Predicting worsening heart failure hospitalizations in patients with implantable cardioverter defibrillators: is it all about alerts? A pooled analysis of nine trials.

AIMS: To predict worsening heart failure hospitalizations (WHFHs) in patients with implantable defibrillators and remote monitoring, the HeartInsight algorithm (Biotronik, Berlin, Germany) calculates a heart failure (HF) score combining seven physiologic parameters: 24 h heart rate (HR), nocturnal HR, HR variability, atrial tachyarrhythmia, ventricular extrasystoles, patient activity, and thoracic impedance. We compared temporal trends of the HF score and its components 12 weeks before a WHFH with 12-week trends in patients without WHFH, to assess whether trends indicate deteriorating HF regardless of alert status. METHODS AND RESULTS: Data from nine clinical trials were pooled, including 2050 patients with a defibrillator capable of atrial sensing, ejection fraction ≤ 35%, NYHA class II/III, no long-standing atrial fibrillation, and 369 WHFH from 259 patients. The mean HF score was higher in the WHFH group than in the no WHFH group (42.3 ± 26.1 vs. 30.7 ± 20.6, P < 0.001) already at the beginning of 12 weeks. The mean HF score further increased to 51.6 ± 26.8 until WHFH (+22% vs. no WHFH group, P = 0.003). As compared to the no WHFH group, the algorithm components either were already higher 12 weeks before WHFH (24 h HR, HR variability, thoracic impedance) or significantly increased until WHFH (nocturnal HR, atrial tachyarrhythmia, ventricular extrasystoles, patient activity). CONCLUSION: The HF score was significantly higher at, and further increased during 12 weeks before WHFH, as compared to the no WHFH group, with seven components showing different behaviour and contribution. Temporal trends of HF score may serve as a quantitative estimate of HF condition and evolution prior to WHFH.

Sensing of concealed ventricular extrasystoles by pacemakers. Fifty years later.

Whether a pacemaker can sense concealed ventricular extrasystoles still remains debatable since its occurrence was first proposed in 1972. It must remain a diagnosis of exclusion if it really exists. Isoelectric complexes and all the causes of oversensing especially discrete false signals generated by a defective pacemaker lead must be excluded before concealed ventricular extrasystoles can be postulated.

Younger postnatal age is associated with a lower heart rate on Holter monitoring during the first week of life.

To evaluate heart rate (HR), the presence of extrasystoles and other Holter findings among healthy newborns, and to collect data for new normal limits for Holter parameters in newborns. For this cross-sectional study, 70 healthy term newborns were recruited to undergo 24-h Holter monitoring. Linear regression analysis was used in HR analyses. The age-specific limits for HRs were calculated using linear regression analysis coefficients and residuals. The mean (SD) age of the infants was 6.4 (1.7) days during the recording. Each consecutive day of age raised the minimum and mean HR by 3.8 beats per minute (bpm) (95% CI: 2.4, 5.2; P < .001) and 4.0 bpm (95% CI: 2.8, 5.2; P < .001), respectively. Age did not correlate with maximum HR. The lowest calculated limit for minimum HR ranged from 56 bpm (aged 3 days) to 78 bpm (aged 9 days). A small number of atrial extrasystoles and ventricular extrasystoles were observed in 54 (77%) and 28 (40%) recordings, respectively. Short supraventricular or ventricular tachycardias were found in 6 newborns (9%). CONCLUSION:  The present study shows an increase of 20 bpm in both the minimum and mean HRs of healthy term newborns between the 3rd and 9th days of life. Daily reference values for HR could be adopted in the interpretation of HR monitoring results in newborns. A small number of extrasystoles are common in healthy newborns, and isolated short tachycardias may be normal in this age group. WHAT IS KNOWN: • The current definition of bradycardia in newborns is 80 beats per minute. • This definition does not fit into the modern clinical setting of continuously monitored newborns, where benign bradycardias are commonly observed. WHAT IS NEW: • A linear and clinically significant increase in heart rate was observed in infants between the ages of 3 and 9 days. • It appears as though lower normal limits for heart rate could be applied to the youngest newborns.

Utility of Substrate Mapping Using Extrasystole to Localise Comprehensive Ventricular Tachycardia Circuits: Results From Intra-operative Mapping Studies.

BACKGROUND: Substrate mapping-based identification of all ventricular tachycardia (VT) circuits (diastolic activation), including partial and complete diastolic circuits in clinical and nonclinical VT, could be beneficial in guiding VT ablation to prevent VT recurrence. The utility of extrasystole induced late potentials has not been compared with late potentials in sinus rhythm (SR) and right ventricular pacing (RVp). METHODS: Intraoperative simultaneous panoramic endocardial mapping of 21 VTs in 16 ischemic heart disease patients was performed with the use of a 112-bipole endocardial balloon. The decrement of near-field electrogram later than surface QRS during extrasystole (eLP) was studied. RESULTS: Patients had a mean age of 52 ± 9 years and were predominantly (75%) male. The mean sensitivity of eLP (0.75 [95% confidence interval [CI] 0.72-0.78]) to detect VT circuits was better than SR (0.33 [0.30-0.36]; P < 0.001) and RVp (0.36 [0.33-0.39]; P < 0.001) without significant differences in specificity, eLP (0.77 [0.74-0.81], SR (0.82 [0.80-0.84]; P = 0.23), and RVp (0.81 [0.78-0.83]; P = 0.11). Both negative (NPV) and positivie (PPV) predictive values were significantly better for eLP mapping. The mean NPV was 0.77 (95% CI 0.74-0.81), 0.57 (0.55-0.59), and 0.58 (0.55-0.61) for eLP, SR, and RVp, respectively (P < 0.0001). PPV was 0.75 (95% CI 0.72-0.78), 0.63 (0.59-0.67), and 0.63 (0.59-0.67) for eLP, SR, and RVp, respectively (P < 0.001). Overall diagnostic performance (area under the receiver operating characteristic curve) was significantly better for eLP (0.85 [95% CI 0.80-0.90] compared with SR (0.63 [0.56-0.72]; P < 0.001) or RVp (0.61 [0.52-0.74]; P < 0.001). CONCLUSIONS: Evoked late potential mapping is a better tool to detect comprehensive diastolic circuits activated during VT, compared with eLP mapping in sinus rhythm or RV pacing.

The predictive value of Tp-Te interval, Tp-Te/QT ratio, and QRS-T angle of idiopathic ventricular tachycardia in patients with ventricular premature beats.

BACKGROUND: Identify idiopathic ventricular tachycardia in patients with ventricular premature beats was required to have effectively treatment. HYPOTHESIS: The aim of this study is to investigate the predictive value of Tp-Te interval, Tp-Te/QT ratio, and QRS-T angle of idiopathic ventricular tachycardia in patients with idiopathic ventricular premature beats. METHODS: One hundred and seventy-eight patients who had undergone premature ventricular complex/ventricular tachycardia (PVC/VT) ablation between January 1, 2020 and August 30, 2022 constituted our study population as ventricular arrhythmia group. Seventy-five healthy people were selected as control group. Patients with no episode of VT were classified as PVC group, while with any episode of VT that has the same morphology with PVC were classified as PVC with VT group. Patients in PVC with VT group were divided into two groups: nonsustained VT group (duration of any episode of VT below 30 s) and sustained VT group (duration of any episode of VT over 30 s). Tp-Te interval, Tp-Te/QT ratio and QRS-T angle were compared in groups. RESULTS: Tp-Te interval, Tp-Te/QT ratio and patients with increased QRS-T angle in PVC with VT group were higher or more than those in PVC group (p < .001). The value of combined diagnosis of these indexes was higher. Tp-Te interval was longer in the sustained VT group compared to the nonsustained VT group (p = .009). CONCLUSION: Tp-Te interval, Tp-Te/QT ratio, and QRS-T angle may have a predictive value of presence of idiopathic VT in patients with premature beats and the combined prediction of these indexes is more valuable. Tp-Te interval maybe helpful for prediction of sustained idiopathic VT.

[Effect of total flavonoids of buckwheat flower and leaf on myocardial cell apoptosis and Wnt/ß-catenin/PPARγ pathway in arrhythmic rats].

This paper aimed to investigate the effect of total flavonoids of buckwheat flower and leaf on myocardial cell apoptosis and Wnt/ß-catenin/peroxisome proliferator-activated receptor γ(PPARγ) pathway in arrhythmic rats. SD rats were randomly divided into a control group, a model group, a low-dose(20 mg·kg~(-1)) group of total flavonoids of buckwheat flower and leaf, a medium-dose(40 mg·kg~(-1)) group of total flavonoids of buckwheat flower and leaf, a high-dose(80 mg·kg~(-1)) group of total flavonoids of buckwheat flower and leaf, a propranolol hydrochloride(2 mg·kg~(-1)) group, with 12 rats in each group. Except the control group, rats in other groups were prepared as models of arrhythmia by sublingual injection of 1 mL·kg~(-1) of 0.002% aconitine. After grouping and intervention with drugs, the arrhythmia, myocardial cells apoptosis, myocardial tissue glutathione peroxidase(GSH-Px), catalase(CAT), malondialdehyde(MDA), serum interleukin-6(IL-6), prostaglandin E2(PGE2) levels, myocardial tissue apoptosis, and Wnt/ß-catenin/PPARγ pathway-related protein expression of rats in each group were measured. As compared with the control group, the arrhythmia score, the number of ventricular premature beats, ventricular fibrillation duration, myocardial cell apoptosis rate, MDA levels in myocardial tissues, serum IL-6 and PGE2 levels, Bax in myocardial tissues, and Wnt1 and ß-catenin protein expression levels increased significantly in the model group, whereas the GSH-Px and CAT levels, and Bcl-2 and PPARγ protein expression levels in myocardial tissues reduced significantly. As compared with the model group, the arrhythmia score, the number of ventricular premature beats, ventricular fibrillation duration, myocardial cell apoptosis rate, MDA leve in myocardial tissues, serum IL-6 and PGE2 levels, Bax in myocardial tissues, and Wnt1 and ß-catenin protein expression levels reduced in the drug intervention groups, whereas the GSH-Px and CAT levels and Bcl-2 and PPARγ protein expression levels in myocardial tissues increased. The groups of total flavonoids of buckwheat flower and leaf were in a dose-dependent manner. There was no significant difference in the levels of each index in rats between the propranolol hydrochloride group and the high-dose group of total flavonoids of buckwheat flower and leaf. The total flavonoids of buckwheat flower and leaf inhibit the activation of Wnt/ß-catenin pathway, up-regulate the expression of PPARγ, reduce oxidative stress and inflammatory damage in myocardial tissues of arrhythmic rats, reduce myocardial cell apoptosis, and improve the symptoms of arrhythmia in rats.

Alternating Early Afterdepolarizations Underlying Bradycardia-Dependent Macroscopic T Wave and Discordant Mechanical Alternans.

BACKGROUND: Macroscopic T wave alternans (macro-TWA) often heralds the onset of Torsades de Pointes in patients with QT prolongation. However, the mechanisms underlying macro-TWA remain unclear. We examined the cellular and ionic basis for macro-TWA in rabbits with left ventricular hypertrophy (LVH). METHODS: The renovascular hypertension model was used to induce LVH in rabbits. Action potentials were simultaneously recorded from epicardium and endocardium together with a transmural ECG and isometric contractility in arterially perfused left ventricular wedges. Late sodium current (INa-L) was recorded in single-isolated left ventricular myocytes with the whole cell patch-clamp technique. RESULTS: Macro-TWA and accompanied mechanical alternans occurred spontaneously in 8 of 33 LVH rabbits (P<0.05, versus 0/15 in controls) and were induced by an INa-L enhancer ATX-II at 1 to 3 nM in additional 7. Macro-TWA and mechanical alternans occurred discordantly, that is, that longer QT interval and larger T wave were associated with weaker isometric contvractility. Alternating early afterdepolarizations in the endocardium caused macro-TWA in 12 of 15 LVH rabbits and, therefore, early afterdepolarization-dependent R-from-T extrasystoles and Torsades de Pointes always originated from the beats with longer QT and larger T wave during macro-TWA. INa-L density was significantly larger in LVH myocytes than that of control myocytes. Macro-TWA, mechanical alternans, R-from-T extrasystoles, and Torsades de Pointes were all abolished by INa-L blocker ranolazine or mexiletine. CONCLUSIONS: LVH enhances INa-L density and promotes alternating early afterdepolarizations in the left ventricular endocardium that manifest as macro-TWA with discordant mechanical alternans. INa-L blockade abolishes macro-TWA, mechanical alternans, early afterdepolarization-dependent R-from-T extrasystoles, and Torsades de Pointes.

The incidence of cardiac arrhythmias during exercise stress testing: a focus on patients with severe obesity undergoing sleeve gastrectomy.

INTRODUCTION: Obesity is associated with a higher risk of cardiac arrhythmias. Sleeve gastrectomy (SG) is a common bariatric surgery with beneficial effects on weight loss and comorbidities. The study aimed to investigate the prevalence of arrhythmias during maximal exercise testing in patients with moderate-severe obesity and to evaluate the impact of SG on these arrhythmic events. METHODS: All patients with moderate or severe obesity who were considered suitable candidates for SG between June 2015 and September 2020 were recruited. Each patient underwent three incremental, maximal, ECG-monitored cardiopulmonary exercise test 1 month before and 6 and 12 months after SG; the frequency and complexity of ventricular premature beats (VPBs) and atrial premature beats (APBs) have been evaluated during rest, exercise and recovery phases. RESULTS: Fifty patients with severe obesity (BMI 46.39 ± 7.89 kg/m2) were included in the study. After SG, patients presented a decreased BMI (34.15 ± 6.25 kg/m2 at 6 months post-SG and 31.87 ± 5.99 kg/m2 at 12 months post-SG). At 6 months post-SG, an increase in VPBs, mainly during the recovery phase, was observed. At 12 months post-SG, a reduction in VPBs compared with the 6 months evaluation was showed. CONCLUSION: Although in the early post-surgical phase the risk of exercise-induced arrhythmias may be higher, SG does not seem to increase the occurrence of arrhythmias in the long-term. No life-threating arrhythmias were found during post-SG evaluations.

Premature beat of selective left bundle branch: a novel marker for reaching and capturing the left bundle branch.

BACKGROUND: It was recently shown that template beats and fixation beats of the premature ventricular contractions (PVCs) were generated during lead deployment. These could be exploited to guide the left bundle branch (LBB) pacing (LBBP) procedure. However, lack of a revolving connector that can continuously record and pace during lead rotations has been a limitation when using the traditional implant technique. Here, we report ten cases in which a revolving connector was used and showed that the premature beats of selective left bundle branch (SLBB-PBs) were generated as the lead was reached and the electrical stimulus selectively captured the LBB. METHODS AND RESULTS: Ten patients who underwent the transseptal placement of the pacing lead using a revolving connector were included in the study. We aimed to examine whether the SLBB-PB was a marker of LBB capture during LBBP and the clinical significance of SLBB-PB. LBBP was performed and data of these cases were analyzed to show the characteristics of the electrocardiogram and the intracardiac electrogram of SLBB-PBs. CONCLUSIONS: This is the first case series on SLBB-PBs in LBBP. The presence of SLBB-PBs suggested that the LBB was reached and selectively captured and possibly increased the safety of lead implantation.

Effect of total flavonoids of buckwheat flower and leaf on myocardial cell apoptosis and Wnt/β-catenin/PPARγ pathway in arrhythmic rats / 中国中药杂志

This paper aimed to investigate the effect of total flavonoids of buckwheat flower and leaf on myocardial cell apoptosis and Wnt/β-catenin/peroxisome proliferator-activated receptor γ(PPARγ) pathway in arrhythmic rats. SD rats were randomly divided into a control group, a model group, a low-dose(20 mg·kg~(-1)) group of total flavonoids of buckwheat flower and leaf, a medium-dose(40 mg·kg~(-1)) group of total flavonoids of buckwheat flower and leaf, a high-dose(80 mg·kg~(-1)) group of total flavonoids of buckwheat flower and leaf, a propranolol hydrochloride(2 mg·kg~(-1)) group, with 12 rats in each group. Except the control group, rats in other groups were prepared as models of arrhythmia by sublingual injection of 1 mL·kg~(-1) of 0.002% aconitine. After grouping and intervention with drugs, the arrhythmia, myocardial cells apoptosis, myocardial tissue glutathione peroxidase(GSH-Px), catalase(CAT), malondialdehyde(MDA), serum interleukin-6(IL-6), prostaglandin E2(PGE2) levels, myocardial tissue apoptosis, and Wnt/β-catenin/PPARγ pathway-related protein expression of rats in each group were measured. As compared with the control group, the arrhythmia score, the number of ventricular premature beats, ventricular fibrillation duration, myocardial cell apoptosis rate, MDA levels in myocardial tissues, serum IL-6 and PGE2 levels, Bax in myocardial tissues, and Wnt1 and β-catenin protein expression levels increased significantly in the model group, whereas the GSH-Px and CAT levels, and Bcl-2 and PPARγ protein expression levels in myocardial tissues reduced significantly. As compared with the model group, the arrhythmia score, the number of ventricular premature beats, ventricular fibrillation duration, myocardial cell apoptosis rate, MDA leve in myocardial tissues, serum IL-6 and PGE2 levels, Bax in myocardial tissues, and Wnt1 and β-catenin protein expression levels reduced in the drug intervention groups, whereas the GSH-Px and CAT levels and Bcl-2 and PPARγ protein expression levels in myocardial tissues increased. The groups of total flavonoids of buckwheat flower and leaf were in a dose-dependent manner. There was no significant difference in the levels of each index in rats between the propranolol hydrochloride group and the high-dose group of total flavonoids of buckwheat flower and leaf. The total flavonoids of buckwheat flower and leaf inhibit the activation of Wnt/β-catenin pathway, up-regulate the expression of PPARγ, reduce oxidative stress and inflammatory damage in myocardial tissues of arrhythmic rats, reduce myocardial cell apoptosis, and improve the symptoms of arrhythmia in rats.

Syndrome de QT long découvert en postpartum: à propos d'un cas à Fianarantsoa, Madagascar / Long QT syndrome discovered in postpartum: about a case in Fianarantsoa, Madagascar

Le syndrome de QT long congénital est une canalopathie arythmogène rare mais grave pouvant être responsable d'une mort subite prématurée chez l'enfant et les sujets jeunes. La période du postpartum est particulièrement à risque de survenue d'évènement cardiaque chez la femme. Nous rapportons le cas d'une femme de 29 ans porteuse d'un syndrome de QT long congénitale probable déclenché avec trouble du rythme cardiaque déclenché par le postpartum dont le risque de mort subite à court terme a été imminent en absence de traitement

Cryptogenic Stroke In The Context of Pandemic-Related Stress: The Role of Arterial Hemodynamics.

BACKGROUND: Up to 45% of ischemic strokes are cryptogenic, which is an impediment to proposing preventative measures. In this investigation we aimed to study underlying heart arrhythmias in patients with cryptogenic stroke, taking into consideration the context of the COVID-19 pandemic and stressful lockdown conditions. SUBJECTS AND METHODS: In this cross-sectional study we observed 52 patients with cryptogenic stroke >1 month after acute presentation, and a control group consisting of 88 patients without stroke. All patients undewent the laboratory and instrumental investigation consisting of the following: lipid spectrum; hemostasiograms; hemoglobin A1c; transthoracic or/and transesophageal echocardiography; 24-hours monitoring of ECG; computer tomography or magnetic resonance imaging of the brain. We studied the hemodynamics of the common carotid arteries using Doppler ultrasound imaging and digital sphygmography (SG). RESULTS: The groups were indentical with respect to the preponderance of study parameters (sex, age, comorbidities, instrumental and laboratory data). The ischemic stroke group had a statistically significant difference in the prevalence of the first type of extrasystolic arrhythmia according to our gradation of extrasystoles, which are ventricular systoles of extrasystolic contraction appearing before the transmitral blood flow peak (peak E in echocardiography). We observed that earlier ventricular systoles of extrasystole in the cardiac cycle predicted for greater growth of hemodynamic and kinetic parameters. Calculating the indices of a four-field table established the significant relationship between the moment of appearance of extrasystolic ventricular contraction in the cardiac cycle and the risk for cryptogenic stroke (normalized value of the Pearson coefficient (C`) of the two paramaters was 0.318). CONCLUSIONS: Extrasystolic arrhythmia appeared as an additional risk factor of earlier stroke. The most dangerous type of arrhythmia was when the ventricular contraction of the extrasystole appeared before the transmitral blood flow peak in the cardiac cycle. This observation could present a risk-marker for brain-related cardiovascular complications such as stroke, which might be patients suffering from different internal diseases, especially in the context of environmental stress conditions of the current pandemic and its related lockdown measures.

Inferior Vena Cava as a Trigger for Paroxysmal Atrial Fibrillation: Incidence, Characteristics, and Implications.

BACKGROUND: Identifying nonpulmonary vein triggers during atrial fibrillation (AF) ablation is of great importance. Currently, there are limited data on AF triggered by the inferior vena cava (IVC). OBJECTIVES: This study was performed to investigate the incidence, characteristics, and implications of IVC triggers for AF. METHODS: A total of 661 patients who underwent initial paroxysmal AF ablation were included. After pulmonary vein isolation, ectopic beats that triggered AF were further studied. Activation mapping and angiography were performed to confirm the location of ectopic origin. Electrocardiographic analysis of the ectopic P-wave (P'-wave) was performed. RESULTS: Six patients (0.91%) with AF triggered by the IVC were confirmed. The mean distance from the earliest activation site to the IVC ostium was 6.8 ± 2.5 mm (5.2 to 11.2 mm). Furthermore, the arrhythmogenic foci within the IVC were all located at the apical hemisphere of the IVC (3 at the septal side and 3 at the anterior side). A total of 2.3 ± 0.5 applications of radiofrequency energy were delivered to eliminate IVC triggers. The mean duration of the P' wave was 91.2 ± 11.2 milliseconds (81 to 108 milliseconds), which was narrower than that of the sinus P-wave (115.2 ± 19.3 milliseconds [87 to 139 milliseconds]; P = 0.002). Moreover, the configuration of all P' waves in the inferior leads was negative. During a mean follow-up period of 25.5 ± 7.3 months, all 6 patients remained arrhythmia free without antiarrhythmic drugs. CONCLUSIONS: IVC trigger, a rare but latent source of paroxysmal AF, could be identified and safely eliminated by focal radiofrequency ablation. Ectopic beats originating from the IVC presented with narrow P'-wave duration and negative P' waves in all inferior leads.

Extrasystoles or short bradycardias of the newborn seldom require subsequent 24-hour electrocardiographic monitoring.

AIM: To retrospectively assess the indications for and findings on 24-hour electrocardiographic (Holter) monitoring in newborns, focussing on bradycardias and extrasystoles. METHODS: Data included 337 term-born infants. Holter indications were categorised into bradycardias below 80 beats per minute, extrasystoles, any tachycardia and other. Heart rate below 60 beats per minute, pathological atrioventricular conduction, supraventricular or ventricular tachycardia, or either atrial premature contractions over 10% or ventricular premature contractions over 5% of total beats were defined as significant arrhythmia on Holter. RESULTS: The median age was 6 days (range: 2-62 days). Bradycardia (42%) or extrasystoles (32%) were the most common Holter indications. Fifty-three infants (16%) had significant arrhythmia on Holter. Heart disease or 12-lead electrocardiogram expressing extrasystoles or conduction abnormalities were associated with significant arrhythmias (p = 0.046 and p < 0.001, respectively). Twenty-seven of 109 infants (25%) with extrasystoles as a Holter indication had abnormal Holter results, but only seven (6.4%) had significant arrhythmia on Holter if the 12-lead electrocardiogram was normal. No pathology was found behind bradycardias below 80 beats per minute in the absence of heart disease. CONCLUSION: Among term newborns with extrasystoles or bradycardias, Holter monitoring could be targeted to infants with heart disease or abnormal electrocardiograms.

Location and coupling interval of an ectopic excitation determine the initiation of atrial fibrillation from the pulmonary veins.

INTRODUCTION: Ectopic beats originating from the pulmonary vein (PV) trigger atrial fibrillation (AF). The purpose of this study was to clarify the electrophysiological determinant of AF initiation from the PVs. METHODS: Pacing studies were performed with a single extra stimulus mimicking an ectopic beat in the left superior PVs (LSPVs) in 62 patients undergoing AF ablation. Inducibility of AF, effective refractory period (ERP), and conduction properties within the PVs were analyzed. RESULTS: A single extra stimulus in LSPV induced AF in 20 patients (32% of all patients) at the mean coupling interval (CI) of 172 ms. A CI-dependent anisotropic conduction at the AF onset was visualized in a three-dimensional mapping. Onset of AF was site-specific with reproducibility in each individual. Mean ERP in LSPV in the AF-inducible group was shorter than that in the AF-noninducible group (182 ± 55 vs. 254 ± 51 ms, p < .0001). LSPV ERP dispersion was greater in the AF-inducible group than in the AF-noninducible group (45 ± 28 vs. 27 ± 19 ms, p < .01). Circumferential intra-PV conduction time (IPVCT) exhibited decremental properties in response to shortening of CI and the prolongation of IPVCT in the AF-inducible site was greater than that in the AF-noninducible site (p < .05) in each individual. CONCLUSIONS: Location and CI of an ectopic excitation ultimately determine the initiation of AF from the PVs. ERP dispersion and circumferential conduction delay may lead to anisotropic conduction and reentry within the PVs that initiate AF.