P-wave Morphology Research Articles

Paced P-wave morphology templates to guide atrial tachycardia localization: A derivation and validation study.

Surface ECG is a useful tool to guide mapping of focal atrial tachycardia (AT). We aimed to construct 12-lead ECG templates for P-wave morphology (PWM) during endocardial pacing from different sites in both atria in patients with no apparent structural heart disease (derivation cohort), with the goal of creating a localization algorithm, which could subsequently be validated in a cohort of patients undergoing catheter ablation of focal AT (validation cohort). We prospectively enrolled consecutive patients who underwent electrophysiology study, had no structural heart disease and no atrial enlargement. Atrial pacing, at twice diastolic threshold, was carried out at different anatomical sites in both atria. Paced PWM and duration were assessed. An algorithm was generated from the constructed templates of each pacing site. The algorithm was applied on a retrospective series of successfully ablated AT patients. Overall and site-specific accuracy were determined. Derivation cohort included 65 patients (25 men, age 37±13 years). Atrial pacing was performed in 1025 sites in 61 patients (95%) in RA and in 15 patients (23%) in LA. The validation cohort included 71 patients (28 men, age 52±19 years). AT were right atrial in 66.2%. The algorithm successfully predicted AT origin in 91.5% of patients (100% in LA and 87.2% in RA). It was off by one adjacent segment in the remaining 8.5%. A simple ECG algorithm based on paced PWM templates was highly accurate in localizing site of origin of focal AT in patients with structurally normal hearts.

Individuals with chronic epilepsy have elevated P-wave heterogeneity comparable to patients with atrial fibrillation.

Identification of epilepsy patients with elevated risk for atrial fibrillation (AF) is critical given the heightened morbidity and premature mortality associated with this arrhythmia. Epilepsy is a worldwide health problem affecting nearly 3.4 million people in the United States alone. The potential for increased risk for AF in patients with epilepsy is not well appreciated, despite recent evidence from a national survey of 1.4 million hospitalizations indicating that AF is the most common arrhythmia in people with epilepsy. We analyzed inter-lead heterogeneity of P-wave morphology, a marker reflecting arrhythmogenic nonuniformities of activation/conduction in atrial tissue. The study groups consisted of 96 patients with epilepsy and 44 consecutive patients with AF in sinus rhythm before clinically indicated ablation. Individuals without cardiovascular or neurological conditions (n = 77) were also assessed. We calculated P-wave heterogeneity (PWH) by second central moment analysis of simultaneous beats from leads II, III, and aVR ("atrial dedicated leads") from standard 12-lead electrocardiography (ECG) recordings from admission day to the epilepsy monitoring unit (EMU). Female patients composed 62.5%, 59.6%, and 57.1% of the epilepsy, AF, and control subjects, respectively. The AF cohort was older (66 ± 1.1 years) than the epilepsy group (44 ± 1.8 years, p < .001). The level of PWH was greater in the epilepsy group than in the control group (67 ± 2.6 vs. 57 ± 2.5 μV, p = .046) and reached levels observed in AF patients (67 ± 2.6 vs. 68 ± 4.9 μV, p = .99). In multiple linear regression analysis, PWH levels in individuals with epilepsy were mainly correlated with the PR interval and could be related to sympathetic tone. Epilepsy remained associated with PWH after adjustments for cardiac risk factors, age, and sex. Patients with chronic epilepsy have increased PWH comparable to levels observed in patients with AF, while being ~20 years younger, suggesting an acceleration in structural change and/or cardiac electrical instability. These observations are consistent with emerging evidence of an "epileptic heart" condition.

Diagnosing Atypical Flutter in the Post-atrial Fibrillation Ablation Patient: A Case Report.

Late atrial arrhythmias after catheter ablation for atrial fibrillation occur in up to 30% of post-ablation patients and are increasingly encountered by emergency physicians. However, diagnosing the exact mechanism of the arrhythmia on the surface electrocardiogram (ECG) remains challenging due to atrial scarring leading to heterogeneous P-wave morphology. A 74-year-old male with a history of prior catheter ablation for atrial fibrillation presented with palpitations and subacute symptoms of heart failure. The patient's ECG revealed narrow complex tachycardia with more P waves than QRS complexes. The differential diagnosis included typical flutter, atypical flutter, and focal atrial tachycardias with 2:1 conduction block. P waves were positive in V1 and across all precordial leads (absent precordial transition). This favors atypical flutter originating from the left atrium over typical cavotricuspid isthmus-dependent right atrial flutter. Transthoracic echocardiogram showed a reduced ejection fraction due to tachycardia-mediated cardiomyopathy. The patient underwent a repeat electrophysiology study and ablation, which confirmed the presence of an atypical flutter circuit using the mitral annulus, known as perimitral flutter. Repeat catheter ablation resulted in maintenance of sinus rhythm. At follow-up, his ejection fraction recovered. Recognizing ECG findings suggestive of atypical flutter impacts initial emergency department decisions and triage as atypical flutter post-atrial fibrillation ablation is frequently resistant to rate-controlling medications and often requires cardiology and/or electrophysiology consultation if available.

Beat-to-beat variation of P-wave morphology immediately after ablation of persistent atrial fibrillation correlates with long-term clinical outcome

Abstract Funding Acknowledgements Type of funding sources: None. Background P-wave morphology on surface ECG reflects the atrial electrical remodelling, and is regarded as a predictor of ablation outcome for atrial fibrillation (AF). Purpose We sought to investigate whether morphological characteristics of P-waves immediately after a wide circumferential isolation of pulmonary veins (WPVI) in persistent AF (peAF) correlate with long-term maintenance of sinus rhythm (SR). Methods 33 patients (63±10 y, sustained AF 11±7 months) underwent a de-novo WPVI. A second WPVI was performed in patients with recurrent AF in order to provide complete PV disconnection. We defined "success" as patients who remained in SR after one or two procedures, and "failure" otherwise. The average duration and amplitude of the P-waves, and the coefficient of variation (CoV = standard deviation/mean) of the beat-to-beat similarity between ≥30 successive P-waves per patient were computed on ECG lead II during SR after cardioversion. Panel A shows a group of successive P-waves synchronized with regard to their centers of gravity. The similarity between the shapes of two successive synchronized P-waves was assessed using the dynamic time warping distance. Panel B shows the time-evolution of beat-to-beat distance between the P-waves displayed in Panel A. Results Over a mean follow-up of 31±9 months, 21 patients remained free from AF off antiarrhythmics (success group), while 12 patients had AF recurrence after 2 WPVIs (failure group). The clinical characteristics (e.g. age, body mass index, left atrial volume or duration in sustained AF) were similar between groups (p&amp;gt;0.05). The success group displayed significantly lower beat-to-beat variability of P-wave morphology than that of the failure group (p&amp;lt;0.05, Panel C). No significant difference was found in P-wave duration and amplitude between the two groups (p&amp;gt;0.05, Panel D and E). Conclusion Low P-wave beat-to-beat morphological variability immediately after WPVI for persistent AF is associated with long-term maintenance of sinus rhythm.

PO-01-066 IMPACT OF THE MORPHOLOGY-VOLTAGE-P-WAVE DURATION SCORE ON THE OUTCOME OF CATHETER ABLATION OF PERSISTENT ATRIAL FIBRILLATION

The morphology-Voltage-P-wave duration (MVP) score, a score composed of three p-wave variables, is associated with new-onset atrial fibrillation (AF). An association between the MVP score and outcomes of catheter ablation (CA) of persistent AF has not been established. This study aimed to evaluate the predictive value of the MVP score on AF recurrence after CA in patients with persistent AF. One hundred fifty-eight consecutive patients (64.4±11.6 years, 116 male) receiving CA of persistent AF were enrolled. Pharmacological or electrical cardioversion was performed before CA in all patients, and the MVP score was calculated based on the p-wave morphology in the inferior leads, peak voltage in lead I, and p-wave duration on electrocardiography during sinus rhythm. Each variable could be assigned a weight of 0, 1, or 2 points and the total score was calculated. Univariate and multivariate analyses using a Cox proportional hazard model were carried out to determine the factors predicting late recurrence of AF (LRAF), which meant AF recurrence later than 3 months post-CA. During a follow-up of 31.9±18.8 months, 41 patients (26.1%) experienced LRAFs. The MVP score was significantly higher in LRAF patients than in those without LRAF (4.0 [2.0-5.0] versus. 2.0 [2.0-2.0], p<0.001)]. In the univariate analysis, the MVP score, age, left atrial dimension, and brain natriuretic peptide level were related to LRAFs. A multivariate analysis found that a higher MVP score was a significant predictive factor of LRAFs (hazard ratio: 2.12, 95% confidence interval: 1.72-2.65, p<0.001). This study revealed that the MVP score could predict LRAFs post-CA in persistent AF patients.

P-wave morphology variants in patients with interatrial block visualized using CineECG: A new classification approach

High-intensity focused ultrasound (HIFU) can achieve accurate and focused deep tissue ablation through an extracorporeal emission. Cardiac ablation using HIFU applied transthoracically must overcome potential interference from intervening thoracic structures. The aim of this study was to explore the efficacy and safety of septal ablation that was induced using transthoracic HIFU.Twenty-one canines were pretreated to improve acoustic transmission. Single ablations were induced by targeting transthoracic HIFU with acoustic power of 400 W for 3 sec at the middle and basal septum in eight canines. Extended ablations were performed to create larger lesions at the basal septum in eight more canines. The three-dimensional morphology of a basal septum lesion induced by a single ablation was analyzed. The temperature at the ablative targets was measured in the other five canines.The cardiomyocytes in the lesions underwent necrosis with a clear boundary. The three-dimensional morphology of the lesions appeared approximately as ellipsoids with a flatter endocardial side. The peak temperature at a power of 400 W for 3 sec was 93.27 ± 2.54°C, and it remained >50°C for nearly 10 sec. No procedure-related complications were observed.Ultrasound-guided transthoracic HIFU has the potential to safely create small dot or large mass lesions in the septum without a thoracotomy or a catheter.

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.

Association of electrocardiographic spatial heterogeneity of repolarization and spatial heterogeneity of atrial depolarization with left ventricular fibrosis.

To evaluate the relationship between spatial heterogeneity of electrocardiographic repolarization and spatial heterogeneity of atrial depolarization with arrhythmic substrate represented by left ventricular fibrosis. We assessed the associations of T- and P-wave morphology parameters analysed from the standard 12-lead electrocardiograms with left ventricular fibrosis in 378 victims of unexpected sudden cardiac death (SCD) who underwent medico-legal autopsy. Based on autopsy findings, the SCD victims were categorized into four different groups according to different stages of severity of left ventricular fibrosis (substantial fibrosis, moderate patchy fibrosis, scattered mild fibrosis, no fibrosis). T-wave and P-wave area dispersion (TWAd: 0.0841 ± 0.496, 0.170 ± 0.492, 0.302 ± 404, 0.296 ± 0.476, P = 0.008; PWAd: 0.574 ± 0.384, 0.561 ± 0.367, 0.654 ± 0.281, 0.717 ± 0.257, P = 0.011, respectively; low values abnormal), non-dipolar components of T-wave and P-wave morphology (T_NonDipolarABS: 0.0496 ± 0.0377, 0.0571 ± 0.0487, 0.0432 ± 0.0476, 0.0380 ± 0.0377, P = 0.027; P_NonDipolarABS: 0.0132 ± 0.0164, 0.0130 ± 0.0135, 0.0092 ± 0.0117, 0.0069 ± 0.00472, P = 0.005, respectively, high values abnormal), T-wave morphology dispersion (TMD: 45.9 ± 28.3, 40.5 ± 25.8, 35.5 ± 24.9, 33.0 ± 24.6, P = 0.030, respectively, high values abnormal), and P-wave heterogeneity (PWH: 20.0 ± 9.44, 19.7 ± 8.87, 17.9 ± 9.78, 15.4 ± 4.60, P = 0.019, respectively, high values abnormal) differed significantly between the groups with different stages of left ventricular fibrosis. After adjustment with heart weight, T_NonDipolarABS [standardized β (sβ) = 0.131, P = 0.014], PWAd (sβ = -0.161, P = 0.003), P_NonDipolarABS (sβ = 0.174, P = 0.001), and PWH (sβ = 0.128, P = 0.015) retained independent association, and TWAd (sβ = -0.091, P = 0.074) and TMD (sβ = 0.097, P = 0.063) tended to retain their association with the degree of myocardial fibrosis. Our findings suggest that abnormal values of T- and P-wave morphology are associated with arrhythmic substrate represented by ventricular fibrosis partly explaining the mechanism behind their prognostic significance.

Abstract 12452: Relation of T-Wave Morphology And P-Wave Morphology Parameters With Left Ventricular Fibrosis in Sudden Cardiac Death Victims

Introduction: T-wave morphology and P-wave morphology have been observed to have prognostic significance. However, data about their relation with arrhythmic substrate represented by left ventricular fibrosis are limited. Methods: We evaluated associations of T- and P-wave morphology parameters analyzed from the standard 12-lead ECGs with left ventricular fibrosis in 379 victims of unexpected sudden cardiac death who underwent medico-legal autopsy. Results: T-wave and P-wave area dispersion (TWAd, PWAd) (low values abnormal), non-dipolar components of T-wave and P-wave morphology (T_NonDipolarABS, P_NonDipolarABS) (high values abnormal) all had a significant association with left ventricular fibrosis (p=0.008, p=0.011, p=0.027, p=0.005 between the groups with different stages of left ventricular fibrosis, respectively, post hoc Bonferroni p-values are shown in Figures). Conclusions: Abnormal values of T- and P-wave morphology are associated with arrhythmic substrate represented by ventricular fibrosis partly explaining the mechanism behind their prognostic significance.

Morphology-Voltage-P-wave duration (MVP) score in prediction of incident atrial fibrillation in an elderly epidemiologic cohort

Abstract Background Interatrial block (IAB) on electrocardiography (ECG) and reduced P wave voltage reflect atrial abnormalities which may contribute to development of atrial fibrillation (AF). Purpose We aimed to assess the value of a recently proposed ECG risk score that combines the morphology, voltage and length of the P wave (MVP score) for prediction of incident AF in a prospective population-based setting. Material and methods The study population is based on the large, prospective Malmö Preventative Project (MPP) cohort. We included subjects without a history of AF, with a readable ECG in sinus rhythm and an echocardiography performed in 2002–2006 (n=983, mean age 70±5 years, 38% females). Median follow-up was 4.2 (IQR 3.7–4.8) years. ECGs were digitally processed using the Glasgow algorithm. Advanced IAB (aIAB) was defined as a P-wave ≥120 ms and biphasic morphology (+/−) in inferior leads, partial IAB (pIAB) as P-wave ≥120 ms and a monophasic positive morphoology in inferior leads. MVP score was calculated based on the P-wave morphology in inferior leads, voltage in lead 1, and P-wave duration (Table 1).Incident AF events (n=66, 7%) were obtained from the Swedish Hospital Discharge Register and Cause of Death Register. Cox regression analysis and Kaplan Meier curve analysis were used to study the association of echocardiographic and P-wave characteristics with the risk of new onset AF. Results At baseline the mean MVP score was 1±1, none of the subjects had MVP score above 4. MVP score correlated with left atrial (LA) area: Pearson r=0.192, p&amp;lt;0.001. After adjustment for age, gender and LA enlargement expressed as LA area &amp;gt;20 cm2, new onset AF was associated with MVP score 4 (HR 6.17, 95% CI 1.76–21.64 compared to those with MVP score &amp;lt;4, Figure 1). Neither aIAB (univariate HR 1.93 CI 95% 0.82–4.56), nor pIAB (univariate HR 1.16 CI 95% 0.52–2.55) predicted incident AF. Conclusion In a population-based elderly epidemiological cohort, the ECG-based MVP score was significantly associated with incident AF, independently of LA enlargement. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The Swedish Heart-Lung Foundation

P-wave beat-to-beat analysis to predict atrial fibrillation recurrence after catheter ablation

Abstract Introduction Identification of patients prone to atrial fibrillation (AF) relapse after catheter ablation is essential for better patient selection and risk stratification. Purpose The current prospective cohort study aims to validate a novel P-wave index based on beat-to-beat (B2B) P-wave morphological and wavelet analysis designed to detect patients with low burden AF, as a predictor of AF recurrence within a year after successful catheter ablation. Methods 12-lead ECG and 10-minute vectorcardiogram (VCG) recordings were obtained from 138 consecutive patients scheduled for AF ablation. Pre-ablation B2B P-wave index, along with standard P-wave indices, clinical scores and patients history and physical examination parameters were evaluated as AF recurrence predictors. Results Univariate analysis revealed that patients with higher B2B P-wave index had a two-fold risk for AF recurrence (HR: 2.35, 95% CI: 1.24–4.44, p: 0.010). Prolonged P-wave, interatrial block, early AF recurrence, female gender, heart failure history, previous stroke, and CHA2DS2-VASc score ≥2 were also found to be related to higher recurrence rate. Multivariate analysis of predictors that can be assessed before ablation revealed that B2B P-wave index, along with heart failure history and history of previous stroke or transient ischemic attack are independent predicting factors of AF relapse. Conclusion B2B P-wave morphology and wavelet analysis, is a promising, non-invasive technique, able to identify patients prone to AF recurrence after pulmonary veins ablation. Further studies are needed to assess the predictive value of B2B index with greater accuracy and evaluate a possible relationship with atrial substrate analysis. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Hellenic Society of Cardiology

A closed-chest model of selective atrial myocardial infarction for the study of induced electrophysiological and structural derangements

Abstract Background The diagnosis of atrial infarction is often masked by the frequent association with ventricular infarction. For this reason, the electrophysiological and structural consequences of selective atrial ischemia are poorly understood. Purpose The objective of this study was to analyze the alterations in the ECG, local electrograms, and multifrequential atrial myocardial impedance in a new experimental model of acute and chronic atrial infarction. Methods Seven anesthetized pigs were subjected to 4h of atrial ischemia induced by selective catheter occlusion of the atrial coronary branches originating in the left circumflex coronary artery. The surface ECG was recorded and the changes in P-wave morphology analyzed. Four weeks later the animals were subjected to endocardial voltage mapping (Carto) and multifrequential impedance. The hearts were processed for anatomopathological study. Results Selective occlusion of the coronary atrial branches induced atrial infarction with fibrosis in the left atrium in 6 of the 7 cases (Figure). The surface ECG showed prolongation of the P-wave duration (Figure) (P-wave in lead II: from 72±8ms at baseline vs. 97±18ms at 4 weeks, ANOVA p&amp;lt;0.01; P-wave in lead aVR: from 71±3ms at baseline vs 87±9ms at 4 weeks, ANOVA p&amp;lt;0.01) with no appreciable displacement of the PR segment. Endocardial mapping of the left atrium showed low-voltage bipolar zones with decreased multi-frequency impedance phase angle values, as compared with preserved zones of the same atrium (bipolar electrograms: from 0.6±1mV to 2.0±1.9mV, T-Test p&amp;lt;0.01; Phase angle at 300KHz: from −5.5±2° to −9.0±4.4° T-Test p&amp;lt;0.05). Conclusion We developed a closed-chest swine model of selective atrial infarction suitable for the study of ECG patterns and electrophysiological mechanisms linked to atrial myocardial ischemia and infarction. The structural derangements are detectable by endocardial mapping of local voltage electrograms and local tissue impedance. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by grants from ISCI-MINECO (FIS PI17/00069), FEDER, CIBERCV (CB16/11/00276)

Value of a 12-Lead Electrocardiogram for Assessing P Waves.

Scenario: The rhythm strip below was printed from the bedside monitor of a 71-year-old man admitted to the intensive care unit for hypoxemic respiratory failure, fluid overload, and septic shock. The patient’s history includes coronary artery disease, hypertension, diabetes, paroxysmal atrial fibrillation after successful cardioversion (prescribed at-home apixaban), alcoholic cirrhosis, heart failure (ejection fraction, 50%), and chronic obstructive pulmonary disease (COPD). When this electrocardiogram (ECG) was generated, his blood pressure was 119/63 mm Hg, heart rate was 95/min, and oxygen saturation was 97% while receiving mechanical ventilation with a fraction of inspired oxygen of 0.8. The nurse noted that the rhythm looked like either a heart block or multifocal atrial tachycardia (MAT) and decided to record a 12-lead ECG (see next page). What is your interpretation?Atrial flutter (AFL) with 3:1 conduction with a ventricular rate of ~100/min and right bundle branch block (RBBB).Atrial flutter is common in patients with hypertension, diabetes, COPD, alcohol misuse, and atrial fibrillation (risk factors in this scenario) and is typically initiated or terminated by a premature complex (atrial or ventricular) or rapid atrial pacing. When a premature stimulus excites an area in the atrium, it travels in a single stable reentry circuit (either clockwise or counterclockwise) that is long enough to allow initially depolarized myocardial tissue to recover and then be capable of depolarizing again owing to the reentered stimulus. This mechanism can be seen in this example, particularly in leads III and aVF, as regular, uniform flutter waves (or F waves). The typical atrial rate for AFL is 200-350/min and is characterized by the absence of an atrial diastolic interval, as is seen in sinus rhythm.The rhythm strip displayed only leads II and V1 and showed upright P waves in V1 with various PR intervals, which could be confused with third-degree heart block. In lead II, the P wave is negative, suggesting a junctional rhythm with retrograde conduction of the atria. However, the sharp negative P wave in lead II raises the suspicion of AFL, which was confirmed on the 12-lead ECG. The unique feature of F waves (ie, “sawtooth” pattern) associated with AFL can be seen clearly in leads III and aVF. The F waves that are negative in the inferior leads but positive in V1 indicate the AFL is moving in a counterclockwise direction, which is most common (~75% of cases). The flutter waves should not be confused with MAT, which typically exhibits at least 3 different P-wave morphologies and is irregular because of multiple focal sites of atrial impulse formation. In contrast, AFL is a self-sustaining macroreentrant atrial arrhythmia without focal sites of impulse formation. The ventricular rate in AFL is usually a multiple of the FF interval. In this case, the F waves occur at a rate of 300/min and result in a ventricular rate of ~100/min and can be slightly irregular.Left ventricular hypertrophy in the presence of RBBB can be examined by using an S wave >2 mm in V1 or an R wave >15 mm in V5 or V6, both of which are absent on this ECG.Clinical management is focused on converting AFL to normal sinus rhythm, which will reduce the heart rate and prevent embolic stroke. In this case, the cardiology service was consulted, and ibutilide, an antiarrhythmic, was prescribed with a return to normal sinus rhythm. The patient’s anticoagulant was changed to clopidogrel, an antiplatelet. Given this patient’s underlying risk factors and the risk of prolonging QT with ibutilide, the QT interval should be closely monitored to prevent torsades de pointes. The patient's hospital course was complicated by continued respiratory distress and acute alcohol withdrawal. He was later transferred to the step-down unit.

Association of atrial depolarization variability and cardiac autonomic regulation with sudden cardiac death in coronary artery disease.

To evaluate the prognostic significance of the temporal variability of P-wave morphology, specifically in relation to cardiac autonomic regulation. We analyzed the standard deviation of P-wave residuum (PWRSD) from five consecutive beats of the standard 12-lead ECG in 1236 patients with angiographically verified coronary artery disease (CAD). We evaluated the prognostic value of PWRSD, of PWRSD and PWR in relation to the 24 h standard deviation of normal-to-normal intervals (PWRSD/SDNN and PWR/SDNN). After 8.7 ± 2.2 years of follow-up on average, 43 patients (3.5%) experienced sudden cardiac death (SCD) or were resuscitated from sudden cardiac arrest (SCA), 34 (2.8%) succumbed to non-sudden cardiac death (NSCD) and 113 (9.1%) to non-cardiac death (NCD). In the Cox regression analysis, PWRSD (≥0.002727) had a significant univariate (uv) [hazard ratio (HR): 4.27, 95% confidence interval (CI): 2.26-8.08, P = 0.000008] and multivariate (mv) (HR: 2.58, 95% CI: 1.31-5.08, P = 0.006) association with SCD/SCA but not with NSCD (uv P = 0.76, mv P = 0.33) or NCD (uv P = 0.57, mv P = 0.66). All the studied P-morphology parameters retained a significant association with the risk of SCD/SCA after relevant adjustment (mv P-values from 0.00003 to <0.05) but not with NSCD or NCD. When dichotomized PWRSD, PWR, PWRSD/SDNN, and PWR/SDNN were added to the clinical risk model for SCD/SCD, the C-index increased from 0.799 to 0.834 and integrated discrimination index and net reclassification index improved significantly (P < 0.001). Variability of P-morphology representing temporo-spatial heterogeneity of atrial depolarization, specifically when combined with cardiac autonomic regulation, independently predicts the risk of SCD in patients with CAD.

Prognostic value of P-wave morphology in general population.

To evaluate the prognostic significance of novel P-wave morphology descriptors in general population. Novel P-wave morphology variables were analyzed from orthogonal X-, Y-, Z-leads of the digitized electrocardiogram using a custom-made software in 6906 middle-aged subjects of the Mini-Finland Health Survey. A total of 3747 (54.3%) participants died during the follow-up period of 24.3 ± 10.4 years; 379 (5.5%) of the study population succumbed to sudden cardiac death (SCD), 928 (13.4%) to non-SCD (NSCD) and 2440 (35.3%) patients to non-cardiac death (NCD). In univariate comparisons, most of the studied P-wave morphology parameters had a significant association with all modes of death (P from <0.05 to <0.001). After relevant adjustments in the Cox multivariate hazards model, P-wave morphology dispersion (PMD) still tended to predict SCD [hazard ratio (HR): 1.006, 95% confidence interval (CI): 1.000-1.012, P = 0.05) but not NSCD (HR: 0.999, 95% CI: 0.995-1.003, P = 0.68) or NCD (HR: 0.999, 95% CI: 0.997-1.001, P = 0.44). The P-wave maximum amplitude in the lead Z (P-MaxAmp-Z) predicted SCD even after multivariate adjustments (HR: 1.010, 95% CI: 1.005-1.015, P = 0.0002) but also NSCD (HR: 1.005, 95% CI: 1.002-1.009, P = 0.0005) and NCD (HR: 1.002, 95% CI: 1.000-1.005, P = 0.03). Abnormalities of P-wave morphology are associated with the risk of all modes of death in general population. After relevant adjustments, PMD was still closely associated with the risk of SCD but not with NSCD or NCD. P-MaxAmp-Z predicted SCD even after adjustments, however, it also retained its association with NSCD and NCD.

Prediction of occult atrial fibrillation in patients after cryptogenic stroke and transient ischaemic attack: PROACTIA.

Studies with implantable cardiac monitors (ICMs) show that one-third of patients with cryptogenic stroke/transient ischaemic attack (TIA) have episodes of subclinical atrial fibrillation (SCAF) and benefit switching from antiplatelet- to anticoagulant therapy. However, ICMs are costly and resource demanding. We aimed to build a score based on participant's baseline characteristics that could assess individual risk of SCAF. In a prospective study, 236 eligible patients with a final diagnosis of cryptogenic stroke/TIA had an ICM implantated during the index hospitalization. Pre-specified evaluated variables were: CHA2DS2-VASc, P-wave duration, P-wave morphology, premature atrial beats (PAC)/24 h, supraventricular tachycardia/24 h, left atrial end-systolic volume index (LAVI), Troponin-T, NT-proBNP, and D-dimer. SCAF was detected in 84 patients (36%). All pre-specified variables were significantly associated with SCAF detection in univariate analysis. P-wave duration, followed by PAC/24 h, NT-proBNP, and LAVI, had the largest ratio of SCAF prevalence between its upper and lower quartiles (3.3, vs. 3.2, vs. 3.1 vs. 2.8, respectively). However, in a multivariate analysis, only PAC/24t, P-wave duration, P-wave morphology, and LAVIs remained significant predictors and were included in the PROACTIA score. Subclinical atrial fibrillation prevalence was 75% in the highest vs. 10% in the lowest quartile of the PROACTIA score with a 10-fold higher number of patients with an atrial fibrillation burden >6 h in the highest vs. the lowest quartile. The PROACTIA score can identify patients with cryptogenic stroke/TIA at risk of subsequent SCAF detection. The large difference in SCAF prevalence between groups may provide a basis for future tailored therapy. Clinical Trial Registration: ClinicalTrials.gov; NCT02725944.

Sex differences in atrial electrical properties

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Swiss Heart Foundation Background Pronounced sex differences are known in the incidence and recurrence rates of atrial fibrillation (AF). In general, men carry a higher risk for AF - particularly at younger age - during which women are protected. Purpose In this project, we aimed to investigate electrophysiological properties of the atria that may underlie sex differences in AF development in the younger population. Methods First, we assessed sex differences in P-wave morphology (duration: PWD; area: PWA, amplitude) in 12-lead ECG in healthy volunteers (men 31.3±1.6 y, n=10; women 29.8±1.6 y, n=10) and wildtype (WT) rabbits (3-6 months, males n=12, females n=15). We investigated sex differences in atrial action potential (AP) in WT rabbits of both sexes using sharp electrode recording technique (males n=5, females n=6). To elucidate underlying mechanisms, sex differences on atrial inwardly rectifying potassium current IK1 at 37°C were evaluated using whole-cell patch-clamp technique in isolated atrial rabbit cardiomyocytes; to evaluate the long-term effect of sex hormones on IK1, we incubated the isolated cardiomyocytes for 24h with 3 or 10µM of 17β-estradiol (EST) or of dihydrotestosterone (DHT). Results Analyzing ECG parameters (figure 1), we observed a prolonged PWD and an increased PWA both in healthy men (p&amp;lt;0.0001) and in male rabbits (p&amp;lt;0.0001) as compared to healthy women or female rabbits, which may theoretically be due to a slower conduction velocity or longer AP duration in males. Intracellular AP recordings (figure 2A) showed a more negative atrial resting membrane potential (RMP, males -83.07±0.3mV vs. females -74.33±2.6mV, p&amp;lt;0.05) and a prolonged atrial AP duration (APD10, 18.20±3.6ms vs. 10.06±1.9ms, p=0.06; APD50, 36.60±6.6ms vs. 20.06±1.9ms, p&amp;lt;0.05; APD90, 91.00±10.3ms vs. 74.00±4.0ms, p=0.13) in males as compared to females. As highlighted in figure 2B, male atrial cardiomoycytes had smaller IK1 current densities, which could be due to high DHT concentration; in line with these findings (figure 2C) 24h DHT incubation of atrial cardiomyocytes from females reduced IK1, mimicking the sex differences observed. Conclusions Sex impacts on atrial electrophysiology, resulting in sex differences in P-wave morphology, AP parameters and ionic current densities. Delayed (early) repolarization in males may be causatively linked to the observed changes in P-wave morphology. The reduction of IK1 observed in males may be due to testosterone, since this reduction was observed even in female cardiomyocytes when incubated with DHT.

Pre-ablation interatrial conduction delay or block predicts atrial fibrillation recurrence after ablation among obese patients

Abstract Funding Acknowledgements Type of funding sources: None. Background Obesity is associated with greater risk of atrial fibrillation (AF) recurrence post-ablation and higher incidence of conduction delay compared to non-obese patients. Pre-ablation P-wave duration (PWD) and morphology (PWM) indicating interatrial delay are easily assessed in the clinic and may predict AF recurrence post-ablation in these patients. Purpose Evaluate the predictive value of PWD and PWM on AF recurrence post-ablation in obese patients. Methods Pre-ablation PWD and PWM (negative P-wave in lead II or III) were analyzed on consecutive patients with BMI ≥30 kg/m2 who underwent initial AF ablation from 2012–19. The primary outcome was recurrent AF after a 3-month post-ablation blanking period. Multivariate analysis adjusted for baseline characteristics was performed. Results For 205 patients (61.0±9.5 years old, 39.0% female), mean BMI was 36.9±5.7 kg/m2 and 71.7% had persistent AF pre-ablation. Recurrent AF post-ablation occurred in 115 (56.1%) during a median follow up of 491 (270, 1001) days. PWD &amp;gt;130 ms was significantly associated with higher AF recurrence (AHR of 1.62, 95%CI 1.04-2.57, p=0.03) after adjusting for age, persistent AF and left atrial volume index (LAVI). In a subgroup with LAVI &amp;lt;42 mL/m2 (n=112), PWD &amp;gt;130 ms and negative P-waves in lead II or III were independently associated with increased risk of recurrent AF (AHR 2.06, 95%CI 1.12-3.91; p=0.019 and AHR 1.94, 95% CI 1.00-3.56; p=0.05, respectively) (Figure 1). Conclusion AF recurred in &amp;gt;50% of obese patients within 1.5 years of ablation. Pre-ablation PWD &amp;gt;130 ms and negative P-waves in lead II or III independently predicted recurrent AF post-ablation in this cohort of obese patients. These easily assessed findings add predictive value to other risk factors.

Atrial Fibrillation in a Patient with Interatrial Block after Successful Atrial Flutter Ablation: May Interatrial Block Be a Link for a Continuum of Atrial Arrhythmias?

Background: Electrocardiographic interatrial block (IAB) typically exists when a conduction delay over the Bachmann’s bundle is present. By analogy to other types of block, there is a continuum of IAB severity; partial IAB is defined as a P-wave duration 120 ms and advanced interatrial block (aIAB) is defined as a P-wave duration 120 ms in conjunction with biphasic P-wave morphology in inferior leads II, III, and aVF. Moreover, IAB seems to be a key factor in the genesis of atrial fibrillation (AF). On the contrary, it is not clear if the presence of advanced IAB may be associated with an occurrence of AF after cavotricuspid atrial flutter ablation in patients without previous episodes of atrial fibrillation. So, may be useful to evaluate on surface electrocardiogram the P-wave morphology and duration in sinus rhythm after the ablation procedure just to identify patients at high risk for atrial fibrillation development. Advanced IAB is frequently associated with atrial tachyarrhythmias, and it was found to predict AF and may be helpful for clinical decisions. Case presentation: In this case involving a man who underwent a typical atrial flutter ablation, we documented that aIAB during the post-ablation period which seems to induce atial fibrillation episodes. To our knowledge, it is unusual to detect an aIAB after cavotricuspid atrial flutter ablation and subsequently associate it with a new onset of AF. Conclusions: Our observation supports a possible aIAB induction of AF after cavotricuspid atrial flutter ablation and potentially may representing a link in the continuum of atrial arrhythmias. P-wave morphology and duration should be better evaluated soon after AFlu ablation to better stratify patients who are at high risk for atrial fibrillation development and eventually prolonged anti-coagulation therapy.

Clinical impact of Bachmann's bundle pacing defined by electrocardiographic criteria on atrial arrhythmia outcomes.

Evaluate whether Bachmann's bundle pacing (BBp) defined by electrocardiographic (ECG) criteria is associated with less atrial fibrillation/tachycardia (AF/AT) compared with anatomically defined right atrial septal pacing (RASp) and right atrial appendage pacing (RAAp). This is a retrospective study comparing BBp with non-specific RASp and RAAp on new incidence, burden, and recurrence of AF/AT. We included patients who underwent atrial lead placement between 2006 and 2019 and received > 20% atrial pacing. BBp was defined by paced P-wave morphology and fluoroscopic lead position. Compared with RASp (n = 107) and RAAp (n = 108), AF/AT burden was lower in the BBp (n = 134) group by repeated measures ANOVA (P < 0.001). Over 2-year follow-up, AF/AT burden increased in the RASp (P < 0.01) and RAAp (P < 0.01) groups but did not significantly change in the BBp group (P = 0.91). Atrial arrhythmia burden was lower in the BBp group than the RASp and RAAp groups at 12-15, 18-21, and 24-27 months (P < 0.05) after pacemaker placement. Risk of AF/AT recurrence was lower in BBp than RASp (HR 0.43; P < 0.01) and RAAp patients (HR 0.29, P < 0.01). Risk of de novo AF/AT was also lower in BBp than in RASp (OR 0.12; P < 0.01) and RAAp patients (OR 0.20, P < 0.01). Bachmann's bundle pacing defined using P-wave criteria was associated with decreased atrial arrhythmia burden, recurrence, and de novo incidence compared with right atrial septal pacing and right atrial appendage pacing.