Interatrial Block Association With Adverse Cardiovascular Outcomes in Patients Without a History of Atrial Fibrillation.

BACKGROUND: Interatrial block (IAB) is associated with thromboembolism and atrial arrhythmias. However, prior studies included small patient cohorts so it remains unclear whether IAB predicts adverse outcomes particularly in context of atrial fibrillation (AF)/atrial flutter (AFL). OBJECTIVES: This study sought to determine whether IAB portends increased stroke risk in a large cohort in the presence or absence of AFAF/AFL. METHODS: We performed a 5-center retrospective analysis of 4,837,989 electrocardiograms (ECGs) from 1,228,291 patients. IAB was defined as P-wave duration ≥120 ms in leads II, III, or aVF. Measurements were extracted as .XML files. After excluding patients with prior AF/AFL, 1,825,958 ECGs from 458,994 patients remained. Outcomes were analyzed using restricted mean survival time analysis and restricted mean time lost. RESULTS: There were 86,317 patients with IAB and 355,032 patients without IAB. IAB prevalence in the cohort was 19.6% and was most common in Black (26.1%), White (20.9%), and Hispanic (18.5%) patients and least prevalent in Native Americans (9.2%). IAB was independently associated with increased stroke probability (restricted mean time lost ratio coefficient [RMTLRC]: 1.43; 95% CI: 1.35-1.51; tau = 1,895), mortality (RMTLRC: 1.14; 95% CI: 1.07-1.21; tau = 1,924), heart failure (RMTLRC: 1.94; 95% CI: 1.83-2.04; tau = 1,921), systemic thromboembolism (RMTLRC: 1.62; 95% CI: 1.53-1.71; tau = 1,897), and incident AF/AFL (RMTLRC: 1.16; 95% CI: 1.10-1.22; tau = 1,888). IAB was not associated with stroke in patients with pre-existing AF/AFL. CONCLUSIONS: IAB is independently associated with stroke in patients with no history of AF/AFL even after adjustment for incident AF/AFL and CHA2DS2-VASc score. Patients are at increased risk of stroke even when AF/AFL is not identified.

New electrocardiographic aspects of the P wave: Its value in clinical cardiology.

In this article, we will comment on new aspects of P-wave morphology that help us to better diagnose atrial blocks and atrial enlargement, and their clinical implications. These include: (1) Atypical ECG patterns of advanced interatrial block; (2) The ECG diagnosis of left atrial enlargement versus interatrial block; (3) Atrial fibrillation and advanced interatrial block: The two sides of the same coin; and (4) P-wave parameters: Clinical implications.

Interatrial Block Predicts Life-Threatening Arrhythmias in Dilated Cardiomyopathy.

Background Interatrial block (IAB) has been associated with supraventricular arrhythmias and stroke, and even with sudden cardiac death in the general population. Whether IAB is associated with life-threatening arrhythmias (LTA) and sudden cardiac death in dilated cardiomyopathy (DCM) remains unknown. This study aimed to determine the association between IAB and LTA in ambulant patients with DCM. Methods and Results A derivation cohort (Maastricht Dilated Cardiomyopathy Registry; N=469) and an external validation cohort (Utrecht Cardiomyopathy Cohort; N=321) were used for this study. The presence of IAB (P-wave duration>120 milliseconds) or atrial fibrillation (AF) was determined using digital calipers by physicians blinded to the study data. In the derivation cohort, IAB and AF were present in 291 (62%) and 70 (15%) patients with DCM, respectively. LTA (defined as sudden cardiac death, justified shock from implantable cardioverter-defibrillator or anti-tachypacing, or hemodynamic unstable ventricular fibrillation/tachycardia) occurred in 49 patients (3 with no IAB, 35 with IAB, and 11 patients with AF, respectively; median follow-up, 4.4 years [2.1; 7.4]). The LTA-free survival distribution significantly differed between IAB or AF versus no IAB (both P<0.01), but not between IAB versus AF (P=0.999). This association remained statistically significant in the multivariable model (IAB: HR, 4.8 (1.4-16.1), P=0.013; AF: HR, 6.4 (1.7-24.0), P=0.007). In the external validation cohort, the survival distribution was also significantly worse for IAB or AF versus no IAB (P=0.037; P=0.005), but not for IAB versus AF (P=0.836). Conclusions IAB is an easy to assess, widely applicable marker associated with LTA in DCM. IAB and AF seem to confer similar risk of LTA. Further research on IAB in DCM, and on the management of IAB in DCM is warranted.

Cardiovascular Complications of Interatrial Conduction Block: JACC State-of-the-Art Review.

Interatrial block (IAB) is an electrocardiographic pattern describing the conduction delay between the right and left atria. IAB is classified into 3 degrees of block that correspond to decreasing conduction in the region of Bachmann's bundle. Although initially considered benign in nature, specific subsets of IAB have been associated with atrial arrhythmias, elevated thromboembolic stroke risk, cognitive impairment, and mortality. As the pathophysiologic relationships between IAB and stroke are reinforced, investigation has now turned to the potential benefit of early detection, atrial imaging, cardiovascular risk factor modification, antiarrhythmic pharmacotherapy, and stroke prevention with oral anticoagulation. This review provides a contemporary overview of the epidemiology, pathophysiology, diagnosis, and management of IAB, with a focus on future directions.

P Wave Parameters and Indices: A Critical Appraisal of Clinical Utility, Challenges, and Future Research-A Consensus Document Endorsed by the International Society of Electrocardiology and the International Society for Holter and Noninvasive Electrocardiology.

Atrial cardiomyopathy, characterized by abnormalities in atrial structure and function, is associated with increased risk of adverse cardiovascular and neurocognitive outcomes, independent of atrial fibrillation. There exists a critical unmet need for a clinical tool that is cost-effective, easy to use, and that can diagnose atrial cardiomyopathy. P wave parameters (PWPs) reflect underlying atrial structure, size, and electrical activation; alterations in these factors manifest as abnormalities in PWPs that can be readily ascertained from a standard 12-lead ECG and potentially be used to aid clinical decision-making. PWPs include P wave duration, interatrial block, P wave terminal force in V1, P wave axis, P wave voltage, P wave area, and P wave dispersion. PWPs can be combined to yield an index (P wave index), such as the morphology-voltage-P-wave duration ECG risk score. Abnormal PWPs have been shown in population-based cohort studies to be independently associated with higher risks of atrial fibrillation, ischemic stroke, sudden cardiac death, and dementia. Additionally, PWPs, either individually or in combination (as a P wave index), have been reported to enhance prediction of atrial fibrillation or ischemic stroke. To facilitate translation of PWPs to routine clinical practice, additional work is needed to standardize measurement of PWPs (eg, via semiautomated or automated measurement), confirm their reliability and predictive value, leverage novel approaches (eg, wavelet analysis of P waves and machine learning algorithms), and finally, define the risk-benefit ratio of specific interventions in high-risk individuals. Our ultimate goal is to repurpose the ubiquitous 12-lead ECG to advance the study, diagnosis, and treatment of atrial cardiomyopathy, thus overcoming critical challenges in prevention of cardiovascular disease and dementia.

Periodic repolarization dynamics as predictor of risk for sudden cardiac death in chronic heart failure patients.

The two most common modes of death among chronic heart failure (CHF) patients are sudden cardiac death (SCD) and pump failure death (PFD). Periodic repolarization dynamics (PRD) quantifies low-frequency oscillations in the T wave vector of the electrocardiogram (ECG) and has been postulated to reflect sympathetic modulation of ventricular repolarization. This study aims to evaluate the prognostic value of PRD to predict SCD and PFD in a population of CHF patients. 20-min high-resolution (1000 Hz) ECG recordings from 569 CHF patients were analyzed. Patients were divided into two groups, [Formula: see text] and [Formula: see text], corresponding to PRD values above and below the optimum cutoff point of PRD in the study population. Univariate Cox regression analysis showed that SCD risk in the [Formula: see text] group was double the risk in the [Formula: see text] group [hazard ratio (95% CI) 2.001 (1.127-3.554), [Formula: see text]]. The combination of PRD with other Holter-based ECG indices, such as turbulence slope (TS) and index of average alternans (IAA), improved SCD prediction by identifying groups of patients at high SCD risk. PFD could be predicted by PRD only when combined with TS [hazard ratio 2.758 (1.572-4.838), [Formula: see text]]. In conclusion, the combination of PRD with IAA and TS can be used to stratify the risk for SCD and PFD, respectively, in CHF patients.

[Bayés Syndrome, Stroke and Dementia]. / Síndrome de bayés, accidente cerebrovascular y demencia.

Bayés's syndrome is a clinical entity based on the association between advanced interatrial block and the development of supraventricular tachyarrhythmia, being atrial fibrillation (AF) the most frequent. This association was discovered by Prof. Antoni Bayés de Luna in the '80s. Further studies by other groups found a strong relationship between Bayés's syndrome and thromboembolic phenomena, being stroke the most serious. Moreover, patients with this syndrome have an increased incidence of cognitive impairment and dementia. This observation triggered the question about whether the use of anticoagulation therapy prior to the documentation of AF could prevent A-IAB associated thromboembolic events. There are ongoing studies in different phases of development aiming to compare the efficacy of anticoagulation in patients with A-IAB with no prior documentation of AF. The outcomes of these studies will allow determining the efficacy of this early therapeutic intervention, and help deciding the role of anticoagulation in patients with A-IAB and no demonstrated AF.

Síndrome de Bayés. Lo que todo clínico debe conocer / What every clinician should know about Bayés syndrome

El síndrome de Bayés es una nueva entidad clínica, caracterizada por la combinación de bloqueo interauricular (BIA) avanzado en el electrocardiograma de superficie con fibrilación auricular (FA) y otras arritmias auriculares. Este síndrome se asocia con un riesgo incrementado de ictus, demencia y mortalidad. El BIA avanzado se diagnostica con la presencia de una onda P ≥ 120ms de morfología bifásica (±) en derivaciones de cara inferior. Se produce por un bloqueo completo del haz de Bachmann que causa una despolarización retrógrada de la aurícula izquierda desde zonas cercanas a la unión auriculoventricular. La miocardiopatía auricular fibrótica es el sustrato anatómico del BIA avanzado. La disincronía inducida por el BIA avanzado funciona como desencadenante y mecanismo de mantenimiento de la FA. Esta alteración de la arquitectura auricular produce remodelado auricular, estasis sanguínea e hipercoagulabilidad, lo cual desencadena la cascada trombogénica. El BIA avanzado, incluso sin arritmias auriculares documentadas, también se ha relacionado con FA, ictus, demencia y mortalidad. Sin embargo, todavía no se ha demostrado el beneficio de la anticoagulación para los pacientes sin FA documentada. Por lo tanto, es recomendable una búsqueda proactiva de FA en los pacientes con BIA avanzado

Bayés syndrome is a new clinical entity, characterized by the association of advanced interatrial block (IAB) on surface electrocardiogram with atrial fibrillation (AF) and other atrial arrhythmias. This syndrome is associated with an increased risk of stroke, dementia, and mortality. Advanced IAB is diagnosed by the presence of a P-wave ≥ 120ms with biphasic morphology (±) in inferior leads. The cause of IAB is complete Bachmann bundle blockade, leading to retrograde depolarization of the left atrium from areas near the atrioventricular junction. The anatomic substrate of advanced IAB is fibrotic atrial cardiomyopathy. Dyssynchrony induced by advanced IAB is a trigger and maintenance mechanism of AF. This alteration of the atrial architecture produces atrial remodeling, blood stasis and hypercoagulability, triggering the thrombogenic cascade. The presence of advanced IAB, even in patients without documented atrial arrhythmias, has also been associated with AF, stroke, dementia, and mortality. However, in these patients, there is no evidence to support the use of anticoagulation. Therefore, in patients with advanced IAB, a proactive search for AF is recommended

What every clinician should know about Bayés syndrome.

Bayés syndrome is a new clinical entity, characterized by the association of advanced interatrial block (IAB) on surface electrocardiogram with atrial fibrillation (AF) and other atrial arrhythmias. This syndrome is associated with an increased risk of stroke, dementia, and mortality. Advanced IAB is diagnosed by the presence of a P-wave ≥ 120ms with biphasic morphology (±) in inferior leads. The cause of IAB is complete Bachmann bundle blockade, leading to retrograde depolarization of the left atrium from areas near the atrioventricular junction. The anatomic substrate of advanced IAB is fibrotic atrial cardiomyopathy. Dyssynchrony induced by advanced IAB is a trigger and maintenance mechanism of AF. This alteration of the atrial architecture produces atrial remodeling, blood stasis and hypercoagulability, triggering the thrombogenic cascade. The presence of advanced IAB, even in patients without documented atrial arrhythmias, has also been associated with AF, stroke, dementia, and mortality. However, in these patients, there is no evidence to support the use of anticoagulation. Therefore, in patients with advanced IAB, a proactive search for AF is recommended.

A counterpoint paper: Comments on the electrocardiographic part of the 2018 Fourth Universal Definition of Myocardial Infarction endorsed by the International Society of Electrocardiology and the International Society for Holter and Noninvasive Electrocardiology.

The Fourth Universal Definition of Myocardial Infarction (FUDMI) focuses on the distinction between nonischemic myocardial injury and myocardial infarction (MI), along with the role of cardiovascular magnetic resonance, in order to define the etiology of myocardial injury. As a consequence, there is less emphasis on updating the parts of the definition concerning the electrocardiographic (ECG) changes related to MI. Evidence of myocardial ischemia is a prerequisite for the diagnosis of MI, and the ECG is the main available tool for (a) detecting acute ischemia, (b) triage, and (c) risk stratification upon presentation. This review focuses on multiple aspects of ECG interpretation that we firmly believe should be considered for incorporation in any future update to the Universal Definition of MI.

Relation of Advanced Interatrial Block to Risk of Atrial Fibrillation and Stroke.

Advanced interatrial block (A-IAB) has been associated to atrial fibrillation (AF) and ischemic stroke, raising the question as to whether such patients, even when still in sinus rhythm without documented AF, could benefit from oral anticoagulation. AF and A-IAB are both markers of stroke. The anatomical substrate in both is fibrotic atrial cardiomyopathy, resulting in atrial electromechanical dyssynchrony, dysfunction, and left atrial remodelling, that favour blood stasis and hypercoagulation. Under these conditions thrombogenic cascade may be triggered, resulting in systemic embolization. Before proposing oral anticoagulation in the management of selected patients with A-IAB, as is currently recommended in patients with AF and high CHA2DS2-Vasc score, a randomized clinical trial will have to demonstrate efficacy and safety of anticoagulation in this setting. In the meantime, an individualized approach may be considered based on the recognition of those patients at a higher risk of stroke. These may be elderly patients with A-IAB and several risk factors and, thus, with a high CHA2DS2-Vasc score and the presence of environmental arrhythmias.

Interatrial block can occur in the absence of left atrial enlargement: New experimental model.

We present the surface electrocardiogram of an open-chest anesthetized healthy adult swine after direct application of ice at the transversus sinus of the pericardium where the Bachmann's region is located. Gradual and transient interatrial block (IAB) in the absence of structural atrial disease is described. This new experimental model demonstrated that IAB is an independent entity from left atrial enlargement.

The prevalence and prognostic significance of interatrial block in the general population.

Introduction: Partial and advanced interatrial block (IAB) in the electrocardiographic (ECG) represents inter-atrial conduction delay. IAB is associated with atrial fibrillation (AF) and stroke in the general population.Material and methods: A representative sample of Finnish subjects (n = 6354) aged over 30 years (mean: 52.2 years, standard deviation: 14.6) underwent a health examination including a 12-lead ECG. Five different IAB groups based on automatic measurements were compared to normal P waves using multivariate-adjusted Cox proportional hazard model. Follow-up lasted up to 15 years.Results: The prevalence of advanced and partial IAB was 1.0% and 9.7%, respectively. In the multivariate model, both advanced (hazard ratio (HR): 1.63 (95% confidence interval (CI): 1.00-2.65)) and partial IAB (HR: 1.39 (1.09-1.77)) were associated with increased risk of AF. Advanced IAB was associated with increased risk of stroke or transient ischaemic attack (TIA) independently of associated AF (HR: 2.22 (1.20-4.13)). Partial IAB was also associated with increased risk of being diagnosed with coronary heart disease (HR: 1.26 (1.01-1.58)).Discussion: IAB is a rather frequent finding in the general population. IAB is a risk factor for AF and is associated with an increased risk of stroke or TIA independently of associated AF.Key messagesBoth partial and advanced interatrial block are associated with increased risk of atrial fibrillation in the general population.Advanced interatrial block is an independent risk factor for stroke and transient ischaemic attack.The clinical significance of interatrial block is dependent on the subtype classification.

Atrial Failure as a Clinical Entity: JACC Review Topic of the Week.

Atrial dysfunction has been widely considered a marker or consequence of other cardiac conditions rather than the cause itself. Here, we propose the term atrial failure as a clinically relevant entity, defined as any atrial dysfunction causing impaired heart performance, symptoms, and worsening quality of life or life expectancy. Aspects of the etiology, mechanisms, and consequences of atrial failure are discussed. Recent advances in cardiac electrophysiology and imaging have improved our understanding of the highly complex atrial anatomy and function, underlying the paramount importance of the atria in optimal heart performance. It is time to reappraise the concept of the failing atrium as a primary cause or aggravating factor of the symptoms in many of our patients. The concept of atrial failure may foster basic and translational research to gain a better understanding of how to identify and manage atrial dysfunction.