Interatrial Block to Guide the Thromboembolic Prevention Strategy: Should It be the Next Step?

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.

Interatrial block as a predictor of atrial fibrillation in patients with ST-segment elevation myocardial infarction

INTRODUCTION

Interatrial block (IAB) is strongly associated with recurrence of atrial fibrillation (AF) in different clinical scenarios. Atrial fibrosis is considered the responsible mechanism underlying the pathogenesis of IAB. The aim of this study was to investigate whether IAB predicted AF at 12 months follow-up in a population of patients with ST segment elevation myocardial infarction (STEMI).

HYPOTHESIS

We aimed to investigate whether IAB predicted AF at 12 months follow up in a population of patients with STEMI.

METHODS

Prospective, single center, observational study of patients presenting with ST-segment elevation myocardial infarction (STEMI) and referred to primary percutaneous coronary intervention (P-PCI). Surface electrocardiograms (ECG) were recorded on admission and at 6th hour post P-PCI. Patients were screened for the occurrence of AF at a 12-months visit.

RESULTS

A total of 198 patients were included between September 2015 and September 2016. IAB (partial and advanced) was detected in 102 (51.5%) patients on admission. Remodeling of the P-wave and subsequent normalization reduced the prevalence of IAB to 47 (23.7%) patients at 6th hour. AF was detected in 17.7% of study patients at 12 months. Partial IAB (p-IAB) on admission (OR 5.10; 95% CI, 1.46-17.8; P = 0.011) and on 6th hour (OR 4.15; 95% CI, 1.29-13.4; P = 0.017), presence of a lesion in more than one coronary artery (OR 3.29; 95% CI, 1.32-8.16; P = 0.010) found to be independent predictors of AF at 12 months.

CONCLUSION

IAB is common in patients with STEMI and along with the presence of diffuse coronary artery disease is associated with new onset of AF.

Role of Antiplatelet Therapy in Stroke Prevention in Patients With Atrial Fibrillation

Patients with atrial fibrillation are at increased risk of having a cardioembolic stroke. The use of oral anticoagulation is now well established to prevent strokes in patients with atrial fibrillation and a CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years [2 points], diabetes mellitus, prior stroke/transient ischemic attack or thromboembolism [2 points], vascular disease, age 65 to 74 years, and sex category) score of greater than 1, beyond sex. However, the role of antiplatelet therapy, specifically aspirin in low-risk patients or as an alternative to oral anticoagulation, remains controversial. The most recent US guidelines conflict with the European guidelines, which do not recommend antiplatelet monotherapy for stroke prevention irrespective of stroke risk. The aim of this review is to summarize published studies that question the role of aspirin in preventing strokes associated with atrial fibrillation. Overall, aspirin is found to play a limited role in the prevention of stroke in patients with atrial fibrillation and is associated with a similar risk of hemorrhagic events compared with anticoagulants. The benefit of dual antiplatelet therapy as an alternative to oral anticoagulation requires further study.

Anticoagulation in patients at high risk of stroke without documented atrial fibrillation. Time for a paradigm shift?

Atrial fibrillation (AF) is currently considered a risk factor for stroke. Depending on the severity of clinical factors (risk scores) a recommendation for full anticoagulation is made. Although AF is most certainly a risk factor for ischemic stroke, it is not necessarily the direct cause of it. The causality of association between AF and ischemic stroke is questioned by the reported lack of temporal relation between stroke events and AF paroxysms (or atrial high-rate episodes detected by devices). In different studies, only 2% of patients had subclinical AF > 6 minutes in duration at the time of stroke or systemic embolism. Is it time to consider AF only one more factor of endothelial disarray rather than the main contributor to stroke? In this "opinion paper" we propose to consider not only clinical variables predicting AF/stroke but also electrocardiographic markers of atrial fibrosis, as we postulate this as a strong indicator of risk of AF/stroke. We ask if it is time to change the paradigm and to consider, in some special situations, to protect patients (preventing stroke) who have no evidence of AF.