Prolonged P-wave duration is associated with atrial fibrillation recurrence after radiofrequency catheter ablation: A systematic review and meta-analysis

Left atrial remodeling and voltage-guided ablation outcome in persistent atrial fibrillation patients according to CHA2DS2-VASc score

BACKGROUND

CHA2DS2-VASc score-related differences have been reported in atrial fibrotic remodeling and prognosis of atrial fibrillation (AF) patients after ablation. There are currently no data on the efficacy of low voltage zone (LVZ)-guided ablation in persistent AF patients according to CHA2DS2-VASc score. We assessed in a cohort of persistent AF patients the extent of LVZ, the regional distribution of LA voltage and the outcome of LA voltage-guided substrate ablation in addition to PVI according to CHA2DS2-VASc score.

METHODS

138 consecutive persistent AF patients undergoing a first voltage-guided catheter ablation were enrolled. 58 patients with CHAD2DS2-VASc score ≥ 3 and 80 patients with CHAD2DS2-VASc score ≤ 2 were included. LA voltage maps were obtained using 3D-electroanatomical mapping system in sinus rhythm. LVZ was defined as < 0.5 mV.

RESULTS

In the high CHAD2DS2-VASc score group, LA voltage was lower (1.5 [1.1-2.5] vs. 2.3 [1.5-2.8] mV, p = 0.02) and LVZs were more frequently identified (40% vs. 18%), p < 0.01). Female with CHA2DS2-VASc score ≥ 3 (p = 0.031), LA indexed volume (p = 0.009) and P-wave duration ≥ 150 ms (p = 0.001) were predictors of LVZ. After a 36-month follow-up, atrial arrhythmia-free survival was similar between the two groups (logrank test, P = 0.676).

CONCLUSIONS

AF patients with CHAD2DS2-VASc score ≥ 3 display more LA substrate remodeling with lower voltage and more LVZs compared with those with CHAD2DS2-VASc score ≤ 2. Despite this atrial remodeling, they had similar and favorable 36 months results after one single procedure. Unlike male with CHAD2DS2-VASc score ≥ 3, female with CHAD2DS2-VASc score ≥ 3 was predictor of LVZ occurrence.

The Effect of Obesity on Repolarization and Other ECG Parameters

Background: Overweight and obesity are important risk factors in the development of cardiovascular diseases. New repolarization markers, such as the Tpeak-Tend interval and JTpeak intervals, have not yet been profoundly studied in obese patients. The study aims to analyze whether, in patients with obesity and overweight, repolarization markers, including the Tpeak-Tend interval, are prolonged and simultaneously check the frequency of other ECG pathologies in a 12-lead ECG in this group of patients. Methods: A study group consisted of 181 adults (90 females and 91 males) with overweight and first-class obesity. The participants completed a questionnaire, and the ECG was performed and analyzed. Results: When analyzing the classic markers, only QT dispersion was significantly higher in obese people. The Tpeak-Tend parameter (97.08 ms ± 23.38 vs. 89.74 ms ± 12.88, respectively), its dispersion, and JTpeak-JTend parameters were statistically significantly longer in the obese group than in the controls. There were also substantial differences in P-wave, QRS duration, and P-wave dispersion, which were the highest in obese people. Tpeak-Tend was positively correlated with body mass and waist circumference, while JTpeak was with BMI, hip circumference, and WHR. Tpeak/JT was positively correlated with WHR and BMI. In backward stepwise multiple regression analysis for JTpeak-WHR, type 2 diabetes and smoking had the highest statistical significance. Conclusions: Only selected repolarization markers are significantly prolonged in patients with class 1 obesity and, additionally, in this group, we identified more pathologies of P wave as well as prolonged QRS duration.

Association of beat-to-beat P-wave analysis index to the extent of left atrial low-voltage areas in patients with paroxysmal atrial fibrillation

BACKGROUND

Left atrial (LA) fibrosis has been shown to be associated with atrial fibrillation (AF) recurrence. Beat-to-beat (B2B) index is a non-invasive classifier, based on B2B P-wave morphological and wavelet analysis, shown to be associated with AF incidence and recurrence. In this study, we tested the hypothesis that the B2B index is associated with the extent of LA low-voltage areas (LVAs) on electroanatomical mapping.

METHODS

Patients with paroxysmal AF scheduled for pulmonary vein isolation, without evident structural remodeling, were included. Pre-ablation electroanatomical voltage maps were used to calculate the surface of LVAs (<0.5 mV). B2B index was compared between patients with small versus large LVAs.

RESULTS

35 patients were included (87% male, median age 62). The median surface area of LVAs was 7.7 (4.4-15.8) cm2 corresponding to 5.6 (3.3-12.1) % of LA endocardial surface. B2B index was 0.57 (0.52-0.59) in patients with small LVAs (below the median) compared to 0.65 (0.56-0.77) in those with large LVAs (above the median) (p = 0.009). In the receiver operator characteristic curve analysis for predicting large LVAs, the c-statistic was 0.75 (p = 0.006) for B2B index and 0.81 for the multivariable model including B2B index (multivariable p = 0.04) and P-wave duration.

CONCLUSION

In patients with paroxysmal AF without overt atrial myopathy, B2B P-wave analysis appears to be a useful non-invasive correlate of low-voltage areas-and thus fibrosis-in the LA. This finding establishes a pathophysiological basis for B2B index and its potential usefulness in the selection process of patients who are likely to benefit most from further invasive treatment.

Prolonged PR intervals are associated with epicardial adipose tissue and recurrence after catheter ablation in persistent atrial fibrillation

Epicardial adipose tissue (EAT) has been reported to promote myocardial fibrosis and to affect intracardiac conduction. The PR interval reflects the conduction from the atria to the Purkinje fibers and may be associated with the EAT volume, especially in persistent atrial fibrillation (AF) patients. We aimed to investigate the relationship between the EAT and PR interval in patients with persistent AF. We enrolled 268 persistent AF patients who underwent catheter ablation (CA) and divided the patients into two groups: the normal PR interval group (PR interval less than 200 ms: Group N) and long PR interval group (PR interval 200 ms or more: Group L). We then analyzed the association between the total EAT volume around the heart and PR interval and calculated the ratio of the duration of the P wave (PWD) to the PR interval (PWD/PR interval). Moreover, we investigated whether a long PR interval was associated with the outcomes after ablation. The total EAT volume was significantly larger in Group L than Group N (Group N: 131.4 ± 51.8 ml vs. Group L: 151.3 ± 63.3 ml, p = 0.039). A positive correlation was also observed between the PWD/PR interval and EAT volume in Group L (r = 0.345, p = 0.039). A multivariate analysis also revealed that a long PR interval was independently associated with AF recurrence after CA (hazard ratio [HR] 2.071, p = 0.032). The total EAT volume was associated with a long PR interval, and a long PR interval was a significant risk factor for recurrence after ablation in persistent AF patients.

Ratio of P-Wave Duration to P-Wave Amplitude and Left Atrial Remodeling: Insights from Electrophysiological Findings and Myocardial Injury After Cryoballoon Ablation

The impact of the P-wave morphology on clinical outcomes postcatheter ablation (post-CA) and recurrent arrhythmia characteristics or electrophysiologic findings in patients with paroxysmal atrial fibrillation (PAF) remains unclear. Patients with PAF who underwent cryoballoon ablation were enrolled. In 12-lead electrocardiography recorded within 1 month before CA, the P-wave duration (Pd) and P-wave vector magnitude (Pvm) (square root of the sum of the squared P-wave amplitude in leads II, V6, and one-half of the P-wave amplitude in V2) were measured and divided into 2 groups: patients with high and low Pd/Pvm based on a statistically calculated cut-off value. We evaluated the incidence of late recurrence of atrial fibrillation (LRAF), myocardial injury (high-sensitive troponin I), and the electrophysiologic findings in repeat ablation sessions. This study included 269 patients with PAF. The median follow-up duration was 697 days. The cut-off value of the Pd/Pvm for predicting LRAF was 740.7 ms/mV (area under the curve = 0.81, sensitivity = 58.2%, and specificity = 89.6%). Multivariable Cox proportional hazards analysis showed that high Pd/Pvm (>740.7 ms/mV) was significantly associated with LRAF (p <0.001). The high-sensitive troponin I level was significantly lower, and the ratio of DR-FLASH score >3 was significantly higher in those with high than low Pd/Pvm (p = 0.044 and p = 0.002, respectively). In the repeat ablation sessions, the Pd/Pvm in patients with atrial tachycardia-induced or spontaneously occurring during the repeat CA sessions was significantly higher than in those without (p = 0.009). There was a significant difference between the Pd/Pvm and low-voltage area (p <0.001). In conclusion, the Pd/Pvm is significantly associated with LRAF after cryoballoon ablation in patients with PAF and predicts left atrial low-voltage areas and atrial tachycardia inducibility.

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

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

Mechanisms and Prediction of Ischemic Stroke in Atrial Fibrillation Patients

Atrial fibrillation (AF) is the most common arrhythmia in adults worldwide and represents an important burden for patients, physicians, and healthcare systems. AF is associated with substantial mortality and morbidity, due to the disease itself and its specific complications, such as the increased risk of stroke and thromboembolic events associated with AF. The temporal relation between AF episodes and stroke is nonetheless incompletely understood. The factors associated with an increased thromboembolic risk remain unclear, as well as the stroke risk stratification. Therefore, in this review, we intend to expose the mechanisms and physiopathology leading to intracardiac thrombus formation and stroke in AF patients, together with the evidence supporting the causal hypothesis. We also expose the risk factors associated with increased risk of stroke, the current different risk stratification tools as well as future prospects for improving this risk stratification.

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.

Analysis of the amplified p-wave enables identification of patients with atrial fibrillation during sinus rhythm

Aim

This study sought to develop and validate diagnostic models to identify individuals with atrial fibrillation (AF) using amplified sinus-p-wave analysis.

Methods

A total of 1,492 patients (491 healthy controls, 499 with paroxysmal AF and 502 with persistent AF) underwent digital 12-lead-ECG recording during sinus rhythm. The patient cohort was divided into training and validation set in a 3:2 ratio. P-wave indices (PWI) including duration of standard p-wave (standard PWD; scale at 10 mm/mV, sweep speed at 25 mm/s) and amplified sinus-p-wave (APWD, scale at 60-120 mm/mV, sweep speed at 100 mm/s) and advanced inter-atrial block (aIAB) along with other clinical parameters were used to develop diagnostic models using logistic regression. Each model was developed from the training set and further tested in both training and validation sets for its diagnostic performance in identifying individuals with AF.

Results

Compared to standard PWD (Reference model), which achieved an AUC of 0.637 and 0.632, for training and validation set, respectively, APWD (Basic model) importantly improved the accuracy to identify individuals with AF (AUC = 0.86 and 0.866). The PWI-based model combining APWD, aIAB and body surface area (BSA) further improved the diagnostic performance for AF (AUC = 0.892 and 0.885). The integrated model, which further combined left atrial diameter (LAD) with parameters of the PWI-based model, achieved optimal diagnostic performance (AUC = 0.916 and 0.902).

Conclusion

Analysis of amplified p-wave during sinus rhythm allows identification of individuals with atrial fibrillation.

Use of P wave indices to evaluate efficacy of catheter ablation and atrial fibrillation recurrence: a systematic review and meta-analysis

BACKGROUND

To investigate the changes of P wave indices in atrial fibrillation (AF) patients after catheter ablation and the association between P wave indices and AF recurrence.

METHODS

PubMed, Embase, and Cochrane Database were searched through September 15th 2021 for studies on the association between P wave indices and AF with catheter ablation. Heterogeneity was estimated using the I² statistic, the random effects model was used to calculate the pooled results, and summary receiver operating characteristic curve (SROC) was used to evaluate the predictive value.

RESULTS

Among included fourteen studies with 1674 AF patients, we found significantly decreased P wave dispersion (P_dis) (mean difference [MD]: - 6.5 ms, 95% confidence interval [95% CI]: - 11.81 to - 1.18, P = 0.02) after cryoballoon ablation (CBA) or radiofrequency ablation (RFA), and maximum P wave (P_max) (MD: - 8.57 ms, 95% CI: - 17.03 to - 0.10, P = 0.05) after RFA only, but increased minimum P wave (P_min) (MD: 3.43 ms, 95% CI: 1.07 to 5.79, P < 0.01) after CBA only. P_dis measured before ablation was remarkably higher (MD: 5.79 ms, 95% CI: 2.23 to 9.36, P < 0.01) in patients with recurrence than without; meanwhile, P_max was higher measured both before and after ablation (MD: 6.49 ms, 95% CI: 2.30 to 10.69, P < 0.01 and MD: 11.2 ms, 95% CI: 2.88 to 19.52, P < 0.01). Furthermore, SROC analysis showed acceptable predictive efficiencies of P_dis (AUC = 0.776) and P_max (AUC = 0.759) for AF recurrence.

CONCLUSION

P_dis was significantly decreased after AF catheter ablation. Higher P_dis and P_max may have predictive values for AF recurrence.

P-wave duration and atrial fibrillation recurrence after catheter ablation: a systematic review and meta-analysis

AIMS

Atrial fibrillation (AF) is a global health problem with high morbidity and mortality. Catheter ablation (CA) can reduce AF burden and symptoms, but AF recurrence (AFr) remains an issue. Simple AFr predictors like P-wave duration (PWD) could help improve AF therapy. This updated meta-analysis reviews the increasing evidence for the association of AFr with PWD and offers practical implications.

METHODS AND RESULTS

Publication databases were systematically searched and cohort studies reporting PWD and/or morphology at baseline and AFr after CA were included. Advanced interatrial block (aIAB) was defined as PWD ≥ 120 ms and biphasic morphology in inferior leads. Random-effects analysis was performed using the Review Manager 5.3 and R programs after study selection, quality assessment, and data extraction, to report odds ratio (OR) and confidence intervals. : Among 4175 patients in 22 studies, 1138 (27%) experienced AFr. Patients with AFr had longer PWD with a mean pooled difference of 7.8 ms (19 studies, P < 0.001). Pooled OR was 2.04 (1.16-3.58) for PWD > 120 ms (13 studies, P = 0.01), 2.42 (1.12-5.21) for PWD > 140 ms (2 studies, P = 0.02), 3.97 (1.79-8.85) for aIAB (5 studies, P < 0.001), and 10.89 (4.53-26.15) for PWD > 150 ms (4 studies, P < 0.001). There was significant heterogeneity but no publication bias detected.

CONCLUSION

P-wave duration is an independent predictor for AF recurrence after left atrium ablation. The AFr risk is increasing exponentially with PWD prolongation. This could facilitate risk stratification by identifying high-risk patients (aIAB, PWD > 150 ms) and adjusting follow up or interventions.

Atrial late potentials are associated with atrial fibrillation recurrence after catheter ablation

Background

Previous studies have identified noninvasive methods for predicting atrial fibrillation (AF) recurrence after catheter ablation (CA). We assessed the association between AF recurrence and atrial late potentials (ALPs), which were measured using P‐wave signal‐averaged electrocardiography (P‐SAECG).

Methods

Consecutive patients with paroxysmal AF who underwent their first CA at our institution between August 2015 and August 2019 were enrolled. P‐SAECG was performed before CA. Two ALP parameters were evaluated: the root‐mean‐square voltage during the terminal 20 ms (RMS₂₀) and the P‐wave duration (PWD). Positive ALPs were defined as an RMS₂₀ <2.2 μV and/or a PWD >115 ms. Patients were allocated to either the recurrence or nonrecurrence group based on the presence of AF recurrence at the 1‐year follow‐up post‐CA.

Results

Of the 190 patients (age: 65 ± 11 years, 37% women) enrolled in this study, 21 (11%) had AF recurrence. The positive ALP rate was significantly higher in the recurrence group than in the nonrecurrence group (86% vs. 64%, p = .04), despite the absence of differences in other baseline characteristics between the two groups. In the multivariate analysis, positive ALP was an independent predictor of AF recurrence (odds ratio: 3.83, 95% confidence interval: 1.05–14.1, p = .04).

Conclusions

Positive ALP on pre‐CA P‐SAECG is associated with AF recurrence after CA.

Impact of atrial fibrillation ablation on long‐term outcomes in patients with tachycardia‐bradycardia syndrome

Background

Methods

Results

Conclusions

Reduced atrial conduction velocity is associated with the recurrence of atrial fibrillation after catheter ablation

The recurrence of atrial fibrillation (AF) after catheter ablation (CA) is still an unsolved issue. Although structural remodeling is relatively well defined, the method to assess electrical remodeling of the atrium is not well established. In this study, we evaluated the relationship between atrial conduction properties and recurrence after CA for AF. One hundred six consecutive patients (66 ± 11 years old, male: 68%) who underwent CA for AF with a CARTO system from July 2016 to July 2019 were enrolled in this study. An activation map of both atria was constructed to precisely evaluate the total conduction time, distance, and conduction velocity between the earliest and latest activation sites during sinus rhythm. All parameters were compared between the patients with or without AF recurrence. Of the patients, 27 had an AF recurrence (Rec group). The left atrial (LA) conduction velocity was significantly slower in the Rec group than in the non-Rec group (101.2 ± 17.9 vs. 116.9 ± 18.0 cm/s, P < 0.01). Likewise, the right atrial (RA) conduction velocity was significantly slower in the Rec group than in the non-Rec group (81.1 ± 17.5 vs. 103.6 ± 25.4 cm/s, P < 0.01). A multivariate logistic analysis demonstrated that the LA and RA conduction velocities were independent predictors of AF recurrence, with adjusted odds ratios of 0.95 (95% confidential interval: 0.91-0.98, P < 0.01) and 0.94 (0.89-0.98, P < 0.01), respectively. In conclusion, slower conduction velocity of the atrium was associated with AF recurrence after pulmonary vein isolation.

Electrocardiographic predictors of early recurrence of atrial fibrillation

BACKGROUND

Electrical cardioversion (ECV) is an effective method for restoring sinus rhythm after atrial fibrillation (AF). However, early recurrence of AF occurs in a significant number of patients after ECV. This study aimed to identify electrocardiographic (ECG) predictors of early AF recurrence after ECV.

METHODS

A total of 272 patients with persistent AF undergoing successful ECV were consecutively enrolled in this study. We investigated clinical, echocardiographic, and ECG data. The 12-lead ECG parameters were measured during sinus rhythm right after ECV using a digital caliper. The early AF recurrence was defined as recurrence within 2 months.

RESULTS

Of the 272 patients, 165 patients (60.7%) experienced an early AF recurrence. Maximum P-wave duration (PWD) in limb leads (OR: 1.086; 95% CI: 1.019-1.157; p = .012) and P-terminal force (PTF) in V₁ (OR: 1.019; 95% CI: 1.004-1.033; p = .011) were independent predictors of early AF recurrence after ECV. The optimal cutoff value of the maximum PWD in limb leads for predicting early AF recurrence was 134 ms, characterized by 90.3% sensitivity and 72.0% specificity. Likewise, the optimal cutoff value of PTF in V₁ was 50 ms × mm, characterized by 80.0% sensitivity and 64.5% specificity.

CONCLUSION

A longer PWD (>134 ms) and a larger PTF (>50 ms × mm) were useful predictors of early recurrence of AF after successful ECV in clinical practice. A more effective rhythm control therapy such as catheter ablation or rate control strategy rather than a repeat ECV should be considered.

Amplified sinus-P-wave reveals localization and extent of left atrial low-voltage substrate: implications for arrhythmia freedom following pulmonary vein isolation

AIMS

Presence of arrhythmogenic left atrial (LA) low-voltage substrate (LVS) is associated with reduced arthythmia freedom rates following pulmonary vein isolation (PVI) in persistent atrial fibrillation (AF). We hypothesized that LA-LVS modifies amplified sinus-P-wave (APW) characteristics, enabling identification of patients at risk for arrhythmia recurrences following PVI.

METHODS AND RESULTS

Ninety-five patients with persistent AF underwent high-density (>1200 sites) voltage mapping in sinus rhythm. Left atrial low-voltage substrate (<0.5 and <1.0 mV) was quantified in a 10-segment LA model. Amplified sinus-P-wave-morphology and -duration were evaluated using digitized 12-lead electrocardiograms (40-80 mm/mV, 100-200 mm/s). 12-months arrhythmia freedom following circumferential PVI was assessed in 139 patients with persistent AF. Left atrial low-voltage substrate was most frequently (84%) found at the anteroseptal LA. Characteristic changes of APW were related to the localization and extent of LA-LVS. At an early stage, LA-LVS predominantly located to the LA-anteroseptum and was associated with APW-prolongation (≥150 ms). More extensive LA-LVS involved larger areas of LA-anteroseptum, leading to morphological changes of APW (biphasic positive-negative P-waves in inferior leads). Severe LA-LVS involved the LA-anteroseptum, roof and posterior LA, but spared the inferior LA, lateral LA, and LA appendage. In this advanced stage, widespread LVS at the posterior LA abolished the negative portion of P-wave in the inferior leads. The delayed activation of the lateral LA and LA appendage produced the late positive deflections in the anterolateral leads, resulting in the "late-terminal P"-pattern. Structured analysis of APW-duration and -morphology stratified patients to their individual extent of LA-LVS (Grade 1: mean LA-LVS 4.9 cm2 at <1.0 mV; Grade 2: 28.6 cm2; Grade 3: 42.3 cm2; P < 0.01). The diagnostic value of APW-duration for identification of LA-LVS was significantly superior to standard P-wave-amplification (c-statistic 0.945 vs. 0.647). Arrhythmia freedom following PVI differed significantly between APW-predicted grades of LA-LVS-severity [hazard ratio (HR) 2.38, 95% confidence interval (CI) 1.18-4.83; P = 0.015 for Grade 1 vs. Grade 2; HR 1.79, 95% CI 1.00-3.21, P = 0.049 for Grade 2 vs. Grade 3). Arrhythmia freedom 12 months after PVI was 77%, 53%, and 33% in Grades 1, 2 and 3, respectively.

CONCLUSION

Localization and extent of LA-LVS modifies APW-morphology and -duration. Analysis of APW allows accurate prediction of LA-LVS and enables rapid and non-invasive estimation of arrhythmia freedom following PVI.

Short P-Wave Duration is a Marker of Higher Rate of Atrial Fibrillation Recurrences after Pulmonary Vein Isolation: New Insights into the Pathophysiological Mechanisms Through Computer Simulations

Background Short ECG P-wave duration has recently been demonstrated to be associated with higher risk of atrial fibrillation (AF). The aim of this study was to assess the rate of AF recurrence after pulmonary vein isolation in patients with a short P wave, and to mechanistically elucidate the observation by computer modeling. Methods and Results A total of 282 consecutive patients undergoing a first single-pulmonary vein isolation procedure for paroxysmal or persistent AF were included. Computational models studied the effect of adenosine and sodium conductance on action potential duration and P-wave duration (PWD). About 16% of the patients had a PWD of 110 ms or shorter (median PWD 126 ms, interquartile range, 115 ms-138 ms; range, 71 ms-180 ms). At Cox regression, PWD was significantly associated with AF recurrence (P=0.012). Patients with a PWD <110 ms (hazard ratio [HR], 2.20; 95% CI, 1.24-3.88; P=0.007) and patients with a PWD ≥140 (HR, 1.87, 95% CI, 1.06-3.30; P=0.031) had a nearly 2-fold increase in risk with respect to the other group. In the computational model, adenosine yielded a significant reduction of action potential duration 90 (52%) and PWD (7%). An increased sodium conductance (up to 200%) was robustly accompanied by an increase in conduction velocity (26%), a reduction in action potential duration 90 (28%), and PWD (22%). Conclusions One out of 5 patients referred for pulmonary vein isolation has a short PWD which was associated with a higher rate of AF after the index procedure. Computer simulations suggest that shortening of atrial action potential duration leading to a faster atrial conduction may be the cause of this clinical observation.

Assessing Atrial Fibrillation Substrates by P Wave Analysis: A Comprehensive Review

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Pharmacologic and non-pharmacologic rhythm control strategies impact on AF-related symptoms, while leaving largely unaffected the risk of stroke. Moreover, up to 20% of AF patients are asymptomatic during paroxysmal relapses of arrhythmia, thus underlying the need for early markers to identify at-risk patients and prevent cerebrovascular accidents. Indeed, non-invasive assessment of pre-clinical substrate changes that predispose to AF could provide early identification of at-risk patients and allow for tailored care paths. ECG-derived P wave analysis is a simple-to-use and inexpensive tool that has been successfully employed to detect AF-associated structural and functional atrial changes. Beyond standard electrocardiographic techniques, high resolution signal averaged electrocardiography (SAECG), by recording microvolt amplitude atrial signals, allows more accurate analysis of the P wave and possibly AF risk stratification. This review focuses on the evidence that support P wave analysis to assess AF substrates, predict arrhythmia relapses and guide rhythm-control interventions.

Predictive value of P wave terminal force in lead V1 for atrial fibrillation: A meta-analysis

Background

Several studies have explored the association between P wave terminal force in lead V1 (PTFV1) and risk of atrial fibrillation (AF) occurrence, but the results were controversial. This meta‐analysis aimed to examine whether abnormal PTFV1 could predict AF occurrence.

Methods

We searched PubMed, Embase, and Cochrane Library databases for articles published before August 25, 2018. Pooled odds ratios (ORs) of AF occurrence were calculated using random‐effects models to explore the significance of PTFV1.

Results

A total of 12 studies examining 51,372 participants were included, with 9 studies analyzing PTFV1 as a categorical variable and 4 studies analyzing PTFV1 as a continuous variable. As a categorical variable, abnormal PTFV1 (>0.04 mm s) was significantly associated with AF occurrence with a pooled OR of 1.39 (95% confidence interval [CI] 1.08–1.79, p = .01). Subgroup analysis found that ORs of studies in hemodialysis patients (OR = 4.89, 95% CI 2.54–9.90, p < .001) and acute ischemic stroke patients (OR = 1.60, 95% CI 1.14–2.25, p = .007) were higher than general population (OR = 1.15, 95% CI 1.03–1.29, p = .01). Studies from Europe (OR = 1.05, 95% CI 0.91–1.20, p = .51) yielded lower OR of endpoints compared with Asia (OR = 1.89, 95% CI 1.38–2.60, p < .001) and United States (OR = 1.43, 95% CI 1.19–1.72, p < .001). As a continuous variable, PTFV1 was also significantly associated with AF occurrence with a polled OR per 1 standard deviation (SD) change of 1.27 (95% CI 1.02–1.59, p = .03).

Conclusions

PTFV1 was significantly associated with the risk of AF and was considered to be a good predictor of AF occurrence in population with or without cardiovascular diseases.

Individualised Approaches for Catheter Ablation of AF: Patient Selection and Procedural Endpoints

Pulmonary vein isolation (PVI) is the cornerstone of AF ablation, but studies have reported improved efficacy with high rates of repeat procedures. Because of the large interindividual variability in the underlying electrical and anatomical substrate, achieving optimal outcomes requires an individualised approach. This includes optimal candidate selection as well as defined ablation strategies with objective procedure endpoints beyond PVI. Candidate selection is traditionally based on coarse and sometimes arbitrary clinical stratification such as AF type, but finer predictors of treatment efficacy including biomarkers, advanced imaging and electrocardiographic parameters have shown promise. Numerous ancillary ablation strategies beyond PVI have been investigated, but the absence of a clear mechanistic and evidence-based endpoint, unlike in other arrhythmias, has remained a universal limitation. Potential endpoints include functional ones such as AF termination or non-inducibility and substrate-based endpoints such as isolation of low-voltage areas. This review summarises the relevant literature and proposes guidance for clinical practice and future research.

The Value of Baseline and Arrhythmic ECG in the Interpretation of Arrhythmic Mechanisms

Owing to the rapid development of new electrophysiologic techniques, our understanding of arrhythmias and their underlying mechanisms has reached unprecedented levels. In some cases, baseline ECG alterations can be identified before arrhythmia development; early recognition of these alterations is of utmost importance to start appropriate preventive therapies and stratify the risk according to patients' outcomes. Hereby, we report a systematic revision of main baseline ECG abnormalities and their implications on clinical outcomes.

Impact of a prolonged interatrial conduction time for predicting the recurrence of atrial fibrillation after circumferential pulmonary vein isolation of persistent atrial fibrillation

There are some cases that are difficult to cure with only circumferential pulmonary vein isolation (CPVI) of persistent atrial fibrillation (PerAF). Recently, prolonged interatrial conduction times (IACTs), which seem to be associated with progressive remodeled atria, have been reported as a predictor of new-onset AF. This study aimed to investigate the prognostic value of a prolonged IACT for predicting AF recurrences after CPVI of PerAF. One hundred thirteen patients who underwent CPVI without an empirical substrate modification of PerAF were retrospectively analyzed. The IACT was defined as the interval from the earliest P-wave onset on the ECG to the latest activation in the coronary sinus and was measured after achieving the CPVI and conversion to sinus rhythm. During a mean 22.7-month follow-up after the initial procedure, 56 patients (50%) had AF recurrences. Patients with AF recurrence had a longer IACT than those without AF recurrence (p < 0.001). The best discriminative cut-off value for the IACT was 123 ms (sensitivity 53%, specificity 85%). In a Cox multivariate analysis, a prolonged IACT of ≥ 123 ms was the only independent predictor (hazard ratio: 2.38; 95% confidence interval: 1.36-4.16, p = 0.002) of being associated with the incidence of an AF recurrence. Even after multiple CPVI procedures, patients with an IACT ≥ 123 ms had a higher AF recurrence rate than those with an IACT < 123 ms (p = 0.002). In conclusion, a prolonged IACT of ≥ 123 ms may be a useful marker for predicting AF recurrences after both initial and multiple CPVI procedures for PerAF.

The Effect of Atrial Fibrillation Ablation Techniques on P Wave Duration and P Wave Dispersion

BACKGROUND

A reduction in surface electrocardiogram (ECG) P wave duration and dispersion is associated with improved outcomes in atrial fibrillation ablation. We investigated the effects of different ablation strategies on P wave duration and dispersion, hypothesising that extensive left atrial (LA) ablation with left atrial posterior wall isolation would give a greater reduction in P wave duration than more limited ablation techniques.

METHODS

A retrospective analysis of ECGs from patients who have undergone atrial fibrillation (AF) ablation was performed and pre-procedural sinus rhythm ECGs were compared with the post procedure ECGs. Maximal P wave duration was measured in leads I or II, minimum P wave duration in any lead and values were calculated for P wave duration and dispersion. Left atrial dimensions and medications at the time of ECG were documented. Ablation strategies compared were; pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) and the persistent AF (PsAF) ablation strategies of pulmonary vein isolation plus additional linear lesions (Lines), left atrial posterior wall isolation via catheter (PWI) and left atrial posterior wall isolation via staged surgical and catheter ablation (Hybrid).

RESULTS

Sixty-nine patients' ECGs were analysed: 19 PVI, 21 Lines, 14 PWI, 15 Hybrid. Little correlation was seen between pre-procedure left atrial size and P wave duration (r=0.24) but LA size and P wave duration was larger in PsAF patients. A significant difference was seen in P wave reduction driven by Hybrid AF ablation (p<0.005) and Lines (<0.02). There was no difference amongst P wave dispersion between groups but the largest reduction was seen in the Hybrid ablation group.

CONCLUSIONS

P wave duration increased with duration of continuous atrial fibrillation. Hybrid AF ablation significantly reduced P wave duration and dispersion compared to other ablation strategies including posterior wall isolation via catheter despite this being the same lesion set.