Toon Wei Lim

Medium-Term Efficacy of Segmental Ostial Pulmonary Vein Isolation for the Treatment of Permanent and Persistent Atrial Fibrillation

Introduction: Previous studies suggest that segmental ostial isolation of the pulmonary veins for the treatment of patients with persistent and permanent atrial fibrillation is associated with a high rate of recurrence. Recurrence of atrial fibrillation is usually associated with electrical reconnection of the pulmonary veins to the left atrium.

Atrial arrhythmias after single-ring isolation of the posterior left atrium and pulmonary veins for atrial fibrillation: mechanisms and management.

Background—Single-ring isolation of the posterior left atrium is feasible, but the incidence and mechanisms of postprocedural arrhythmias have not been described in detail. Methods and Results—The first 100 consecutive patients (58.8±11.2 years old, 80 male) who underwent single-ring isolation for atrial fibrillation (66 intermittent, 18 persistent, 16 long-standing persistent) were followed up for 9.1±4.5 months. Recurrences were diagnosed by clinical symptoms and Holter monitoring. Patients with recurrences of sustained atrial arrhythmia >3 months after the procedure were offered a repeat procedure and were studied to determine the mechanisms of recurrence. Forty-six patients (46%) experienced sustained postprocedural atrial arrhythmias (35 had atrial fibrillation, and 34 had atrial flutter). Of these, 34 required a second procedure 7.0±3.1 months after their initial procedure. Reconnection of the posterior left atrium was seen in all patients with atrial fibrillation. Atrial flutter was most commonly due to mitral isthmus-dependent macroreentry (n=8, cycle length 368±116 ms) or macroreentry through 2 gaps in the ring of lesions (n=6, cycle length 328±115 ms). Posterior left atrium reisolation was achieved at the second procedure in all patients. Atrial flutter was successfully ablated and rendered noninducible in all patients. Six months after their last procedure, the Kaplan-Meier estimate of freedom from recurrence for all 100 patients was 81±5%. Conclusions—Atrial fibrillation and atrial flutter recurrence is common after single-ring isolation. Reconnection of the posterior left atrium and macroreentry are the common mechanisms. Repeat ablation results in satisfactory short-term outcomes.

Single-Ring Posterior Left Atrial (Box) Isolation Results in a Different Mode of Recurrence Compared With Wide Antral Pulmonary Vein Isolation on Long-Term Follow-Up Longer Atrial Fibrillation–Free Survival Time but Similar Survival Time Free of Any Atrial Arrhythmia

Background—Electric isolation of the pulmonary veins and posterior left atrium with a single ring of radiofrequency lesions (single-ring isolation [SRI]) may result in fewer atrial fibrillation (AF) recurrences than wide antral pulmonary vein isolation (wide antral isolation [WAI]) by abolishing extravenous AF triggers. The effect of mitral isthmus line (MIL) ablation on outcomes after SRI has not previously been assessed. Methods and Results—We randomly assigned 220 consecutive patients (58±10 years old; 82% men) with highly symptomatic AF (61% paroxysmal, 39% persistent/longstanding persistent) to undergo either SRI or WAI. Half of each cohort was also randomly allocated to have left lateral MIL ablation (2×2 factorial study design). Patients were followed clinically and with 7-day Holter studies for arrhythmia recurrences. The primary end points were recurrence of AF and organized atrial tachyarrhythmias. AF-free survival at 2 years was better after SRI (74% [95% CI, 65%–82%]) than WAI (61% [51%–70%]; P=0.031). Organized atrial tachyarrhythmia–free survival was similar after SRI and WAI (67% [57%–75%] ersus 64% [54%–72%], respectively, at 2 years; P=0.988). MIL ablation resulted in better 2-year organized atrial tachyarrhythmia–free survival (71% [62%–79%] versus 60% [50%–69%]; P=0.07), which approached statistical significance. Survival free of any atrial arrhythmia after one procedure was not significantly affected by isolation technique or MIL ablation. Conclusions—SRI resulted in fewer AF recurrences compared with WAI on long-term follow-up but did not reduce the recurrence of all atrial arrhythmias. MIL ablation may reduce organized atrial tachyarrhythmia recurrences. Clinical Trial Registration—http://www.anzctr.org.au; ACTRN12606000467538.

Vitamin K antagonist control in patients with atrial fibrillation in Asia compared with other regions of the world: Real-world data from the GARFIELD-AF registry ☆

OBJECTIVE To compare the distribution of international normalized ratios (INRs) in patients receiving vitamin K antagonist (VKA) for newly diagnosed atrial fibrillation in Eastern and Southeastern Asia and in other regions of the world (ORW) represented in the ongoing, global observational study GARFIELD-AF. METHODS AND RESULTS 3621 and 13,541 patients were recruited prospectively in 2010-2013 from Asia and ORW, respectively. At baseline, excluding patients with unknown antithrombotic treatment, 1356 (37.8%) in Asia and 7081 (53.3%) in ORW received VKA (±antiplatelets). INR readings during 1-year follow-up were analyzed for VKA-treated patients with ≥3 measurements (878 [64.7%] patients in Asia, 4452 [62.9%] in ORW). VKA-treated patients in Asia were younger than those in ORW (mean 67.1 vs 71.3years), with a lower CHA2DS2-VASc score (3.0 vs 3.5), but a similar HAS-BLED score (1.3 vs 1.4). Mean INR was lower in Asia than in ORW (2.0 vs 2.4). The proportion of time in the therapeutic range, defined using the multinational target of 2.0-3.0, was substantially lower in Asia (31.1% vs 54.1%). In Asia and ORW, 59.3% and 28.2% of INRs were <2, and 9.6% and 17.7% were >3, respectively. The same trend was found in different age groups (<65, 65-74, ≥75years). CONCLUSION GARFIELD-AF data demonstrate a difference in the distribution of INRs in patients from Asia versus other regions under current real-world practice. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362.

2017 consensus of the Asia Pacific Heart Rhythm Society on stroke prevention in atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia, causing a 2‐fold increase in mortality and a 5‐fold increase in stroke. The Asian population is rapidly aging, and in 2050, the estimated population with AF will reach 72 million, of whom 2.9 million may suffer from AF‐associated stroke. Therefore, stroke prevention in AF is an urgent issue in Asia. Many innovative advances in the management of AF‐associated stroke have emerged recently, including new scoring systems for predicting stroke and bleeding risks, the development of non‐vitamin K antagonist oral anticoagulants (NOACs), knowledge of their special benefits in Asians, and new techniques. The Asia Pacific Heart Rhythm Society (APHRS) aimed to update the available information, and appointed the Practice Guideline sub‐committee to write a consensus statement regarding stroke prevention in AF. The Practice Guidelines sub‐committee members comprehensively reviewed updated information on stroke prevention in AF, emphasizing data on NOACs from the Asia Pacific region, and summarized them in this 2017 Consensus of the Asia Pacific Heart Rhythm Society on Stroke Prevention in AF. This consensus includes details of the updated recommendations, along with their background and rationale, focusing on data from the Asia Pacific region. We hope this consensus can be a practical tool for cardiologists, neurologists, geriatricians, and general practitioners in this region. We fully realize that there are gaps, unaddressed questions, and many areas of uncertainty and debate in the current knowledge of AF, and the physician׳s decision remains the most important factor in the management of AF.

Clinical significance of early atrial arrhythmia type and timing after single ring isolation of the pulmonary veins

AIMS Early atrial arrhythmia following atrial fibrillation (AF) ablation is associated with higher recurrence rates. Few studies explore the impact of early AF (EAF) and atrial tachycardia (EAT) on long-term outcomes. Furthermore, EAF/EAT have not been characterized after wide pulmonary vein isolation. We aimed to characterize EAF and EAT and its impact on late AF (LAF) and AT (LAT) after single ring isolation (SRI). METHODS AND RESULTS We recruited 119 (females 21, age 58 ± 10 years) consecutive patients with AF (paroxysmal 76, persistent 43) undergoing SRI. Early atrial fibrillation/ early atrial tachycardia was defined as AF/AT within 3 months post-procedure (blanking period). Patients were followed for median 2.8[2.2-4] years. Early atrial fibrillation occurred in 28% (n = 33) and EAT in 25% (n = 30). At follow-up, 25% (n = 30) had LAF and 28% (n = 33) had LAT. Patients with EAF and EAT had higher rates of LAF (48 vs. 16%, P<0.0001) and LAT (60 vs. 16%, P < 0.0001), respectively. Independent predictors of LAF were EAF (3.53(1.72-7.29) P = 0.001); and of LAT were EAT (5.62(2.88-10.95) P < 0.0001) and procedure time (1.38/ h(1.07-1.78) P = 0.04). Importantly, EAF did not predict LAT and EAT did not predict LAF. Early atrial fibrillation late in the blanking period was associated with higher rates of LAF (73% for month 3 vs. 25% for Months 1-2, P = 0.004). However, EAT timing did not predict LAT. CONCLUSION Early atrial fibrillation and EAT are predictive of LAF and LAT, respectively. Early atrial fibrillation late in the blanking period has greater predictive significance for LAF. This timing is not relevant for LAT. Early arrhythmia type and timing have important prognostic significance following SRI. CLINICAL TRIAL REGISTRATION http://www.anzctr.org.au;ACTRN12606000467538.

High spatial resolution thermal mapping of radiofrequency ablation lesions using a novel thermochromic liquid crystal myocardial phantom.

Radiofrequency (RF) ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro ablation lesions.

Atrial Ectopy Predicts Late Recurrence of Atrial Fibrillation after Pulmonary Vein Isolation

Background—Late recurrence of atrial fibrillation (AF) after radiofrequency ablation remains significant. Asymptomatic recurrence poses a difficult clinical problem as it is associated with an equally increased risk of stroke and death compared with symptomatic AF events. Meta-analyses reveal that no single preablation patient characteristic efficiently predicts these AF recurrences. This study aimed to evaluate the prognostic value of premature atrial complex (PAC) occurrence with regard to the risk of late AF recurrence after radiofrequency ablation. Methods and Results—The study cohort consisted of 124 patients with 7-day Holter recordings at 6 months post radiofrequency ablation for AF. No patients had AF recurrence before this time. Patients were followed-up every 6 months. Holter-detected PACs were defined as any supraventricular complexes occurring >30% earlier than expected. During a median follow-up of 4.2 years (first quartile to third quartile [Q1–Q3]=1.6–4.5), 32 patients (26%) had late recurrences of AF at a median of 462 days (Q1–Q3=319–1026) post radiofrequency ablation. The number of PACs per 24 hours was 248 (Q1–Q3=62–1026) in patients with and 77 (Q1–Q3=24–448) in patients without recurrence of AF (P=0.02). Multivariate analysis of the risk of late AF recurrence found ≥142 PACs per 24 hours to have a hazard ratio 2.84 (confidence interval, 1.26–6.43), P=0.01. Conclusions—This study showed that occurrence of ≥142 PACs per day at 6 months after PVI was independently associated with a significantly increased risk of late AF recurrence. These results could have important clinical implications for the design of post-PVI follow-up. Clinical Trial Registration—URL: http://www.anzctr.org.au. Unique identifier: ACRTN12606000467538.

P-wave Measurements and Electrical Reconnection of the Posterior Left Atrium after Catheter Ablation for Atrial Fibrillation

Background: Recurrent atrial arrhythmias (RAAs) following posterior left atrial isolation (PLAI) for atrial fibrillation are common and are associated with reconnection of the PLA and pulmonary veins. We aimed to show that P‐wave duration (PWD) and P‐wave area under the curve (PWAUC) changes in patients undergoing PLAI can be measured using signal‐averaged electrocardiogram (SAECG), and that reversal of these changes in patients with RAAs can be used to noninvasively detect reconnection.

Percutaneous microwave ablation with a long side-firing antenna array can successfully treat a nonsurgical chronic ovine atrial flutter model.

Introduction: Long side‐firing microwave (MW) arrays can deliver energy uniformly over its length without the need for intimate endocardial contact. We hypothesize that a novel 6 Fr 20 mm long percutaneous high‐efficiency MW antenna array ablation catheter can rapidly create long, continuous, and transmural linear ablation lesions.