Wee Siong Teo

Characteristics of accessory pathways exhibiting decremental conduction

The prevalence, electrophysiologic characteristics and functional significance of decremental conduction over an accessory pathway were examined in this retrospective study of 653 patients who had an accessory pathway demonstrated at electrophysiologic study. Decremental conduction was identified in 50 patients (7.6%). In 15 patients with anterograde decremental conduction, the accessory pathway was right parietal or septal in 14 patients and left parietal in 1 patient. In the 40 patients with retrograde decrement, the accessory pathway was left parietal in 19, posteroseptal in 13, right parietal in 2 and right anteroseptal in 6 patients. Anterograde conduction over the accessory pathway was absent in 11 of the 40 patients with retrograde decrement. Retrograde conduction over the accessory pathway was absent in 9 patients with anterograde decrement. There was no significant difference in the accessory pathway effective refractory period, or shortest cycle length with 1:1 conduction over the accessory pathway in anterograde and retrograde directions. The shortest RR interval in atrial fibrillation between 2 preexcited QRS complexes was longer in patients with anterograde decremental conduction than in a control group of patients with anterograde-conducting accessory pathways without decremental properties. These data demonstrate that decremental conduction over accessory pathways is uncommon. Anterograde decremental conduction usually occurs in right-sided or septal pathways that often do not conduct in the retrograde direction.

Multiple accessory pathways in the Wolff-Parkinson-White syndrome as a risk factor for ventricular fibrillation

Abstract Ventricular fibrillation (VF) after atrial fibrillation is the mechanism of sudden death in most patients with Wolff-Parkinson-White (WPW) syndrome. 1–3 Initial data from Duke University 1 suggested that patients who had VF had a shortest RR interval between preexcited beats during atrial fibrillation 4 Several studies 1,5 have also noted the increased frequency of multiple accessory pathways in VF patients with WPW syndrome although other investigators 6 suggested that this was not the case. We sought to determine whether VF occurs more frequently in patients with multiple accessory pathways and whether multiple pathways may be considered as an additional risk factor for this complication.

Comparison of effectiveness of an 8-mm versus a 4-mm tip electrode catheter for radiofrequency ablation of typical atrial flutter

An 8-mm catheter does not appear superior to 4-mm tip electrode for atrial flutter ablation. The potential advantage of allowing higher energy delivery on a larger surface is compensated by the lack of consistent contact with the endocardial surface.

Epicardial mapping in patients with "nodoventricular" accessory pathways.

Some patients with electrophysiologic features suggesting nodoventricular fibers have been shown to have right parietal atrioventricular (AV) accessory pathways with decremental conduction properties intraoperatively. The experience with 11 patients (7 women and 4 men, mean age +/- standard deviation 25 +/- 5 years) who had electrophysiologic features consistent with a nodoventricular pathway and who underwent operative correction was reviewed. At electrophysiologic study, all patients had absent or minimal preexcitation in sinus rhythm. During atrial pacing and extrastimulus testing, maximal preexcitation with left bundle branch block morphology developed and the AH and AV intervals progressively prolonged. Preexcited tachycardia was initiated in all patients (AV reentrant tachycardia in 10 patients and AV node reentrant tachycardia in 1 patient). At operation all patients had a right parietal accessory pathway demonstrated. Intraoperative mapping demonstrated the earliest site of ventricular activation during anterograde preexcitation to be at the midanterior right ventricle, consistent with insertion of these pathways into the right bundle branch system, in 7 patients. The ventricular insertion was at the AV groove in 4 patients, in keeping with the typical Wolff-Parkinson-White syndrome. Retrograde conduction over the pathway was not demonstrated in any patient. Two patients had evidence of a second accessory AV pathway in the left paraseptal region. Operative AV node ablation was electively performed in 2 patients without affecting preexcitation in either case. In 1 of these patients, accessory pathway conduction was temporarily abolished by ice mapping in the right anterolateral AV groove.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial fibrillation management in Asia: From the Asian expert forum on atrial fibrillation

Atrial fibrillation (AF), the most common sustained cardiac arrhythmia, is associated with increased morbidity and mortality. AF has a slightly lower incidence and prevalence in Asian populations than in Western populations, but the associated relative risk of stroke and mortality is similar. Patients with AF in Asia have similar disease profiles and CHADS2 score distributions compared to those in the West, with the exception of a slightly higher prevalence of valvular heart diseases in Asia. Acute ventricular rate control should be the initial consideration in patients with AF and rapid ventricular rate. Anti-arrhythmic drugs have only a modest long-term effect on maintenance of sinus rhythm, and clinical trials in both the West and the East show that chronic rhythm control is not superior to chronic rate control in terms of cardiovascular outcomes, most likely because the benefit of anti-arrhythmic drugs in these trials was often offset by proarrhythmic effects. ECG-driven trials for AF should be replaced by outcome-driven ones. ATHENA is the largest outcome trial to confirm the superiority of a new anti-arrhythmic drug in improving cardiovascular outcomes. The choice of anti-arrhythmic drugs for AF should be based on both safety and efficacy in improving cardiovascular outcomes. For long-term rate control, a lenient strategy with a ventricular rate of less than 110bpm may be adequate, but more strict rate control may be required if patients continue to complain of symptoms. Catheter ablation should be reserved for patients who remain symptomatic despite optimal medical therapy.

Clinical markers of organ dysfunction associated with increased 1-year mortality post-implantable cardioverter defibrillator implantation

AIMS Guidelines from the ESC and ACC/AHA recommend implantable cardioverter defibrillators (ICDs) be implanted in clinically indicated patients with a reasonable expectation of >1 year survival. Our study aimed to assess if selected clinical markers of organ dysfunction were associated with increased 1-year mortality despite ICD therapy. METHODS AND RESULTS We retrospectively studied 283 patients with de novo ICDs implanted for primary or secondary prevention in ischaemic heart disease and dilated cardiomyopathy. We investigated the association of the following clinical markers of organ dysfunction with 1 year mortality: liver dysfunction (aspartate transaminase/alanine transaminase ≥ 3× upper limit of normal or prothrombin time/international normalized ratio ≥ 1.5 in the absence of anticoagulation), respiratory dysfunction (recent mechanical ventilation within 3 months prior to ICD implant), renal dysfunction (creatinine ≥150 µmol/L or glomerular filtration rate ≤ 30 mL/min/1.73 m(2)), anaemia (Hb ≤ 100 g/L), and prior cerebral vascular injury. With no organ dysfunction, 1 year mortality was 1.9%. In the presence of a single organ dysfunction, mortality was increased to 14.3%. With two or more markers of organ dysfunction mortality was 38.1% at 1 year (log-rank test P < 0.001). CONCLUSIONS Clinical markers of liver dysfunction, recent mechanical ventilation, and renal impairment were independently associated with increased 1 year mortality. Presence of more than one clinical marker of organ dysfunction was associated with significantly increased risk of mortality in our study.

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.

Significance of minimal preexcitation in Wolff-Parkinson-White syndrome.

Abstract The degree of preexcitation in the Wolff-ParkinsonWhite (WPW) syndrome depends on the relative degree of ventricular activation through the accessory pathway and the atrioventricular nodal system. A minimal preexcitation pattern may be related to rapid conduction over the normal atrioventricular conduction system, delayed intraatrial conduction to the atrial insertion of the accessory pathway, slower conduction over the accessory pathway, or a combination of these factors. We hypothesized that a minimal preexcitation pattern generally reflects a longer intraatrial conduction time and may be of value in localizing a pathway to the left lateral region. This study examined the incidence of minimal preexcitation pattern and its potential as an electrocardiographic pathway-localizing feature in patients with WPW syndrome.

A Unique Preexcitation Pattern Related to an Atypical Anteroseptal Accessory Pathway

Accessory atrioventricular pathways have traditionally been classified by anatomical Jocation to four areas, namely anteroseptal, posteroseptal, and right and left free walls. Each of these have been associated with a relatively distinct preexcitafion pattern electrocardiographically. We describe a patient with a unique EGG pattern suggesting preexcitation to the right ventricular outflow region, Preoperative and intraoperative electrophysioJogicaJ testing confirmed the presence of an accessory pathway with an atrial insertion site near the His bundle, decremental anterograde conduction, and a ventricular insertion site in the upper part of the interventricular septum. Operative ablation near the atrial insertion site eliminated preexcitation.

Remote monitoring of patients with cardiac implantable electronic devices: a Southeast Asian, single-centre pilot study.

INTRODUCTION Remote monitoring of cardiac implantable electronic devices (CIED) has been shown to improve patient safety and reduce in-office visits. We report our experience with remote monitoring via the Medtronic CareLink(®) network. METHODS Patients were followed up for six months with scheduled monthly remote monitoring transmissions in addition to routine in-office checks. The efficacy of remote monitoring was evaluated by recording compliance to transmissions, number of device alerts requiring intervention and time from transmission to review. Questionnaires were administered to evaluate the experiences of patients, physicians and medical technicians. RESULTS A total of 57 patients were enrolled; 16 (28.1%) had permanent pacemakers, 34 (59.6%) had implantable cardioverter defibrillators and 7 (12.3%) had cardiac resynchronisation therapy defibrillators. Overall, of 334 remote transmissions scheduled, 73.7% were on time, 14.5% were overdue and 11.8% were missed. 84.6% of wireless transmissions were on time, compared to 53.8% of non-wireless transmissions. Among all transmissions, 4.4% contained alerts for which physicians were informed and only 1.8% required intervention. 98.6% of remote transmissions were reviewed by the second working day. 73.2% of patients preferred remote monitoring. Physicians agreed that remote transmissions provided information equivalent to in-office checks 97.1% of the time. 77.8% of medical technicians felt that remote monitoring would help the hospital improve patient management. No adverse events were reported. CONCLUSION Remote monitoring of CIED is safe and feasible. It has possible benefits to patient safety through earlier detection of arrhythmias or device malfunction, permitting earlier intervention. Wireless remote monitoring, in particular, may improve compliance to device monitoring. Patients may prefer remote monitoring due to possible improvements in quality of life.