P-wave Morphology Research Articles

A case of paroxysmal atrioventricular block with atrial pacemaker shift during ventricular arrest.

We present a case of paroxysmal atrioventricular block with atrial pacemaker shift, focusing on the change of P-wave morphology.

Orthogonal P-wave morphology, conventional P-wave indices, and the risk of atrial fibrillation in the general population using data from the Finnish Hospital Discharge Register.

Identifying subjects at high and low risk of atrial fibrillation (AF) is of interest. This study aims to assess the risk of AF associated with electrocardiographic (ECG) markers linked to atrial fibrosis: P-wave prolongation, 3rd-degree interatrial block, P-terminal force in lead V1, and orthogonal P-wave morphology. P-wave parameters were assessed in a representative Finnish population sample aged ≥30 years (n = 7217, 46.0% male, mean age 51.4 years). Subjects (n = 5489) with a readable ECG including the orthogonal leads, sinus rhythm, and a predefined orthogonal P-wave morphology type [positive in leads X and Y and either negative (Type 1) or ± biphasic (Type 2) in lead Z; Type 3 defined as positive in lead X and ± biphasic in lead Y], were followed 10 years from the baseline examinations (performed 1978-80). Subjects discharged with AF diagnosis after any-cause hospitalization (n = 124) were defined as having developed AF. Third-degree interatrial block was defined as P-wave ≥120 ms and the presence of ≥2 ± biphasic P waves in the inferior leads. Hazard ratios (HRs) and confidence intervals (CIs) were assessed with Cox models. Third-degree interatrial block (n = 103, HR 3.18, 95% CI 1.66-6.13; P = 0.001) and Type 3 morphology (n = 216, HR 3.01, 95% CI 1.66-5.45; P < 0.001) were independently associated with the risk of hospitalization with AF. Subjects with P-wave <110 ms and Type 1 morphology (n = 2074) were at low risk (HR 0.46, 95% CI 0.26-0.83; P = 0.006), compared to the rest of the subjects. P-wave parameters associate with the risk of hospitalization with AF.

P322Understanding the multiple P-wave morphologies in paroxysmal atrial fibrillation, during sinus rhythm, using computer simulation

Abstract Background Atrial Fibrillation (AF) is the most common atrial arrhythmia. The initiation and perpetuation of AF are related to atrial remodeling affecting the electrical and structural atrial characteristics. The beat-to-beat analysis of the P-wave morphology (PWM), during sinus rhythm (SR), revealed the existence of a secondary PWM, while the proportion of the P-waves which follow the secondary morphology is higher in patients with a history of paroxysmal AF (pAF). This observation has led to the hypothesis that the multiple PWM may be the result of a transient shift in the stimulus origin, possibly within the broader anatomical region of the sinoatrial (SA) node, and it is the atrial electrical remodeling that contributes to more frequent P-waves following a secondary morphology in patients with pAF. Purpose To better understand the pathophysiology of AF there is a need to link different levels of analysis, in order to interpret macroscopic observations, through a surface electrocardiogram, with changes occurring at cell and tissue level. Towards this direction, computational modeling can be used as it is a non-invasive and reproducible method of analyzing the electrical activity of the heart. Methods The CRN atrial model was used, and a two-dimensional geometry of the atrial architecture was considered, including the major anatomical structures, like Crista Terminalis, Pectinate Muscles and Pulmonary Veins. Using existing knowledge, the CRN model was adapted to describe the ionic properties of the atrial structures as well as the electrical remodeling occurring under pAF conditions. Several scenarios were considered related to the extent of the electrical remodeled tissue and Heart Rate (HR) values. The stimulation protocol was designed as 5 stimuli originated at a specific point within the SA node area whereas the sixth stimulus originated either at the same location or 1 mm far from the previous one. The temporal variations of the atrial activation as a result of the transient shift of the sixth stimulus origin were computed. Results In electrically remodeled tissue, the displacement of the excitation site within the SA node resulted in a significant increase of the differences in atrial activation compared to healthy tissue, and the greater the spatial extent of the remodeling the greater the differences in the completion of the electrophysiological processes. In addition, increased HR or HR variability led to the increase of the differences especially when electrical remodeling coexists. Conclusions The observed differences in atrial substrate activation can explain the increased number of P-waves that match a secondary PWM in pAF patients during SR, while a future perspective is to use PWM as a marker to estimate the electrical remodeling extent in the atrial tissue. These results underline the need to link the macroscopic findings to the suspected microscopic electrical activity in order to better understand the pathophysiology of AF.

244An automated beat exclusion algorithm to improve beat-to-beat P-wave morphology analysis

Abstract Background A manually beat-to-beat P-wave analysis has previously revealed the existence of multiple P-wave morphologies in patients with paroxysmal Atrial Fibrillation (AF) while on sinus rhythm, distinguishing them from healthy, AF free patients. Purpose The aim of this study was to investigate the effectiveness of an Automated Beat Exclusion algorithm (ABE) that excludes noisy or ectopic beats, replacing manual beat evaluation during beat-to-beat P-wave analysis, by assessing its effect on inter-rater variability and reproducibility. Methods Beat-to-beat P-wave morphology analysis was performed on 34 ten-minute ECG recordings of patients with a history of AF. Each recording was analyzed independently by two clinical experts for a total of four analysis runs; once with ABE and once again with the manual exclusion of ineligible beats. The inter-rater variability and reproducibility of the analysis with and without ABE were assessed by comparing the agreement of analysis runs with respect to secondary morphology detection, primary morphology ECG template and the percentage of both, as these aspects have been previously used to discriminate PAF patients from controls. Results Comparing ABE to manual exclusion in detecting secondary P-wave morphologies displayed substantial (Cohen"s k = 0.69) to almost perfect (k = 0.82) agreement. Area difference among auto and manually calculated main morphology templates was in every case &amp;lt;5% (p &amp;lt; 0.01) and the correlation coefficient was &amp;gt;0.99 (p &amp;lt; 0.01). Finally, the percentages of beats classified to the primary or secondary morphology per recording by each analysis were strongly correlated, for both main and secondary P-wave morphologies, ranging from ρ=0.756 to ρ=0.940 (picture) Conclusion The use of the ABE algorithm does not diminish inter-rater variability and reproducibility of the analysis. The primary and secondary P-wave morphologies produced by all analyses were similar, both in terms of their template and their frequency. Based on the results of this study, the ABE algorithm incorporated in the beat-to-beat P-wave morphology analysis drastically reduces operator workload without influencing the quality of the analysis. Abstract Figure.

219A machine learning classification algorithm to detect patients with paroxysmal atrial fibrillation during sinus rhythm

Abstract Background Atrial fibrillation (AF) - the most common sustained cardiac arrhythmia - while not a life-threatening condition itself, leads to an increased risk of stroke and high rates of mortality. Early detection and diagnosis of AF is a critical issue for all health stakeholders. Purpose The aim of this study is to identify P-wave morphology patterns encountered in patients with Paroxysmal AF (PAF) and to develop a classifier discriminating PAF patients from healthy volunteers. Methods Three-dimensional 1000Hz ECG signals of 5 minutes duration were obtained through the use of a Galix GBI-3S Holter monitor from a total of 68 PAF patients and 52 healthy individuals. Signal pre-processing, consisting of denoising, QRS auto-detection, and ectopic beats removal was performed and a signal window of 250ms prior to the Q-wave (Pseg) was considered for every single beat. P‑wave morphology analysis based on the dynamic application of the k‑means clustering process was performed. For those Pseg that were assigned in the largest cluster, the mean P-wave was computed. The correlation of every P-wave with the mean P-wave of the main cluster was calculated. In case that it exceeded a prespecified threshold, the P-wave was allocated to the main morphology. For the remaining P‑waves, the same approach was followed once again, and the secondary morphology was extracted (picture). The P-waves of the dominant morphology were further analyzed using wavelet transform, whereas time-domain characteristics were also extracted. A Support Vector Machine (SVM) model was created using the Gaussian Radial Basis Function kernel and the forward feature selection wrapper approach was followed. ECGs were allocated to the training, internal validation, and testing datasets in a 3:1:1 ratio. Results The percentage of P-waves following the main morphology in all three leads was lower in PAF patients (91.2 ±7.3%) than in healthy subjects (96.1 ±3.5%, p = 0.02). Classification between the two groups highlighted 7 features, while the SVM classifier resulted in a balanced accuracy of 91.4 ± 0.2% (sensitivity 94.2 ± 0.3%, specificity 88.6 ± 0.1%) Conclusion An Artificial Intelligence based ECG Classifier can efficiently identify PAF patients during normal sinus rhythm. Abstract Figure.

Electrocardiogram and left atrial abnormality: Design of an observational study to clarify diagnostic criteria.

BackgroundThe criteria applied for diagnosis of left atrial (LA) abnormality using electrocardiogram (ECG) have high specificity but low sensitivity. In fact, some authors have suggested classifying P‐wave anomalies associated with LA abnormality and interatrial block as “atrial abnormalities.” The most widely known ECG criteria for LA abnormality include P‐wave duration, morphology and voltage of P wave in inferior leads, presence of P‐wave terminal force in V1 (PtfV1), and P‐wave axis and area. PtfV1 has also been reported to vary according to misplacement of the V1 and V2 electrodes.MethodsThe objective of this observational cohort study is to determine the degree of correlation between ECG criteria for LA abnormality and left atrium volume and functionality, as determined by speckle tracking echocardiography. The study also aims to investigate the correlation between these echocardiographic parameters and PtfV1 value by placing the V1 and V2 electrodes in the second, third, and fourth intercostal spaces.Results and ConclusionsOur results could help to clarify whether the decrease in left atrial deformity, which is currently considered a surrogate target of fibrosis, correlates better with ECG criteria for LA abnormality than atrial volumes.

Significance of fragmented QRS complexes for predicting new-onset atrial fibrillation after cavotricuspid isthmus–dependent atrial flutter ablation

Atrial fibrillation (AF) and cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) are 2 separate entities that coexist in a significant proportion of patients. In patients with CTI ablation of AFL, the decision to hold anticoagulation often becomes an issue. This study aimed to describe the incidence of the development of AF after CTI ablation in patients without a history of AF and to identify the risk predictors of the occurrence of AF. The present study included 120 consecutive patients (106 men; mean age 68 ± 12 years) who underwent radiofrequency catheter ablation (RFCA) of typical AFL since 2010. Patients with a history of AF before RFCA were excluded. The P-wave and QRS morphology, characteristics, and duration were evaluated by 12-lead electrocardiography the day after ablation. During 3.6 ± 2.6 years of follow-up after RFCA, 49 patients (41%) developed new-onset AF. A univariate analysis revealed that the presence of fragmented QRS (fQRS) complexes (hazard ratio [HR], 4.63; 95% confidence interval [CI] 2.31-9.29; P < .001) and advanced interatrial block (IAB), defined as P-wave duration > 120 ms and biphasic morphology in the inferior leads (HR 4.44; 95% CI 2.45-8.01; P < .001), were predictors of new-onset AF. A multivariate analysis revealed that fQRS complexes (HR 3.35; 95% CI 1.58-7.10; P = .002) and advanced IAB (HR 2.64; 95% CI 1.38-5.07; P < .004) were independent predictors. The present study indicated that new-onset AF developed in a significant proportion of patients undergoing AFL ablation. The presence of fQRS complexes and advanced IAB were predictors of new-onset AF.

Device profile of the Coala Heart Monitor for remote monitoring of the heart rhythm: overview of its efficacy

ABSTRACTIntroduction: Several handheld thumb ECG devices for on-demand recording of heart rhythm have become available lately. These can be used both by health-care providers and purchased by laypersons for private use.Area covered: This profile describes the Coala Heart Monitor. This device differs from other handheld ECG monitors in three aspects: 1) it records both thumb and chest ECGs, 2) it uses both RR-dispersion and P-wave morphology for detecting atrial fibrillation, and 3) in synchronization with the chest ECG, it also records heart sounds presented as a phonocardiogram making measurement of systolic time intervals possible. The sensitivity and specificity for detecting atrial fibrillation are high. The use of systolic time interval in patients with heart failure has so far not been evaluated.Expert opinion: The increasing use of long-term prescribed and privately owned handheld ECG devices for on-demand recording of heart rhythm will most probably cause a paradigm shift in arrhythmia diagnostics. Coala Heart Monitor´s use of both chest and thumb recordings as well as analyzing both RR-dispersion and P-wave morphology may offer an advantage in diagnosing atrial fibrillation.

Accuracy of electrocardiography guidance for depth of insertion of central venous catheters in children: A prospective observational study

Context: Central venous catheters (CVCs) have become integral in the pediatric intensive care setting as well as in the operating room (OR). In the OR, these lines are usually used without prior confirmation of correct position, and a chest radiograph is performed postoperatively, several hours later. Hence, it is desirable to confirm the correct CVC position immediately after placement. Aim: This observational study was designed to evaluate the accuracy of electrocardiography (ECG) guidance on correct CVC positioning in pediatric population. Settings and Design: This was a prospective observational study. Subjects and Methods: Patients till 12 years of age were included in the study. Ultrasound was used to guide initial cannulation of the vessel. Certodyn® universal adaptor was connected to the guidewire via a sterile alligator clip. The CVC along with the guidewire was advanced till it lies in the right atrium which was seen by an increase in the amplitude of P-wave on the intracardiac ECG. The CVC was then withdrawn slowly until the P-wave morphology returned to normal or preprocedural configuration. Statistical Analysis Used: Data were expressed as percentage. Results: Out of the 68 patients, the percentage of patients having appropriate position of CVC tip was 95.5% (65 patients). Out of the three patients with incorrect tip position, in two patients, the tip was distal to the appropriate position and in one case, the ECG changes could not be appreciated. Conclusions: ECG-guided CVC placement has high accuracy of correct positioning in infants and children.

Data mining analysis of the influences of electrocardiogram P-wave morphology parameters on atrial fibrillation

Atrial fibrillation (AF) is a type of paroxysmal cardiac disease that presents no obvious symptoms during onset, and even the electrocardiograms (ECG) results of patients with AF appear normal under a premorbid status, rendering AF difficult to detect and diagnose. However, it can result in deterioration and increased risk of stroke if not detected and treated early. This study used the ECG database provided by the Physionet website (https://physionet.org), filtered data, and employed parameter-extraction methods to identify parameters that signify ECG features. A total of 31 parameters were obtained, consisting of P-wave morphology parameters and heart rate variability parameters, and the data were further examined by implementing a decision tree, of which the topmost node indicated a significant causal relationship. The experiment results verified that the P-wave morphology parameters significantly affected the ECG results of patients with AF.

3056Orthogonal P wave morphology, traditional P wave indices, and the risk of atrial fibrillation in the general population

Abstract Background A substantial portion of the risk of atrial fibrillation (AF) remains unexplained by the established risk markers. However, accurate assessment of AF risk would be beneficial, especially among stroke patients and subjects with symptoms attributable to arrhythmia. Purpose To study the associations of P-wave indices with AF risk in the general population. Methods Electrocardiograms, including orthogonal leads, of 7217 Finnish subjects aged over 30 years who took part in the baseline examinations of the Mini-Finland Health Survey in 1978–80, were digitized. P-wave duration, third-degree interatrial block (IAB), and P terminal force (PTF) were assessed manually. PTF was considered abnormal when the amplitude of the negative terminal part of the P wave in lead V1 was ≥0.1mV and duration ≥40ms. Third-degree IAB was defined as P-wave duration ≥120ms and the presence of ≥2 +/− biphasic P-waves in the inferior leads. Orthogonal P-wave morphology, which is related to left atrial breakthrough site and affected by atrial fibrosis (1 being considered benign, 2 borderline, and 3 shown to be associated with adverse events), was assessed with an automated algorithm, and ascertained manually. Subjects were followed 10 years for AF hospitalization and mortality. The risk of AF associated with P wave parameters was assessed using Cox proportional hazards models. Model discrimination improvement was quantified by the change in C index, integrated discrimination improvement (IDI), and continuous net reclassification improvement (cNRI). Results There were 5489 subjects (47.8% male, mean age 50.5 years) with a readable ECG, sinus rhythm, no missing data, and a predefined orthogonal P-wave morphology. Type 3 orthogonal P morphology (n=216, multivariate adjusted HR [maHR] 3.01, 95% confidence interval [CI] 1.66–5.45, p&lt;0.001), P-wave duration ≥120ms (n=752, maHR 1.67, 95% CI 1.06–2.64, p=0.027), and third-degree IAB (n=103, maHR 3.18, 95% CI 1.66–6.13, p=0.001) were independently associated with the risk of AF in separate models. PTF did not independently predict AF. Subjects presenting with both Type 1 orthogonal P-wave morphology and P-wave duration &lt;110ms (n=2074) were at low risk of AF (maHR 0.46, 95% CI 0.26–0.83, p=0.006) when compared to the rest of the subjects. The inclusion of variables combining orthogonal P-wave morphology and P-wave duration to a multivariate model including conventional AF risk factors improved C index from 0.815 to 0.832 (change 0.017, 95% CI 0.001–0.033), IDI was 0.012 (95% CI 0.006–0.051), and cNRI was 0.220 (95% CI 0.048–0.357). Conclusions P-wave indices and orthogonal P-wave morphology can be used to identify subjects at high and low risk for AF and possibly direct extensive AF screening protocols towards high-risk subjects in the general population in order to decrease the risk of cardioembolic stroke. However, more research is needed in this topic. Acknowledgement/Funding Finnish Medical Foundation, Onni and Hilja Tuovinen's Foundation, Orion Research Foundation, Paavo Nurmi's Foundation, Veritas Foundation

Electrocardiogram characteristics of P wave associated with successful pulmonary vein isolation in patients with paroxysmal atrial fibrillation: Significance of changes in P-wave duration and notched P wave.

BackgroundThe mechanisms involved in changes in P wave following catheter ablation for atrial fibrillation (AF) are uncertain. This study aimed to assess the relationship between changes in P‐wave morphology and pulmonary vein (PV) reconnection following ablation by the assessment of 12‐lead surface electrocardiogram and signal‐averaged electrocardiogram.MethodsThis retrospective study included 115 consecutive patients with paroxysmal AF that underwent repeat ablation for recurrence following initial ablation. We investigated changes in P‐wave morphology between baseline and repeat procedure in patients with and without PV reconnection. The study also included as validation group without recurrence (n = 67) following initial ablation.ResultsThe maximum P‐wave duration (PWD) was significantly decreased from baseline to just after the procedure in all groups. However, for the PV reconnection group (n = 100), the maximum PWD was significantly increased again at the repeat procedure. In contrast, the maximum PWD was significantly reduced between baseline and repeat procedure in the non‐PV reconnection group (n = 15). The signal‐averaged PWD was significantly decreased from baseline to repeat procedure in the non‐PV reconnection group, but, conversely, was increased in the PV reconnection group. In the non‐PV reconnection group, the disappearance of notched P wave was detected in 8 of 15 patients (53%), which was significantly higher than in other groups (p = .001). A new or delayed notched P wave was identified in the PV reconnection group only. These results were confirmed in the validation group.ConclusionsThe reverse dynamics of PWD after initial shortening directly following ablation were significantly associated with PV reconnection.

Efficacy of hybrid therapy using prior administration of bepridil hydrochloride and cryoballoon ablation in patients with persistent atrial fibrillation

BackgroundRhythm control before catheter ablation for persistent atrial fibrillation (PeAF) can improve clinical outcomes. We sought to investigate the efficacy of pretreatment with bepridil prior to cryoballoon ablation (CBA) with respect to clinical outcomes in patients with PeAF. MethodsWe retrospectively analyzed 65 consecutive patients with PeAF who underwent CBA following pretreatment with bepridil hydrochloride (bepridil). Electrical cardioversion was additionally performed in cases involving failure of pharmacological sinus restoration before CBA. The primary endpoint was survival free from atrial tachyarrhythmia at the one-year follow-up, and the secondary endpoints were changes in P-wave morphology and left atrium diameter (LAD) before CBA. ResultsAt the one-year follow-up, 51 patients (78.5%) achieved the primary endpoint (non-recurrence group). Compared to the P-wave duration (Pdur) and dispersion at the time of sinus restoration, they significantly shortened at the time of CBA in the non-recurrence group, while they did not change in the recurrence group. There were no changes in LAD in both groups. Multivariate analysis revealed that refractoriness of bepridil (p = 0.03, odds ratio = 4.72, 95% confidence interval = 1.18–18.92), and longer Pdur at admission for CBA (p = 0.003, odds ratio = 1.08, 95% confidence interval = 1.01–1.14) were independent predictors of recurrence. ConclusionsRhythm control with bepridil induced electrical reverse remodeling; bepridil may improve clinical outcomes after CBA.

The P wave morphology in lead V7 on the synthesized 18-lead ECG is a useful parameter for identifying arrhythmias originating from the right inferior pulmonary vein.

Atrial tachyarrhythmias often originate from the superior vena cava (SVC), and right superior (RSPV) and inferior pulmonary veins (RIPV). However, a precise differentiation of those origins is challenging using the standard 12-lead electrocardiogram (ECG) P-wave morphology due to the anatomical proximity. The recently developed synthesized 18-lead ECG provides virtual waveforms of the right-sided chest and back leads. This study evaluated the utility of the synthesized 18-lead ECG to differentiate atrial arrhythmias originating from 3 adjacent structures. Synthesized 18-lead ECGs were obtained during SVC-, RSPV-, and RIPV-pacing in 20 patients with lone paroxysmal atrial fibrillation to develop an algorithm. The P-wave morphologies were classified into 4 patterns: positive, negative, biphasic, and isoelectric. Subsequently, the algorithm's accuracy was validated prospectively in another 40 patients. In retrospective analyses, isoelectric P-waves in synthesized V7 distinguished RIPV-pacing from the others (sensitivity = 81%, specificity = 92%) (first criteria). The P wave morphologies in Leads II (sensitivity = 83%, specificity = 94%) and V1 (sensitivity = 84%, specificity = 80%) distinguished SVC- and RSPV-pacing (second criteria). In a prospective evaluation, the sensitivity, specificity, positive predictive value [PPV], negative predictive value [NPV], and accuracy of the first criteria for identifying RIPV-pacing was 97%, 90%, 78%, 99%, and 92%, respectively. The sensitivity, specificity, RPV, NPV, and accuracy of the second criteria (amplitudes > 1mV in lead II or biphasic P-waves in lead V1) for discriminating SVC- and RSPV-pacing was 66%, 95%, 98%, 50%, and 74%, respectively. The P wave morphology pattern in lead V7 in synthesized 18-lead ECGs is useful for differentiating RIPV origins from RSPV/SVC origins.

Understanding the Beat-to-Beat Variations of P-Waves Morphologies in AF Patients During Sinus Rhythm: A Scoping Review of the Atrial Simulation Studies.

The remarkable advances in high-performance computing and the resulting increase of the computational power have the potential to leverage computational cardiology toward improving our understanding of the pathophysiological mechanisms of arrhythmias, such as Atrial Fibrillation (AF). In AF, a complex interaction between various triggers and the atrial substrate is considered to be the leading cause of AF initiation and perpetuation. In electrocardiography (ECG), P-wave is supposed to reflect atrial depolarization. It has been found that even during sinus rhythm (SR), multiple P-wave morphologies are present in AF patients with a history of AF, suggesting a higher dispersion of the conduction route in this population. In this scoping review, we focused on the mechanisms which modify the electrical substrate of the atria in AF patients, while investigating the existence of computational models that simulate the propagation of the electrical signal through different routes. The adopted review methodology is based on a structured analytical framework which includes the extraction of the keywords based on an initial limited bibliographic search, the extensive literature search and finally the identification of relevant articles based on the reference list of the studies. The leading mechanisms identified were classified according to their scale, spanning from mechanisms in the cell, tissue or organ level, and the produced outputs. The computational modeling approaches for each of the factors that influence the initiation and the perpetuation of AF are presented here to provide a clear overview of the existing literature. Several levels of categorization were adopted while the studies which aim to translate their findings to ECG phenotyping are highlighted. The results denote the availability of multiple models, which are appropriate under specific conditions. However, the consideration of complex scenarios taking into account multiple spatiotemporal scales, personalization of electrophysiological and anatomical models and the reproducibility in terms of ECG phenotyping has only partially been tackled so far.

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

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. 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. Mean age was 65years, 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 (258weeks; 95% CI 205-310weeks) compared to the intermediate- (278weeks; 95% CI 252-303weeks) and low-risk groups (322weeks 95% CI 307-338weeks), p=0.005. 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.

Genetic variants on chromosomes 7p31 and 12p12 are associated with abnormal atrial electrical activation in patients with early-onset lone atrial fibrillation.

Abnormal P-wave morphology (PWM) has been associated with a history of atrial fibrillation (AF) in earlier studies. Although lone AF is believed to have substantial genetic basis, studies on associations between single nucleotide polymorphisms (SNP) linked to lone AF and PWM have not been reported. We aimed to assess whether SNPs previously associated with lone AF (rs2200733, rs13376333, rs3807989, and rs11047543) are also linked to P-wave abnormalities. Four SNPs were studied in 176 unrelated individuals with early-onset lone AF (age at onset <50years), median age 38years (19-63years), 149 men. Using sinus rhythm ECG, orthogonal PWM was classified as Type 1-positive in leads X and Y and negative in lead Z, Type 2-positive in leads X and Y and biphasic (-/+) in lead Z, Type 3-positive in lead X and biphasic in lead Y (+/-), and the remaining as atypical. Two SNPs were found to be significantly associated with altered P-wave morphology distribution: rs3807989 near the gene CAV1/CAV2 and rs11047543 near the gene SOX5. Both SNPs were associated with a higher risk of non-Type 1 P-wave morphology (rs3807989: OR=4.8, 95% CI=2.3-10.2, p<0.001; rs11047543: OR=4.7, 95% CI=1.1-20.5, p=0.04). No association was observed for rs2200733 and rs13376333. In this study, the two variants rs3807989 and rs11047543, previously associated with PR interval and lone AF, were associated with altered P-wave morphology distribution in patients with early-onset lone AF. These findings suggest that common genetic variants may modify atrial conduction properties.

P-wave morphology and multipolar intracardiac atrial activation to facilitate nonpulmonary vein trigger localization.

Nonpulmonary vein (non-PV) triggers of atrial fibrillation (AF) are targets for ablation but their localization remains challenging. The aim of this study was to describe P-wave (PW) morphologic characteristics and intra-atrial activation patterns and timing from multipolar coronary sinus (CS) and crista terminalis (CT) catheters that localize non-PV triggers. Selective pacing from six right and nine left atrial common non-PV trigger sites was performed in 30 consecutive patients. We analyzed 12 lead ECG features based on PW duration, amplitude and morphology, and patterns and timing of multipolar activation for all 15 sites. Regionalization and then precise localization required criteria present in at least 70% of assessments at each pacing site. The algorithm was then prospectively evaluated by four blinded observers in a validation cohort of 18 consecutive patients undergoing the same pacing protocol and 60 consecutive patients who underwent successful non-PV trigger ablation. The algorithm for site regionalization included 1) negative PW in V1, ≥30 µV change in PW amplitude across the leads V1-V3, and PW duration ≤100 milliseconds in lead 2 and 2) unique intra-atrial activation patterns and timing noted in the multipolar catheters. Specific ECG and intra-atrial activation timing characteristics included in the algorithm allowed for more precise site localization after regionalization. In the prospective evaluation, the algorithm identified the site of origin for 72% of paced and 70% of spontaneous non-PV trigger sites. An algorithm based on PW morphology and intra-atrial multipolar activation pattern and timing can help identify non-PV trigger sites of origin.

Obstructive sleep apnea and electrocardiographic P-wave morphology.

Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder with important cardiovascular implications. Left atrial abnormality can be identified by electrocardiographic P-wave morphology and is considered an important risk for atrial fibrillation (AF) and stroke, both of which have been associated with OSA. We hypothesized that severity of OSA would be associated with more abnormal electrocardiographic P-wave morphology as indicated by P-wave terminal force in V1 (PTFV1 ) and P-wave area in V1 (PWAV1 ). Patients who underwent clinically indicated polysomnography and had 12-lead ECG were identified through medical record review. Logistic regression was used to determine the associations between the measures of OSA severity (apnea hypopnea index [AHI] and mean nocturnal oxygen [O2 ] saturation) and abnormal PTFV1 and PWAV1 (defined by >75% percentile value of the studied cohort) adjusting for age, sex, body mass index, and hypertension. A total of 261 patients (mean age: 57years old, male: 52%) were included in the study. Multivariate analysis showed that AHI was associated with abnormal PTFV1 (>7,280µVms) and PWAV1 (>1,000µVms; OR: 1.5; 95% CI [1.1, 2.0], p=0.008; OR: 1.5 [1.1, 2.1], p=0.005 per 1 SD increase in AHI, respectively). Mean O2 saturation was associated with abnormal PWAV1 (OR: 0.72 [0.54, 0.98], p=0.03). Results remained unchanged after excluding patients taking AV nodal blocking agents. In a sleep clinic cohort, there was significant association between OSA severity and ECG-defined left atrial abnormality.

Influence of left atrial size on P-wave morphology: differential effects of dilation and hypertrophy.

Chronic left atrial enlargement (LAE) increases the risk of atrial fibrillation. Electrocardiogram (ECG) criteria might provide a means to diagnose LAE and identify patients at risk; however, current criteria perform poorly. We seek to characterize the potentially differential effects of atrial dilation vs. hypertrophy on the ECG P-wave. We predict effects on the P-wave of (i) left atrial dilation (LAD), i.e. an increase of LA cavity volume without an increase in myocardial volume, (ii) left atrial concentric hypertrophy (LACH), i.e. a thickened myocardial wall, and (iii) a combination of the two. We performed a computational study in a cohort of 72 anatomical variants, derived from four human atrial anatomies. To model LAD, pressure was applied to the LA endocardium increasing cavity volume by up to 100%. For LACH, the LA wall was thickened by up to 3.3 mm. P-waves were derived by simulating atrial excitation propagation and computing the body surface ECG. The sensitivity regarding changes beyond purely anatomical effects was analysed by altering conduction velocity by 25% in 96 additional model variants. Left atrial dilation prolonged P-wave duration (PWd) in two of four subjects; in one subject a shortening, and in the other a variable change were seen. Left atrial concentric hypertrophy, in contrast, consistently increased P-wave terminal force in lead V1 (PTF-V1) in all subjects through an enlarged amplitude while PWd was unaffected. Combined hypertrophy and dilation generally enhanced the effect of hypertrophy on PTF-V1. Isolated LAD has moderate effects on the currently used P-wave criteria, explaining the limited utility of PWd and PTF-V1 in detecting LAE in clinical practice. In contrast, PTF-V1 may be a more sensitive indicator of LA myocardial hypertrophy.