Advanced Interatrial Block Predicts New Onset Atrial Fibrillation in Patients with Severe Heart Failure and Cardiac Resynchronization Therapy

P-wave duration and interatrial block as predictors of new-onset atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Early detection of atrial fibrillation (AF) could improve patient outcomes. P-wave duration (PWD) and interatrial block (IAB) are known predictors of new-onset AF and could improve selection for AF screening. This meta-analysis reviews the published evidence and offers practical implications.

METHODS

Publication databases were systematically searched, and studies reporting PWD and/or morphology at baseline and new-onset AF during follow-up were included. IAB was defined as partial (pIAB) if PWD≥120 ms or advanced (aIAB) if the P-wave was biphasic in the inferior leads. After quality assessment and data extraction, random-effects analysis calculated odds ratio (OR) and confidence intervals (CI). Subgroup analysis was performed for those with implantable devices (continuous monitoring).

RESULTS

Among 16,830 patients (13 studies, mean 66 years old), 2,521 (15%) had new-onset AF over a median of 44 months. New-onset AF was associated with a longer PWD (mean pooled difference: 11.5 ms, 13 studies, p < 0.001). The OR for new-onset AF was 2.05 (95% CI: 1.3-3.2) for pIAB (5 studies, p = 0.002) and 3.9 (95% CI: 2.6-5.8) for aIAB (7 studies, p < 0.001). Patients with pIAB and devices had higher AF-detection risk (OR: 2.33, p < 0.001) than those without devices (OR: 1.36, p = 0.56). Patients with aIAB had similarly high risk regardless of device presence. There was significant heterogeneity but no publication bias.

CONCLUSION

Interatrial block is an independent predictor of new-onset AF. The association is stronger for patients with implantable devices (close monitoring). Thus, PWD and IAB could be used as selection criteria for intensive screening, follow-up or interventions.

Electrocardiographic Predictors of Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common pathological arrhythmia, and its complications lead to significant morbidity and mortality. However, patients with AF can often go undetected, especially if they are asymptomatic or have a low burden of paroxysms. Identification of those at high risk of AF development may help refine screening and management strategies.

METHODS

PubMed and Embase databases were systematically searched for studies looking at electrocardiographic predictors of AF from inception to August 2021.

RESULTS

A total of 115 studies were reported which examined a combination of atrial and ventricular parameters that could be electrocardiographic predictors of AF. Atrial predictors include conduction parameters, such as the PR interval, p-wave index and dispersion, and partial interatrial or advanced interatrial block, or morphological parameters, such as p-wave axis, amplitude and terminal force. Ventricular predictors include abnormalities in QRS amplitude, morphology or duration, QT interval duration, r-wave progression and ST segment, i.e., t-wave abnormalities.

CONCLUSIONS

There has been significant interest in electrocardiographic prediction of AF, especially in populations at high risk of atrial AF, such as those with an embolic stroke of undetermined source. This review highlights the breadth of possible predictive parameters, and possible pathological bases for the predictive role of each parameter are proposed.

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.

Current ECG Aspects of Interatrial Block

Interatrial blocks like other types of block may be of first degree or partial second degree, also named transient atrial block or atrial aberrancy, and third degree or advanced. In first degree, partial interatrial block (P-IAB), the electrical impulse is conducted to the left atrium, through the Bachmann’s region, but with delay. The ECG shows a P-wave ≥ 120 ms. In third-degree, advanced interatrial block (A-IAB), the electrical impulse is blocked in the upper part of the interatrial septum (Bachmann region); the breakthrough to LA has to be performed retrogradely from the AV junction zone. This explains the p ± in leads II, III and aVF. In typical cases of A-IAB, the P-wave morphology is biphasic (±) in leads II, III and aVF, because the left atrium is activated retrogradely and, therefore, the last part of the atrial activation falls in the negative hemifield of leads II, III and aVF. Recently, some atypical cases of A-IAB have been described. The presence of A-IAB is a risk factor for atrial fibrillation, stroke, dementia, and premature death.

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.

Relationship between electrocardiographic interatrial blocks and echocardiographic indices of left atrial function in acute heart failure

The presence of an interatrial block (IAB) on surface ECG should be considered as a hallmark of atrial electrical remodelling. This is often accompanied by morphological abnormalities. We aimed to investigate the frequency of IAB and its relationship with the echocardiographic indices of left atrial (LA) remodelling in patients hospitalised with acute HF. Ninety-four consecutive HF patients underwent 12-lead ECG, transthoracic echocardiogram including a detailed study of the LA, and blood tests (including NT-proBNP) on the same day. Thirty-six patients were excluded from the analysis because of atrial fibrillation or rhythms other than sinus. Twenty-eight over 58 (48%) were males. Median age was 72 (IQR 60-82) years. The majority of patients (72%) were diagnosed as having an HF with reduced ejection fraction. Overall, 27 (46%) patients presented with an advanced III or IV NYHA functional class. Median plasma NT-proBNP was 3046 (IQR 1066-5460) pg/ml. Nearly, all the enrolled patients (90%) showed LA dilation. Nineteen patients (33%) presented with advanced IAB. There was a trend toward a more advanced age in patients with advanced IAB (median age 79 vs 68, p = 0.051). Moreover, they were more frequently treated with anticoagulants (42% vs 13%, p = 0.01), and they exhibited greater LA structural and functional remodelling documented by larger area (28 vs 26 cm², p = 0.04) and greater minimum LA volume index-LAVi (43 ± 16 vs 36 ± 10, p = 0.04). Advanced IAB resulted to be an independent determinant of LA area (Beta 3.49 (0.37-6.60), p = 0.03) and minimum LAVi (Beta 7.22 (0.15-14.30), p = 0.045), and vice versa. LA electrical and structural remodelling is highly prevalent in a non-selected cohort of patients with acute HF. Advanced IAB on surface ECG is present in a high percentage of cases. Patients with advanced IAB tend to be older, and they exhibit higher degrees of LA structural and functional remodelling.

Interatrial Block Predicts Atrial Fibrillation and Total Mortality in Patients with Cardiac Resynchronization Therapy

BACKGROUND

Interatrial block (IAB) and abnormal P-wave terminal force in lead V1 (PTFV1) are electrocardiographic (ECG) abnormalities that have been shown to be associated with new-onset atrial fibrillation (AF) and death. However, their prognostic importance has not been proven in cardiac resynchronization therapy (CRT) recipients.

OBJECTIVE

To assess if IAB and abnormal PTFV1 are associated with new-onset AF or death in CRT recipients.

METHODS

CRT recipients with sinus rhythm ECG at CRT implantation and no AF history were included (n = 210). Automated analysis of P-wave duration (PWD) and morphology classified patients as having either no IAB (PWD <120 ms), partial IAB (pIAB: PWD ≥120 ms, positive P waves in leads II and aVF), or advanced IAB (aIAB: PWD ≥120 ms and biphasic or negative P wave in leads II or aVF). PTFV1 >0.04 mm•s was considered abnormal. Adjusted Cox regression analyses were performed to assess the impact of IAB and abnormal PTFV1 on the primary endpoint new-onset AF, death, or heart transplant (HTx) and the secondary endpoint death or HTx at 5 years of follow-up.

RESULTS

IAB was found in 45% of all patients and independently predicted the primary endpoint with HR 1.9 (95% CI 1.2-2.9, p = 0.004) and the secondary endpoint with HR 2.1 (95% CI 1.2-3.4, p = 0.006). Abnormal PTFV1 was not associated with the endpoints.

CONCLUSIONS

IAB is associated with new-onset AF and death in CRT recipients and may be helpful in the risk stratification in the context of heart failure management. Abnormal PTFV1 did not demonstrate any prognostic value.

Bayés' Syndrome-A Comprehensive Short Review

Prediction and early detection of atrial fibrillation (AF) remain a permanent challenge in everyday practice. Timely identification of an increased risk for AF episodes (which are frequently asymptomatic) is essential in the primary and secondary prevention of cardioembolic events. One of the noninvasive modalities of AF prediction is represented by the electrocardiographic P-wave analysis. This includes the study and diagnosis of interatrial conduction block (Bachmann’s bundle block). Bayés’ Syndrome (named after its first descriptor) denotes the association between interatrial conduction defect and supraventricular arrhythmias (mainly AF) predisposing to cardioembolic events. Our short review presents an update of the most important data concerning this syndrome: brief history, main ECG features, pathophysiological background and clinical implications.

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.

Beyond CHA2DS2-VASc in atrial fibrillation: the atrium and the risk of stroke

Pathology affecting the atria have a significant impact on the occurrence of arrhythmias and the risk of stroke. The causal relationship between atrial fibrillation (AF) and ischaemic stroke has been challenged by the recent uncovering of the lack of temporal association between thrombo-embolic cerebral events and paroxysmal AF or tachycardia. General conditions, such as the one considered in the definition of the CHA₂DS₂-VASc score, or specific atrial pathology (also independently occurring), could predispose to cerebral embolism.

New electrocardiographic score for the prediction of atrial fibrillation: The MVP ECG risk score (morphology-voltage-P-wave duration)

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia and has significant morbidity. A score composed of easily measured electrocardiographic variables to identify patients at risk of AF would be of great value in order to stratify patients for increased monitoring and surveillance. The purpose of this study was to develop an electrocardiographic risk score for new-onset AF.

METHODS

A total of 676 patients without previous AF undergoing coronary angiography were retrospectively studied. Points were allocated based on P-wave morphology in inferior leads, voltage in lead 1, and P-wave duration (MVP). Patients were divided into three risk groups and followed until development of AF or last available clinical appointment.

RESULTS

Mean age was 65 years, and 68% were male. The high- and intermediate-risk groups were more likely to develop AF than the low-risk group (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.3-4.4; p = 0.006 and OR 2.1, 95% CI 1.4-3.27; p = 0.009, respectively). The high-risk group had a significantly shorter mean time to development of AF (258 weeks; 95% CI 205-310 weeks) compared to the intermediate- (278 weeks; 95% CI 252-303 weeks) and low-risk groups (322 weeks 95% CI 307-338 weeks), p = 0.005.

CONCLUSIONS

A simple risk score composed of easy-to-measure electrocardiographic variables can help to predict new-onset AF. Further validation studies will be needed to assess the ability of this risk score to predict AF in other populations.

Value of Interatrial Block for the Prediction of Silent Ischemic Brain Lesions

Introduction

Previous studies demonstrated that interatrial block (IAB) is associated with atrial fibrillation (AF) in different clinical scenarios. The aim of our study was to determine whether IAB could predict silent ischemic brain lesions (sIBL), detected by magnetic resonance imaging (MRI).

Methods

Patients presented to a neurology clinic with transient ischemic attack (TIA) symptoms and underwent brain MRI were included to the study. sIBL were defined as lesions without corresponding clinical symptoms regarding lesion localization evaluated by two neurologists. A 12-lead surface ECG was obtained from each patient. IAB was defined as P-wave duration > 120 ms with (advanced IAB) or without (partial IAB) biphasic morphology in the inferior leads.

Results

sIBL was detected in 61 (49.6%) patients. Patients with sIBL were older (P<0.001), had more left ventricular hypertrophy (LVH) (P=0.02) and higher CHA2DS2-VASc score compared to those without (P<0.001). P-wave duration was significantly longer in patients with sIBL (124 [110.5 - 129] msvs 107 [102 - 116.3] ms) (P<0.001). IAB was diagnosed in 36 patients (59%) with sIBL (+) and in 11 patients (18%) with sIBL (-); p<0.001. Multivariate logistic regression analysis identified age [Odds ratio (OR), 1.061; 95% confidence interval (CI), 1.012 - 1.113; p=0.014], CHA2DS2-VASc score (OR, 1.758; 95% CI, 1.045 - 2.956; p=0.034), LVH (OR, 3.062; 95% CI, 1.161 - 8.076; p=0.024) and IAB (including both partial and advanced) (OR, 5.959; 95% CI, 2.269 - 15.653; p<0.001) as independent predictors of sIBL.

Conclusion

IAB is a strong predictor of sIBL and can be easily diagnosed by performing surface 12-lead ECG.

Update on Bayés' syndrome: the association between an interatrial block and supraventricular arrhythmias

INTRODUCTION

The past few years have given rise to extensive research on an interatrial block and its clinical relevance, mainly its association with supraventricular arrhythmias. In 2015, the authors of this article reviewed the Bayes syndrome for the first time and after three years there has been so much evidence accumulated that it seems reasonable to rewrite an update, based fundamentally on the new findings. Focused on its relationship with cardioembolic strokes, today efforts are being targeted at understanding its pathophysiology, its diagnosis, and its prognostic implications, in order to learn if it should be treated. Areas covered: A non-systematic review of the literature was developed using the Pubmed and Cochrane databases, focusing on randomized clinical trials and large observational studies that evaluated new physiopathological and epidemiological aspects, new clinical scenarios in which it has been assessed and its association with dementia. Finally, those studies that proposed new possible treatments were reviewed. Expert commentary: Interatrial block is not only a predictor of supraventricular arrhythmias, is a subclinical disease that might be considered as a marker of risk for adverse outcomes. Although there is some evidence to suggest that early treatment may be beneficial, potential therapies have yet to be investigated.

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.

Advanced interatrial block is an electrocardiographic marker for recurrence of atrial fibrillation after electrical cardioversion

BACKGROUND

Early recurrence of atrial fibrillation (AF) is common following a successful electrical cardioversion (ECV). The purpose of this study was to investigate the hypothesis that AF recurrence is related to atrial electrical inhomogeneity, which may influence the P wave characteristics.

METHODS

Two hundred ninety-one consecutive persistent AF patients who underwent ECV were enrolled, and evaluated for AF recurrences one month after the ECV. Patients with open-heart surgery, a history of catheter ablation, and an unsuccessful ECV were excluded. The P wave duration, dispersion and P wave morphology were evaluated by 12‑lead ECGs 30 min after the ECV.

RESULTS

In total, 141 patients were investigated. One month after the ECV, 60 (43%) patients maintained sinus rhythm. The advanced interatrial block (aIAB; P wave duration >120 ms and biphasic P waves in the inferior leads) (Hazard ratio [HR], 4.51; 95% confidence interval [CI] 1.45-14.01, P = 0.009), P wave dispersion (HR, 1.06; 95%CI 1.02-1.09, P = 0.001), and duration of AF per month (HR, 1.03; 95%CI 1.01-1.04, P = 0.004) were independent predictors of AF recurrence. An aIAB was not associated with structural parameters such as the left atrial volume index or right atrial area. There were no differences in the serum BNP level and frequency of administering anti-arrhythmic drugs between the patients with and without recurrence.

CONCLUSIONS

The risk of AF recurrence after the ECV can be predicted by the P wave characteristics. A longer P wave dispersion and the duration of AF also had a tendency for recurrence.

Bayés' syndrome: Time to consider early anticoagulation?

In the past few decades, extensive research has been conducted on atrial conduction disorders and their clinical relevance. An association between interatrial block (IAB) and supraventricular arrhythmias [most commonly atrial fibrillation (AF)] has been discovered and extensively investigated. We coined the term "Bayés Syndrome" to describe this association, and the medical community has accepted the eponym in recognition to the scientist who discovered most of the aspects associated with it. In this non-systematic review, we will focus on the association between IAB and AF, with special emphasis on the value of the surface 12-lead ECG as a valid tool to predict AF.

Advanced interatrial block predicts new-onset atrial fibrillation and ischemic stroke in patients with heart failure: The "Bayes' Syndrome-HF" study

AIMS

Advanced interatrial block (IAB) is characterized by a prolonged (≥120 ms) and bimodal P wave in the inferior leads. The association between advanced IAB and atrial fibrillation (AF) is known as "Bayes' Syndrome", and there is scarce information about it in heart failure (HF). We examined the prevalence of IAB and whether advanced IAB could predict new-onset AF and/or stroke in HF patients.

METHODS AND RESULTS

The prospective observational "Bayes' Syndrome-HF" study included consecutive outpatients with chronic HF. The primary endpoints were new-onset AF, ischemic stroke, and the composite of both. A secondary endpoint included all-cause death alone or in combination with the primary endpoint. Comprehensive multivariable Cox regression analyses were performed. Among 1050 consecutive patients, 536 (51.0%) were in sinus rhythm, 464 with a measurable P wave are the focus of this study. Two-hundred and sixty patients (56.0%) had normal atrial conduction, 95 (20.5%) partial IAB, and 109 (23.5%) advanced IAB. During a mean follow-up of 4.5 ± 2.1 years, 235 patients experienced all-cause death, new-onset AF, or stroke. In multivariable comprehensive Cox regression analyses, advanced IAB was associated with new-onset AF (HR 2.71 [1.61-4.56], P < 0.001), ischemic stroke (HR 3.02 [1.07-8.53], P = 0.04), and the composite of both (HR 2.42 [1.41-4.15], P < 0.001).

CONCLUSIONS

In patients with HF advanced IAB predicts new-onset AF and ischemic stroke. Future studies must assess whether anticoagulant treatment in Bayes' Syndrome leads to better outcomes in HF.

Interatrial block to predict atrial fibrillation in myotonic dystrophy type 1

Paroxysmal atrial fibrillation frequently occurs in Myotonic dystrophy type 1 (DM1) patients. Interatrial block is recognized as predictor of atrial arrhythmias, particularly atrial fibrillation (AF). The aim of this study was to evaluate the role of interatrial block in predicting the onset of atrial fibrillation during 2-year follow-up in DM1 patients who underwent pacemaker implantation for conduction system disorders. The study prospectively enrolled 70 DM1 patients (aged 36-69; 31 M) who underwent pacemaker implantation for cardiac rhythm abnormalities in accordance with the current guidelines. All DM1 patients underwent 12-lead surface ECG, 2D color Doppler echocardiogram and device interrogation at implantation, one month after and every six months thereafter for a minimum of 2-year follow-up. 12-lead surface ECGs were analyzed to diagnose interatrial block (IAB), defined as a P-wave duration ≥120 ms without (partial IAB) or with (advanced IAB) biphasic morphology (±) in the inferior leads. Device interrogation was performed to evaluate the development of new onset atrial high rate electrograms compatible with paroxysmal atrial fibrillation episodes. Interatrial block was detected in 22 patients (31.4%): 18 partial (25.7%) and 4 advanced (5.7%). During follow-up, AF episodes were detected in 18 DM1 patients (25.7%). The study population was divided into 2 groups according to the presence of AF (AF+ Group vs AF- Group). The AF+ Group was older and showed higher prevalence of IAB than the AF- Group. IAB was found to be independent predictor of AF in DM1 population (P < 0.001). A cut-off value of 121 ms for IAB had a sensitivity of 83.3% and specificity of 90.3% in identifying DM1 patients at high risk of developing AF. Interatrial block represents an independent predictor of AF occurrence in our DM1 population with conduction disturbances who had previously undergone pacemaker implantation.

Prevalence of P wave dispersion and interatrial block in patients with systolic heart failure and their relationship with functional status, hospitalization and one year mortality

Background and objectives

P-wave dispersion (PWD) and Interatrial block (IAB) are common in heart failure (HF), and could be associated with adverse cardiac events. We aimed to assess the prevalence of PWD and IAB and their relationship with functional status, hospitalization and mortality rate in patients with systolic HF.

Methods

We enrolled 110 HF patients in sinus rhythm & LVEF <50%. Patients had undergone clinical evaluation, 6 min walking test (6MWT), 12-lead electrocardiography (ECG), 24-h Holter ECG & echocardiogram. Hospitalization and mortality rate were followed-up for one year. PWD was defined as the difference between maximum & minimum P-wave duration >40 ms. IAB was defined as maximum P duration >110 ms. Measurements were done by 2 blinded investigators using a caliber, a ruler and a magnifying lens.

Results

Mean age was 58.9 ± 9.7 years and 67.3% were males. Prevalence of PWD and IAB was 68.2% and 57.3%, respectively. Patients with PWD showed these features: 84% in NYHA class III or IV HF, 77.4% had LVEF <35%, 78.7% had paroxysmal Atrial Fibrillation (AF) and 89.4% couldn’t complete >200 m (m) in 6MWT. Patients with PWD had more hospitalizations (72% vs 28.6%, P value <0.02) and higher 1-year mortality rate (20% vs 8.6%, P value <0.04) than patients without PWD. Likewise, patients with IAB had nearly similar clinical features, hospitalization and mortality as patients with PWD.

Conclusion

PWD and IAB are prevalent in patients with systolic HF and they are significantly associated with low LVEF, paroxysmal AF, poor functional capacity, hospitalization and mortality rate.

P-wave and interatrial block: New predictor for atrial high rate episodes in patients with cardiac implantable electronic devices

BACKGROUND

The presence of interatrial block (IAB) is associated with the development of atrial fibrillation (AF). The aim of this study was to determine whether P-wave duration and presence of IAB before the implantation of a cardiac implantable electronic device (CIED) are associated with the presence of atrial high rate episodes (AHRE), during long-term follow-up.

METHODS

380 patients (57% men; 75 ± 10 years) were included. IAB was defined according to the International Consensus Criteria. AHRE was defined as an episode of atrial rate ≥225 beats/min with a minimum duration of 5 minutes.

RESULTS

Documented paroxysmal AF before the implantation was present in 24% of the patients; 80% had hypertension and 32% structural heart disease. Mean P-wave duration was 123 ± 23 ms, and 39% of the patients had IAB (32% partial, 7% advanced). After a mean follow-up of 18 ± 12 months, 33% of the patients presented AHRE. Patients with AHRE had a P-wave duration significantly longer (130 ± 24 ms vs 119 ± 21 ms; P < 0.001) and a greater prevalence of IAB (53% vs 32%; P < 0.001). In a multivariate analysis, predictors of AHRE were: IAB (odds ratio [OR] 2.1; 95% confidence interval [CI] [1.3-3.4], P < 0.001) and previous paroxysmal AF (OR 2.6; 95% CI [1.5-4.3], P < 0.001). In patients without previous AF, the presence of IAB was also a significant predictor of AHRE (OR 3.1; 95% CI [1.8-5.5], P < 0.001).

CONCLUSIONS

IAB is a strong predictor of AHRE in patients with CIED. This finding is independent of the presence of prior paroxysmal AF.

Reduced P-wave Voltage in Lead I is Associated with Development of Atrial Fibrillation in Patients with Coronary Artery Disease

Background

Reduced P-wave voltage in lead 1 (PVL1) has been associated with atrial fibrillation (AF) recurrence.This study sought to determine the association between reduced PVL1 and AF in the NSTEMI population and the correlation between reduced PVL1 and interatrial block (IAB)/coronary artery disease (CAD).

Methods

Data were recorded for clinical, echocardiographic, angiographic, electrocardiographic and outcome variables. Patients were followed for a minimum of one year. Chi-square tests, independent samples t-tests and one-way ANOVA were used for the analysis, which was done using IBM SPSSResults:: A total of 322 consecutive patients were included in the analysis. Patients with new-onset AF had a significantly lower PVL1 (0.085 ± 0.030mV vs. 0.103 ± 0.037mV; p=0.007). There was a significant difference in mean PVL1 between those with no IAB, partial IAB and advanced IAB (p = <0.001). Those with any type of IAB had a significantly lower mean PVL1 than those without (0.094 ± 0.032 mV vs. 0.106 ± 0.038 mV; p=0.005). Patients who developed AF had a significantly longer P-wave duration (126 ± 20ms vs. 119 ± 17ms; p=0.022). Patients with IAB were more likely to develop new-onset AF (15.4% versus 7.5%, p=0.025). There were significant co-linear associations between reduced PVL1 and IAB (p=0.005); reduced PVL1 and diffuse CAD (p=0.031) and IAB and diffuse CAD (p=0.022).

Electrocardiogram (ECG) for the Prediction of Incident Atrial Fibrillation: An Overview

Electrocardiograms (ECGs) have been employed to medically evaluate participants in population-based studies, and ECG-derived predictors have been reported for incident atrial fibrillation (AF). Here, we reviewed the status of ECG in predicting new-onset AF. We surveyed population-based studies and revealed ECG variables to be risk factors for incident AF. When available, the predictive values of each ECG risk marker were calculated. Both the atrium-related and ventricle-related ECG variables were risk factors for incident AF, with significant hazard risks (HRs) even after multivariate adjustments. The risk factors included P-wave indices (maximum P-wave duration, its dispersion or variation and P-wave morphology) and premature atrial contractions (PACs) or runs. In addition, left ventricular hypertrophy (LVH), ST-T abnormalities, intraventricular conduction delay, QTc interval and premature ventricular contractions (PVCs) or runs were a risk of incident AF. An HR of greater than 2.0 was observed in the upper 5th percentile of the P-wave durations, P-wave durations greater than 130 ms, P-wave morpholyg, PACs (PVCs) or runs, LVH, QTc and left anterior fascicular blocks. The sensitivity , specificity and the positive and negative predictive values were 3.6-53.8%, 61.7-97.9%, 2.9-61.7% and 77.4-97.7%, respectively. ECG variables are risk factors for incident AF. The correlation between the ECG-derived AF predictors, especially P-wave indices, and underlying diseases and the effects of the reversal of the ECG-derived predictors on incident AF by treatment of comorbidities require further study.

Predictive value of inter-atrial block for new onset or recurrent atrial fibrillation: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Inter-atrial block (IAB) is characterized by a delay of inter-atrial conduction and is defined electrocardiographically by a P-wave duration (PWD)>120ms. Several studies have implicated IAB in the development of new onset atrial fibrillation (AF), whereas others have reported no significant associations. Moreover, there has been no systematic evaluation of the predictive value of IAB in AF recurrence. Therefore, we conducted a systematic review and meta-analysis to examine whether IAB predicts new onset AF or AF recurrence.

METHODS

PubMed and Embase databases were searched through 30th July 2017 for studies investigating the relationship between IAB and AF.

RESULTS

The initial search identified 260 studies, of which 16 studies met the inclusion criteria. This meta-analysis included 18,204 patients (mean age 56±13, 48% male) with a mean follow-up period of 15.1years. IAB significantly predicted new onset AF (hazard ratio [HR]: 2.42, 95% confidence interval [CI]: 1.44 to 4.07, P=0.001; 84%). For partial IAB, the risk of new onset AF did not reach statistical significance (HR: 1.42, 95% CI: 0.85 to 2.34; P=0.18; I²=13%). Contrastingly, advanced IAB was a significant predictor of new onset AF with a pooled HR of 2.58 (95% CI: 1.35 to 4.96; P<0.01; I²=67%). IAB also predicted AF recurrence after ablation (HR: 2.59, 95% CI: 1.35 to 4.96; P<0.01; I²=67%).

CONCLUSIONS

IAB is a significant predictor of both new onset AF and AF recurrence.

Management of Patients with Atrial Fibrillation: Focus on Treatment Options

Atrial fibrillation (AF) is leading cardiac arrhythmia with important clinical implications. Its diagnosis is usually made on the basis on 12-lead ECG or 24-hour Holter monitoring. More and more clinical evidence supports diagnostic use of cardiac event recorders and cardiovascular implantable electronic devices (CIED). Treatment options in patients with atrial fibrillation are extensive and are based on chosen rhythm and/or rate control strategy. The use and selected contraindications to AF related pharmacotherapy, including anticoagulants are shown. Nonpharmacological treatments, comorbidities and risk factors control remain mainstay in the treatment of patients with AF. Electrical cardioversion consists important choice in rhythm control strategy. Much progress has been made in the field of catheter ablation and cardiac surgery methods. Left atrial appendage occlusion/closure may be beneficial in patients with AF. CIED are used with clinical benefits in both, rhythm and rate control. Pacemakers, implantable cardioverter-defibrillators and cardiac resynchronization therapy devices with different pacing modes have guaranteed place in the treatment of patients with AF. On the other hand, the concepts of permanent leadless cardiac pacing, atrial dyssynchrony syndrome treatment and His-bundle or para-Hisian pacing have been proposed. This review summarizes and discusses current and novel treatment options in patients with atrial fibrillation.

Reverse atrial electrical remodeling induced by cardiac resynchronization therapy

PURPOSE

Cardiac resynchronization therapy (CRT) has been shown to improve left atrial function; however the effect on reverse electrical remodeling has been poorly evaluated. We hypothesized that CRT might induce reverse atrial electrical remodeling manifesting in the surface ECG as a shortening in P-wave duration.

METHODS

Patients with CRT and more than 92% biventricular pacing at minimum follow-up of 1 year were included in the analysis. Those with prior history of atrial fibrillation (AF) were excluded. Data were recorded for clinical, echocardiographic and ECG variables prior to implant and at least 12 months post implantation. Semiautomatic calipers and scanned ECGs at 300 DPI maximized × 8 were used to measure P-wave duration and diagnose advanced interatrial block (aIAB) during sinus rhythm. The occurrence of AF was assessed through analyses of intracardiac electrograms and clinical presentations.

RESULTS

41 patients were included in the study with mean age of 67.4 ±9.6 years, 71% were male, left atrial diameter 41.1 ± 8.5 mm and LV EF 28.5 ± 6.5%. Over a mean follow up of 55 months, a significant reduction in P-wave duration (142.7 ms vs. 133.1 ms; p < 0.001) was noted. The presence of aIAB was significantly reduced (36% vs. 17%; p = 0.03). The incidence of new onset AF was 36%. Time to AF onset after CRT implantation was not influenced by a reduction in P-wave duration.

CONCLUSION

CRT induces atrial reverse electrical remodeling manifested as a reduction in P-wave duration. Larger studies are needed to determine the impact on AF incidence after CRT implantation.

Comparison of the Extent of Coronary Artery Disease in Patients With Versus Without Interatrial Block and Implications for New-Onset Atrial Fibrillation

Interatrial block (IAB) represents delay or block of conduction between the atria. IAB has been shown to predict the development or recurrence of atrial fibrillation (AF) in various clinical scenarios. Few studies have examined the correlation between coronary artery disease and the prevalence of IAB and its impact on AF. The aim of this study was to determine if specific coronary artery lesions (location and number) are associated with the presence of IAB and development of new-onset AF. Retrospective analysis of patients presenting with non-ST-segment elevation myocardial infarction (NSTEMI) to our institution. Data were recorded for clinical, echocardiographic, angiographic, electrocardiographic, and outcome variables. Semiautomatic calipers and scanned electrocardiograms at 300 DPI maximized × 8 were used to measure P-wave duration, with a follow-up for a minimum of 1 year. The chi-square and independent-sample t tests were done using IBM SPSS. A total of 322 patients were included in the analysis. Men 72.3%, mean age 65.4 ± 11.9 years, mean ejection fraction of 55.2 ± 12.7% and mean left atrial diameter of 38.7 ± 6 mm. The prevalence of partial IAB was 31.9%, and advanced IAB was 6.5%. Patients with IAB were significantly older (<0.001) and had a greater prevalence of hypertension (0.014). The presence of diffuse coronary artery disease defined as >1 significant coronary artery lesion was associated with IAB (0.026). No specific coronary artery lesion location was found to be associated with IAB nor increased P-wave duration. Patients who developed AF during the follow-up had a significantly higher prevalence of IAB (p = 0.021) and also higher prevalence of diffuse coronary artery disease (p = 0.001). IAB is significantly associated with diffuse coronary artery disease in patients with NSTEMI. IAB is significantly associated with the development of new-onset AF within 12 months after NSTEMI.

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.

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.

Interatrial block and interatrial septal thickness in patients with paroxysmal atrial fibrillation undergoing catheter ablation: Long-term follow-up study

BACKGROUND

Interatrial block (IAB) is a strong predictor of recurrence of atrial fibrillation (AF). IAB is a conduction delay through the Bachman region, which is located in the upper region of the interatrial space. During IAB, the impulse travels from the right atrium to the interatrial septum (IAS) and coronary sinus to finally reach the left atrium in a caudocranial direction. No relation between the presence of IAB and IAS thickness has been established yet.

OBJECTIVE

To determine whether a correlation exists between the degree of IAB and the thickness of the IAS and to determine whether IAS thickness predicts AF recurrence.

METHODS

Sixty-two patients with diagnosis of paroxysmal AF undergoing catheter ablation were enrolled. IAB was defined as P-wave duration ≥120 ms. IAS thickness was measured by cardiac computed tomography.

RESULTS

Among 62 patients with paroxysmal AF, 45 patients (72%) were diagnosed with IAB. Advanced IAB was diagnosed in 24 patients (39%). Forty-seven patients were male. During a mean follow-up period of 49.8 ± 22 months (range 12-60 months), 32 patients (51%) developed AF recurrence. IAS thickness was similar in patients with and without IAB (4.5 ± 2.0 mm vs. 4.0 ± 1.4 mm; p = .45) and did not predict AF. Left atrial size was significantly enlarged in patients with IAB (40.9 ± 5.7 mm vs. 37.2 ± 4.0 mm; p = .03). Advanced IAB predicted AF recurrence after the ablation (OR: 3.34, CI: 1.12-9.93; p = .03).

CONCLUSIONS

IAS thickness was not significantly correlated to IAB and did not predict AF recurrence. IAB as previously demonstrated was an independent predictor of AF recurrence.

The P-wave morphology: what does it tell us?

P-wave morphology and duration reveals several aspects of the atria: Proper function, fibrosis, dyssynchrony, and activation paths can be inferred from the surface P-wave analysis. Surface electrocardiogram (ECG) can help differentiating enlargements of the atria from conduction defects including intra- and interatrial block.The purpose of this paper is to review normal atrial morphology and the most relevant abnormal patterns.

Progressive interatrial block associated with atrial fibrillation in a patient with hypertrophic cardiomyopathy

Progressive interatrial block is a clinically significant condition that has previously been reported in various patient populations. It is a manifestation of progressive fibrosis affecting the Bachmann region. This report presents a case of progressive interatrial block associated with atrial fibrillation in the context of hypertrophic cardiomyopathy.

Advanced interatrial block and ischemic stroke: The Atherosclerosis Risk in Communities Study

OBJECTIVE

Given that recent reports have suggested left atrial disease to be an independent risk factor for ischemic stroke, we sought to examine if advanced interatrial block (aIAB) is an independent stroke risk factor.

METHODS

We examined the association between aIAB and incident ischemic stroke in 14,716 participants (mean age 54 ± 5.8 years; 55% female; 26% black) from the Atherosclerosis Risk in Communities Study (ARIC). Cases of aIAB were identified from digital ECGs recorded during the baseline ARIC visit (1987-1989) and the first 3 follow-up study visits (1990-1992, 1993-1995, and 1996-1998). Adjudicated ischemic stroke events were ascertained through December 31, 2010.

RESULTS

There were 266 (1.8%) participants who had evidence of aIAB. Over a median follow-up of 22 years, 916 (6.2%) ischemic stroke events were detected. The incidence rate (per 1,000 person-years) of ischemic stroke among those with aIAB (incidence rate 8.05, 95% confidence interval [CI] 5.7, 11.4) was more than twice the rate in those without aIAB (incidence rate 3.14, 95% CI 2.94, 3.35). In a multivariable Cox regression analysis adjusted for stroke risk factors and potential confounders, aIAB was associated with an increased risk of ischemic stroke (hazard ratio 1.63, 95% CI 1.13, 2.34). The results were consistent across subgroups of participants stratified by age, sex, and race.

CONCLUSIONS

In the ARIC, aIAB was associated with incident ischemic stroke, which strengthens the hypothesis that left atrial disease should be considered an independent stroke risk factor.

Electrocardiographic Advanced Interatrial Block and Atrial Fibrillation Risk in the General Population

Although advanced interatrial block (aIAB) is an established electrocardiographic phenotype, its prevalence, incidence, and prognostic significance in the general population are unclear. We examined the prevalence, incidence, and prognostic significance of aIAB in 14,625 (mean age = 54 ± 5.8 years; 26% black; 55% female) participants from the Atherosclerosis Risk in Communities (ARIC) study. aIAB was detected from digital electrocardiograms recorded during 4 study visits (1987 to 1989, 1990 to 1992, 1993 to 1995, and 1996 to 1998). Risk factors for the development of aIAB were examined using multivariable Poisson regression models with robust variance estimates. Cox regression was used to compute hazard ratios and 95% CIs for the association between aIAB, as a time-dependent variable, and atrial fibrillation (AF). AF was ascertained from study electrocardiogram data, hospital discharge records, and death certificates thorough 2010. A total of 69 participants (0.5%) had aIAB at baseline, and 193 (1.3%) developed aIAB during follow-up. The incidence for aIAB was 2.27 (95% CI 1.97 to 2.61) per 1,000 person-years. Risk factors for aIAB development included age, male gender, white race, antihypertensive medication use, low-density lipoprotein cholesterol, body mass index, and systolic blood pressure. In a Cox regression analysis adjusted for sociodemographics, cardiovascular risk factors, and potential confounders, aIAB was associated with an increased risk for AF (hazard ratio 3.09, 95% CI 2.51 to 3.79). In conclusion, aIAB is not uncommon in the general population. Risk factors for developing aIAB are similar to those for AF, and the presence of aIAB is associated with an increased risk for AF.

Advanced interatrial block predicts clinical recurrence of atrial fibrillation after catheter ablation

BACKGROUND

It has been demonstrated that advanced interatrial block (IAB) is associated with an increased risk of atrial fibrillation (AF); however, the impact of advanced IAB on recurrence of paroxysmal AF after catheter ablation is not clear.

METHODS

204 consecutive patients with paroxysmal AF who underwent index circumferential pulmonary vein (PV) isolation were prospectively enrolled. In all patients, a resting electrocardiogram in sinus rhythm was evaluated for the presence of advanced IAB, defined as a P-wave duration >120ms and biphasic (±) morphology in the inferior leads. Advanced IAB was detected in 20.1% of patients. AF recurrence was defined as the occurrence of confirmed atrial tachyarrhythmia lasting more than 30s beyond 3 months after the catheter ablation in the absence of any antiarrhythmic treatment.

RESULTS

During the mean follow-up period of 13.9±6.2 months (range, 3-27 months), 62 patients (30.4%) developed recurrence of AF. The recurrence rate was higher in patients with advanced IAB than those without advanced IAB (46.3% vs. 26.4%, p=0.006). Cox regression analysis with adjustment for age, P-wave duration, CHADS2 score, and PV isolation identified advanced IAB (hazard ratio, 2.111; 95% confidence interval, 1.034-4.308; p=0.040) and left atrial diameter (hazard ratio, 1.051; 95% confidence interval, 1.004-1.100; p=0.034) as two independent predictors of recurrence of AF.

CONCLUSIONS

Patients with advanced IAB were at an increased risk of AF recurrence after catheter ablation.

The Diagnosis and Clinical Implications of Interatrial Block

Impaired interatrial conduction or interatrial block is now well-documented but is not described as an individual electrocardiographic (ECG) pattern in the majority of ECG literature. In fact the term atrial abnormality has been adopted to encompass both left atrial enlargement (LAE) and interatrial block. In this paper, we maintain that interatrial blocks and atrial enlargement are separate entities, and that interatrial blocks, similar to other types of blocks at sinoatrial, AV junctional, and ventricular level, exhibit a specific ECG pattern that may present first, second, and third degree types of conduction block. The third degree or advanced interatrial block (A-IAB) is frequently associated with atrial fibrillation/atrial flutter (AF/AFl), and constitutes a true newly-described syndrome.