Tachapong Ngarmukos

Prevention of Ventricular Fibrillation Episodes in Brugada Syndrome by Catheter Ablation Over the Anterior Right Ventricular Outflow Tract Epicardium

Background— The underlying electrophysiological mechanism that causes an abnormal ECG pattern and ventricular tachycardia/ventricular fibrillation (VT/VF) in patients with the Brugada syndrome (BrS) remains unelucidated. However, several studies have indicated that the right ventricular outflow tract (RVOT) is likely to be the site of electrophysiological substrate. We hypothesized that in patients with BrS who have frequent recurrent VF episodes, the substrate site is the RVOT, either over the epicardium or endocardium; abnormal electrograms would be identified at this location, which would serve as the target site for catheter ablation. Methods and Results— We studied 9 symptomatic patients with the BrS (all men; median age 38 years) who had recurrent VF episodes (median 4 episodes) per month, necessitating implantable cardioverter defibrillator discharge. Electroanatomic mapping of the right ventricle, both endocardially and epicardially, and epicardial mapping of the left ventricle were performed in all patients during sinus rhythm. All patients had typical type 1 Brugada ECG pattern and inducible VT/VF; they were found to have unique abnormal low voltage (0.94±0.79 mV), prolonged duration (132±48 ms), and fractionated late potentials (96±47 ms beyond QRS complex) clustering exclusively in the anterior aspect of the RVOT epicardium. Ablation at these sites rendered VT/VF noninducible (7 of 9 patients [78%]; 95% confidence interval, 0.40 to 0.97, P=0.015) and normalization of the Brugada ECG pattern in 89% (95% confidence interval, 0.52 to 0.99; P=0.008). Long-term outcomes (20±6 months) were excellent, with no recurrent VT/VF in all patients off medication (except 1 patient on amiodarone). Conclusions— The underlying electrophysiological mechanism in patients with BrS is delayed depolarization over the anterior aspect of the RVOT epicardium. Catheter ablation over this abnormal area results in normalization of the Brugada ECG pattern and prevents VT/VF, both during electrophysiological studies as well as spontaneous recurrent VT/VF episodes in patients with BrS.

Clinical outcomes of catheter substrate ablation for high-risk patients with atrial fibrillation.

OBJECTIVES The purpose of this study was to determine the long-term clinical outcomes of catheter ablation of atrial fibrillation (AF) substrate for high-risk patients with AF. BACKGROUND The benefits of catheter ablation for high-risk AF patients with respect to mortality and stroke reductions remain unclear. METHODS We performed AF substrate ablation guided by complex fractionated atrial electrogram (CFAE) mapping in 674 high-risk AF patients. The clinical end points were sinus rhythm (SR), death, stroke, or bleeding. Of these 674 patients, 635 were available for follow-up and made up the study cohort. The patients were relatively old (mean age 67 +/- 12 years) and 129 had an ejection fraction (EF) <40%. RESULTS After the mean follow-up period of 836 +/- 605 days, 517 were in SR (81.4%). There were 15 deaths among the patients who stayed in SR compared with 14 deaths among those who remained in AF (5-year survival rate, 92% vs. 64%, respectively; p < 0.0001). SR was the most important independent favorable parameter for survival (hazard ratio 0.14, 95% confidence interval 0.06 to 0.36, p < 0.0001), whereas old age was unfavorable. Warfarin therapy was discontinued in 434 of the 517 patients in SR post-ablation (84%) whose annual stroke rate was only 0.4% compared with 2% in those with continuing warfarin treatment (p = 0.004). CONCLUSIONS CFAE-targeted ablation of AF is effective in maintaining SR in selected high-risk AF patients and might allow patients to stop warfarin therapy. SR after AF ablation is a marker of relatively low mortality and stroke risk. Our findings support conducting further randomized studies to determine whether AF ablation is associated with mortality and/or stroke reduction.

Asian Sudden Cardiac Death in Heart Failure (ASIAN-HF) registry.

Our aim is to determine mortality and morbidity in Asian patients under clinical management for heart failure (HF). Specifically, we will define the incidence of, and risk factors for, sudden cardiac death, as well as the socio‐cultural factors influencing therapeutic choices in these patients.

Predictors of Sinus Rhythm after Radiofrequency Maze and Mitral Valve Surgery

The prevalence and predictors of postoperative sinus rhythm in patients undergoing a radiofrequency ablation maze operation and mitral valve surgery were assessed in 63 patients of whom 54 (86%) were in permanent atrial fibrillation. Operative mortality was 3.17%. At a median follow-up of 18 months, 54 (88.5%) patients were in sinus rhythm and 7 (11.5%) were in atrial fibrillation. The probability of sinus rhythm at 30 months was 92%. Left atrial diameter was the most significant prognostic factor for sinus rhythm on multivariate proportional-hazard regression analysis. The cutoff value of preoperative left atrial diameter for predicting persistent atrial fibrillation at 6 months was 6 cm (100% sensitivity and 73.6% specificity). The radiofrequency ablation maze operation can be performed in addition to mitral surgery with a high rate of successful conversion to sinus rhythm. Preoperative left atrial diameter < 6 cm is an important prognostic factor for sinus rhythm conversion.

A Prospective Randomized Study to Assess the Efficacy of Rate and Site of Atrial Pacing on Long-Term Development of Atrial Fibrillation

The Septal Pacing for Atrial Fibrillation Suppression Evaluation (SAFE) study is a single‐blinded, parallel randomized designed multicenter study in pacemaker indicated patients with paroxysmal atrial fibrillation (AF). The objective is to evaluate whether the site of atrial pacing–‐conventional right atrial appendage versus low atrial septal—with or without atrial overdrive pacing will influence the development of persistent AF. The study will provide a definitive answer to whether a different atrial pacing site or the use of AF suppression pacing or both can give incremental antiarrhythmic benefit when one is implanting a device for a patient with a history of paroxysmal AF.

Fragmented QRS as a Predictor of Appropriate Implantable Cardioverter-defibrillator Therapy.

Background Fragmented QRS (fQRS) has been shown to be a marker of local myocardial conduction abnormalities and a predictor of cardiac events in selected populations. We hypothesized that the presence of a fQRS might predict arrhythmic events in patients who received an implantable cardioverter-defibrillator (ICD), regardless of the indications for implantation. Methods and Results A cohort of 107 consecutive patients (mean age, 53 years; 82% male) who underwent an ICD implantation was studied. We defined fQRS, on a routine 12-lead ECG, as the presence of an additional R wave or notching in the nadir of the S wave in 2 consecutive leads corresponding to a major coronary artery territory. In the presence of bundle branch block, more than 2 notches in the R or S waves in 2 consecutive leads were required to characterize fQRS. Patients were followed for 21.3±23 months for appropriate ICD therapy (antitachycardia pacing and/or shock). ICDs were implanted predominantly in patients with ischemic cardiomyopathy (N=45, 42.1%), followed by Brugada syndrome (N=26, 24.3%). fQRS presented in 42 patients (39.3%). During follow-up, patients with fQRS received more appropriate ICD therapy than those without fQRS (45.2% vs. 10.8%, P<0.0001). After adjustment for covariates, fQRS remained an independent predictor for appropriate ICD therapy (hazard ratio=5.32, 95% confidence interval=2.11-13.37, P<0.0001). Conclusion The presence of fQRS appeared to be directly associated with appropriate ICD therapy.

Association of statin therapy with ventricular arrhythmias among patients with acute coronary syndrome

Background In addition to lowering cholesterol, statins stabilise atherosclerotic plaques and can potentially reduce the incidence of ventricular arrhythmias. We tested the hypothesis that prior statin therapy is associated with a lower incidence of inhospital ventricular arrhythmias among patients with acute coronary syndrome (ACS). Methods The study population consisted of 2007 patients (mean age 64 years, 67.5% male) enrolled in the Thai Registry of Acute Coronary Syndrome, a prospective, multicentre, nationwide, observational study of patients with ACS. Patients were categorised as either statin users or non-users according to their reports of statin use before enrolment at their initial presentation. The primary endpoint was inhospital ventricular arrhythmias. The secondary endpoint was a composite endpoint of inhospital ventricular arrhythmias or inhospital cardiac death. A propensity-adjusted multivariate model was developed to assess the effects of statin use on the primary and secondary endpoints. Results During a mean hospital stay of 7 days, a total of 96 patients (4.8%) died; 82 (4.1%) of the deaths were due to cardiac causes. The primary and secondary endpoints were reached in 163 patients (8.1%) and 194 patients (9.7%), respectively. A total of 525 patients (26.2%) had used statins prior to hospitalisation. After adjusting for the propensity scores and other relevant covariates, statin use was associated with lower risks of the primary (adjusted OR 0.505, 95% CI 0.276 to 0.923) and secondary endpoints (adjusted OR 0.498, 95% CI 0.276 to 0.897). Conclusions The use of statins is associated with a reduced incidence of ventricular arrhythmias among patients with ACS.

Heart failure with preserved ejection fraction in Asia: HFpEF in Asia

Heart failure with preserved ejection fraction (HFpEF) is a global public health problem. Unfortunately, little is known about HFpEF across Asia.

Prevalence, clinical correlates, and outcomes of anaemia in multi-ethnic Asian patients with heart failure with reduced ejection fraction: Anaemia in multi-ethnic Asian patients with heart failure with reduced ejection fraction

Recent international heart failure (HF) guidelines recognize anaemia as an important comorbidity contributing to poor outcomes in HF, based on data mainly from Western populations. We sought to determine the prevalence, clinical correlates, and prognostic impact of anaemia in patients with HF with reduced ejection fraction across Asia.

Disparity Between Indications for and Utilization of Implantable Cardioverter Defibrillators in Asian Patients With Heart Failure

Background— Implantable cardioverter defibrillators (ICDs) are lifesaving devices for patients with heart failure (HF) and reduced ejection fraction. However, utilization and determinants of ICD insertion in Asia are poorly defined. We determined the utilization, associations of ICD uptake, patient-perceived barriers to device therapy and, impact of ICDs on mortality in Asian patients with HF. Methods and Results— Using the prospective ASIAN-HF (Asian Sudden Cardiac Death in Heart Failure) registry, 5276 patients with symptomatic HF and reduced ejection fraction (HFrEF) from 11 Asian regions and across 3 income regions (high: Hong Kong, Japan, Korea, Singapore, and Taiwan; middle: China, Malaysia, and Thailand; and low: India, Indonesia, and Philippines) were studied. ICD utilization, clinical characteristics, as well as device perception and knowledge, were assessed at baseline among ICD-eligible patients (EF ⩽35% and New York Heart Association Class II-III). Patients were followed for the primary outcome of all-cause mortality. Among 3240 ICD-eligible patients (mean age 58.9±12.9 years, 79.1% men), 389 (12%) were ICD recipients. Utilization varied across Asia (from 1.5% in Indonesia to 52.5% in Japan) with a trend toward greater uptake in regions with government reimbursement for ICDs and lower out-of-pocket healthcare expenditure. ICD (versus non-ICD) recipients were more likely to be older (63±11 versus 58±13 year; P<0.001), have tertiary (versus ⩽primary) education (34.9% versus 18.1%; P<0.001) and be residing in a high (versus low) income region (64.5% versus 36.5%; P<0.001). Among 2000 ICD nonrecipients surveyed, 55% were either unaware of the benefits of, or needed more information on, device therapy. ICD implantation reduced risks of all-cause mortality (hazard ratio, 0.71; 95% confidence interval, 0.52–0.97) and sudden cardiac deaths (hazard ratio, 0.33; 95% confidence interval, 0.14–0.79) over a median follow-up of 417 days. Conclusions— ICDs reduce mortality risk, yet utilization in Asia is low; with disparity across geographic regions and socioeconomic status. Better patient education and targeted healthcare reforms in extending ICD reimbursement may improve access. Clinical Trial Registration— URL: https://clinicaltrials.gov/ct2/show/NCT01633398. Unique identifier: NCT01633398.