Association between interatrial block, left atrial fibrosis, and mechanical dyssynchrony: Electrocardiography-magnetic resonance imaging correlation

Association Between P-Wave Duration, Dispersion, and Interatrial Block and Atrial High-Rate Episodes in CIED Patients

INTRODUCTION

Atrial high-rate episodes (AHRE) have been linked to increased thromboembolic risk and all-cause mortality in patients with cardiac implantable electronic devices (CIEDs). Various predictors of AHRE development have been identified, emphasizing the need for close monitoring and the potential transition to clinical atrial fibrillation (AF). However, the predictive value of P wave characteristics on AHRE development remains conflicting. This meta-analysis aims to summarize existing data to investigate this association.

METHOD

We examined studies from MEDLINE and EMBASE databases up to May 2024 to investigate the association of baseline P-wave duration (PWD), P-wave dispersion (PWDIS), and interatrial block (IAB) with the risk of developing AHRE. We extracted the mean and standard deviations of PWD and PWDIS to calculate the pooled mean difference (MD). Risk ratios (RR) and 95% confidence intervals (CIs) were used to assess the association between IAB and AHRE risk, using the generic inverse variance method for combination.

RESULTS

The meta-analysis included nine studies. Patients with AHRE had longer PWD and PWDIS compared to those without AHRE, with a pooled MD for PWD of 9.17 ms (95% CI: 4.74-13.60; I2 = 47%, p < 0.001) and a pooled MD for PWDIS of 20.56 ms (95% CI: 11.57-29.56; I2 = 57%, p < 0.001). Additionally, patients with IAB had a higher risk of developing AHRE, with a pooled RR of 3.33 (95% CI: 2.53-4.38; I2 = 0%, p < 0.001), compared to those without IAB.

CONCLUSIONS

Our meta-analysis found that patients with AHRE had higher PWD and PWDIS than those without AHRE. Additionally, IAB was associated with a higher risk of developing AHRE. These findings emphasize the importance of close monitoring and risk stratification, particularly for patients with P wave abnormalities.

Predictors of atrial fibrillation after embolic stroke of undetermined source in patients with implantable loop recorders

BACKGROUND

In patients with embolic stroke of undetermined source (ESUS), underlying subclinical atrial fibrillation (AF) is often suspected. Previous studies identifying predictors of AF have been limited in their ability to diagnose episodes of AF. Implantable loop recorders enable prolonged, continuous, and therefore more reliable detection of AF. The aim of this study was to identify clinical and ECG parameters as predictors of AF in ESUS patients with implantable loop recorders.

METHODS

101 ESUS patients who received an implantable loop recorder between 2012 and 2020 were included in this study. Patients were followed up regularly on a three-monthly outpatient interval.

RESULTS

During a mean follow-up of 647 ± 385 days, AF was detected in 26 patients (26%). Independent risk factors of AF were age ≥ 60 years (HR 2.753, CI 1.129-6.713, p = 0.026), P-wave amplitude in lead II ≤ 0.075 mV (HR 3.751, CI 1.606-8.761, p = 0.002), and P-wave duration ≥ 125 ms (HR 4.299, CI 1.844-10.021, p < 0.001). In patients without risk factors, the risk of developing AF was 16%. In the presence of one risk factor, the probability increased only slightly to 18%. With two or three risk factors, the risk of AF increased to 70%.

CONCLUSION

AF was detected in about one in four patients after ESUS in this study. A comprehensive evaluation involving multiple parameters and the existence of multiple risk factors yields the highest predictive accuracy for detecting AF in patients with ESUS.

Presystolic wave as a predictor of interatrial block in patients with supraventricular tachycardia

The identification of interatrial block (IAB) through electrocardiography (ECG) has been correlated with an elevated likelihood of developing atrial fibrillation (AF) and stroke. IAB is diagnosed by evaluating P-wave prolongation on a surface ECG. The presystolic wave (PSW) is an echocardiographic marker determined by pulse-wave examination of the aortic root during late diastole. As IAB and PSW share similar pathophysiological mechanisms, we speculated that PSW, as a component of the P wave, might be useful in predicting IAB. In the present study, we aimed to determine the relationship between PSW and IAB. Patients with pre-diagnosis of supraventricular tachycardia (SVT) on electrocardiography or rhythm Holter monitoring between January 2021 and December 2022 were included in the study. Surface 12-lead ECG and transthoracic echocardiography (TTE) were performed for the diagnosis of IAB and PSW. Patients were divided into two groups based on the presence of IAB, and PSW was compared between the groups. In total, 104 patients were enrolled in this study. IAB was diagnosed in 16 patients (15.3%) and PSW was detected in 33 patients (31.7%). The PSW was higher in the IAB ( +) group than in the IAB ( -) group (10 patients (71.4%) vs. 23 patients (32.4%), p = 0.008). PSW may be a useful tool for predicting IAB in patients with SVT. Further studies are needed to determine the clinical utility of PSW in the diagnosis and management of IAB.

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.

TRPV2 inhibitor tranilast prevents atrial fibrillation in rat models of pulmonary hypertension

Atrial fibrillation (AF) is common in pulmonary hypertension (PH), whereas the mechanisms and treatments remain to be explored. TRPV2 regulates the structure and function of the cardiovascular system; however, little attention has been given to its role in AF. This study was to determine whether TRPV2 was involved in PH-induced AF and the effects of TRPV2 inhibitor tranilast on AF in rat models of PH. Monocrotaline (MCT) and SU5416/hypoxia (SuHx)-induced PH models were performed to detect atrial electrophysiological parameters. Daily tranilast (a TRPV2 inhibitor) or saline was given starting 1 day before PH establishment. PH increased the susceptibility to AF, with TRPV2 up-regulated in the right atria. Compared to PH rats, tranilast reduced AF inducibility and the prolongations of ERP and APD; mitigated cardiopulmonary remodeling and the increases in P-wave duration and P-R interval; partially reversed the down-regulation of ion channels such as Cav1.2, Nav1.5, Kv4.3, Kv4.2, Kv1.5, Kir2.1, Kir3.1, Kir3.4 as well as connexin (Cx) 40 and Cx43; improved right atrial (RA) fibrosis, enlargement, and myocardial hypertrophy; decreased the accumulation of inflammatory cells; down-regulated inflammatory indicators such as TNF-α, IL-1β, CXCL1, and CXCL2; and inhibited the activation of the PI3K-AKT-NF-κB signaling pathway. Our results reveal that TRPV2 participates in PH-induced AF, and TRPV2 inhibitor tranilast prevents PH-induced RA remodeling. TRPV2 might be a promising target for PH-induced AF.

Predictive value of P wave parameters, indices, and a novel electrocardiographic marker for silent cerebral infarction and future cerebrovascular events

BACKGROUND

Silent cerebral infarction (SCI) is a neuronal injury without a clinically apparent stroke or transient ischaemic attack. Left atrial cardiomyopathy is closely associated with SCI. P wave changes in the electrocardiogram (ECG) provide significant information about the development of atrial cardiomyopathy. This study evaluated the role of P wave parameters and indices and a novel ECG parameter in predicting SCI, future cerebrovascular events, and atrial fibrillation/flutter.

MATERIALS AND METHODS

A total of 272 patients were retrospectively screened and divided into two groups according to SCI. Cerebrovascular events and atrial fibrillation/flutter were defined as the study's outcomes. P wave parameters, indices, and a novel ECG parameter called the P wave ratio (PWR) were calculated from ECGs, and the relationship between SCI and outcomes was investigated.

RESULTS

The maximum P wave duration (PWD), P wave dispersion (PWdisp), PWD measured from the D2 lead (PWDD2), P wave peak time measured from the D2 lead (PWPTD2), PWPT measured from the V1 lead (PWPTV1), and P wave terminal force (PWTFV1) were significantly longer in the SCI group. Both partial and advanced inter atrial block (IAB) were significantly high in the SCI group. The novel parameter P wave ratio (PWR) was significantly longer in the SCI group (0.55 ± 0.08 vs. 0.46 ± 0.09; p < 0.001). In multivariate regression analysis, PWdisp (OR: 1.101, p < 0.001), PWPTD2 (OR: 1.095, p = 0.017), and PWR (OR: 1.231, p < 0.001) were found to be independent predictors of SCI. Cox regression analysis revealed that the PWR (HR 1.077; 95% CI 1.029-1.128; p = 0.001) was associated with cerebrovascular events and atrial fibrillation/flutter.

CONCLUSION

In our study, we observed that PWR could be a valuable parameter for predicting SCI and future cerebrovascular events.

P-wave duration as a marker of atrial remodeling in patients referred to ablation for atrial fibrillation: A new stratification tool emerging?

Ablation of atrial fibrillation is one of the most widely applied invasive procedures in cardiovascular medicine, and populations with atrial fibrillation continuously rise. Recurrence rates are, however, consistently high, even in patients without severe comorbidities. Robust stratification algorithms to distinguish patients suitable for ablation are generally lacking. This is a fact caused by the inability to incorporate evidence of atrial remodeling and fibrosis, e.g., atrial remodeling, in the decision pathways. Cardiac magnetic resonance is a powerful tool in identifying fibrosis; however, it is costly and not routinely used. Electrocardiography has been generally underutilized in clinical practice during pre-ablative screening. One of the characteristics of the electrocardiogram that can give us valuable data depicting the existence and the extent of atrial remodeling and fibrosis is the duration of the P-wave. Currently, many studies support the implementation of P-wave duration in the routine practice of patient evaluation as a surrogate marker of existing atrial remodeling, that in turn predicts recurrence after ablation of atrial fibrillation. Further research is guaranteed to establish this electrocardiographic characteristic in our stratification quiver.

Assessment of P Wave Indices in Healthy Standardbred Horses

P wave indices are used as non-invasive electrocardiographic markers of atrial remodelling in humans. Few studies have investigated their use in animals. The aim of this study was to measure P wave duration and P wave dispersion (Pd) in healthy standardbred horses and investigate variables that might influence these measurements. A 12-lead electrocardiogram was recorded at rest and P wave indices were calculated in 53 horses. A general linear model was used to investigate the main effects: age, bodyweight, sex, resting heart rate, presence of a murmur, exercise status and the number of years raced. There were significant associations with exercise status for both the maximum P wave duration and Pd, with both values being increased in strenuously exercising versus non-active horses. Furthermore, a significant moderate positive correlation was identified between the duration of exercise (number of years raced) and both Pmax and Pd. No other significant associations were identified. These findings are similar to those reported in elite human athletes versus sedentary individuals. The increases in these P wave indices most likely occur due to prolongation and heterogeneity in atrial conduction time, which are associated with structural and electrical remodelling, and may explain the increased risk of atrial fibrillation in athletic horses.

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

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

Prognostic significance of atrial cardiopathy in patients with acute ischemic stroke

Introduction:

Whether atrial cardiopathy is associated with stroke prognosis remains unclear. We evaluated the association between atrial cardiopathy markers and outcomes in patients with ischemic stroke using a nationwide prospective registry.

Patients and methods:

Based on the Third China National Stroke Registry, we evaluated different atrial cardiopathy markers including increased P-wave terminal force in V1 (PTFV1), advanced interatrial block (aIAB), prolonged P-wave duration, prolonged P-wave dispersion, paroxysmal supraventricular tachycardia, premature atrial contractions, prolonged PR interval, and severe left atrial enlargement in ischemic stroke patients. The outcomes were death and ischemic stroke recurrence at 1 year. The association between atrial cardiopathy markers and outcomes was analyzed using Cox regression models.

Results:

At 1-year follow-up, 486 (3.4%) patients had died and 1317 (9.3%) patients had experienced ischemic stroke recurrence. After adjustment for clinical risk factors including atrial fibrillation, PTFV1 > 5000 μV·ms (adjusted hazard ratio [HR] 1.70, 95% confidence interval [CI]: 1.18–2.45, p = 0.004) and aIAB (adjusted HR 1.47, 95% CI: 1.14–1.91, p = 0.003) were significantly associated with mortality. PTFV1 > 5000 μV·ms was significantly associated with ischemic stroke recurrence (adjusted HR 1.54, 95% CI: 1.22–1.96, p = 0.0004). This association was observed although we excluded patients diagnosed with atrial fibrillation.

Discussion and Conclusion:

Atrial cardiopathy markers, especially PTFV1 and aIAB, are significantly associated with a higher risk of poor prognosis in patients with ischemic stroke.

Association of electrocardiographic markers with myocardial fibrosis as assessed by cardiac magnetic resonance in different clinical settings

BACKGROUND

Cardiac magnetic resonance (CMR) is a unique tool for non-invasive tissue characterization, especially for identifying fibrosis.

AIM

To present the existing data regarding the association of electrocardiographic (ECG) markers with myocardial fibrosis identified by CMR - late gadolinium enhancement (LGE).

METHODS

A systematic search was performed for identifying the relevant studies in Medline and Cochrane databases through February 2021. In addition, we conducted a relevant search by Reference Citation Analysis (RCA) (https://www.referencecitationanalysis.com).

RESULTS

A total of 32 studies were included. In hypertrophic cardiomyopathy (HCM), fragmented QRS (fQRS) is related to the presence and extent of myocardial fibrosis. fQRS and abnormal Q waves are associated with LGE in ischemic cardiomyopathy patients, while fQRS has also been related to fibrosis in myocarditis. Selvester score, abnormal Q waves, and notched QRS have also been associated with LGE. Repolarization abnormalities as reflected by increased Tp-Te, negative T-waves, and higher QT dispersion are related to myocardial fibrosis in HCM patients. In patients with Duchenne muscular dystrophy, a significant correlation between fQRS and the amount of myocardial fibrosis as assessed by LGE-CMR was observed. In atrial fibrillation patients, advanced inter-atrial block is defined as P-wave duration ≥ 120 ms, and biphasic morphology in inferior leads is related to left atrial fibrosis.

CONCLUSION

Myocardial fibrosis, a reliable marker of prognosis in a broad spectrum of cardiovascular diseases, can be easily understood with an easily applicable ECG. However, more data is needed on a specific disease basis to study the association of ECG markers and myocardial fibrosis as depicted by CMR.

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

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

Electrocardiographic predictors of atrial fibrillation in patients with cryptogenic stroke

BACKGROUND

Empiric anticoagulation is not routinely indicated in patients with cryptogenic stroke without documentation of atrial fibrillation (AF). Therefore, identification of patients at increased risk of AF from this vulnerable group is vital.

OBJECTIVES

To identify electrocardiographic (ECG) predictors of AF in patients with cryptogenic stroke or transient ischemic attack (TIA) undergoing insertion of an implantable cardiac monitor (ICM).

METHODS

In this single-center study, 48 patients with cryptogenic stroke or TIA had an ICM implanted for detection of AF between January 2013 and September 2019. Patients with and without AF were compared in terms of p-wave duration and a novel index (MVP score).

RESULTS

During a mean follow-up of 16±14 months, AF was detected in 7 patients (15%). Diagnosis of AF was made after a mean of 10 ± 14 months, with time to first AF detection ranging between 1 and 40 months. Patients with AF had a longer p-wave duration (136±9 ms vs 116±10 ms; p = 0.0001) and a higher MVP score (4.5±1.2 vs 2.0±0.9, p = 0.0001) than those without AF. Advanced interatrial block was observed in 43% of patients with ICM evidence of AF and 0% of those without AF (p = 0.002). Age, LA size or LVEF were not predictors of AF.

CONCLUSION

An increased p-wave duration, advanced interatrial block and high MVP score are associated with AF occurrence in patients with cryptogenic stroke. Identifying patients with these markers may be helpful as they may benefit from more exhaustive and prolonged monitoring. This article is protected by copyright. All rights reserved.

The significance of the morphology-voltage-P-wave duration (MVP) ECG score for prediction of in-hospital and long-term atrial fibrillation in ischemic stroke

BACKGROUND

Atrial fibrillation (AF) is the most common preventable cause of stroke. Diagnosis of new AF is frequent after acute ischemic stroke (AIS). We aimed to evaluate the predictive value of the recently developed morphology-voltage-P-wave duration (MVP) ECG risk score for in-hospital and long-term AF diagnosis following AIS.

MATERIAL AND METHODS

In this observational investigation, we evaluated the ability of the MVP ECG risk score to predict AF in 266 consecutive patients with AIS. The study population was divided into three groups according to their calculated MVP ECG risk score on admission electrocardiography. The groups were compared in terms of their predictive value for in-hospital and long-term AF diagnosis.

RESULTS

After adjustment for confounding baseline variables, MVP ECG risk score 5-6 group had 13.2 times higher rates of in-hospital AF compared to MVP ECG risk score 0-2 group, which was used as the reference group. For long-term follow-up, MVP ECG risk score 5-6 group had 5.2 times higher rates of long-term AF compared to MVP ECG risk score 0-2 group. A ROC analysis showed that the optimal cut-off value of the MVP ECG risk score to predict in-hospital AF was 4 with 78% sensitivity and 76% specificity (AUC: 0.80; 95% CI: 0.64-0.96; p < 0.001), the optimal cut-off value of the MVP ECG risk score to predict long-term AF was 3 with 85% sensitivity and 59% specificity (AUC: 0.81; 95% CI: 0.76-0.86; p < 0.001).

CONCLUSION

The MVP ECG risk score, which can be easily calculated from a surface ECG, can be used to guide who needs stricter monitoring for the diagnosis of long-term AF in patients with AIS.

The usefulness of morphology-voltage-P wave duration ECG score for predicting early left atrial dysfunction in hypertensive patients

OBJECTIVE

Left atrial (LA) function is an important predictor of adverse cardiovascular outcomes in patients with hypertension (HT). Therefore, recognition of subtle LA dysfunction in the early stages of HT is essential for controlling modifiable variables. Several electrocardiographic and echocardiographic parameters have been studied to show early LA dysfunction. The goal of this study was to investigate the relationship between newly defined morphology-voltage-P wave duration electrocardiography (MVP ECG) score and early LA dysfunction in hypertensive patients.

MATERIALS AND METHODS

Eighty-nine hypertensive patients were included in this study. Based on speckle tracking echocardiography results, the patients were divided into two groups: 67 patients with normal LA function were included in Group 1, and 22 patients with abnormal LA function in Group 2.

RESULTS

Age, diabetes mellitus history, duration of HT history, left ventricular mass index, E/Em, and MVP ECG score values were statistically significant between the two groups. Based on the results of the multivariate logistic regression test, duration of HT history, E/Em, and MVP ECG score were determined as independent predictive parameters for early LA dysfunction in hypertensive patients.

CONCLUSION

In conclusion, MVP ECG score assessment could be a novel approach to detect early LA dysfunction in hypertensive patients.

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.

Impact of P-wave indices in prediction of atrial fibrillation-Insight from loop recorder analysis

BACKGROUND

Several P-wave indices are associated with the development of atrial fibrillation (AF). However, previous studies have been limited in their ability to reliably diagnose episodes of AF. Implantable loop recorders allow long-term, continuous, and therefore more reliable detection of AF.

HYPOTHESIS

The aim of this study is to identify and evaluate ECG parameters for predicting AF by analyzing patients with loop recorders.

METHODS

This study included 366 patients (mean age 62 ± 16 years, mean LVEF 61 ± 6%, 175 women) without AF who underwent loop recorder implantation between 2010-2020. Patients were followed up on a 3 monthly outpatient interval.

RESULTS

During a follow-up of 627 ± 409 days, 75 patients (20%) reached the primary study end point (first detection of AF). Independent predictors of AF were as follows: age ≥68 years (hazard risk [HR], 2.66; 95% confidence interval [CI], 1.668-4.235; p < .001), P-wave amplitude in II <0.1 mV (HR, 2.11; 95% CI, 1.298-3.441; p = .003), P-wave terminal force in V₁  ≤ -4000 µV × ms (HR, 5.3; 95% CI, 3.249-8.636; p < .001, and advanced interatrial block (HR, 5.01; 95% CI, 2.638-9.528; p < .001). Our risk stratification model based on these independent predictors separated patients into 4 groups with high (70%), intermediate high (41%), intermediate low (18%), and low (4%) rates of AF.

CONCLUSIONS

Our study indicated that P-wave indices are suitable for predicting AF episodes. Furthermore, it is possible to stratify patients into risk groups for AF using simple ECG parameters, which is particularly important for patients with cryptogenic stroke.

Vectorial theory surpasses the local theory in explaining the origin of P-wave dispersion

BACKGROUND

Local theory and the vectorial theory are used to explain the origin of P-wave dispersion (PWD). There are no previous studies that analyze both at the same time.

OBJECTIVES

We set out to determine the implication of local and vectorial theories in the origin of PWD.

METHODS

Cross-sectional study in 153 randomly selected patients aged 18-70 years, undergoing electrophysiological study. Inhomogeneous atrial conduction was evaluated by atrial electrogram dispersion in terms of duration (EGM_durdis) and morphology (EGM_morph dis). P-distal coronary sinus interval (P-DCS) was also measured. P-wave was measured twice, firstly at a calibration of 20 mm/mV and a sweep speed of 50 mm/s, enhancement 10× (basic measurement [BM]), and second time at sweep speed of 150 mm/s, enhancement 80-160× (high precision measurement [HPM]).

RESULTS

PWD with BM was 48 ms [36-54 ms] while with HPM it was 4 ms [0-10 ms], p < 0.001. With BM, maximum and minimum P- wave duration presented a moderate correlation (r = 0.342; p < 0.001), using HPM it becomes strong (r = 0.750; p < 0.001). In cases with P-DCS < 80 ms (r = 0.965; p < 0.001), but not with P-DCS ≥ 80 ms (r = 0.649; p < 0.001), the previous correlation became almost perfect with HPM. EGM_durdis and EGM_morphdis were weak but significantly correlated with PWD. This correlation became moderate in patients with P-DCS ≥ 80 ms and disappeared in those with P-DCS, using BM and HPM.

CONCLUSION

Vectorial theory explains almost entirely the PWD phenomenon. Inhomogeneous conduction could be an additional mechanism to explain PWD, but its contribution is small.

[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.

Relation of Interatrial Block to Cognitive Impairment in Patients ≥ 70 Years of Age (From the CAMBIAD Case-control Study)

The association between atrial fibrillation, stroke, and interatrial block (IAB) (P-wave duration ≥120 ms) is well recognized, particularly in the case of advanced IAB. We aimed to assess the association of IAB with mild cognitive impairment. Advanced Characterization of Cognitive Impairment in Elderly with Interatrial Block was a case-control multicenter study, conducted in subjects aged ≥70 years in sinus rhythm without significant structural heart disease. Diagnosis of mild cognitive impairment was performed by an expert geriatrician, internist, or neurologist in the presence of changes in cognitive function (Mini Mental State Examination score 20 to 25) without established dementia. A total of 265 subjects were included. Mean age was 79.6 ± 6.3 years and 174 (65.7%) were women; there were 143 cases with mild cognitive impairment and 122 controls with normal cognitive function. Compared with controls, cases had longer P-wave duration (116.2 ± 13.8 ms vs 112.5 ± 13.3 ms, p = 0.028), higher prevalence of IAB (73 [51.0%] vs 38 [31.1%], p = 0.001), higher prevalence of advanced IAB (28 [19.6%] vs 10 [8.2%], p = 0.002), and higher MVP ECG risk score (2.7 ± 1.4 vs 2.2 ± 1.3, p = 0.004). IAB was independently associated with mild cognitive impairment, both for partial (odds ratio 2.0, 95% CI: 1.1 to 3.9) and advanced IAB (odds ratio 2.8, 95% CI: 1.1 to 6.7). In conclusion, in subjects aged ≥70 years without significant structural heart disease, IAB is independently associated with mild cognitive impairment. This association is stronger in the case of advanced IAB.

Baseline ECG and Prognosis After Transcatheter Aortic Valve Implantation: The Role of Interatrial Block

Background The clinical significance of conduction disturbances after transcatheter aortic valve implantation has been described; however, little is known about the influence of baseline ECGs in the prognosis of these patients. Our aim was to study the influence of baseline ECG parameters, including interatrial block (IAB), in the prognosis of patients treated with transcatheter aortic valve implantation. Methods and Results The BIT (Baseline Interatrial Block and Transcatheter Aortic Valve Implantation) registry included 2527 patients with aortic stenosis treated with transcatheter aortic valve implantation. A centralized analysis of baseline ECGs was performed. Patients were divided into 4 groups: normal P wave duration (<120 ms); partial IAB (P wave duration ≥120 ms, positive in the inferior leads); advanced IAB (P wave duration ≥120 ms, biphasic [+/-] morphology in the inferior leads); and nonsinus rhythm (atrial fibrillation/flutter and paced rhythm). The mean age of patients was 82.6±9.8 years and 1397 (55.3%) were women. A total of 960 patients (38.0%) had a normal P wave, 582 (23.0%) had partial IAB, 300 (11.9%) had advanced IAB, and 685 (27.1%) presented with nonsinus rhythm. Mean follow-up duration was 465±171 days. Advanced IAB was the only independent predictor of all-cause mortality (hazard ratio [HR], 1.48; 95% CI, 1.10-1.98 [P=0.010]) and of the composite end point (death/stroke/new atrial fibrillation) (HR, 1.51; 95% CI, 1.17-1.94 [P=0.001]). Conclusions Baseline ECG characteristics influence the prognosis of patients with aortic stenosis treated with transcatheter aortic valve implantation. Advanced IAB is present in about an eighth of patients and is associated with all-cause death and the composite end point of death, stroke, and new atrial fibrillation during follow-up.