Interatrial block in the modern era

Association of the interatrial block and left atrial fibrosis in the patients without history of atrial fibrillation

Presence of left atrial (LA) fibrosis reflects underlying atrial cardiomyopathy. Interatrial block (IAB) is associated with LA fibrosis in patients with atrial fibrillation (AF). The association of IAB and LA fibrosis in the patients without history of AF is unknown. We examined association of IAB and LA fibrosis in the patients without AF history. This is a retrospective analysis of 229 patients undergoing cardiac magnetic resonance imaging (CMR). LA fibrosis was reported from spatial extent of late gadolinium enhancement of CMR. IAB was measured from 12-lead electrocardiography using digital caliper. Of 229 patients undergoing CMR, prevalence of IAB was 50.2%. Patients with IAB were older (56.9±13.9 years vs. 45.9±19.2 years, p<0.001) and had higher prevalence of co-morbidities. Left ventricular ejection fraction was lower in IAB group. LA volume index (LAVI) was greater in IAB group (54.6±24.9 ml/m2 vs. 43.0±21.1 ml/m2, p<0.001). Patients with IAB had higher prevalence of LA fibrosis than those without IAB (70.4% vs. 21.2%; p<0.001). After multivariable analysis, only IAB and LAVI were independent factors that predict LA fibrosis. Prevalence of IAB in patients undergoing CMR was high. IAB was highly associated with LA fibrosis and larger LA size in patients without AF history.

Paradoxical interatrial conduction recovery after cavotricuspid isthmus ablation: A case report

We present a case of a patient with advanced interatrial block who was admitted for cavotricuspid isthmus ablation as treatment of typical atrial flutter. A baseline advanced interatrial block pattern turned into partial interatrial block pattern and prolonged PR interval after the procedure. We discuss the mechanism underlying that change.

P-wave characteristics as electrocardiographic markers of atrial abnormality in prediction of incident atrial fibrillation - The Malmö Preventive Project

BACKGROUND

P-wave indices reflect atrial abnormalities contributing to atrial fibrillation (AF). We aimed to assess a comprehensive set of P-wave characteristics for prediction of incident AF in a population-based setting.

METHODS

Malmö Preventative Project (MPP) participants were reexamined in 2002-2006 with electrocardiographic (ECG) and echocardiographic examinations and followed for 5 years. AF-free subjects (n = 983, age 70 ± 5 years, 38% females) with sinus rhythm ECGs were included in the study. ECGs were digitally processed using the Glasgow algorithm. P-wave duration, axis, dispersion, P-terminal force in lead V1 and interatrial block (IAB) were evaluated. ECG risk score combining the morphology, voltage and length of P-wave (MVP score) was calculated. New-onset diagnoses of AF were obtained from nation-wide registers.

RESULTS

During follow up, 66 patients (7%) developed AF. After adjustment for age and gender, the independent predictors of AF were abnormal P-wave axis > 75° (HR 1.63 CI95% 1.95-11.03) and MVP score 4 (HR 6.17 CI 95% 1.76-21.64), both correlated with LA area: Person r - 0.146, p < 0.001 and 0.192, p < 0.001 respectively. Advanced IAB (aIAB) with biphasic P-wave morphology in leads III and aVF was the most prevalent variant of aIAB and predicted AF in a univariate model (HR 2.59 CI 95% 1.02-6.58).

CONCLUSION

P-wave frontal axis and MVP score are ECG-based AF predictors in the population-based cohort. Our study provides estimates for prevalence and prognostic importance of different variants of aIAB, providing a support to use biphasic P-wave morphology in lead aVF as the basis for aIAB definition.

Interatrial Block and Electrocardiographic Markers of Repolarization in Patients Hospitalized with COVID-19: Classical and Bayesian Analysis

Objective

Coronavirus disease-2019 (COVID-19) is associated with atrial fibrillation (AF) and ventricular arrhythmias. Several electrophysiological abnormalities on surface electrocardiography (ECG) are associated with AF and ventricular arrhythmias, either as markers of abnormal interatrial conduction or abnormal repolarization. The present study sought to understand whether such ECG markers are more common in patients hospitalized with COVID-19 infection during the pandemic.

Methods

A total of 87 COVID-19 patients formed the study group, whereas 64 patients who were hospitalized for any reason other than COVID-19 infection served as controls. The frequency of partial and advanced interatrial block (IAB), QT and corrected QT (QTc) durations, QT dispersion (QTd), and T peak-to-end duration (Tpe) were measured from ECGs at admission.

Results

Both partial and advanced IAB were more common in patients with COVID-19, although statistical significance was only observed for advanced IAB (11.5% in COVID-19 patients vs. 0.0% in controls, p=0.005). There were no differences between the groups for QTc, QTd or Tpe. On Bayesian analyses, there was strong evidence favoring an association between COVID-19 and advanced IAB (BF10:16), whereas there was no evidence for an association for partial IAB, QTc, QTd, or Tpe (BF10<1 for all).

Conclusions

Patients hospitalized with COVID-19 were more likely to have advanced IAB, which may explain why AF is more frequent in these patients.

The Cardiac Calcium Handling Machinery is Remodeled in Friedreich's Ataxia

Background

Friedreich's ataxia (FA) is an inherited neurodegenerative disorder that causes progressive nervous system damage resulting in impaired muscle coordination. FA is the most common autosomal recessive form of ataxia and is caused by an expansion of the DNA triplet guanine-adenine-adenine (GAA) in the first intron of the Frataxin gene (FXN), located on chromosome 9q13. In the unaffected population, the number of GAA repeats ranges from 6 to 27 repetitions. In FA patients, GAA repeat expansions range from 44 to 1,700 repeats which decreases frataxin protein expression. Frataxin is a mitochondrial protein essential for various cellular functions, including iron metabolism. Reduced frataxin expression is thought to negatively affect mitochondrial iron metabolism, leading to increased oxidative damage. Although FA is considered a neurodegenerative disorder, FA patients display heart disease that includes hypertrophy, heart failure, arrhythmias, conduction abnormalities, and cardiac fibrosis.

Objective

In this work, we investigated whether abnormal Ca 2+ handling machinery is the molecular mechanism that perpetuates cardiac dysfunction in FA.

Methods

We used the frataxin knock-out (FXN-KO) mouse model of FA as well as human heart samples from donors with FA and from unaffected donors. ECG and echocardiography were used to assess cardiac function in the mice. Expression of calcium handling machinery proteins was assessed with proteomics and western blot. In left ventricular myocytes from FXN-KO and FXN-WT mice, the IonOptix system was used for calcium imaging, the seahorse assay was utilized to measure oxygen consumption rate (OCR), and confocal imaging was used to quantify the mitochondrial membrane potential (Δψm) and reactive oxygen species (ROS).

Results

We found that major contractile proteins, including SERCA2a and Ryr2, were downregulated in human left ventricular samples from deceased donors with FA compared to unaffected donors, similar to the downregulation of these proteins in the left ventricular tissue from FXN-KO compared to FXN-WT. On the ECG, the RR, PR, QRS, and QTc were significantly longer in the FXN-KO mice compared to FXN-WT. The ejection fraction and fractional shortening were significantly decreased and left ventricular wall thickness and diameter were significantly increased in the FXN-KO mice versus FXN-WT. The mitochondrial membrane potential Δψm was depolarized, ROS levels were elevated, and OCR was decreased in ventricular myocytes from FXN-KO versus FXN-WT.

Conclusion

The development of left ventricular contractile dysfunction in FA is associated with reduced expression of calcium handling proteins and mitochondrial dysfunction.

Heart age gap estimated by explainable advanced electrocardiography is associated with cardiovascular risk factors and survival

Aims

Deep neural network artificial intelligence (DNN-AI)-based Heart Age estimations have been presented and used to show that the difference between an electrocardiogram (ECG)-estimated Heart Age and chronological age is associated with prognosis. An accurate ECG Heart Age, without DNNs, has been developed using explainable advanced ECG (A-ECG) methods. We aimed to evaluate the prognostic value of the explainable A-ECG Heart Age and compare its performance to a DNN-AI Heart Age.

Methods and results

Both A-ECG and DNN-AI Heart Age were applied to patients who had undergone clinical cardiovascular magnetic resonance imaging. The association between A-ECG or DNN-AI Heart Age Gap and cardiovascular risk factors was evaluated using logistic regression. The association between Heart Age Gaps and death or heart failure (HF) hospitalization was evaluated using Cox regression adjusted for clinical covariates/comorbidities. Among patients [n = 731, 103 (14.1%) deaths, 52 (7.1%) HF hospitalizations, median (interquartile range) follow-up 5.7 (4.7-6.7) years], A-ECG Heart Age Gap was associated with risk factors and outcomes [unadjusted hazard ratio (HR) (95% confidence interval) (5 year increments): 1.23 (1.13-1.34) and adjusted HR 1.11 (1.01-1.22)]. DNN-AI Heart Age Gap was associated with risk factors and outcomes after adjustments [HR (5 year increments): 1.11 (1.01-1.21)], but not in unadjusted analyses [HR 1.00 (0.93-1.08)], making it less easily applicable in clinical practice.

Conclusion

A-ECG Heart Age Gap is associated with cardiovascular risk factors and HF hospitalization or death. Explainable A-ECG Heart Age Gap has the potential for improving clinical adoption and prognostic performance compared with existing DNN-AI-type methods.

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.

Alteraciones electrofisiológicas en el músculo auricular de rata con síndrome metabólico

El estilo de vida actual ha aumentado la prevalencia de Síndrome Metabólico (SM) el cual se ha relacionado con la arritmia más común a nivel mundial: la fibrilación auricular. En un modelo de rata con SM se han reportado cambios en el nodo senoauricular, sin embargo, el papel del músculo auricular en esta patología aún sigue sin conocerse. El objetivo de este trabajo es determinar si el SM genera arritmias supraventriculares en un modelo de rata y su relación con alteraciones en la morfología del potencial de acción auricular. Metodología: se utilizaron ratas Wistar macho a las cuales se indujo SM. Se midieron parámetros metabólicos, morfométricos, se registró el electrocardiograma (ECG) in vivo y potenciales de acción auriculares (PA) en una preparación de tejido aislado en donde se midió la excitabilidad. Resultados: en los animales del grupo SM se observaron alteraciones en el ECG como onda P bifásica y onda P mellada relacionado con la disminución en la duración del PA durante la repolarización en endocardio de la aurícula derecha y epicardio de aurícula izquierda, también se observaron cambios transmurales en la duración del PA en ambas aurículas y un desplazamiento hacia la derecha en la gráfica de excitabilidad en los registros del grupo SM.  Concusiones:  el SM remodela la actividad eléctrica supraventricular ya que modifica la heterogeneidad transmural de las aurículas aumentando la excitabilidad. Se propone que estos cambios contribuyen a la generación y mantenimiento de arritmias supraventriculares.

Heart age estimated using explainable advanced electrocardiography

Electrocardiographic (ECG) Heart Age conveying cardiovascular risk has been estimated by both Bayesian and artificial intelligence approaches. We hypothesised that explainable measures from the 10-s 12-lead ECG could successfully predict Bayesian 5-min ECG Heart Age. Advanced analysis was performed on ECGs from healthy subjects and patients with cardiovascular risk or proven heart disease. Regression models were used to predict patients’ Bayesian 5-min ECG Heart Ages from their standard, resting 10-s 12-lead ECGs. The difference between 5-min and 10-s ECG Heart Ages were analyzed, as were the differences between 10-s ECG Heart Age and the chronological age (the Heart Age Gap). In total, 2,771 subjects were included (n = 1682 healthy volunteers, n = 305 with cardiovascular risk factors, n = 784 with cardiovascular disease). Overall, 10-s Heart Age showed strong agreement with the 5-min Heart Age (R² = 0.94, p < 0.001, mean ± SD bias 0.0 ± 5.1 years). The Heart Age Gap was 0.0 ± 5.7 years in healthy individuals, 7.4 ± 7.3 years in subjects with cardiovascular risk factors (p < 0.001), and 14.3 ± 9.2 years in patients with cardiovascular disease (p < 0.001). Heart Age can be accurately estimated from a 10-s 12-lead ECG in a transparent and explainable fashion based on known ECG measures, without deep neural network-type artificial intelligence techniques. The Heart Age Gap increases markedly with cardiovascular risk and disease.

Embolic stroke of undetermined source: beyond atrial fibrillation

INTRODUCTION

Embolic stroke of undetermined source (ESUS) accounts for 25% of all cerebral infarcts; only 30% are associated with paroxysmal atrial fibrillation (AF). Various biochemical, electrocardiographic, and echocardiographic findings may suggest left atrial damage and increased risk of embolism in the absence of clinically documented AF or atrial flutter. In this review, we analyse the available evidence on atrial cardiopathy or atrial disease, its involvement in ESUS, and its identification through electrocardiographic, echocardiographic, and serum markers and its possible therapeutic implications.

DEVELOPMENT

A systematic search was conducted on MEDLINE (PubMed) using the following MeSH terms: MeSH [ESUS]+[atrial cardiopathy]+[atrial fibrillation]+[interatrial block]+[treatment]. We selected what we considered to be the most useful original prospective or retrospective studies and systematic reviews. We then read the full texts of the articles and checked the references cited in each article. We analyse epidemiological and demographic variables of patients with ESUS, as well as recent evidence related to presentation and prognosis and factors associated with recurrence and mortality. We review the contribution of atrial cardiopathy diagnosis prior to the detection of AF and the clinical, electrocardiographic, and echocardiographic variables and the biochemical markers associated with its development and its potential contribution to cerebral embolism.

CONCLUSIONS

The systematic search of biochemical and electrocardiographic, and echocardiographic alterations can be useful to identify ESUS patients at higher risk of recurrence.

Embolic stroke of undetermined source: Beyond atrial fibrillation

INTRODUCTION

Embolic stroke of undetermined source (ESUS) accounts for 25% of all cerebral infarcts; only 30% are associated with paroxysmal atrial fibrillation (AF). Various biochemical, electrocardiographic, and echocardiographic findings may suggest left atrial damage and increased risk of embolism in the absence of clinically documented AF or atrial flutter. In this review, we analyse the available evidence on atrial cardiopathy or atrial disease, its involvement in ESUS, and its identification through electrocardiographic, echocardiographic, and serum markers and its possible therapeutic implications.

DEVELOPMENT

A systematic search was conducted on MEDLINE (PubMed) using the following MeSH terms: MeSH [ESUS]+[atrial cardiopathy]+[atrial fibrillation]+[interatrial block]+[treatment]. We selected what we considered to be the most useful original prospective or retrospective studies and systematic reviews. We then read the full texts of the articles and checked the references cited in each article. We analyse epidemiological and demographic variables of patients with ESUS, as well as recent evidence related to presentation and prognosis and factors associated with recurrence and mortality. We review the contribution of atrial cardiopathy diagnosis prior to the detection of AF and the clinical, electrocardiographic, and echocardiographic variables and the biochemical markers associated with its development and its potential contribution to cerebral embolism.

CONCLUSIONS

The systematic search of biochemical and electrocardiographic, and echocardiographic alterations can be useful to identify ESUS patients at higher risk of recurrence.

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.

A meta-analysis of the association of atrial septal abnormalities and atrial vulnerability

BACKGROUND

The mechanism of cryptogenic stroke (CS) in patients with atrial septal abnormalities remains unclear, and the increased incidence of atrial vulnerability may be one of the reasons. We performed this meta-analysis to clarify the association between atrial septal abnormalities and atrial vulnerability, and to provide evidence-based basis for the prevention and mechanism of CS.

METHODS

We systematically searched for studies on the association between atrial septal abnormalities and atrial vulnerability, and pooled available data on types of atrial septal abnormalities, types of atrial vulnerability, and methods of atrial vulnerability detection. The primary endpoints were the occurrence of atrial arrhythmias or P wave abnormalities. Random-effects models were used to calculate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Twelve case-control studies were eligible. Compared with the control group, patients with atrial septal abnormalities had a higher risk of atrial vulnerability (OR: 1.93; 95% CI: 1.13-3.30, P = .02). Data based on stroke patients showed that the group with atrial septal abnormalities had a higher risk of atrial vulnerability than the control group (OR: 2.00; 95% CI: 1.13-3.53, P = .02). However, there was no significant difference in the incidence of atrial vulnerability between the 2 groups of nonstroke patients. Subgroup analysis showed that although atrial septal abnormality increased the risk of atrial vulnerability in the subgroup of atrial septal aneurysm (OR: 1.68; 95% CI: 0.47-5.95, P = .42), the subgroup of atrial fibrillation (AF)/atrial fluster (OR: 1.81; 95% CI: 0.94-3.46, P = .07) and the subgroup of subcutaneous recording system (OR: 1.33; 95% CI: 0.68-2.61, P = .41), the difference was not statistically significant.

CONCLUSIONS

Atrial septal abnormalities can increase the risk of atrial vulnerability, and atrial arrhythmia caused by atrial septal abnormalities may be one of the mechanisms of CS.

Sex-Specific Impacts of Exercise on Cardiovascular Remodeling

Cardiovascular diseases (CVD) remain the leading cause of death in men and women. Biological sex plays a major role in cardiovascular physiology and pathological cardiovascular remodeling. Traditionally, pathological remodeling of cardiovascular system refers to the molecular, cellular, and morphological changes that result from insults, such as myocardial infarction or hypertension. Regular exercise training is known to induce physiological cardiovascular remodeling and beneficial functional adaptation of the cardiovascular apparatus. However, impact of exercise-induced cardiovascular remodeling and functional adaptation varies between males and females. This review aims to compare and contrast sex-specific manifestations of exercise-induced cardiovascular remodeling and functional adaptation. Specifically, we review (1) sex disparities in cardiovascular function, (2) influence of biological sex on exercise-induced cardiovascular remodeling and functional adaptation, and (3) sex-specific impacts of various types, intensities, and durations of exercise training on cardiovascular apparatus. The review highlights both animal and human studies in order to give an all-encompassing view of the exercise-induced sex differences in cardiovascular system and addresses the gaps in knowledge in the field.

The Prevalence of Advanced Interatrial Block and Its Relationship to Left Atrial Function in Patients with Transthyretin Cardiac Amyloidosis

BACKGROUND

Advanced interatrial block (aIAB), which is associated with incident atrial fibrillation and stroke, occurs in the setting of blocked interatrial conduction. Atrial amyloid deposition could be a possible substrate for reduced interatrial conduction, but the prevalence of aIAB in patients with transthyretin cardiac amyloidosis (ATTR-CA) is unknown. We aimed to describe the prevalence of aIAB and its relationship to left atrial function in patients with ATTR-CA in comparison to patients with HF and left ventricular hypertrophy but no CA.

METHODS

The presence of aIAB was investigated among 75 patients (49 patients with ATTR-CA and 26 with HF but no CA). A comprehensive echocardiographic investigation was performed in all patients, including left atrial strain and strain rate measurements.

RESULTS

Among patients with ATTR-CA, 27% had aIAB and in patients with HF but no CA, this figure was 21%, (p = 0.78). The presence of aIAB was associated with a low strain rate during atrial contraction (<0.91 s-1) (OR: 5.2 (1.4-19.9)), even after adjusting for age and LAVi (OR: 4.5 (1.0-19.19)).

CONCLUSIONS

Advanced interatrial block is common among patients with ATTR-CA, as well as in patients with heart failure and left ventricular hypertrophy but no CA. aIAB is associated with reduced left atrial contractile function.

Does Parkinson's Disease Increase the Risk of Atrial Fibrillation? Insights From Electrocardiogram and Risk Scores From a Case-Control Study

Background: Previous studies suggested that Parkinson's Disease (PD) patients could have an increased risk of atrial fibrillation. However, data supporting this association is not robust. We aimed to compare the potential risk of atrial fibrillation associated with PD in an age and gender matched case-control study, comparing the p-wave indexes from electrocardiograms and clinical risk scores among groups.

Methods: A cross-sectional case-control study was performed. All subjects included in the analysis were clinically evaluated and subjected to a 12-lead electrocardiogram. Two blinded independent raters measured the p-wave duration. Subjects were classified as having normal P-wave duration (<120 ms), partial IAB (P-wave duration ≥ 120 ms, positive in inferior leads), and advanced IAB (p-wave duration ≥ 120 ms with biphasic morphology in inferior leads). Atrial fibrillation risk scores (CHARGE-AF, HATCH, and HAVOC) were calculated.

Results: From 194 potential participants, three were excluded from the control group due to a previous diagnosis of atrial fibrillation. Comparing the PD patients (n = 97) with controls (n = 95), there were no statistically significant differences regarding the mean p-wave duration (121 ms vs. 122 ms, p = 0.64) and proportion of advanced interatrial block (OR = 1.4, 95%CI = 0.37–5.80, p = 0.58). All patients had a low or medium risk of developing atrial fibrillation based on the clinical scores. There were no differences between the PD patients and controls regarding the mean values of CHARGE-AF, HATCH, and HAVOC.

Conclusions: Our results do not support the hypothesis that PD patients have an increased risk of atrial fibrillation based on the p-wave predictors and atrial fibrillation clinical scores.

Resumption of interatrial conduction after atrial premature beat in baseline interatrial aberrancy

Interatrial block (IAB) is a delay or blockage of interatrial conduction from the right atrium to the left atrium, causing prolongation of the P‐wave duration on the electrocardiogram. This condition is unfortunately not uncommon in clinical practice, especially among the elderly. It is often overlooked because the P wave is small and abnormalities can be difficult to detect. An isolated IAB does not usually cause any abnormal symptoms and may not require any specific treatment. Nevertheless, a relationship between an IAB and other cardiovascular conditions including left atrial electromechanical dysfunction, atrial remodeling, atrial fibrosis, atrial fibrillation, and stroke has been reported. Early diagnosis of this condition is critical. This case report presents a functional interatrial block or interatrial aberrancy that returned to normal after an atrial premature complex where the interatrial conduction remained normal in subsequent beats.

[Bayés Syndrome, Stroke and Dementia]

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.

Cardiac arrhythmia caused by a novel type of atrial conduction block: A case report

INTRODUCTION

We report an extremely rare case of atrial conduction block with unusual electrocardiogram (ECG) results, which has never been reported before. There are 2 types of atrial conduction block that result in atrial irregularities or complete atrial conduction block. The former is similar to other types of cardiac blocks such as sinus node to atrial block, atrial to ventricular block, or bundle branch blocks, which are characterized by 2 P waves at a specific frequency. This is due to the complete inner atrial block that results in the atrial muscle being divided into 2 parts without conduction between them so that each part has its rhythm generator. The objective of this report is to examine the cause of inner atrial conduction block and to promote awareness of this disorder.

PATIENT CONCERNS

An 81-year-old Chinese male patient was examined after complaining about chest discomfort, and it was found that he had atrial tachycardia; ECG results revealed a P wave loss at specific intervals (or P wave separation).

DIAGNOSIS

A diagnosis of P wave loss at specific intervals (or P wave separation) was made based on ECG results.

INTERVENTIONS

An ECG was performed on the patient OUTCOMES:: It was unclear whether this patient has atrial separation or a new type of atrial conduction block, but our results revealed that this case presents a novel type of atrial conduction block, which we named 'P wave block.'

CONCLUSION

The type of EKG shown in this case has never been reported. This EKG shows a new type of conduction block in the atrium, temporarily named as a new type of P wave block.

Intra-Atrial Block: Definition and Relationship to Atrial Fibrillation and Other Adverse Outcomes

In 1916, Bachmann first reported on the inter-auricular time interval. However relatively little attention was paid to this ECG measurement for decades. Then, in 1956, Samuel Bradley and Henry JJ Marriott reported on intra-atrial block (IAB) in 4,500 ECGs.As defined by them, IAB was a P wave duration of 0.12 sec or longer. Since that time, others have defined IAB as 0.11 sec or longer or 0.12 sec or longer. Several authors have suggested subcategories, such as first-, second-, and third-degree patterns and some have defined specific intra-atrial and inter-atrial pathways. These are of electrocardiographic interest but have not been substantiated as related to different clinical outcomes. Many disorders have been associated with IAB. More importantly, however, IAB has been associated with several adverse outcomes, including sinus node dysfunction, atrial tachyarrhythmias - especially atrial fibrillation, thromboembolic events, and increased mortality. This brief review will detail the above to emphasize to ECG readers the importance of not overlooking IAB in their interpretations.

Independent associations of blood pressure and body mass index with interatrial block: a cross-sectional study in general Chinese population

OBJECTIVES

This current study was performed to characterise the independent associations of obesity and hypertension with interatrial block (IAB) after adjusting for cardiovascular risk factors, echocardiographic left atrial diameter (LAD) and left ventricular mass index (LVMI) in a large general Chinese population.

DESIGN

A cross-sectional study.

SETTING AND PARTICIPANTS

A total of 11 956 permanent residents (≥35 years of age) from Liaoning Province in China were included in this study. Following the completion of a questionnaire, the enrolled participants were subjected to physical examinations, laboratory analyses, ECG and echocardiogram. Linear and logistic regression analyses were performed to evaluate the associations of hypertension and obesity with IAB.

OUTCOME MEASURES

IAB was defined as a prolongation of the P wave duration ≥120 ms on a digital 12-lead ECG.

RESULTS

The prevalence of IAB in hypertensive individuals was higher than the normotensive in both men (9.5 vs 5.9%; p<0.001) and women (6.6 vs 3.6%; p<0.001). In addition, the prevalence of IAB exhibited a sharp increase with advancing body mass index (BMI) in both men (from 4.9% to 13.0%) and women (from 3.5% to 6.9%) (ps- for trend <0.001). Multiple relevant clinical covariates, echocardiographic LAD and LVMI were adjusted in the multivariate linear and logistic regression analyses. The results revealed that systolic blood pressure, diastolic blood pressure and BMI were all independently associated with P wave duration (β=0.02, 0.09 and 0.25, respectively; all ps <0.005). Furthermore, hypertension was found to be independently associated with IAB (OR=1.27; p=0.018), while both overweight and obesity exhibited higher odds of IAB (OR=1.42 and 1.67, respectively; ps <0.005), compared with BMI <24.0 kg/m².

CONCLUSIONS

The key findings of this study highlighted that hypertension and overweight/obesity were independently and significantly associated with IAB in general Chinese population.

Electrocardiographic evidence of abnormal atrial phenotype in Brugada syndrome

BACKGROUND

Brugada syndrome (BrS) is an inherited ion channelopathy that may predispose affected individuals to atrial cardiomyopathy. We tested the hypothesis that BrS patients have higher degrees of atrial electrophysiological abnormalities compared to controls, and these can be reflected by changes in P-wave parameters determined on the electrocardiogram (ECG).

METHODS

This was a single-center retrospective study comparing BrS patients to age- and gender-matched control subjects. Mean P-wave duration (PWD_mean), maximum PWD (PWD_max) and minimum PWD (PWD_min), P-wave dispersion (PWD_max - PWD_min), and P-wave terminal force in V1 (PTFV1) were measured. PWD_max ≥ 120 ms, in the presence and absence of biphasic P-waves in the inferior leads, were termed advanced and partial inter-atrial block (IAB), respectively.

RESULTS

The proportion of IAB was significantly higher in BrS patients (28/51; 55%) than in control subjects (14/51; 27%; Fisher's Exact test; P < 0.01). Advanced IAB was observed in two BrS patients but none of the control subjects (P = 0.50). Compared to controls, BrS patients showed higher PWD_mean (107 [98-113] vs. 97 [90-108] ms; KWANOVA, P < 0.01), PWD_max (123 [110-132] vs. 113 [107-121] ms; P < 0.001) but statistically indistinguishable PWD_min (82 [72-92] vs. 77 [69-85]; P = 0.09), and P-wave dispersion (38 [26-52] vs. 37 [23-45] ms; P = 0.14). PTFV1 was significantly higher in BrS patients than in control subjects (24 [0-40] vs. 0 [0-27] mm.ms; P < 0.05).

CONCLUSION

Atrial conduction abnormalities are frequently observed in BrS. These patients may require monitoring for future development of atrial fibrillation and stroke.

Simulation of inter atrial block based on a human atrial model

Inter atrial block (IAB) is a prevailing cardiac conduction abnormality that is under-recognized in clinical practice. IAB has strong association with atrial arrhythmia, left atrial enlargement, and electromechanical discordance, increasing the risk of atrial fibrillation (AF) and myocardial ischemia. IAB was generally believed to be caused by impaired conduction along the Bachmann bundle (BB). However, there are three other conduction pathways, including the fibers posteriorly in the vicinity of the right pulmonary veins (VRPV), transseptal fibers in the fossa ovalis (FO), and muscular bundles on the inferior atrial surface near the coronary sinus (CS). We hypothesized that the importance of BB on IAB might have been overestimated. To test this hypothesis, various combinations of conduction pathway blocks were simulated based on a realistic human atrial model to investigate their effects on the index of clinical diagnosis standard of IAB using a simulated 12-lead electrocardiogram (ECG). Firstly, the results showed that the BB block alone could not generate typical P wave morphology of IAB, and that the combination of BB and VRPV pathway block played important roles in the occurrence of IAB. Secondly, although single FO and CS pathways play subordinate roles in inter atrial conduction, their combination with BB and VRPV block could also produce severe IAB. In summary, this simulation study has demonstrated that the combinations of different inter atrial conduction pathways, rather than BB alone, resulted in ECG morphology of IAB. Attention needs to be paid to this in future pathophysiological and clinical studies of IAB.

Association Between CHADS2 Score and the Development of Interatrial Block

Interatrial block (IAB) is associated with a multitude of medical conditions. The aim of this retrospective study was to investigate whether CHADS₂ (congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, prior stroke) score is positively associated with the development of IAB. A total of 1072 patients (men, 555; women, 517; mean age, 61 ± 14 years) were included in the study. P-wave duration was measured manually using a caliper. IAB was defined as a P-wave duration of ≥ 120 ms on a 12-lead electrocardiogram. CHADS₂ scores were calculated retrospectively. Among the 1072 patients, the prevalence of IAB was 36.1% (387/1072). In multivariate analysis, increased CHADS₂ score (odds ratio [OR], 1.810; 95% confidence interval [CI], 1.577-2.077; P < 0.001), coronary artery disease (OR, 1.536; 95% CI, 1.065-2.216; P = 0.022), and increased left atrial diameter (OR, 1.039; 95% CI, 1.008-1.071; P = 0.013) were independently associated with IAB. The percentages of patients with IAB among those with a CHADS₂ score of 0, 1, 2, 3, 4, 5, and 6 were 20.6%, 33.0%, 45.0%, 55.9%, 61.9%, 77.8%, and 100%, respectively (P < 0.001). There was a greater percentage of patients with a CHADS₂ score of ≥ 2 with IAB compared with a CHADS₂ score of < 2 (26.5% vsrsus 52.0%; P < 0.001). In receiver operating curve (ROC) analysis, CHADS₂ score (area under the curve, 0.670; 95% CI, 0.636-0.704; P < 0.001) was predictive of IAB. In conclusion, CHADS₂ score was significantly associated with the development of IAB in this study population.

[Bayes' syndrome in cardiac surgery: prevalence of interatrial block in patients younger than 65 years undergoing cardiac surgery and association with postoperative atrial fibrillation]

OBJECTIVE

Interatrial block (IAB) is a well-known entity that is associated with an increased risk of atrial fibrillation (AF). This association is called Bayes' syndrome. The aim of our study was to define the prevalence of IAB among patients younger than 65 years undergoing cardiac surgery and determine whether there is an association between the presence of interatrial conduction delay and postoperative atrial fibrillation (POAF).

METHOD

A total of 207 patients were enrolled. Partial IAB was defined as P-wave>120ms. Advanced IAB was defined as P-wave>120ms+biphasic morphology in the inferior leads. Ocurrence of POAF was assessed and a comparative analysis was conducted between patients that did and did not develop AF.

RESULTS

IAB prevalence was 78.3% (partial 66.2%, advanced 12.1%). POAF occurred in 28.5% of all patients, and was more frequent among patients with advanced IAB (44%) compared to 27.7% and 24.4% of POAF among patients with partial IAB and without IAB, respectively. Patients who developed POAF were significantly older, had significantly higher NTproBNP, higher prevalence of atrial enlargement and thyroid disease. After multivariate analysis, advanced IAB was found to be independently associated with POAF.

CONCLUSIONS

IAB is a frequent finding among patients undergoing cardiac surgery. According to our results, advanced IAB is independently associated with POAF in younger patients (<65 years) undergoing cardiac surgery.

ECG markers associated with ischemic stroke at young age - a case-control study

INTRODUCTION

Certain electrocardiographic (ECG) abnormalities are associated with ischemic stroke (IS), especially cardioembolic subtype. Besides atrial fibrillation, markers of left ventricular hypertrophy (LVH) or atrial pathology also reflect elevated risk. We studied the association of ECG markers with IS in young adults.

METHODS

We performed a case-control study including 567 consecutive IS patients aged 15-49 years (inclusion period: 1994-2007) and one or two age- and sex-matched control subjects enrolled during 1978-1980 (n = 1033), and investigated also the stroke aetiologic subgroups. We studied ECGs of all participants for markers of atrial abnormality, i.e. P-terminal force (PTF) on lead V1, interatrial blocks (IAB; P-wave duration ≥110 ms), and LVH. Conditional logistic regression analyses were used.

RESULTS

IAB (hazard ratio [HR]: 1.57, 95% confidence interval [CI]: 1.16-2.13) and PTF combined with LVH (HR: 6.83, 95% CI: 1.65-28.31), were independently associated with IS. LVH, abnormal P-wave (HR: 6.87, 95% CI: 1.97-135.29), PTF, IAB, and combinations of these P-wave abnormalities with LVH - were associated with cardioembolic subtype. Abnormal P-wave and IAB were associated with cryptogenic stroke subtype. In unadjusted analysis, LVH was associated with small-vessel disease subtype.

CONCLUSION

P-wave abnormalities on ECG were associated with cardioembolic but also with a cryptogenic subtype of IS. Key messages ECG patterns associated with atrial pathology are markers of increased risk of ischemic stroke in young adults. The ECG markers reflecting atrial pathology were seen in patients with cardioembolic and cryptogenic subtypes of ischemic stroke.

P-Wave Indices and Risk of Ischemic Stroke: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Atrial cardiomyopathy is associated with an increased risk of ischemic stroke. P-wave terminal force in lead V₁, P-wave duration, and maximum P-wave area are electrocardiographic parameters that have been used to assess left atrial abnormalities related to developing atrial fibrillation. The aim of this systematic review and meta-analysis was to examine their values for predicting ischemic stroke risk.

METHODS

PubMed and EMBASE databases were searched until December 2016 for studies that evaluated the association between P-wave indices and stroke risk. Both fixed- and random-effects models were used to calculate the overall effect estimates.

RESULTS

Ten studies examining P-wave terminal force in lead V₁, P-wave duration, and maximum P-wave area were included. P-wave terminal force in lead V₁ was found to be an independent predictor of stroke as both a continuous variable (odds ratio [OR] per 1 SD change, 1.18; 95% confidence interval [CI], 1.12-1.25; P<0.0001) and categorical variable (OR, 1.59; 95% CI, 1.10-2.28; P=0.01). P-wave duration was a significant predictor of incident ischemic stroke when analyzed as a categorical variable (OR, 1.86; 95% CI, 1.37-2.52; P<0.0001) but not when analyzed as a continuous variable (OR, 1.05; 95% CI, 0.98-1.13; P=0.15). Maximum P-wave area also predicted the risk of incident ischemic stroke (OR per 1 SD change, 1.10; 95% CI, 1.04-1.17).

CONCLUSIONS

P-wave terminal force in lead V₁, P-wave duration, and maximum P-wave area are useful electrocardiographic markers that can be used to stratify the risk of incident ischemic stroke.

Analysis of the Association Between Electrocardiographic P-wave Characteristics and Atrial Fibrillation in the REGICOR Study

INTRODUCTION AND OBJECTIVES

Atrial fibrillation (AF) is the most common clinically significant cardiac arrhythmia. P-wave duration and interatrial blocks (IAB) have been reported to be associated with AF. Our aim was to determine the individual and combined association of P-wave duration and advanced IAB morphology with AF.

METHODS

We designed an age-, sex-, and survey-matched case-control study nested in a population-based cohort (REGICOR: REgistre GIroní del COR). Two different surveys recruited a total of 9380 participants from 1999 to 2005; all participants were invited to a second examination between 2009 and 2013. For the present study, we selected participants aged 25 to 79 years with follow-up through the end of the study. All electrocardiograms were analyzed by 2 observers to determine P-wave duration and morphology (normal, partial, or advanced IAB).

RESULTS

The median follow-up was 7.12 years. Eighty participants presented with AF, had a legible baseline electrocardiogram, and were included in the study, along with 160 controls. P-wave duration and the presence of partial or advanced IAB were associated with AF. When P-wave duration and morphology were considered together, only P-wave duration (≥ 110 milliseconds) showed an independent and strong association with AF. The odds ratio for AF of P-wave duration between 110-119, 120-129 and ≥ 130 milliseconds vs < 110 milliseconds were 5.33; 95%CI, 1.74-16.33, 5.08; 95%CI, 1.73-14.90 and 5.44; 95%CI, 1.95-15.15, respectively.

CONCLUSIONS

A P-wave longer than 110 milliseconds increases the risk of AF. Advanced IAB morphology did not seem to provide an additional AF risk beyond that of P-wave duration.

Bayés syndrome and acute cardioembolic ischemic stroke

Bayés syndrome is an under-recognized clinical condition characterized by advanced interatrial block. Bayés syndrome is a subclinical disease that manifests electrocardiographically as a prolonged P wave duration > 120 ms with biphasic morphology ± in the inferior leads. The clinical relevance of Bayés syndrome lies in the fact that is a clear arrhythmological syndrome and has a strong association with supraventricular arrhythmias, particularly atypical atrial flutter and atrial fibrillation. Likewise, Bayés syndrome has been recently identified as a novel risk factor for non-lacunar cardioembolic ischemic stroke and vascular dementia. Advanced interatrial block can be a risk for embolic stroke due to its known sequelae of left atrial dilation, left atrial electromechanical dysfunction or atrial tachyarrhythmia (paroxysmal or persistent atrial fibrillation), conditions predisposing to thromboembolism. Bayés syndrome may be responsible for some of the unexplained ischemic strokes and shall be considered and investigated as a possible cause for cryptogenetic stroke. In summary, Bayés syndrome is a poorly recognized cardiac rhythm disorder with important cardiologic and neurologic implications.

Bayes Syndrome and Imaging Techniques

BACKGROUND

Interatrial block (IAB) is due to disruption in the Bachmann region (BR). According to whether interatrial electrical conduction is delayed or completely blocked through the BR, it can be classified as IAB of first, second or third degree. On the surface electrocardiogram, a P wave ≥ 120 ms (partial IAB) is observed or associated to the prolongation of the P wave with a biphasic (positive / negative) morphology in the inferior leads (advanced IAB). Bayes syndrome is defined as an advanced IAB associated with atrial arrhythmia, more specifically atrial fibrillation. Objective and Conclusion: The purpose of this review is to describe the latest evidence about an entity considered an anatomical and electrical substrate with its own name, which may be a predictor of supraventricular arrhythmia and cardioembolic cerebrovascular accidents, as well as the role of new imaging techniques, such as echocardiographic strain and cardiac magnetic resonance imaging, in characterizing atrial alterations associated with this syndrome and generally in the study of anatomy and atrial function.

CHADS2 and CHA2DS2-VASc Scores Predict the Risk of Ischemic Stroke Outcome in Patients with Interatrial Block without Atrial Fibrillation

Aim: To evaluate the role of CHADS₂ and CHA₂DS₂-VASc scores in predicting the risk of ischemic stroke or transient ischemic attack (TIA) outcomes in patients with interatrial block (IAB) without a history of atrial fibrillation (AF).

Methods: A retrospective study was conducted, including 1,046 non-anticoagulated inpatients (612 males, 434 females; mean age: 63 ± 10 years) with IAB and without AF. IAB was defined as P-wave duration > 120 ms using a 12-lead electrocardiogram. CHADS₂ and CHA₂DS₂-VASc scores were retrospectively calculated. The primary outcomes evaluated were ischemic stroke or TIA.

Results: During the mean follow-up period of 4.9 ± 0.7 years, 55 (5.3%) patients had an ischemic stroke or TIA. Receiver operating characteristic (ROC) curve analysis showed that the CHADS₂ score [area under the curve (AUC), 0.638; 95% confidence interval (CI), 0.562–0.715; P = 0.001] and the CHA₂DS₂-VASc score (AUC, 0.671; 95% CI, 0.599–0.744; P <0.001) were predictive of ischemic strokes or TIA. Cut-off point analysis showed that a CHADS₂ score ≥ 3 (sensitivity = 0.455 and specificity = 0.747) and a CHA₂DS₂-VASc score ≥ 4 (sensitivity = 0.564 and specificity = 0.700) provided the highest predictive value for ischemic stroke or TIA. The multivariate Cox regression analysis showed that CHADS₂ [hazard ratio (HR), 1.442; 95% CI, 1.171–1.774; P = 0.001] and CHA₂DS₂-VASc (HR, 1.420; 95% CI, 1.203–1.677; P <0.001) scores were independently associated with ischemic stroke or TIA following adjustment for smoking, left atrial diameter, antiplatelet agents, angiotensin inhibitors, and statins.

Conclusions: CHADS₂ and CHA₂DS₂-VASc scores may be predictors of risk of ischemic stroke or TIA in patients with IAB without AF.