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

Comparing Artificial Intelligence-Enabled Electrocardiogram Models in Identifying Left Atrium Enlargement and Long-term Cardiovascular Risk

BACKGROUND

The role of P-wave in identifying left atrial enlargement (LAE) with the use of artificial intelligence (AI)-enabled electrocardiography (ECG) models is unclear. It is also unknown if AI-enabled single-lead ECG could be used as a diagnostic tool for LAE surveillance. We aimed to build AI-enabled P-wave and single-lead ECG models to identify LAE using sinus rhythm (SR) and non-SR ECGs, and compare the prognostic ability of severe LAE, defined as left atrial diameter ≥ 50 mm, assessed by AI-enabled ECG models vs echocardiography.

METHODS

This retrospective study used data from 382,594 consecutive adults with paired 12-lead ECG and echocardiography performed within 2 weeks of each other at Chang Gung Memorial Hospital. UNet++ was used for P-wave segmentation. ResNet-18 was used to develop deep convolutional neural network-enabled ECG models for discriminating LAE. External validation was performed with the use of data from 11,753 patients from another hospital.

RESULTS

The AI-enabled 12-lead ECG model outperformed other ECG models for classifying LAE, but the single-lead ECG models also showed excellent performance at a left atrial diameter cutoff of 50 mm. AI-enabled ECG models had excellent and fair discrimination on LAE using the SR and the non-SR data set, respectively. Severe LAE identified by AI-enabled ECG models was more predictive of future cardiovascular disease than echocardiography; however, the cumulative incidence of new-onset atrial fibrillation and heart failure was higher in patients with echocardiography-severe LAE than with AI-enabled ECG-severe LAE.

CONCLUSIONS

P-Wave plays a crucial role in discriminating LAE in AI-enabled ECG models. AI-enabled ECG models outperform echocardiography in predicting new-onset cardiovascular diseases associated with severe LAE.

P-wave Indices as Predictors of Atrial Fibrillation: The Lion from a Claw

The P wave, representing the electrical fingerprint of atrial depolarization, contains information regarding spatial and temporal aspects of atrial electrical-and potentially structural-properties. However, technical and biological reasons, including-but not limited to-the low amplitude of the P wave and large interindividual variations in normal or pathologic atrial electrical activity, make gathering and utilizing this information for clinical purposes a rather cumbersome task. However, even crude ECG descriptors, such as P-wave dispersion, have been shown to be of predictive value for assessing the probability that a patient already has or will shortly present with AF. More sophisticated methods of analyzing the ECG signal, on a single- or multi- beat basis, along with novel approaches to data handling, namely machine learning, seem to be leading up to more accurate and robust ways to obtain clinically useful information from the humble P wave.

Comparison of Electrocardiographic Parameters by Gender in Heart Failure Patients with Preserved Ejection Fraction via Artificial Intelligence

BACKGROUND

Heart failure (HF) causes high morbidity and mortality worldwide. The prevalence of HF with preserved ejection fraction (HFpEF) is increasing compared with HF with reduced ejection fraction (HFrEF). Patients with HFpEF are a patient group with a high rate of hospitalization despite medical treatment. Early diagnosis is very important in this group of patients, and early treatment can improve their prognosis. Although electrocardiographic (ECG) findings have been adequately studied in patients with HFrEF, there are not enough studies on these parameters in patients with HFpEF. There are very few studies in the literature, especially on gender-specific changes. The current research aims to compare gender-specific ECG parameters in patients with HFpEF based on the implications of artificial intelligence (AI).

METHODS

A total of 118 patients participated in the study, of which 66 (56%) were women with HFpEF and 52 (44%) were men with HFpEF. Demographic, echocardiographic, and electrocardiographic characteristics of the patients were analyzed to compare gender-specific ECG parameters in patients with HFpEF. The AI approach combined with machine learning approaches (gradient boosting machine, k-nearest neighbors, logistic regression, random forest, and support vector machines) was applied for distinguishing male patients with HFpEF from female patients with HFpEF.

RESULTS

After determining the parameters (demographic, echocardiographic, and electrocardiographic) to distinguish male patients with HFpEF from female patients with HFpEF, machine learning methods were applied, and among these methods, the random forest model achieved an average accuracy of 84.7%. The random forest algorithm results showed that smoking, P-wave dispersion, P-wave amplitude, T-end P/(PQ*Age), Cornell product, and P-wave duration were the most influential parameters for distinguishing male patients with HFpEF from female patients with HFpEF.

CONCLUSIONS

The proposed model serves as a valuable tool for physicians, facilitating the diagnosis, treatment, and follow-up for distinguishing male patients with HFpEF from female patients with HFpEF. Analyzing readily accessible electrocardiographic parameters empowers medical professionals to make informed decisions and provide enhanced care to a wide range of individuals.

Single-arm diagnostic electrocardiography with printed graphene on wearable textiles

Stimulated by the COVID-19 outbreak, the global healthcare industry better acknowledges the necessity of innovating novel methods for remote healthcare monitoring and treating patients outside clinics. Here we report the development of two different types of graphene textile electrodes differentiated by the employed fabrication techniques (i.e., dip-coating and spray printing) and successful demonstration of ergonomic and truly wearable, single-arm diagnostic electrocardiography (SADE) using only 3 electrodes positioned on only 1 arm. The performance of the printed graphene e-textile wearable systems were benchmarked against the "gold standard" silver/silver chloride (Ag/AgCl) "wet" electrodes; achieving excellent correlation up to ∼ 96% and ∼ 98% in ECG recordings (15 s duration) acquired with graphene textiles fabricated by dip-coating and spray printing techniques, respectively. In addition, we successfully implemented automatic detection of heartrate of 8 volunteers (mean value: 74.4 bpm) during 5 min of static and dynamic daily activities and benchmarked their recordings with a standard fingertip photoplethysmography (PPG) device. Heart rate variability (HRV) was calculated, and the root means successive square difference (rMMSD) metric was 30 ms during 5 min of recording. Other cardiac parameters such as R-R interval, QRS complex duration, S-T segment duration, and T-wave duration were also detected and compared to typical chest ECG values.

Splitting the P-Wave: Improved Evaluation of Left Atrial Substrate Modification after Pulmonary Vein Isolation of Paroxysmal Atrial Fibrillation

Atrial substrate modification after pulmonary vein isolation (PVI) of paroxysmal atrial fibrillation (pAF) can be assessed non-invasively by analyzing P-wave duration in the electrocardiogram (ECG). However, whether right (RA) and left atrium (LA) contribute equally to this phenomenon remains unknown. The present study splits fundamental P-wave features to investigate the different RA and LA contributions to P-wave duration. Recordings of 29 pAF patients undergoing first-ever PVI were acquired before and after PVI. P-wave features were calculated: P-wave duration (PWD), duration of the first (PWDon-peak) and second (PWDpeak-off) P-wave halves, estimating RA and LA conduction, respectively. P-wave onset (PWon-R) or offset (PWoff-R) to R-peak interval, measuring combined atrial/atrioventricular and single atrioventricular conduction, respectively. Heart-rate fluctuation was corrected by scaling. Pre- and post-PVI results were compared with Mann–Whitney U-test. PWD was correlated with the remaining features. Only PWD (non-scaling: Δ=−9.84%, p=0.0085, scaling: Δ=−17.96%, p=0.0442) and PWDpeak-off (non-scaling: Δ=−22.03%, p=0.0250, scaling: Δ=−27.77%, p=0.0268) were decreased. Correlation of all features with PWD was significant before/after PVI (p<0.0001), showing the highest value between PWD and PWon-R (ρmax=0.855). PWD correlated more with PWDon-peak (ρ= 0.540–0.805) than PWDpeak-off (ρ= 0.419–0.710). PWD shortening after PVI of pAF stems mainly from the second half of the P-wave. Therefore, noninvasive estimation of LA conduction time is critical for the study of atrial substrate modification after PVI and should be addressed by splitting the P-wave in order to achieve improved estimations.

Splitting the P-Wave: Improved Evaluation of Left Atrial Substrate Modification after Pulmonary Vein Isolation of Paroxysmal Atrial Fibrillation

Atrial substrate modification after pulmonary vein isolation (PVI) of paroxysmal atrial fibrillation (pAF) can be assessed non-invasively by analyzing P-wave duration in the electrocardiogram (ECG). However, whether right (RA) and left atrium (LA) contribute equally to this phenomenon remains unknown. The present study splits fundamental P-wave features to investigate the different RA and LA contributions to P-wave duration. Recordings of 29 pAF patients undergoing first-ever PVI were acquired before and after PVI. P-wave features were calculated: P-wave duration (PWD), duration of the first (PWDon-peak) and second (PWDpeak-off) P-wave halves, estimating RA and LA conduction, respectively. P-wave onset (PWon-R) or offset (PWoff-R) to R-peak interval, measuring combined atrial/atrioventricular and single atrioventricular conduction, respectively. Heart-rate fluctuation was corrected by scaling. Pre- and post-PVI results were compared with Mann-Whitney U-test. PWD was correlated with the remaining features. Only PWD (non-scaling: Δ=-9.84%, p=0.0085, scaling: Δ=-17.96%, p=0.0442) and PWDpeak-off (non-scaling: Δ=-22.03%, p=0.0250, scaling: Δ=-27.77%, p=0.0268) were decreased. Correlation of all features with PWD was significant before/after PVI (p<0.0001), showing the highest value between PWD and PWon-R (ρmax=0.855). PWD correlated more with PWDon-peak (ρ= 0.540-0.805) than PWDpeak-off (ρ= 0.419-0.710). PWD shortening after PVI of pAF stems mainly from the second half of the P-wave. Therefore, noninvasive estimation of LA conduction time is critical for the study of atrial substrate modification after PVI and should be addressed by splitting the P-wave in order to achieve improved estimations.

Risk of New-Onset Atrial Fibrillation Post-cavotricuspid Isthmus Ablation in Typical Atrial Flutter Without History of Atrial Fibrillation

Aims: The aim was to describe the incidence of atrial fibrillation (AF) after cavotricuspid isthmus (CTI) ablation in patients with typical atrial flutter (AFL) without history of AF and to identify risk factors for new-onset AF after the procedure.

Methods: A total of 191 patients with typical AFL undergoing successful CTI ablation were enrolled. Patients who had history of AF, structural heart disease, cardiac surgery, or ablation or who received antiarrhythmic drug after procedure were excluded. Clinical and electrophysiological data were collected.

Results: There were 47 patients (24.6%) developing new AF during a follow-up of 3.3 ± 1.9 years after CTI ablation. Receiver operating characteristic (ROC) curves indicated that the cut-off values of left atrial diameter (LAD) and CHA₂DS₂-VASc score were 42 mm and 2, with area under the curve of 0.781 and 0.550, respectively. The multivariable Cox regression analysis revealed that obstructive sleep apnea (OSA) [hazard ratio (HR) 3.734, 95% confidence interval (CI) 1.470–9.484, P = 0.006], advanced interatrial block (aIAB) (HR 2.034, 95% CI 1.017–4.067, P = 0.045), LAD > 42 mm (HR 2.710, 95% CI 1.478–4.969, P = 0.001), and CHA₂DS₂-VASc score > 2 (HR 2.123, 95% CI 1.118–4.034, P = 0.021) were independent risk factors of new-onset AF.

Conclusion: A combination of OSA, aIAB, LAD > 42 mm, and CHA₂DS₂-VASc > 2 was a strongly high risk for new-onset AF after ablation for typical AFL, and it had significance in postablation management in clinical practice.

Enhancing electrocardiographic analysis by combining a high-resolution 12-lead ECG with novel software tools

INTRODUCTION

Signal-averaged electrocardiography is a non-invasive, computerized technique that amplifies, filters, and averages cardiac electrical signals reducing contaminating noise to obtain a high-resolution record. The most widely used signal averaging (SA) method involves a bipolar X, Y, and Z orthogonal lead system. Information is limited regarding its application in the standard resting 12-lead ECG. A novel system combining a high-resolution 12-lead ECG (HR-ECG) registered by SA with advanced analysis tools is presented.

HISTORY

Original programming of a commercially available signal-averaged HR-ECG device was modified, introducing more exhaustive electrocardiographic assessment instruments.

DESCRIPTION

Using SA techniques and placing surface electrodes in the standard 12-lead ECG positions, a HR-ECG is acquired within a bandwidth of 0.25 to 262 Hz at a rate of 1000 samples per second. It is advisable to average at least 200 cycles, taking three to five minutes to record. The package includes different optional high-frequency filters, manual calipers, zoom/superimposing/amplification functions.

CLINICAL ROLE

The main strength lies in obtaining a low noise HR-ECG with zooming capabilities without definition loss. Other potential advantages are the greater ease in performing high precision analysis and comparing different ECG leads simultaneously.

CURRENT PROBLEMS

The primary limitation is the inability to document intermittent or dynamic electrocardiographic disorders because of averaging similar electrical cardiac cycles.

FUTURE DEVELOPMENTS

Adding artificial intelligence and further refinements in the averaging process could lead to software upgrades.

CONCLUSION

Integrating HR-ECG, obtained through SA techniques, with novel advanced analysis tools can enhance the ability to detect electrocardiographic disorders of permanent expression expeditiously.

Evaluation of electrocardiography, echocardiography and cardiac T2* for cardiac complications in beta thalassemia major

Cardiac complications such as heart failure and arrhythmias caused by "iron-induced" cardiomyopathy are considered as the primary cause of death in the patients with β-thalassemia major. The aim of this study was to evaluate electrocardiography, echocardiography according cardiac T2* and ferritin findings of patients followed-up for β-thalassemia major, and to investigate the importance of these findings for early detection of cardiac complications. The study included 41 patients and 25 healthy individuals with matched age and gender. The cardiac T2* results revealed a cardiac iron load below 20 ms in 12 (29.27%) patients, and above 20 ms in 29 (70.73%) patients. All electrocardiography parameters significantly increased in the patient group when compared to the control group (p < 0.05). All parameters except P wave segment in electrocardiography and T peak-end/QT ratio were significantly higher in the group with cardiac T2* < 20 ms than the group with cardiac T2* > 20 ms (p < 0.05). Intraventricular septum thickness, left ventricular posterior wall thickness, left ventricular mass and left ventricular mass index detected by echocardiography were significantly higher in the group with T2* < 20 ms (p < 0.05). Electrocardiography, echocardiography, cardiac T2* and ferritin findings should be carefully evaluated in these patients in order to detect early signs of cardiac complications.

P Wave Duration/P Wave Voltage Ratio Plays a Promising Role in the Prediction of Atrial Fibrillation: A New Player in the Game

Background

Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice. Identification of patients at risk for developing AF and the opportunity for early targeted intervention might have a significant impact on morbidity and mortality. Prolonged P wave duration and decreased P wave voltage have been shown to be independent predictors of AF. The present study aimed to investigate the role of P wave duration/P wave voltage in predicting new-onset AF.

Methods

We screened a total of 640 consecutive patients who admitted to cardiology outpatient clinic with a complaint of palpitation between 2012 and 2014. 24-h Holter monitoring, echocardiography, and electrocardiography (ECG) recordings were reviewed to identify new-onset AF. Patients were assigned into two groups based on presence (n = 150) and absence (n = 490) of new-onset AF. Previous ECGs with sinus rhythm were analyzed. P wave duration was measured in inferior leads, and P wave voltage was measured in lead one. P wave duration/P wave voltage was also calculated for each patient.

Results

One hundred fifty subjects (23.4%) had new-onset AF among 640 patients. P wave duration (123.27 ± 12.87 vs. 119.33 ± 17.39 ms, p=0.024) and P wave duration/P wave voltage (1284.70 ± 508.03 vs. 924.14 ± 462.06 ms/mV, p < 0.001) were higher, and P wave voltage (0.12 ± 0.04 vs. 0.13 ± 0.04 mV, p < 0.001) was significantly lower in the new-onset AF group compared with non-AFs. P wave duration/P wave voltage, with a cut off of 854.5 ms/mV, had 83.3% sensitivity and 62.0% specificity in a receiver operating characteristic curve (AUC 0.728, 95% CI 0.687-0.769; p < 0.001). Their negative and positive predictive values were 78.7% and 68.6%, respectively. In a univariate regression analysis, age, smoking, C-reactive protein, brain natriuretic peptide, left atrial diameter, left atrial volume index, P wave duration, P wave voltage, and P wave duration/P wave voltage were significantly associated with the development of new-onset AF. Moreover, smoking (OR 4.008, 95% CI 1.707-9.409; p=0.001), left atrial volume index (OR 7.108, 95% CI 4.400-11.483; p < 0.001), and P wave duration/P wave voltage (OR 1.002, 95% CI 1.000-1.003; p=0.044) were found to be significant independent predictors of new-onset AF in a multivariate analysis, after adjusting for other risk parameters.

Conclusion

The P wave duration/P wave voltage ratio is a practical, easy-to-use, cheap, and reliable electrocardiographic parameter, which can play a promising role for both in predicting and elucidating a mechanism of new-onset AF.

A genome-wide association and polygenic risk score study on abnormal electrocardiogram in a Chinese population

Electrocardiography is a common and widely-performed medical examination based on the measurement and evaluation of electrocardiogram (ECG) to assess the up-to-date cardiac rhythms and thus suggest the health conditions of cardiovascular system and on a larger level the individual’s wellness. Abnormal ECG assessment from the detection of abnormal heart rhythms may have clinical implications including blood clots in formation, ongoing heart attack, coronary artery blockage, etc. Past genetic-phenotypic research focused primarily on the physical parameters of ECG but not the medical evaluation. To unbiasedly uncover the underlying links of genetic variants with normal vs. abnormal ECG assessment, a genome-wide association study (GWAS) is carried out in a 1006-participant cohort of Chinese population effectively genotyped for 243487 single nucleotide polymorphisms (SNPs). Both age and sex are influential factors, and six novel SNPs are identified for potential association with abnormal ECG. With the selected SNPs, a polygenic risk score (PRS) differentiates the case–control subgroups, and correlates well with increased risk of abnormal ECG. The findings are reproduced in an independent validation cohort. The derived PRS may function as a potential biomarker for prospectively screening the high-risk subgroup of heart issues in the Chinese population.

The effect of P wave indices on new onset atrial fibrillation after trans-catheter aortic valve replacement

OBJECTIVES

Data is scarce regarding the relation between P wave indices and new onset atrial fibrillation (NOAF) after trans-catheter aortic valve replacement (TAVR).

AIMS

The present study aimed to find out certain characteristics of P wave that may predict NOAF after TAVR procedure.

METHOD

Patients with severe calcific aortic stenosis who had undergone TAVR procedure between 2013 and 2019 in two centers were investigated. P wave abnormalities that have been resumed to reflect impaired atrial conduction; partial and advanced inter atrial block (IAB), P-wave terminal force in lead V1, P wave dispersion, reduced amplitude of P- wave in lead I, P wave peak time in D2 and V1 were evaluated on pre- procedural 12 derivation surface electrocardiography (ECG). The relationship between these parameters and incidence of NOAF during index hospitalization was evaluated.

RESULTS

A total of 227 consecutive patients (median age 79 [74-83]; 134 [59%] female) were included in the study. NOAF occurred in 46 (20.3%) patients. P wave duration, P wave dispersion, number of patients with partial and advanced IAB, left atrium diameter, STS score were higher in NOAF patients. Use of general anesthesia and history of prior open heart surgery were also more frequent in NOAF group. In multivariable logistic regression analysis; advanced IAB (OR 6.413 [2.555-16.095] p < 0.01), P wave dispersion (OR 3.544 [1.431-8.780] p = 0.006) and use of general anesthesia (OR 2.736 [1.225-6.109] p = 0.014) were independent predictors of NOAF.

CONCLUSION

Among P wave abnormalities evaluated on pre-procedural 12-derivation surface ECG, advanced IAB and P wave dispersion may predict NOAF after TAVR procedure.

The Accuracy of Combined Electrocardiogram Criteria to Diagnose Right Atrial Enlargement in Adults With Uncorrected Secundum Atrial Septal Defect

Background:

Right atrium (RA) enlargement in uncorrected atrial septal defect (ASD) is due to chronic volume overload. Several electrocardiogram (ECG) criteria had been proposed for screening RA enlargement. This study aimed to compare the accuracy of ECG criteria in detecting RA enlargement in adults with uncorrected ASD.

Methods:

This was a cross-sectional study involving 120 adults with uncorrected secundum ASD. The subjects underwent ECG examination, transthoracic echocardiography, and right heart catheterization. An RA enlargement was determined with RA volume index by transthoracic echocardiography. Various ECG and combined ECG criteria were evaluated. Statistical analysis was performed to analyze the sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV).

Results:

An RA enlargement was detected in 64.2% subjects. The P wave height > 2.5 mm in lead II criterion had the best specificity (100%) and PPV (100%), but low sensitivity (19%) and accuracy (48%). The combined 2 ECG criteria (QRS axis > 90°, R/S ratio > 1 in V1) had 82% sensitivity, 56% specificity, 73% accuracy, 77% PPV, and 63% NPV. The combined 3 ECG criteria (QRS axis > 90°, R/S ratio > 1 in V1, and P wave height > 1.5 mm in V2) had 35% sensitivity, 86% specificity, 53% accuracy, 82% PPV, and 43% NPV.

Conclusions:

The combined 2 ECG criteria (QRS axis > 90° and R/S ratio > 1 in V1) had increased sensitivity, better accuracy, and more balance of PPV and NPV as compared with P wave > 2.5 mm in II criterion and combined 3 ECG criteria to diagnose RA enlargement in adults with uncorrected ASD.

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.

Second-degree interatrial block: A case series

Advanced interatrial block (IAB) (P-wave ≥120 ms and biphasic P-wave in leads II, III and aVF) is a prevalent ECG pattern frequently associated with supraventricular arrhythmias and stroke, especially in patients with structural heart disease. Intermittent IAB is a much more poorly defined electrocardiographic entity with uncertain clinical significance. In this case series, we review and analyze eight cases of second degree intermittent IAB. In six cases, there is normalization of advanced IAB after a premature supraventricular or ventricular contraction, suggesting a functional block that temporarily recovers post extra-systolic pause. Recognition of intermittent IAB (second degree) may help further characterize the prognostic and clinical implications of this ECG pattern.

Interatrial block predicts atrial fibrillation in patients with carotid and coronary artery disease

Background

Interatrial block (IAB) has been previously shown to predict atrial fibrillation (AF) in cardiac populations. This study sought to evaluate the relationship between IAB and new-onset AF in a population of patients undergoing clinically indicated coronary angiography who received carotid ultrasonography.

Methods

A population of 355 subjects undergoing coronary angiography and carotid ultrasound were retrospectively studied. Common carotid artery (CCA) far-wall intima-media thickness (CIMT), and total carotid plaque area were measured. Coronary artery disease was measured by angiography and IAB by electrocardiograph (ECG).

Results

The mean population age was 64.4 years, 70.4% male, mean BMI 29.9 kg/m². IAB was a predictor of new-onset AF (OR =2.40, 95% CI: 1.33-4.29; P=0.003). There was a significant difference in AF free survival time between patients with IAB and without IAB via Cox proportional hazard analysis [52.9 months (95% CI: 47.1-58.7 months) vs. 62.6 months (95% CI: 58.8-66.5 months); P=0.006]. Patients with IAB had a significantly greater CIMT (0.883±0.193 vs. 0.829±0.192 mm; P=0.013) and a higher prevalence of significant (>70%) right coronary artery lesions than patients without (45.8% vs. 34.4%; P=0.026). Significant predictors of IAB on multivariate analysis were BMI ≥30 kg/m² (OR =3.14, 95% CI: 1.14-6.71, P=0.003), male sex (OR =1.78, 95% CI: 1.05-3.03, P=0.034), increased mean CIMT (per 0.1 mm increase) (OR =1.75, 95% CI: 1.00-3.07, P=0.050) and increased age (per 10-year increase) (OR =1.46, 95% CI: 1.14-1.88, P=0.003).

Conclusions

IAB is a predictor of new-onset AF in patients with carotid and coronary artery disease. Both carotid and coronary artery disease are associated with a higher prevalence of IAB.

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.

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.

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.

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.

Tachycardia-bradycardia syndrome: Electrophysiological mechanisms and future therapeutic approaches (Review)

Sick sinus syndrome (SSS) encompasses a group of disorders whereby the heart is unable to perform its pacemaker function, due to genetic and acquired causes. Tachycardia‑bradycardia syndrome (TBS) is a complication of SSS characterized by alternating tachycardia and bradycardia. Techniques such as genetic screening and molecular diagnostics together with the use of pre-clinical models have elucidated the electrophysiological mechanisms of this condition. Dysfunction of ion channels responsible for initiation or conduction of cardiac action potentials may underlie both bradycardia and tachycardia; bradycardia can also increase the risk of tachycardia, and vice versa. The mainstay treatment option for SSS is pacemaker implantation, an effective approach, but has disadvantages such as infection, limited battery life, dislodgement of leads and catheters to be permanently implanted in situ. Alternatives to electronic pacemakers are gene‑based bio‑artificial sinoatrial node and cell‑based bio‑artificial pacemakers, which are promising techniques whose long-term safety and efficacy need to be established. The aim of this article is to review the different ion channels involved in TBS, examine the three‑way relationship between ion channel dysfunction, tachycardia and bradycardia in TBS and to consider its current and future therapies.

Electrophysiological Mechanisms of Bayés Syndrome: Insights from Clinical and Mouse Studies

Bayés syndrome is an under-recognized clinical condition characterized by inter-atrial block (IAB). This is defined electrocardiographically as P-wave duration > 120 ms and can be categorized into first, second and third degree IAB. It can be caused by inflammatory conditions such as systemic sclerosis and rheumatoid arthritis, abnormal protein deposition in cardiac amyloidosis, or neoplastic processes invading the inter-atrial conduction system, such as primary cardiac lymphoma. It may arise transiently during volume overload, autonomic dysfunction or electrolyte disturbances from vomiting. In other patients without an obvious cause, the predisposing factors are diabetes mellitus, hypertensive heart disease, and hypercholesterolemia. IAB has a strong association with atrial arrhythmogenesis, left atrial enlargement (LAE), and electro-mechanical discordance, increasing the risk of cerebrovascular accidents as well as myocardial and mesenteric ischemia. The aim of this review article is to synthesize experimental evidence on the pathogenesis of IAB and its underlying molecular mechanisms. Current medical therapies include anti-fibrotic, anti-arrhythmic and anti-coagulation agents, whereas interventional options include atrial resynchronization therapy by single or multisite pacing. Future studies will be needed to elucidate the significance of the link between IAB and atrial tachyarrhythmias in patients with different underlying etiologies and optimize the management options in these populations.