardiography during their in-hospital care. Multivariable logistic regression models adjusted for age, sex, stroke characteristics, and echocardiographic indices were used to investigate the association between TR and total AF, and newly diagnosed AF during hospitalization and a 1-year follow-up period, respectively.

Results

TR was present in 877 (12.7%) patients (mild, 9.9%; moderate, 2.4%; severe, 0.5%). AF was identified in 24.1% (medical history, 11.1%; first detected in the emergency room, 6.6%; newly diagnosed after admission, 6.4%). TR was associated with AF [adjusted odds ratio (aOR) 4.87 (95% confidence interval (CI), 2.63-9.03)], compared with no/trivial TR. The association between TR and AF was consistent regardless of severity (aOR [95% CI], 4.57 [2.63-7.94] for mild and 7.05 [2.57-19.31] for moderate-to-severe TR) or subtype of TR (5.44 [2.91-10.14] for isolated and 3.81 [2.00-7.28] for non-isolated TR). Among the AF-naïve patients at admission, TR was associated with newly diagnosed AF during hospitalization and a 1-year follow-up period (aOR [95% CI], 2.68 [1.81-3.97]).

Conclusions

TR is associated with AF in acute ischemic stroke patients regardless of severity and subtypes of TR. TR is also associated with newly diagnosed AF after stroke.

Risk of Dementia Associated With Atrial Cardiopathy: The ARIC Study

Background The contribution of atrial cardiopathy to dementia risk is uncharacterized. We aimed to evaluate the association of atrial cardiopathy with incident dementia and potential mediation by atrial fibrillation (AF) and stroke. Methods and Results We conducted a prospective cohort analysis of participants in the ARIC (Atherosclerosis Risk in Communities) study attending visit 5 (2011-2013). We used Cox regression to determine the association between atrial cardiopathy and risk of dementia. Structural equation modeling methods were used to determine potential mediation by AF and/or stroke. Atrial cardiopathy was defined if ≥1 of the following at visit 5: P-wave terminal force >5000 mV·ms in ECG lead V1, NT-proBNP (N-terminal pro-brain natriuretic peptide) >250 pg/mL or left atrial volume index ≥34 mL/m² by transthoracic echocardiography. We repeated our analysis necessitating ≥2 markers to define atrial cardiopathy. The prevalence of atrial cardiopathy was 34% in the 5078 participants (mean age 75 years, 59% female, 21% Black adults), with 763 participants developing dementia. Atrial cardiopathy was significantly associated with dementia (adjusted HR, 1.35 [95% CI, 1.16-1.58]), with strengthening of the effect estimate when necessitating ≥2 biomarkers (adjusted HR, 1.54 [95% CI, 1.25-1.89]). There was an increased risk of dementia among those with atrial cardiopathy when excluding those with AF (adjusted HR, 1.31 [95% CI, 1.12-1.55]) or stroke (adjusted HR, 1.28 [95% CI, 1.09-1.52]). The proportion of the effect mediated by AF was 4% (P=0.005), and 9% was mediated by stroke (P=0.048). Conclusions Atrial cardiopathy was significantly associated with an increased risk of dementia, with only a small percent mediation of the effect by AF or stroke.

Relationship Between High Blood Pressure, Atrial Cardiopathy, and Mortality in the General Population

BACKGROUND

Atrial cardiopathy is associated with an increased risk of mortality. However, it is unclear whether this association is modified by hypertension, a risk factor for both atrial cardiopathy and mortality.

METHODS

This analysis included 8,023 participants from the Third National Health and Nutrition Examination Survey. Electrocardiographic deep terminal negativity of P-wave in V1 ≥100 µV defined atrial cardiopathy. National Death Index was used to identify the date and cause of death. Cox proportional hazard analysis was used to examine the association of atrial cardiopathy with mortality among participants stratified by hypertension status.

RESULTS

In total 2.7% of the participants had atrial cardiopathy. Over a median follow-up of 14 years, 2,922 all-cause deaths occurred, of which 1,058 were CVD. All-cause death rates were almost double among participants with concomitant atrial cardiopathy and elevated blood pressure (BP) (120-129/<80), stage 1 (130-139/80-89), or stage 2 hypertension (≥140/≥90) compared to their counterparts in the same hypertension stages without atrial cardiopathy (47.8, 61.3, and 80.2 vs. 23, 24.7, and 44.8 per 1,000 person-years (PY), respectively). In multivariable-adjusted models, a stronger association between atrial cardiopathy and all-cause mortality was observed in the presence compared to the absence of hypertension (HR (95% CI): 1.59 (1.25-2.01) vs. 0.67 (0.41-1.10), respectively, interaction P-value = 0.009). Similarly, an association between atrial cardiopathy and cardiovascular disease (CVD) mortality was observed in the presence compared to the absence of hypertension (HR (95% CI): 1.64 (1.08-2.47) vs. 0.63 (0.20-2.00), respectively, interaction P-value = 0.20).

CONCLUSIONS

Concomitant presence of high BP and atrial cardiopathy carries a higher risk of mortality, and the risk increases with higher BP levels.

Markers of Atrial Cardiopathy in Severe Embolic Strokes of Undetermined Source

Background and Purpose

The current definition of embolic strokes of undetermined source (ESUS) seems to be too broad, including strokes due to heterogeneous mechanisms, such as atrial cardiopathy and other occult cardiac conditions, aortic arch plaques, and non-stenosing atherosclerosis, that can be differently associated with clinical stroke severity at the time of presentation. The aim of our study was to assess the possible association between neurological deficit severity and presence of markers of atrial cardiopathy in ESUS.

Methods

We retrospectively reviewed the medical records of a cohort of 226 ESUS patients (105 M, 121 F), that were divided into two groups according to the severity of neurological deficit (99 mild strokes with NIHSS ≤ 5 and 127 severe strokes with NIHSS >5). The following indices of atrial cardiopathy were evaluated: P wave dispersion, P wave max, P wave min, P wave mean, P wave index, P wave axis, left atrial size.

Results

Patients with severe ESUS were significantly older (74 ± 12 vs. 67 ± 14 years, P < 0.001) and female sex was prevalent (67 vs. 36%, P > 0.001); they had higher values of P-wave-dispersion (51 ± 14 vs. 46 ± 13, P = 0.01), P-wave-max (131 ± 20 vs. 125 ± 15 ms, P = 0.01), P-wave-index (16 ± 5 vs. 15 ± 5 ms, P = 0.01), left atrial size (20 ± 6 vs. 18 ± 4 cm², P = 0.01), left atrial volume index (31 ± 14 vs. 27 ± 11 ml/m², P = 0.04), in comparison with mild ESUS. An abnormal P wave axis was detected more frequently in severe ESUS (21 vs. 9%, P = 0.01). Furthermore, multivariate logistic regression showed that age (OR = 1.21 for each 5-year increase, 95% CI 1.09–1.35), sex (OR = 3.24 for female sex, 95% CI 1.82–5.76) and PWD (OR = 1.32 for each 10-ms increase, 95% CI 1.07–1.64) were the best subset of associated variables for severe ESUS.

Conclusions

Our findings shed light on specific clinical characteristics of severe ESUS including the presence of atrial cardiopathy that could play a pathogenic role in this subgroup of patients. Searching for atrial fibrillation in these patients is especially important to perform the most appropriate therapy.

Atrial Cardiopathy and Cryptogenic Stroke

Recent advances in pathophysiology suggest that a pathological atrial substrate can cause embolic stroke even in patients without atrial fibrillation (AF). This pathological condition is called “atrial cardiopathy”, which indicates atrial structural and functional disorders that can precede AF. The objective of this narrative review was to provide a current overview of atrial cardiopathy and cryptogenic stroke. We searched the PubMed database and summarized the recent findings of the identified studies, including the pathogenesis of atrial cardiopathy, biomarkers of atrial cardiopathy, relationship between atrial cardiopathy and cryptogenic stroke, and therapeutic interventions for atrial cardiopathy. Abnormal atrial substrate (atrial cardiopathy) that leads to AF can result in embolic stroke before developing AF, and may explain the source of cryptogenic stroke in some patients. Although there are several potential biomarkers indicative of atrial cardiopathy, P-wave terminal force in lead V1 (>5,000 μV^* ms), N-terminal pro-brain natriuretic peptide (>250 pg/ml), and left atrial enlargement are currently promising biomarkers for the diagnosis of atrial cardiopathy. Because the optimal combination and thresholds of biomarkers for diagnosing atrial cardiopathy remain uncertain, atrial cardiopathy represents a spectrum disorder. The concept of atrial cardiopathy appears to be most valuable as a starting point for therapeutic intervention to prevent stroke. Validation of the diagnosis of atrial cardiopathy and whether it can be used as a new therapeutic target for direct oral anticoagulants are currently being covered in the ARCADIA trial.

Left Atrial Remodeling and Brain Natriuretic Peptide Levels Variation after Left Atrial Appendage Occlusion

Background: Few data are available about brain natriuretic peptide (BNP) variation and left atrial remodeling after the left atrial appendage occlusion (LAAO) technique. Methods: Prospective study included all consecutive patients successfully implanted with an LAAO device. Contrast-enhanced cardiac computed tomography (CT) was performed before and 6 weeks after the procedure with reverse left atrial remodeling defined by an increase in LA volume >10%, together with blood sampling obtained before, 48 h after device implantation and at the first visit after discharge (30–45 days) for BNP measurement. Results: Among the 43 patients implanted with a complete dataset, mean end-diastolic LA volume was 139 ± 64 mL and 141 ± 62 mL at baseline and during follow-up (45 ± 15 days), respectively, showing no statistical difference (p = 0.45). No thrombus was seen on the atrial side of the device. Peridevice leaks (defined as presence of dye in the LAA beyond the device) were observed in 17 patients (40%) but were trivial or mild. Reverse atrial remodeling (RAR) at 6 weeks was observed in six patients (14%). Despite no difference in BNP levels on admission, median BNP levels at 48 h were slightly increased in RAR patients when compared with controls. During FU, BNP levels were strictly identical in both groups. These results were not modified even when each RAR case was matched with two controls on age, LVEF, creatinine levels and ACE inhibitors treatment to avoid potential confounders. Conclusion: Our study showed that despite the fact that the LAAO technique can induce left atrial remodeling measured by a CT scan, it does not seem to impact BNP levels on the follow-up. The results need to be transposed to clinical outcomes of this expanding population in future studies.

Atrial cardiopathy in embolic stroke of undetermined source

INTRODUCTION

Atrial cardiopathy is one of the most common potential sources of thromboembolism for embolic stroke of undetermined source (ESUS). The study aims to investigate the incidence of atrial cardiopathy (defined by severe left atrial enlargement (sLAE) or elevated serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) > 250 pg/ml) in patients with ESUS and compare with other stroke subtypes.

METHODS

We retrospectively collected data of 936 consecutive patients with diffusion-weighted imaging-confirmed acute ischemic stroke. The incidence of atrial cardiopathy was examined in ESUS, large artery atherosclerosis (LAA), and small vessel disease (SVD) strokes. Clinical characteristics were compared between ESUS patients with atrial cardiopathy (AC-ESUS) and patients with atrial fibrillation-induced cardioembolism (AF-CE) stroke.

RESULTS

245 patients were diagnosed with ESUS, while others were diagnosed with LAA (n = 312), SVD (n = 258), and AF-CE (n = 121) strokes. The incidence of sLAE in ESUS patients was higher than in LAA or SVD group (5.3% vs. 1.6% and 1.2%, respectively, p = .005) and higher than in combined LAA/SVD group (5.3% vs. 1.4%, p = .001). The incidence of elevated serum NT-proBNP in ESUS patients was not statistically different from that in LAA or SVD group. Compared with patients with AF-CE stroke, AC-ESUS patients had milder manifestations, had less hemorrhagic transformation, had better short-term outcome, and had fewer in-hospital complications.

CONCLUSIONS

The incidence of sLAE was higher in ESUS patients than in patients with noncardioembolic strokes. AC-ESUS was milder when compared to AF-CE stroke.

Associations Between Atrial Cardiopathy and Cerebral Amyloid: The ARIC-PET Study

Background Atrial fibrillation (AF) is a risk factor for cognitive decline, possibly from silent brain infarction. Left atrial changes in structure or function (atrial cardiopathy) can lead to AF but may impact cognition independently. It is unknown if AF or atrial cardiopathy also acts on Alzheimer disease-specific mechanisms, such as deposition of β-amyloid. Methods and Results A total of 316 dementia-free participants from the ARIC (Atherosclerosis Risk in Communities) study underwent florbetapir positron emission tomography, electrocardiography, and 2-dimensional echocardiography. Atrial cardiopathy was defined as ≥1: (1) left atrial volume index >34 mL/m2; (2) P-wave terminal force >5000 µV×ms; and (3) serum NT-proBNP (N-terminal pro-B-type natriuretic peptide) >250 pg/mL. Cross-sectional associations between global cortical β-amyloid (>1.2 standardized uptake value ratio) and adjudicated history of AF and atrial cardiopathy, each, were evaluated using multivariable logistic regression. Participants (mean age, 76 years) were 56% women and 42% Black individuals. Odds of elevated florbetapir standardized uptake value ratio were significantly increased among those with atrial cardiopathy (odds ratio, 1.81; 95% CI, 1.02-3.22) and doubled for those with enlarged left atrial volume index after adjustment for demographics/risk factors (95% CI, 1.04-4.61). There was no association between P-wave terminal force or NT-proBNP and elevated florbetapir standardized uptake value ratio, nor between AF and elevated standardized uptake value ratio. Conclusions Among healthy, nondemented community-dwelling older individuals, we report an association between atrial cardiopathy, left atrial volume index, and elevated brain amyloid, by positron emission tomography, without a similar association in individuals with AF. Potential limitations include reverse causation and survival bias. Ongoing work will help determine if changes in cardiac structure and function precede or occur simultaneously with amyloid deposition.

P Wave Dispersion and Silent Atrial Fibrillation in Cryptogenic Stroke: The Pathogenic Role of Inflammation

BACKGROUND

Cryptogenic stroke (CS) represents 25% of ischemic strokes. Especially after CS, the detection of atrial fibrillation (AF) is important because it provides clues to the mechanism of stroke. However, the relationship between AF and stroke appears more complex than a simple cause-effect mechanism, suggesting that the association between AF and stroke may be due to other systemic and atrial factors including systemic inflammation that may lead to atrial remodeling and subsequent atrial cardiopathy.

OBJECTIVE

The aim of this study was to evaluate the relationship among different electrocardiographic parameters, inflammatory markers and in-hospital AF occurrence after acute CS.

METHODS

222 patients with CS underwent 12-lead resting ECG at admission and 7-day in-hospital ECG monitoring. The following indices were evaluated: P-wave dispersion (PWD), P-wave index, P-wave axis, atrial size and high-sensitivity-C reactive protein (CRP).

RESULTS

AF was detected in 44 patients. AF-group had significantly higher PWD, P-wave index, PR interval, CRP and greater frequency of abnormal P-wave axis in comparison with no-AF group. There was a significant correlation between CRP and PWD (r=0.28). By using the mediation analysis, performed according to the "bootstrapping" method, we found that PWD is a significant mediator variable of the relationship between CRP and AF occurrence, accounting for 40% of the association.

CONCLUSIONS

In cryptogenic stroke, high PWD is partly due to systemic inflammation that increases AF risk possibly via atrial electric remodeling. These findings could also suggest inflammation as a possible therapeutic target in order to prevent atrial electrical alterations and finally AF occurrence in CS.

Atrial Cardiopathy in the Absence of Atrial Fibrillation Increases Risk of Ischemic Stroke, Incident Atrial Fibrillation, and Mortality and Improves Stroke Risk Prediction

Background Atrial fibrillation (AF) is a major, often undetected, cardiac cause of stroke. Markers of atrial cardiopathy, including left atrial enlargement (LAE) or excessive atrial ectopy (EAE) increase the risk of AF and have shown associations with stroke. We sought to determine whether these markers improve stroke risk prediction beyond traditional vascular risk factors (eg CHA₂DS₂-VASc score). Methods and Results Retrospective longitudinal cohort of 32 454 consecutive community-dwelling adults aged ≥65 years referred for outpatient echocardiogram or Holter in Ontario, Canada (2010-2017). Moderate-severe LAE was defined as men >47 mm and women >43 mm, and EAE was defined as >30 APBs per hour. Cause-specific competing risks Cox proportional hazards used to estimate risk of ischemic stroke (primary), incident AF, and death (secondary). C-statistics, incremental discrimination improvement and net reclassification were used to compare CHA₂DS₂-VASc with LAE and EAE to CHA₂DS₂-VASc alone. Each 10 mm increase in left atrial diameter increased 2- and 5-year adjusted cause-specific stroke hazard almost 2-fold (LAE: 2-year hazard ratio (HR), 1.72; P=0.007; 5-year HR, 1.87; P<0.0001), while EAE showed no significant associations with stroke (2-year HR, 1.00; P=0.99; 5-year HR, 1.08, P=0.70), adjusting for incident AF. Stroke risk estimation improved significantly at 2 (C-statistics=0.68-0.75, P=0.008) and 5 years (C-statistics=0.70-0.76, P=0.003) with LAE and EAE. Conclusions LAE was independently associated with an increased risk of ischemic stroke in the absence of AF and both LAE and EAE improved stroke risk prediction. These findings have implications for stroke risk stratification, AF screening, and stroke prevention before the onset of AF.

Association between advanced interatrial block and small vessel diseases in the brain

Background

The latest evidence shows the association of atrial cardiopathy with embolic strokes of undetermined source. Advanced interatrial block (aIAB) is an electrophysiological mark of atrial cardiopathy. This study investigated the relationship between aIAB and the burden of silent cerebral small vessel diseases (SVD) on magnetic resonance imaging in the absence of atrial fibrillation (AF) and atrial flutter.

Methods

This cross-sectional study included 499 patients with normal left ventricular ejection fraction (LVEF), who were free of AF, atrial flutter, stroke, and acute coronary syndrome in our hospital. aIAB was ascertained by digital electrocardiograms. Left atrial diameter, LVEF, and left ventricular posterior wall thickness (LVPWT) were measured on echocardiograms. Based on the presence of 4 manifestations of SVD, including white matter hyperintensity (WMH), lacunes, microbleeds, and enlarged perivascular spaces (EPVS) on magnetic resonance imaging, an ordinal SVD score (range, 0-4) was devised to reflect the total burden of cerebral SVD. The ordinal regression model was used to explore the association of aIAB with SVD burden after adjusting for confounding factors.

Results

The mean age was 67.7 years, and 327 (65.5%) were male. A total of 23 (4.6%) patients had aIAB. The number of patients with cerebral SVD scores of 0, 1, 2, 3, and 4 was 92 (18.4%), 122 (24.4%), 190 (38.1%), 83 (16.6%), and 12 (2.4%), respectively. After adjusting for age, sex, hypertension, diabetes, hyperlipidemia, left atrial diameter, LVEF, and LVPWT, the regression model showed a significant association of aIAB with cerebral SVD score (OR =2.408, 95% CI, 1.082-5.366).

Conclusions

Atrial cardiopathy indexed by aIAB was independently associated with a high burden of SVD in the brain.

Atrial cardiopathy and stroke mortality in the general population

BACKGROUND

Prior studies examining the link between atrial cardiopathy and stroke risk have focused mainly on non-fatal stroke.

AIMS

To examine the association between atrial cardiopathy and stroke mortality.

METHODS

This analysis included 8028 participants (60.0 ± 13.4 years, 51.9% women, 49.8% white) from the Third National Health and Nutrition Examination (NHANES III) Survey. Atrial cardiopathy was defined as abnormal deep terminal negativity of the P wave in V1 (DTNPV1 = negative p-wave in V1<-100 µv), an electrocardiographic marker of atrial cardiopathy. Stroke mortality was ascertained using the National Death Index over a median follow-up of 14 years.

RESULTS

2.95% (n = 237) of the participants had atrial cardiopathy, and the prevalence was slightly higher in blacks (4%) versus whites (3%). During follow-up, stroke mortality was more common in those with (5.9%) than those without (2.7%) atrial cardiopathy; p = .004. In a multivariable adjusted model, atrial cardiopathy was associated with a 76% increased risk of stroke mortality (HR (95% CI): 1.76 (1.02-3.04)]. This association was stronger in non-whites than whites (HR (95% CI): 3.50 (1.74-7.03) vs. 0.98 (0.40-2.42), respectively; interaction p = 0.03). Among those with baseline atrial cardiopathy, the annualized stroke mortality rates/1000 participants across CHA₂DS₂-VASc scores of 0, 1, and ≥2 were 0.0, 2.2, and 7.8, respectively.

CONCLUSIONS

Atrial cardiopathy is associated with an increased risk of stroke mortality, especially among non-whites. Among those with atrial cardiopathy, the risk of stroke mortality exponentially increases as the CHA₂DS₂-VASc score becomes 2 or above. Randomized controlled trials are needed to assess the efficacy of anticoagulation in the prevention of ischemic stroke and thus, stroke mortality in the presence of atrial cardiopathy.

The AtRial Cardiopathy and Antithrombotic Drugs In prevention After cryptogenic stroke randomized trial: Rationale and methods

RATIONALE

Recent data suggest that a thrombogenic atrial substrate can cause stroke in the absence of atrial fibrillation. Such an atrial cardiopathy may explain some proportion of cryptogenic strokes.

AIMS

The aim of the ARCADIA trial is to test the hypothesis that apixaban is superior to aspirin for the prevention of recurrent stroke in subjects with cryptogenic ischemic stroke and atrial cardiopathy.

SAMPLE SIZE ESTIMATE

1100 participants.

METHODS AND DESIGN

Biomarker-driven, randomized, double-blind, active-control, phase 3 clinical trial conducted at 120 U.S. centers participating in NIH StrokeNet.

POPULATION STUDIED

Patients ≥ 45 years of age with embolic stroke of undetermined source and evidence of atrial cardiopathy, defined as ≥ 1 of the following markers: P-wave terminal force >5000 µV × ms in ECG lead V1, serum NT-proBNP > 250 pg/mL, and left atrial diameter index ≥ 3 cm/m2 on echocardiogram. Exclusion criteria include any atrial fibrillation, a definite indication or contraindication to antiplatelet or anticoagulant therapy, or a clinically significant bleeding diathesis. Intervention: Apixaban 5 mg twice daily versus aspirin 81 mg once daily. Analysis: Survival analysis and the log-rank test will be used to compare treatment groups according to the intention-to-treat principle, including participants who require open-label anticoagulation for newly detected atrial fibrillation.

STUDY OUTCOMES

The primary efficacy outcome is recurrent stroke of any type. The primary safety outcomes are symptomatic intracranial hemorrhage and major hemorrhage other than intracranial hemorrhage.

DISCUSSION

ARCADIA is the first trial to test whether anticoagulant therapy reduces stroke recurrence in patients with atrial cardiopathy but no known atrial fibrillation.

Atrial Cardiopathy and Sympatho-Vagal Imbalance in Cryptogenic Stroke: Pathogenic Mechanisms and Effects on Electrocardiographic Markers

Recently, atrial cardiopathy has emerged as possible pathogenic mechanism in cryptogenic stroke and many electrocardiographic (ECG) markers have been proposed in order to detect an altered atrial substrate at an early stage. The autonomic nervous system (ANS) plays a well-known role in determining significant and heterogeneous electrophysiological changes of atrial cardiomyocytes, that promote atrial fibrillation episodes in cardioembolic stroke. Conversely, the role of ANS in atrial cardiopathy and cryptogenic stroke is less known, as well as ANS effects on ECG markers of atrial dysfunction. In this paper, we review the evidence linking ANS dysfunction and atrial cardiopathy as a possible pathogenic factor in cryptogenic stroke.

Left Atrial Appendage Morphology and Embolic Stroke of Undetermined Source: A Cross-Sectional Multicenter Pilot Study

BACKGROUND

The left atrial appendage (LAA) is the main source of thrombus in atrial fibrillation, and there is an association between non-chicken wing (NCW) LAA morphology and stroke. We hypothesized that the prevalence of NCW LAA morphology would be higher among patients with cardioembolic (CE) stroke and embolic stroke of undetermined source (ESUS) than among those with noncardioembolic stroke (NCS).

METHODS

This multicenter retrospective pilot study included consecutive patients with ischemic stroke from 3 comprehensive stroke centers who previously underwent a qualifying chest computed tomography (CT) to assess LAA morphology. Patients underwent inpatient diagnostic evaluation for ischemic stroke, and stroke subtype was determined based on ESUS criteria. LAA morphology was determined using clinically performed contrast enhanced thin-slice chest CT by investigators blinded to stroke subtype. The primary predictor was NCW LAA morphology and the outcome was stroke subtype (CE, ESUS, NCS).

RESULTS

We identified 172 patients with ischemic stroke who had a clinical chest CT performed. Mean age was 70.1 ± 14.3 years and 51.7% were male. Compared with patients with NCS, the prevalence of NCW LAA morphology was higher in patients with CE stroke (58.7% versus 46.3%, P = .1) and ESUS (58.8% versus 46.3%, P = .2), but this difference did not achieve statistical significance.

CONCLUSION

The prevalence of NCW LAA morphology may be similar in patients with ESUS and CE, and may be higher than that in those with NCS. Larger studies are needed to confirm these associations.

Atrial cardiopathy: a mechanism of cryptogenic stroke

INTRODUCTION

Cryptogenic stroke accounts for approximately 30% of all ischemic strokes. Recently, atrial cardiopathy diagnosed by the presence of one of its serum, imaging, or electrocardiogram biomarkers has been shown to be associated with ischemic stroke, particularly of embolic subtypes. Areas covered: This paper aims to summarize data on occult atrial fibrillation and stroke, provide an overview on mechanisms, such as inflammation and fibrosis, of stroke in atrial cardiopathy, critically review data on biomarkers of atrial cardiopathy and their association with stroke, and suggest therapeutic implications, including directions for future research. Expert commentary: Atrial cardiopathy may constitute one of the mechanisms in cryptogenic stroke, and patients with evidence of atrial cardiopathy constitute a group of patients in whom clinical trials are warranted to test anticoagulation versus antiplatelet therapy to reduce stroke recurrence risk. In addition, more studies are needed to determine the degree of overlap between these atrial cardiopathy biomarkers and which one is more useful in predicting the risk of stroke and response to anticoagulation therapy.

PR Interval Prolongation and Cryptogenic Stroke: A Multicenter Retrospective Study

BACKGROUND

Atrial dysfunction or "cardiopathy" has been recently proposed as a mechanism in cryptogenic stroke. A prolonged PR interval may reflect impaired atrial conduction and thus may be a biomarker of atrial cardiopathy. We aim to compare the prevalence of PR interval prolongation in patients with cryptogenic stroke (CS) when compared with known non-cryptogenic non-cardioembolic stroke (NCNCS) subtypes.

METHODS

We used prospective ischemic stroke databases of 3 comprehensive stroke centers to identify patients 18 years or older with a discharge diagnosis of ischemic non-cardioembolic stroke between December 1, 2013 and August 31, 2015. The main outcome was ischemic stroke subtype (CS versus NCNCS). We compared PR intervals as a continuous and categorical variable (<200 milliseconds; ≥200 milliseconds) and other clinical and demographic factors between the 2 groups and used multivariate regression analyses to determine the association between PR interval prolongation and CS.

RESULTS

We identified 644 patients with ischemic non-cardioembolic stroke (224 CS and 420 NCNCS). Patients with CS were more likely to have a PR of 200 milliseconds or greater when compared with those with NCNCS (23.2% versus 13.8%, P = .009). After adjusting for factors that were significant in univariate analyses, a PR of 200 milliseconds or greater was independently associated with CS (odds ratio [OR] 1.70, 95% CI 1.08-2.70). The association was more pronounced when excluding patients on atrioventricular nodal blocking agents (OR 2.64, 95% CI 1.44-4.83).

CONCLUSIONS

A PR of 200 milliseconds or greater is associated with CS and may be a biomarker of atrial cardiopathy in the absence of atrial fibrillation. Prospective studies are needed to confirm this association.

Atrial cardiopathy: a broadened concept of left atrial thromboembolism beyond atrial fibrillation

Atrial fibrillation (AF) has long been associated with a heightened risk of ischemic stroke and systemic thromboembolism, but recent data require a re-evaluation of our understanding of the nature of this relationship. New findings about the temporal connection between AF and stroke, alongside evidence linking markers of left atrial abnormalities with stroke in the absence of apparent AF, suggest that left atrial thromboembolism may occur even without AF. These observations undermine the hypothesis that the dysrhythmia that defines AF is necessary and sufficient to cause thromboembolism. In this commentary, we instead suggest that the substrate for thromboembolism may often be the anatomic and physiological atrial derangements associated with AF. Therefore, our understanding of cardioembolic stroke may be more complete if we shift our representation of its origin from AF to the concept of atrial cardiopathy.

Atrial Cardiopathy and Cryptogenic Stroke: A Cross-sectional Pilot Study

BACKGROUND

There is increasing evidence that left atrial dysfunction or cardiopathy is associated with ischemic stroke risk independently of atrial fibrillation. We aimed to determine the prevalence of atrial cardiopathy biomarkers in patients with cryptogenic stroke.

METHODS

We included consecutive patients with ischemic stroke enrolled in the New York Columbia Collaborative Specialized Program of Translational Research in Acute Stroke registry between December 1, 2008, and April 30, 2012. Medical records were reviewed and patients with a diagnosis of cryptogenic stroke were identified. Atrial cardiopathy was defined as at least one of the following: serum N-terminal probrain natriuretic peptide (NT-proBNP) level greater than 250 pg/mL, P-wave terminal force velocity in lead V1 (PTFV1) on electrocardiogram (ECG) greater than 5000 µV⋅ms, or severe left atrial enlargement (LAE) on echocardiogram. We compared clinical, echocardiographic, and radiological characteristics between patients with and without atrial cardiopathy.

RESULTS

Among 40 patients with cryptogenic stroke, 63% had at least one of the biomarkers of atrial cardiopathy; 49% had elevated NT-proBNP levels, 20% had evidence of increased PTFV1 on ECG, and 5% had severe LAE. Patients with atrial cardiopathy were more likely to be older (76 versus 62 years, P = .012); have hypertension (96% versus 33%, P < .001), hyperlipidemia (60% versus 27%, P = .05), or coronary heart disease (28% versus 0%, P = .033); and less likely to have a patent foramen ovale (4% versus 40%, P = .007).

CONCLUSION

There is a high prevalence of biomarkers indicative of atrial cardiopathy in patients with cryptogenic stroke. Clinical trials are needed to determine whether these patients may benefit from anticoagulation to prevent stroke.