[Show abstract][Hide abstract] ABSTRACT: Catheter ablation of atrial fibrillation (AF) has evolved over the past 20 years from being a novel, unproven procedure to a commonly performed procedure. Triggers are important for the initiation of AF and a suitable substrate is important for perpetuation of AF. Remodeling, including electrical and structural remodeling, is common in patients with persistent AF. Therefore, targeting the remodeled atrium is a critical issue during persistent AF ablation. However, ablation outcomes remain suboptimal despite aggressive substrate modification. Empirical linear ablation is not recommended because of the difficulty in achieving complete linear block and it is recommended only if macroreentry tachycardia develops during the procedure. Complex fractionated atrial electrogram (CFAE) ablation is recommended in the Heart Rhythm Society Consensus Document but efficacy has been limited in long-term follow-up studies. Rotor ablation is controversial. A combined approach using CFAE, similarity and phase mappings with rotor identification may be helpful in searching for AF sources and subsequent substrate ablation. Nevertheless, more prospective randomized studies are required to validate efficacy and safety.
Preview · Article · Jan 2016 · Circulation Journal
[Show abstract][Hide abstract] ABSTRACT: Background:
Atrial fibrillation (AF) can be associated with an increased risk of developing coronary artery disease (CAD) due to mechanisms of inflammation, endothelial dysfunction and adverse atrial remodelling. It is unclear if adverse coronary events can be further reduced after successful catheter ablation of AF. We hypothesise that AF ablation and sinus maintenance could reduce future adverse cardiac events in patients with underlying CAD.
A total of 310 patients with drug-refractory paroxysmal AF and prior history of percutaneous coronary intervention (PCI) for underlying CAD were recruited in the retrospective case control study. Of these, 155 patients underwent AF ablation (the Ablation Group), while 155 patients received medical treatment (the Medical Group). All patients were followed up for major adverse cardiac events, including acute coronary syndrome requiring hospitalisation, stroke, pulmonary embolism and mortality.
The clinical characteristics were comparable between the two groups, except for higher antiarrhythmic drug use in the Medical Group. During a follow-up duration of 61±32 months, all-cause mortality (8.4% vs. 1.3%, p=0.004) and the overall major adverse events (47.7% vs. 12.3%, p<0.001) were significantly higher in the Medical Group than the Ablation Group. There were also more instances of stroke (10.3% vs. 3.2%, p=0.013) and acute coronary syndrome requiring hospitalisation (29% vs. 7.1%, p<0.001) in the Medical Group than the Ablation Group. Multivariate analysis confirmed that non-ablation was an independent risk factor for major adverse events (p<0.001, HR 3.4, 95% confidence interval 1.9-5.9).
In PAF patients with established CAD who underwent PCI, catheter ablation could lead to fewer major adverse cardiac events compared to medical therapy.
No preview · Article · Jan 2016 · Heart, Lung and Circulation
[Show abstract][Hide abstract] ABSTRACT: Background:
The aim of this study was to investigate the different substrate characteristics of repetitive premature ventricular complexed (PVC) trigger sites by the non-contact mapping (NCM).
Thirty-five consecutive patients, including 14 with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC) and 21 with idiopathic right ventricular outflow tract tachycardia (RVOT VT), were enrolled for electrophysiological study and catheter ablation guided by the NCM. Substrate and electrogram (Eg) characteristics of the earliest activation (EA) and breakout (BO) sites of PVCs were investigated, and these were confirmed by successful PVC elimination.
Overall 35 dominant focal PVCs were identified. PVCs arose from the focal origins with preferential conduction, breakout, and spread to the whole right ventricle. The conduction time and distance from EA to BO site were both longer in the ARVC than the RVOT group. The conduction velocity was similar between the 2 groups. The negative deflection of local unipolar Eg at the EA site (EA slope3,5,10ms values) was steeper in the RVOT, compared to ARVC patients. The PVCs of ARVC occurred in the diseased substrate in the ARVC patients. More radiofrequency applications were required to eliminate the triggers in ARVC patients.
The substrate characteristics of PVC trigger may help to differentiate between idiopathic RVOT VT and ARVC. The slowing and slurred QS unipolar electrograms and longer distance from EA to BO in RVOT endocardium suggest that the triggers of ARVC may originate from mid- or sub-epicardial myocardium. More extensive ablation to the trigger site was required in order to create deeper lesions for a successful outcome.
[Show abstract][Hide abstract] ABSTRACT: Background:
Recent studies from Asia have suggested that the risk of ischemic stroke for patients with atrial fibrillation (AF) with a "low-risk" congestive heart failure, hypertension, age ≥75, diabetes mellitus, prior stroke or transient ischemic attack, vascular disease, age 65 to 74, female (CHA2DS2-VASc) score of 0 (for males) or 1 (for females) might be higher than that for non-Asians.
This study hypothesized that the age threshold (65 years) used in the CHA2DS2-VASc system for initiating oral anticoagulants (OACs) might be lower in Taiwanese AF patients than in non-Asians.
We used the National Health Insurance Research Database in Taiwan to study 186,570 nonanticoagulated AF patients. There were 9,416 males with a CHA2DS2-VASc score of 0 and 6,390 females with a CHA2DS2-VASc score of 1. Their risk of ischemic stroke was analyzed with stratification on the basis of age.
The annual risks of ischemic stroke for males (score 0) and females (score 1) were 1.15% and 1.12%, respectively, and continuously increased from younger to older age groups, with an increment in stroke risk evident for patients >50 years of age. At a cutoff of 50 years, patients could be further stratified into 2 subgroups with different stroke risks (>50 years of age: 1.78%/year; vs. <50 years of age: 0.53%/year). This observation was consistent for males (1.95%/year vs. 0.46%/year, respectively) and females (1.58%/year vs. 0.64%/year, respectively) with AF. In a subgroup analysis, the annual risks of ischemic stroke for males and females with AF 50 to 54 years of age were 1.47% and 1.07%, respectively.
For Taiwanese patients 50 to 64 years of age, the annual stroke risk was 1.78%, which may exceed the threshold for OAC use for stroke prevention. The annual risk of ischemic stroke for AF patients <50 years of age was 0.53%, which was truly low-risk, and OACs could be omitted. Whether resetting the age threshold to 50 years could refine current clinical risk stratification for Asian AF patients deserves further study.
No preview · Article · Sep 2015 · Journal of the American College of Cardiology
[Show abstract][Hide abstract] ABSTRACT: Background:
-Current American and European guidelines emphasized the importance of rate control treatments in treating atrial fibrillation (AF) with a Class I recommendation, although data about the survival benefits of rate control are lacking. The goal of the present study was to investigate whether patients receiving rate control drugs had a better prognosis compared to those without rate-control treatment.
Methods and results:
-This study used the "National Health Insurance Research Database" in Taiwan. There were 43,879, 18,466 and 38,898 AF patients enrolled in the groups of beta-blockers (BBs), calcium channel blockers (CCBs) and digoxin, respectively. The reference group consisted of 168,678 subjects who did not receive any rate-control drug. The clinical endpoint was all-cause mortality. During a follow-up of 4.9±3.7 years, mortality occurred in 88,263 patients (32.7%). After the adjustment for the baseline differences, the risk of mortality was lower in patients receiving BBs (adjusted hazard ratio [HR] = 0.76, 95% confidence interval [CI] = 0.74-0.78) and CCBs (adjusted HR = 0.93, 95% CI = 0.90-0.96) compared to those who did not receive rate-control medications. On the contrary, the digoxin group had a higher risk of mortality with an adjusted HR of 1.12 (95% CI = 1.10-1.14). The results were consistently observed in subgroup analyses and among the cohorts after propensity matching.
-In this nationwide AF cohort, the risk of mortality was lower for patients receiving rate-control treatments with BBs or CCBs, and the use of BBs was associated with a largest risk reduction. Digoxin use was associated with greater mortality. Prospective randomized trials are necessary to confirm these findings.
[Show abstract][Hide abstract] ABSTRACT: The recurrence of atrial fibrillation (AF) is not uncommon in the era of catheter ablation. This study aimed to evaluate the characteristics of AF patients who underwent multiple (>2) ablation procedures.
Of 666 consecutive patients (53 ± 11 y/o, 484 men) who underwent catheter ablation of AF (paroxysmal AF, n = 530), 144 (22%) underwent 2 procedures and 52 (8%) underwent more than 2 procedures due to symptomatic recurrences refractory to medication during 48 ± 23 months of follow-up. Baseline and procedural characteristics at the index procedure were investigated to determine their impact on the necessity of multiple procedures. After 2 procedures, 48 (92%) of 52 patients had pulmonary vein (PV) ectopic beats initiating AF. Coexisting PV and non-PV triggers were found in 23 of 48 patients. In a multivariate analysis, the presence of non-PV triggers (p = 0.004; odds ratio 2.69, 95% CI 1.37 to 5.28) at the index procedure was the only independent predictor of necessary multiple procedures. Among patients with non-PV ectopic beats initiating AF at the index procedure, the presence of ligament of Marshall triggers (p = 0.001, odds ratio 6.74, 95% CI 2.13 to 21.32) could predict the necessity of multiple procedures.
The need for multiple catheter ablation procedures can be predicted by the presence of non-PV ectopic beats initiating AF at the index procedure. However, PV-initiated AF remains the major cause of AF recurrence despite multiple catheter ablation procedures. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
No preview · Article · Jul 2015 · Journal of Cardiovascular Electrophysiology
[Show abstract][Hide abstract] ABSTRACT: Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an inherited genetic disease caused by defective desmosomal proteins, and it has typical histopathological features characterized by predominantly progressive fibro-fatty infiltration of the right ventricle. Clinical presentations of ARVD/C vary from syncope, progressive heart failure (HF), ventricular tachyarrhythmias, and sudden cardiac death (SCD). The 2010 modified Task Force criteria were established to facilitate the recognition and diagnosis of ARVD/C. An implantable cardiac defibrillator (ICD) remains to be the cornerstone in prevention of SCD in patients fulfilling the diagnosis of definite ARVD/C, especially among ARVD/C patients with syncope, hemodynamically unstable ventricular tachycardia (VT), ventricular fibrillation, and aborted SCD. Further risk stratification is clinically valuable in the management of patients with borderline or possible ARVD/C and mutation carriers of family members. However, given the entity of heterogeneous penetrance and non-uniform phenotypes, the standardization of clinical practice guidelines for at-risk individuals will be the next frontier to breakthrough.
No preview · Article · Mar 2015 · Journal of Cardiology
[Show abstract][Hide abstract] ABSTRACT: Ablations of atrial fibrillation (AF) have become more widely performed, and the strategy about long-term usage of oral anticoagulants (OACs) after catheter ablation is an important issue, especially for patients without obvious evidences of recurrences. The annual rate of thromboembolic (TE) event after catheter ablation was less than 1%. CHADS2 and CHA2DS2-VASc scores could be used to identify patients at the risk of TE events after ablations who should continue OACs regardless of the status of recurrence. Despite the improvement in understanding of AF and advancement of technology in catheter ablation, the long-term successful rates of paroxysmal and non-paroxysmal AF are around 50% and 30%, respectively. Patients with a high CHADS2 score are at a high risk of recurrence which could continuously occur after the catheter ablation without reaching a plateau. Among the patients with a CHADS2 score of ≥3, 26.9% of the recurrences happened 2 years post catheter ablation. Compared to the episodes of AF before catheter ablation, the AF episodes after ablation procedures are less symptomatic and shorter in duration. Therefore, it may not be safe to stop OACs for patients with a high risk score since the AF episodes are difficult to be detected after ablation procedures, but remain dangerous. In conclusion, the decision about the long-term strategy of OACs should be based on patients' baseline clinical risk scores, such as CHADS2 and CHA2DS2-VASc scores, rather than the status of recurrence.
No preview · Article · Feb 2015 · Journal of Thoracic Disease
[Show abstract][Hide abstract] ABSTRACT: Atrial fibrillation (AF) is the most common cardiac arrhythmia. However, the development of preventative therapies for AF has been disappointing. The infiltration of immune cells and proteins that mediate the inflammatory response in cardiac tissue and circulatory processes is associated with AF. Furthermore, the presence of inflammation in the heart or systemic circulation can predict the onset of AF and recurrence in the general population, as well as in patients after cardiac surgery, cardioversion, and catheter ablation. Mediators of the inflammatory response can alter atrial electrophysiology and structural substrates, thereby leading to increased vulnerability to AF. Inflammation also modulates calcium homeostasis and connexins, which are associated with triggers of AF and heterogeneous atrial conduction. Myolysis, cardiomyocyte apoptosis, and the activation of fibrotic pathways via fibroblasts, transforming growth factor-β and matrix metalloproteases are also mediated by inflammatory pathways, which can all contribute to structural remodelling of the atria. The development of thromboembolism, a detrimental complication of AF, is also associated with inflammatory activity. Understanding the complex pathophysiological processes and dynamic changes of AF-associated inflammation might help to identify specific anti-inflammatory strategies for the prevention of AF.
No preview · Article · Jan 2015 · Nature Reviews Cardiology
[Show abstract][Hide abstract] ABSTRACT: 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 Taiwan's 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.Kidney International advance online publication, 14 January 2015; doi:10.1038/ki.2014.393.
Preview · Article · Jan 2015 · Kidney International