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Most data on the clinical epidemiology of atrial fibrillation (AF) come from Western populations, and data for Asians are limited. We investigated the lifetime risk and projected number of AF among Asians. The annual risks of adverse events among patients with AF, time trends, and the risks compared with patients without AF were analyzed.

To investigate the impact on outcomes of changing treatment guideline recommendations by comparing the proportion of patients with atrial fibrillation (AF) recommended oral anticoagulants (OACs) under the 2011 and 2014 American College of Cardiology/American Heart Association (ACC/AHA) guidelines.

A new risk model, the R2CHADS2(Renal Dysfunction, Congestive Heart Failure, Hypertension, Age, Diabetes, Stroke/Transient Ischemic Attack) score, was proposed to be a powerful scoring scheme in predicting stroke or systemic embolism in atrial fibrillation (AF). The goal of the present study is to validate the usefulness of the R2CHADS2score among patients with AF after catheter ablation. We also aimed to compare the accuracy of the CHA2DS2-VASc (Congestive Heart Failure, Hypertension, Age [≥ 75 y], Diabetes, Stroke/Transient Ischemic Attack, Vascular Disease, Age [65-74 y], Sex [Female]) and R2CHADS2scores for risk stratification of thromboembolic (TE) events after ablation procedures.

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) can be usually induced by atrial pacing or extrastimulation. However, it is less commonly induced only by ventricular pacing or extrastimulation.

Background:Double atrial potentials recorded in the coronary sinus are not an unusual phenomenon in patients with supraventricular tachyarrhythmias. They have been demonstrated to potentiate the occurrence of atrial tachyarrhythmias. Methods:Two hundred and forty-eight patients were included for investigating the presence of double atrial potentials on the coronary sinus recordings during electrophysiologic study. Group 1 consisted of 136 patients with WPW syndrome and group 2 consisted of 112 patients with atrioventricular nodal reentrant tachycardia (AVNRT). Group 1 patients had a higher incidence of induced atrial fibrillation (AF) (27% vs. 15%, P= 0.045) than group 2 patients. In addition, the incidence of double atrial potentials was significantly higher in group 1 than in group 2 patients (14% vs. 2%, P= 0.001). In group 1, 19 patients with double atrial potentials had a significantly higher incidence of left lateral bypass tracts (79% vs. 39%, P= 0.001) and induced AF (47% vs. 22%, P= 0.01) than 117 patients without double atrial potentials. Conclusions:WPW syndrome, especially with a left lateral bypass tract, had a higher incidence of double atrial potentials and induced AF than AVNRT. WPW patients with double atrial potentials had a higher incidence of induced AF than those without double atrial potentials. These findings may contribute to understanding the mechanism of induced AF in WPW syndrome.

Introduction:The outcome of patients with early recurrence of atrial fibrillation (AF) (within one month) after ablation procedure is controversial. Furthermore, the predictors of early and late (up to mean follow-up 30 months) recurrence of AF are not investigated in depth. Aims of the Study:The aim of the present study was to investigate the predictors of early and late recurrence of AF after catheter ablation of arrhythmogenic foci initiating AF in patients with paroxysmal AF. Methods and Results:The study included 207 patients (155 men; mean age 62 ± 13 years) who received catheter ablation of paroxysmal AF. Eighty-one (39%) patients had early recurrence of AF. Five clinical variables were related to the early recurrence of AF: (1) old age (≥65 years) (P= 0.004); (2) presence of associated cardiovascular disease (P= 0.01); (3) presence of multiple AF foci (P= 0.004); (4) presence of AF foci from left atrial free wall (P= 0.039); (5) left atrial enlargement (P= 0.038). Multivariate analysis demonstrated that presence of multiple AF foci could predict early recurrence of AF (P= 0.013; ratio = 2.24; 95% CI 1.18 to 4.25). During the follow-up period (30 ± 11 months), 70 (34%) patients had late recurrence of AF, and two clinical variables were related to the late recurrence of AF: (1) presence of early recurrence of AF (P= 0.025); (2) presence of multiple AF foci (P= 0.034). Multivariate analysis found that presence of early recurrence of AF could predict late recurrence of AF (P= 0.046; hazard ratio = 1.62; 95% CI 1.01 to 2.59). Late recurrence of AF happened in 35 (43%) of the 81 patients with early recurrence of AF, and in 35 (28%) of the 126 patients without early recurrence of AF. Conclusions:Early AF recurrence could predict late AF recurrence.

Introduction:Recently, several studies showed that focal atrial fibrillation (AF) can be initiated by ectopic beats from the vein of Marshall (VOM). However, the incidence and best fluoroscopic views of VOM have never been reported. Methods and Results:106 patients (Non-AF = 52, AF = 54) underwent balloon-occluded coronary sinus angiography using seven fluoroscopic views (PA, Lateral, RAO 30°, RA 30° + Caudal 20°, LAO 30°, LAO 60°, LAO 60° + Cranial 20°). The total incidence of VOM was 74.5% (79/106), without significant difference in age (81.1 vs. 71.0%, >65 vs. ≤65 yrs, p= 0.257) and sex (male vs. female = 72.7 vs. 77.5%, p= 0.585). Furthermore, similar incidence of VOM was noted in patients with Non-AF (71.2%) and AF group (77.8%, p= 0.434). The RAO 30° fluoroscopic view can demonstrate all the left atrial veins and VOM. However, only the LAO 30° fluoroscopic view could confirm VOM and differentiate it from left atrial veins (after vs. before junction of coronary sinus and great cardiac vein, respectively). Conclusion:VOM was equally distributed in patients with different arrhythmias, and the appropriate fluoroscopic view was important for the differential diagnosis of VOM and left atrial veins.

Background:Patient-activated event re- corders are useful for the diagnosis of arrhythmia in patients with palpitation and presyncope. However, the utility of event recorders in patients suspected of arrhythmia but presenting with other symptoms is not clear. Furthermore, the factors influencing their utility have not been evaluated. Methods:Event recorder reports of six hundred and sixty consecutive patients referred due to clinical suspicion of cardiac arrhythmia were reviewed. We divided symptoms into four groups: palpitation, presyncope, chest tightness, and dyspnea. We calculated the diagnostic yield according to patients' symptoms reported on the record, and analyzed the factors affecting the utility of event recorders. Results:The overall diagnostic yield was 64%, and those of palpitation, presyncope, chest tightness, and dyspnea were 66%, 57%, 51% and 60%, respectively. The most common five findings in our patients were sinus rhythm (36%), sinus tachycardia (30%), atrial premature complex (14%), ventricular premature complex (12%), and atrial fibrillation/atrial flutter (7%). The recording duration (8 ± 4 days) was short in the present study, but the overall diagnostic yield was similar to those of previous ones. Women had lower diagnostic yields than men, especially in atrial flutter-fibrillation. The diagnostic yield was not influenced by age, ordered doctors, or history of cardiovascular disease. Conclusions:Patient-activated event recorders provided a good diagnostic yield in patients with different presentations of cardiac arrhythmia, and women had lower diagnostic yield in atrial flutter-fibrillation.

Monophasic action potential-like electrocardiogram simulating acute myocardial infarction has been reported in patients with hyperkalemia. We report two cases presenting marked diffuse RS-T elevation resembling monophasic action potential. They had abnormal electrolyte levels, including hyperkalemia and hypocalcemia in case 1 and hypokalemia and hypocalcemia in case 2. The ECG abnormality returned to baseline after correction of potassium and calcium. We conclude that monophasic action potential-like electrocardiogram is caused by electrolyte disturbance other than acute myocardial infarction.

Introduction:Radiofrequency catheter ablation of the cavotricuspid isthmus is an effective therapy for typical atrial flutter (AFL), however, the long-term recurrence of AFL and early or late occurrence of atrial fibrillation (AF) are not well defined. This study investigated the long-term (up to 68 months) outcome of patients with typical AFL after catheter ablation of the cavotricuspid isthmus. Methods:This study included 380 patients with typical AFL, who received linear ablation of the cavotricuspid isthmus. They were followed up at the outpatient clinic. A questionnaire was used to evaluate the symptoms suggestive of tachyarrhythmias, and 12-lead ECG, Holter monitoring and event recorders were used to confirm the diagnosis of tachyarrhythmias. Results:At the end of study, 47 patients lost follow-up, so that 333 patients were enrolled into final analysis. Ten (3%) patients had failed ablation of typical AFL. Univariate analysis showed that left atrial dimension was the only factor related to failed ablation. During the long-term follow-up period of 29 ± 17 months (range 7 to 68 months), 29 (9%) patients had recurrent AFL, including 15 with typical and 14 with atypical AFL. Univariate and multivariate analyses showed that incomplete isthmus block and inducible atypical AFL were the independent predictors of recurrent typical and atypical AFL, respectively. One hundred and two (31%) patients developed AF, including 48 with early occurrence of AF (within 3 months after ablation), and 54 with late occurrence of AF (greater than 3 months). Univariate and multivariate analyses showed that prior history of AF and inducible AF were independent predictors of early occurrence of AF, and prior history of AF was the only independent predictor of late occurrence of AF. Conclusions:Linear ablation of the cavotricuspid isthmus is an effective therapy with low recurrence rate for patients with typical AFL. However, one-third patients had early or late occurrence of AF.

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The purpose of this study was to evaluate in vivo the proarrhythmic effects of ibutilide in dogs with or without ventricular hypertrophy. Fourteen dogs received repeated experiments both during the acute and chronic phases (8 weeks, with ventricular hypertrophy) of complete atrioventricular (AV) block. Twelve-lead ECG, monophasic action potentials in the left and right ventricle were recorded before and after each dose of ibutilide (0.01-0.08 mg/kg) during different ventricular rates. In these dogs, ibutilide increased QT interval, biventricular APD90, interventricular ΔAPD90(difference between the left and right ventricular APD90), and QT dispersion, and induced early afterdepolarizations in a dose-dependent manner. The interventricular ΔAPD90, QT dispersion, and increases of QT interval were more pronounced during slower ventricular rates. There were greater QT interval, biventricular APD90, interventricular ΔAPD90, and QT dispersion values during chronic AV block than during acute AV block. Moreover, ibutilide can induce higher incidences of early afterdepolarizations and torsades de pointes six (43%) of 14 versus 0 of 14; p < 0.05 during chronic AV block than during acute AV block. In conclusion, ibutilide can prolong ventricular repolarization and increase dispersion of ventricular repolarization in a dose-dependent and reverse rate-dependent manner. The high incidence of torsades de pointes in the dogs during chronic AV block suggests the importance of ventricular hypertrophy in the occurrence of ibutilide-induced proarrhythmia.

The presence of ectopic rhythm has been considered to be the most important marker for successful slow pathway ablation, but the details of different ectopic rhythms have not been well described. This study included 83 consecutive patients with typical AV node reentrant tachycardia who underwent slow pathway ablation. The interval between the atrial signals of the His bundle electrogram and the distal ablation catheter [A(H)-A(Ab)], and the interval between the atrial components of the distal ablation catheter and the ostium of coronary sinus catheter [A(Ab)-A(CSos)] were measured. One hundred episodes of ectopic rhythm occurred with 81 (81%) successful applications. There are two different origins and three activation sequences of ectopic rhythms, including HIS rhythm (78 applications, the earliest atrial activation in the His bundle electrogram), CSos rhythm (6 applications, the earliest atrial signal in the coronary sinus ostium electrogram) and CSos preceding HIS (CSos→HIS) rhythm (16 applications, the atrial activation sequences changing from CSos to HIS rhythm). The CSos rhythm had a shorter mean cycle length (445 ± 81 vs. 511 ± 132 vs. 579 ± 140 ms, p < 0.05), a shorter [A(Ab)-A(CSos)] interval (−2.5 ± 9.8 vs. 14.1 ± 11.2 vs. 12.8 ± 8.4 ms, p < 0.05) and a lower success rate (33% vs. 84% vs. 94% p < 0.05) than HIS rhythm and CSos→HIS rhythm. Otherwise, the mean cycle length of ectopic rhythm was significant shorter in successful than in failed ablation (506 ± 135 vs. 559 ± 118 ms, p = 0.04). In conclusion, we found two different origins and three activation sequences of ectopic rhythms. CSos rhythm had a lower success rate in ablation of slow pathway, thus it was a poor marker for successful ablation.

A 71-year-old male patient was admitted for catheter ablation of the pulmonary veins to treat paroxysmal atrial fibrillation. Atrial fibrillation originating from the left superior pulmonary vein was induced after a pause of atrial pacing under isoproterenol infusion and became sustained. Spontaneous transition from atrial fibrillation to typical atrial flutter was noted after complete isolation of the pulmonary vein focus from the left atrium. Subsequently linear ablation of the cavotricuspid isthmus was created with completely bi-directional isthmus conduction block. We hypothesized that ectopic pulmonary vein focus played an important role in the spontaneous conversion of atrial fibrillation to typical atrial flutter, and complete isolation of the pulmonary vein could stop the spontaneous transition between the two atrial tachyarrhythmias.

Background: In animal studies, atrial fibrillation has been shown to shorten the atrial refractory period and impair its rate adaptation. However, little is known about the effects of chronic atrial fibrillation on atrial electrophysiology and its recovery course in humans. Methods and results: Nineteen patients, mean age 64±14 years, with chronic atrial fibrillation of more than six months duration were included in this study. All of them were successfully converted to sinus rhythm with an external defibrillator. Atrial effective refractory periods at right atrial appendage and distal coronary sinus were determined with five pacing cycle lengths (300, 400, 500, 600 and 700 ms) at 30 min after cardioversion and once a day for four days. The atrial conduction properties, including P wave duration of surface ECG, and right and left atrial conduction times, were also measured at the same time interval. Twenty age-matched patients without a history of atrial tachyarrhythmia were evaluated as controls. In comparison with controls, chronic atrial fibrillation significantly shortened the atrial effective refractory period, impaired its rate adaptation response, especially at distal coronary sinus, and depressed the conduction properties of atria. The atrial conduction properties did not change during the four-day follow-up period; however, the atrial effective refractory period was gradually prolonged and its rate adaptation response improved after restoration of sinus rhythm. Conclusions: In humans, chronic atrial fibrillation significantly shortened the atrial effective refractory period, and impaired its rate adaptation response. Restoration and maintenance of sinus rhythm could reverse these electrophysiological changes.