Secondary Stroke Prevention Following Embolic Stroke of Unknown Source in the Absence of Documented Atrial Fibrillation: A Clinical Review

Use of Anticoagulation for Thromboembolic Prophylaxis in Patients With Atrial High-Rate Episodes on Device Monitoring: A Narrative Review

Ischemic stroke and systemic thromboembolism are primary drivers of significant morbidity and mortality in patients with atrial fibrillation (AF). Although stroke is commonly the first index presentation of clinically silent AF, the growing use of continuous rhythm monitoring through cardiac implanted electronic devices has enabled earlier and increased detection of AF in patients who are otherwise asymptomatic before stroke development. Atrial high-rate episodes (AHREs) are atrial tachyarrhythmias frequently detected by cardiac implanted electronic devices; these events represent subclinical AF and other atrial tachyarrhythmias that can lead to stroke development and AF. Although the presence of AHREs increases the risk of developing both clinical AF and stroke compared with absence of AHREs, there has been a significant clinical variability in anticoagulation initiation in these subjects. In this narrative review, we explore the current evidence and published research surrounding the association between AHREs and stroke development in addition to the utility of anticoagulation in this population for thromboembolic prophylaxis.

New-onset atrial fibrillation after percutaneous patent foramen ovale closure: a meta-analysis

BACKGROUND

The exact incidence and predictors of new-onset atrial fibrillation (AF) after percutaneous closure of patent foramen ovale (PFO) are unknown.

OBJECTIVE

We sought to find post-procedural AF incidence rates and differences due to different screening strategies and devices.

METHODS

A systematic search was conducted in Cochrane, MEDLINE and EMBASE. Controlled trials fulfilling the inclusion criteria were included into this meta-analysis. The incidence of new-onset AF was the primary outcome. Further parameters were surveillance strategy, device type, AF treatment and neurological events. New AF was determined as early onset within one month after implantation and late thereafter.

RESULTS

8 controlled trials and 16 cohort studies were eligible for quantitative analysis. 7643 patients received percutaneous PFO closure after cryptogenic stroke or transient ischaemic attack, 117 with other indications, whereas 1792 patients formed the control group. Meta-analysis of controlled trials showed an AF incidence of 5.1% in the interventional and 1.6% in the conservative arm, respectively (OR 3.17, 95% CI 1.46-6.86, P = 0.03, I2 = 55%). 4.7% received high-quality surveillance strategy with Holter-ECG or Loop recorder whereby AF incidence was overall higher compared to the low-quality group with 12-lead ECG only (3.3-15% vs. 0.2-4.3%). Heterogeneous results on time of AF onset were found, limited by different follow-up strategies. CardioSEAL and Starflex seemed to have higher AF incidences in early and late onset with 4.5% and 4.2%, respectively.

CONCLUSION

Percutaneous PFO closure led to higher AF post-procedural incidence compared to the conservative strategy. Heterogeneity in surveillance and follow-up strategy limited the generalizability.

TRIAL REGISTRATION

Registered on PROSPERO (CRD42022359945).

Reduced Left Atrial Appendage Flow Is Associated With Future Atrial Fibrillation After Cryptogenic Stroke

BACKGROUND

Hemostasis within the left atrial appendage (LAA) is a common cause of stroke, especially in patients with atrial fibrillation (AF). Although LAA flow provides insights into LAA function, its potential for predicting AF has yet to be established. The aim of this study was to explore whether LAA peak flow velocities early after cryptogenic stroke are associated with future AF on prolonged rhythm monitoring.

METHODS

A total of 110 patients with cryptogenic stroke were consecutively enrolled and underwent LAA pulsed-wave Doppler flow assessment using transesophageal echocardiography within the early poststroke period. Velocity measurements were analyzed offline by an investigator blinded to the results. Prolonged rhythm monitoring was conducted on all participants via 7-day Holter and implantable cardiac monitoring devices, with follow-up conducted over a period of 1.5 years to determine the incidence of AF. The end point of AF was defined as irregular supraventricular rhythm with variable RR interval and no detectable P waves lasting ≥30 sec during rhythm monitoring.

RESULTS

During a median follow-up period of 539 days (interquartile range, 169-857 days), 42 patients (38%) developed AF, with a median time to AF diagnosis of 94 days (interquartile range, 51-487 days). Both LAA filling velocity and LAA emptying velocity (LAAev) were lower in patients with AF (44.3 ± 14.2 and 50.7 ± 13.3 cm/s, respectively) compared with patients without AF (59.8 ± 14.0 and 76.8 ± 17.3 cm/sec, respectively; P < .001 for both). LAAev was most strongly associated with future AF, with an area under the receiver operating characteristic curve of 0.88 and an optimal cutoff value of 55 cm/sec. Age and mitral regurgitation were independent determinants of reduced LAAev.

CONCLUSIONS

Impaired LAA peak flow velocities (LAAev < 55 cm/sec) in patients with cryptogenic stroke are associated with future AF. This may facilitate the selection of appropriate candidates for prolonged rhythm monitoring to improve its diagnostic accuracy and implementation.

Frequent premature atrial contractions as a signalling marker of atrial cardiomyopathy, incident atrial fibrillation and stroke

Premature atrial contractions are a common cardiac phenomenon. Although previously considered a benign electrocardiographic finding, they have now been associated with a higher risk of incident atrial fibrillation and other adverse outcomes such as stroke and all-cause mortality. Since premature atrial contractions can be associated with these adverse clinical outcomes independently of atrial fibrillation occurrence, different explanations have being proposed. The concept of atrial cardiomyopathy, where atrial fibrillation would be an epiphenomenon outside the causal pathway between premature atrial contractions and stroke has received traction recently. This concept suggests that structural, functional and biochemical changes in the atria lead to arrhythmia occurrence and thromboembolic events. Some consensus about diagnosis and treatment of this condition have been published, but this is based on scarce evidence, highlighting the need for a clear definition of excessive premature atrial contractions and for prospective studies regarding antiarrhythmic therapies, anticoagulation or molecular targets in this group of patients.

Atrial Fibrillation Detected After Stroke and Transient Ischemic Attack: A Novel Clinical Concept Challenging Current Views

Atrial fibrillation (AF) can be newly detected in approximately one-fourth of patients with ischemic stroke and transient ischemic attack without previously recognized AF. We present updated evidence supporting that AF detected after stroke or transient ischemic attack (AFDAS) may be a distinct clinical entity from AF known before stroke occurrence (known atrial fibrillation). Data suggest that AFDAS can arise from the interplay of cardiogenic and neurogenic forces. The embolic risk of AFDAS can be understood as a gradient defined by the prevalence of vascular comorbidities, the burden of AF, neurogenic autonomic changes, and the severity of atrial cardiopathy. The balance of existing data indicates that AFDAS has a lower prevalence of cardiovascular comorbidities, a lower degree of cardiac abnormalities than known atrial fibrillation, a high proportion (52%) of very brief (<30 seconds) AF paroxysms, and is more frequently associated with insular brain infarction. These distinctive features of AFDAS may explain its recently observed lower associated risk of stroke than known atrial fibrillation. We present an updated ad-hoc meta-analysis of randomized clinical trials in which the association between prolonged cardiac monitoring and reduced risk of ischemic stroke was nonsignificant (incidence rate ratio, 0.90 [95% CI, 0.71-1.15]). These findings highlight that larger and sufficiently powered randomized controlled trials of prolonged cardiac monitoring assessing the risk of stroke recurrence are needed. Meanwhile, we call for further research on AFDAS and stroke recurrence, and a tailored approach when using prolonged cardiac monitoring after ischemic stroke or transient ischemic attack, focusing on patients at higher risk of AFDAS and, more importantly, at higher risk of cardiac embolism.

Secondary Stroke Prevention Following Embolic Stroke of Unknown Source in the Absence of Documented Atrial Fibrillation: A Clinical Review

Approximately one-third of ischemic strokes are classified as cryptogenic strokes. The risk of stroke recurrence in these patients is significantly elevated with up to one-third of patients with cryptogenic stroke experiencing a further stroke within 10 years. While anticoagulation is the mainstay of treatment for secondary stroke prevention in the context of documented atrial fibrillation (AF), it is estimated that up to 25% of patients with cryptogenic stroke have undiagnosed AF. Furthermore, the historical acceptance of a causal relationship between AF and stroke has recently come under scrutiny, with evidence to suggest that embolic stroke risk may be elevated even in the absence of documented atrial fibrillation attributable to the presence of electrical and structural changes constituting an atrial cardiomyopathy. More recently, the term embolic stroke of unknown source has garnered increasing interest as a subset of patients with cryptogenic stroke in whom a minimum set of diagnostic investigations has been performed, and a nonlacunar infarct highly suspicious of embolic etiology is suspected but in the absence of an identifiable secondary cause of stroke. The ongoing ARCADIA (Atrial Cardiopathy and Antithrombotic Drugs in Prevention After Cryptogenic Stroke) randomized trial and ATTICUS (Apixiban for Treatment of Embolic Stroke of Undetermined Source) study seek to further define this novel term. This review summarizes the relationship between AF, embolic stroke, and atrial cardiomyopathy and provides an overview of the clinical relevance of cardiac imaging, electrocardiographic, and serum biomarkers in the assessment of AF and secondary stroke risk. The implications of these findings on therapeutic considerations is considered and gaps in the literature identified as areas for future study in risk stratifying this cohort of patients.