Fa-Po Chung

Prevalence, Characteristics, Mapping, and Catheter Ablation of Potential Rotors in Nonparoxysmal Atrial Fibrillation

Background— Identification of critical atrial substrates in patients with nonparoxysmal atrial fibrillation (AF) failing to respond to pulmonary vein isolation is important. This study investigated the signal characteristics, substrate nature, and ablation results of rotors during AF. Methods and Results— In total, 53 patients (age=55±8), 31 with persistent AF and 22 with long-lasting AF, underwent pulmonary vein isolation and substrate modification of complex fractionated atrial electrograms. Small-radius-reentrant rotors were identified from signal analyses of the dominant frequency and fractionation interval and nonlinear analyses (newly developed, beat-to-beat nonlinear measurement of the repetitiveness of the electrogram morphology >6 seconds). In 15% of the patients, activation maps demonstrated occurrences of rotor-like small-radius reentrant circuits (n=9; 1.1 per patient; cycle length=110±21 ms; diameter=11±6 mm) with fibrillation occurring outside these areas. Rotors were identified by conventional point-by-point mapping and signal analyses and were subsequently eradicated by catheter ablation in these patients. Persistent AF for <1 year, a smaller left atrial size, substrates with higher mean voltages and shorter total activation durations predicted a higher incidence of rotors (all P<0.05). In the multivariable model, areas of reentrant circuits exhibited a higher dominant frequency, kurtosis, and higher degree of a beat-to-beat electrogram similarity than areas without or outside the rotors (all P<0.05). Conclusions— Rotor-like re-entry with fibrillatory conduction was found in a limited number of patients with nonparoxysmal AF after pulmonary vein isolation. Those areas were characterized by rapid repetitive activity with a high degree of electrogram similarity.

Use of Oral Anticoagulants for Stroke Prevention in Patients With Atrial Fibrillation Who Have a History of Intracranial Hemorrhage

Background— The risk of further intracranial hemorrhage (ICH) and the benefit of stroke risk reduction with the use of oral anticoagulants for patients who have atrial fibrillation with a history of ICH remain unclear. We aimed to investigate the risks and benefits in patients who have atrial fibrillation with a previous ICH treated with warfarin or antiplatelet drugs in comparison with no antithrombotic therapies. Methods and Results— This study used the National Health Insurance Research Database in Taiwan. Among 307 640 patients who have atrial fibrillation with a CHA2DS2-VASc score ≧2, 12 917 patients with a history of ICH were identified and were assigned to 1 of 3 groups, that is, no treatment, antiplatelet therapy, and warfarin. Among patients with previous ICH, the rate of ICH and ischemic stroke in untreated patients was 4.2 and 5.8 per 100 person-years, respectively. The annual ICH and ischemic stroke rates in warfarin users were 5.9% and 3.4%, respectively. Among users of antiplatelet agents, the rates were 5.3% per year and 5.2% per year, respectively. The number needed to treat for preventing 1 ischemic stroke was lower than the number needed to harm for producing 1 ICH with warfarin use for patients with a CHA2DS2-VASc score ≧6 (37 versus 56). The number needed to treat was higher than the number needed to harm for patients with a CHA2DS2-VASc score <6 (63 versus 53). Conclusions— Warfarin use may be beneficial for patients who have atrial fibrillation with a previous ICH having a CHA2DS2-VASc score ≧6. Whether the use of non–vitamin K antagonist oral anticoagulants could lower the threshold for treatment deserves further study.

Incidence and prediction of ischemic stroke among atrial fibrillation patients with end-stage renal disease requiring dialysis.

BACKGROUND Renal dysfunction is a significant risk factor for ischemic stroke in atrial fibrillation (AF). However, the incidence of ischemic stroke and how to predict its occurrence among AF patients with end-stage renal disease (ESRD) are unclear. OBJECTIVE The purpose of this study was to compare the CHADS2 and CHA2DS2-VASc scores for stroke risk stratification in AF patients with ESRD. METHODS A total of 10,999 AF patients with ESRD undergoing renal replacement therapy who were not receiving oral anticoagulants or antiplatelet agents were identified from Taiwans National Health Insurance Research Database. The study end-point was occurrence of ischemic stroke. RESULTS The median (interquartile) CHADS2 and CHA2DS2-VASc scores for the study cohort were 3 (2-5) and 5 (4-7), respectively. During follow-up, 1217 patients (11.7%) experienced ischemic stroke, with an incidence rate of 6.9 per 100 person-years. In Cox regression models, the CHADS2 and CHA2DS2-VASc scores both were significant predictors of ischemic stroke. C-indexes for CHADS2 and CHA2DS2-VASc were 0.608 and 0.682, respectively (P < .001). CHA2DS2-VASc improved the net reclassification index by 4.8% compared with CHADS2 (P < .0001). Among 1409 patients with a CHADS2 score of 0 or 1, the CHA2DS2-VASc score ranged from 1 to 4, with event rates ranging from 2.1 to 4.7 per 100 person-years. CONCLUSION The CHA2DS2-VASc score was useful in predicting ischemic stroke in AF patients with ESRD undergoing dialysis and was superior to the CHADS2 score. The net clinical benefit balancing stroke reduction against major bleeding with anticoagulation in these high-risk patients remains to be defined.

Renal dysfunction and the risk of thromboembolic events in patients with atrial fibrillation after catheter ablation—The potential role beyond the CHA2DS2-VASc score

BACKGROUND Renal dysfunction is recognized as an important risk factor for thromboembolic (TE) events in patients with atrial fibrillation (AF) under medical treatment. OBJECTIVE To investigate whether renal dysfunction is a useful predictor of TE events among patients receiving AF ablation. We also aimed to determine whether the diagnostic accuracy of the CHA(2)DS(2)-VASc score in predicting TE events could be improved by adding renal dysfunction into the scoring system. METHODS We enrolled a total of 547 patients with AF who underwent catheter ablation. Renal dysfunction was defined as an estimated glomerular filtration rate of <60 mL/min/1.73 m(2). The clinical end point was the occurrence of TE events (ischemic stroke, transient ischemic attack, or other systemic embolisms) during follow-up after catheter ablation. RESULTS During a follow-up of 38.9 ± 22.5 months, 16 patients (2.9%) experienced TE events. Both the CHA(2)DS(2)-VASc score and renal dysfunction were independent predictors of TE events in the multivariate analysis. Among patients with a CHA(2)DS(2)-VASc score of 0 or 1, renal dysfunction can further stratify them into 2 groups with different event rates (4.3% vs 0.3%; P = .046). A new scoring system derived by assigning 1 more point representing renal dysfunction to the CHA(2)DS(2)-VASc score could improve its predictive accuracy; the area under the receiver operating characteristic curve increased from 0.84 to 0.88 (P = .043). CONCLUSIONS Renal dysfunction was a significant risk factor for TE events after catheter ablation of AF and may improve the diagnostic accuracy of the CHA(2)DS(2)-VASc score.

Incidence and risk factors for new-onset atrial fibrillation among patients with end-stage renal disease undergoing renal replacement therapy

Atrial fibrillation (AF) is prevalent in end-stage renal disease (ESRD) patients and negatively impacts patient outcomes. We explored the incidence and risk factors for new-onset AF among patients with ESRD undergoing renal replacement therapy, without a prior history of AF, retrieved from Taiwans National Health Insurance Research Database (NHIRD). For each of 134,901 patients with ESRD, one age- and gender-matched control and one similarly matched patient with chronic kidney disease (CKD), a total of 404,703 patients, were selected from the NHIRD. The study endpoint was the occurrence of new-onset AF and patients were followed an average of 5.1 years. The incidence rates of AF were 12.1, 7.3, and 5.0 per 1000 person-years for ESRD, CKD, and control patients, respectively. Among patients with ESRD, age, hypertension, heart failure, coronary artery disease, peripheral arterial occlusive disease, and chronic obstructive pulmonary disease were significant risk factors for new-onset AF. Thus, patients with ESRD had a significantly higher risk of new-onset AF. The presence of multiple risk factors was associated with a higher possibility of AF occurrence.

Long-term follow-up in patients with arrhythmogenic right ventricular cardiomyopathy.

Long‐Term Prognosis in Patients with ARVC. Introduction: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a major cause of sudden cardiac death due to tachyarrhythmias. The purpose of this study was to investigate the long‐term prognosis in patients with ARVC and the incidence of rapid ventricular arrhythmias during follow‐up.

Transforming growth factor-β1 level and outcome after catheter ablation for nonparoxysmal atrial fibrillation

BACKGROUND Atrial fibrosis plays a role in the development of a vulnerable substrate for atrial fibrillation (AF). Transforming growth factor (TGF)-β(1) is related to the degree of atrial fibrosis and the recurrence of AF after surgical maze procedures. Whether TGF-β(1) is associated with the outcome after catheter ablation for AF remains unclear. OBJECTIVE The purpose of this study was to investigate whether plasma TGF-β(1) was an independent predictor of AF recurrence after catheter ablation. METHODS Two hundred consecutive AF patients (154 with paroxysmal AF and 46 with nonparoxysmal AF) underwent catheter ablation. Their TGF-β(1) levels and clinical and echocardiographic data were collected before ablation. RESULTS Thirty patients (65%) with nonparoxysmal AF and 57 (37%) with paroxysmal AF had AF recurrence after catheter ablation. Among patients with nonparoxysmal AF, those experiencing recurrence had higher TGF-β(1) levels than did those who did not experience recurrence (34.63 ± 11.98 ng/mL vs 27.33 ± 9.81 ng/mL; P = .026). In patients with paroxysmal AF, recurrence was not associated with different TGF-β(1) levels. In patients with nonparoxysmal AF, TGF-β(1) levels and left atrial diameter (LAD) were independent predictors of AF recurrence after catheter ablation. Moreover, TGF-β(1) levels had an incremental value over LAD in predicting AF recurrence after catheter ablation (global χ(2) of LAD alone: 6.3; LAD and TGF-β(1) levels: 11.9; increment in global χ(2) = 5.6; P = .013). Patients with small LAD and low TGF-β(1) levels had the lowest AF recurrence rate at 11%. CONCLUSION TGF-β(1) level is an independent predictor of AF recurrence in patients with nonparoxysmal AF and might be useful for identifying those patients likely to have better outcomes after catheter ablation.

Nonlinear Analysis of Fibrillatory Electrogram Similarity to Optimize the Detection of Complex Fractionated Electrograms During Persistent Atrial Fibrillation

Nonlinear Analysis of Atrial Fibrillation. Introduction: Currently, the identification of complex fractionated atrial electrograms (CFEs) in the substrate modification is mostly based on cycle length‐derived algorithms. The characteristics of the fibrillation electrogram morphology and their consistency over time are not clear. The aim of this study was to optimize the detection algorithm of crucial CFEs by using nonlinear measure electrogram similarity.

Radiofrequency Catheter Ablation of Ventricular Arrhythmias Originating from the Continuum between the Aortic Sinus of Valsalva and the Left Ventricular Summit: Electrocardiographic Characteristics and Correlative Anatomy.

BACKGROUND Radiofrequency ablation of ventricular arrhythmias (VAs) originating from the continuum between the aortic sinus of Valsalva (ASV) and the left ventricular (LV) summit is a challenge. OBJECTIVES The objectives of this study were to investigate the electrocardiographic, electrophysiological, and anatomical characteristics of VAs and to develop an algorithm for predicting the successful ablation site. METHODS We recruited 66 patients (mean age, 47 ± 15 years; 42 male patients) with symptomatic VAs originating from the continuum between the ASV and the LV summit who underwent radiofrequency ablation. Patients were classified into 4 groups (group 1: ASV, n = 20; group 2: subvalvular region, n = 15; group 3: great cardiac vein/anterior interventricular vein [GCV/AIV], n = 16; group 4: epicardium requiring pericardial access, n = 15). The QRS morphological characteristics of VAs were compared between the 4 groups. RESULTS Electrocardiographic analysis revealed that the aVL/aVR Q-wave ratio is useful in the prediction of successful ablation sites in the ASV, subvalvular area, GCV/AIV, and epicardium requiring pericardial access at cutoff values of ≤1.415, 1.416-1.535, 1.536-1.740, and >1.740, respectively. The aVL/aVR Q-wave ratio was well correlated with the distance between the successful ablation site and the tip of the LV summit. A distance of >18.9 mm and an LV myocardial thickness of >9.1 mm predicted the need for the epicardial or GCV/AIV approaches. There were no major procedural complications. Eight patients (12.1%) developed VA recurrence during a mean follow-up of 15.9 months (interquartile range 9.2-24.2 months). CONCLUSION The aVL/aVR Q-wave ratio is a useful parameter for predicting the successful ablation sites of VAs originating from the continuum between the ASV and the LV summit.

Prognostic Significance of Premature Atrial Complexes Burden in Prediction of Long‐Term Outcome

Background The prognostic significance of premature atrial complex (PAC) burden is not fully elucidated. We aimed to investigate the relationship between the burden of PACs and long-term outcome. Methods and Results We investigated the clinical characteristics of 5371 consecutive patients without atrial fibrillation (AF) or a permanent pacemaker (PPM) at baseline who underwent 24-hour electrocardiography monitoring between January 1, 2002, and December 31, 2004. Clinical event data were retrieved from the Bureau of National Health Insurance of Taiwan. During a mean follow-up duration of 10±1 years, there were 1209 deaths, 1166 cardiovascular-related hospitalizations, 3104 hospitalizations for any reason, 418 cases of new-onset AF, and 132 PPM implantations. The optimal cut-off of PAC burden for predicting mortality was 76 beats per day, with a sensitivity of 63.1% and a specificity of 63.5%. In multivariate analysis, a PAC burden >76 beats per day was an independent predictor of mortality (hazard ratio: 1.384, 95% CI: 1.230 to 1.558), cardiovascular hospitalization (hazard ratio: 1.284, 95% CI: 1.137 to 1.451), new-onset AF (hazard ratio: 1.757, 95% CI: 1.427 to 2.163), and PPM implantation (hazard ratio: 2.821, 95% CI: 1.898 to 4.192). Patients with frequent PAC had increased risk of mortality attributable to myocardial infarction, heart failure, and sudden cardiac death. Frequent PACs increased risk of PPM implantation owing to sick sinus syndrome, high-degree atrioventricular block, and/or AF. Conclusions The burden of PACs is independently associated with mortality, cardiovascular hospitalization, new-onset AF, and PPM implantation in the long term.