Ethanol ablation for ventricular arrhythmias: A systematic review and meta-analysis.

INTRODUCTION: Ethanol ablation (EA) is an alternative option for subjects with ventricular arrhythmias (VAs) refractory to conventional medical and ablative treatment. However, data on the efficacy and safety of EA remain sparse. METHODS: A systematic literature search was conducted. The primary outcomes were 1) freedom from the targeted VA and 2) freedom from any VAs post-EA. Additional safety outcomes were also analyzed. RESULTS: Ten studies were selected accounting for a population of 174 patients (62.3 ± 12.5 years, 94% male) undergoing 185 procedures. The overall acute success rate of EA was 72.4% (confidence interval [CI95% ]: 65.6-78.4). After a mean follow-up of 11.3 ± 5.5 months, the incidence of relapse of the targeted VA was 24.4% (CI95% : 17.1-32.8), while any VAs post-EA occurred in 41.3% (CI95% : 33.7-49.1). The overall incidence of procedural complications was 14.1% (CI95% : 9.8-19.8), with pericardial complications and complete atrioventricular block being the most frequent. An anterograde transarterial approach was associated with a higher rate of VA recurrences and complications compared to a retrograde transvenous route; however, differences in the baseline population characteristics and in the targeted ventricular areas should be accounted. CONCLUSION: EA is a valuable therapeutic option for VAs refractory to conventional treatment and can result in 1-year freedom from VA recurrence in 60%-75% of the patients. However, anatomical or technical challenges preclude acute success in almost 30% of the candidates and the rate of complication is not insignificant, highlighting the importance of well-informed patient selection. The certainty of the evidence is low, and further research is necessary.

Post-operative cardiac implantable electronic devices in patients undergoing cardiac surgery: a contemporary experience.

AIMS: Optimum timing of pacemaker implantation following cardiac surgery is a clinical challenge. European and American guidelines recommend observation, to assess recovery of atrioventricular block (AVB) (up to 7 days) and sinus node (5 days to weeks) after cardiac surgery. This study aims to determine rates of cardiac implantable electronic devices (CIEDs) implants post-surgery at a high-volume tertiary centre over 3 years. Implant timing, patient characteristics and outcomes at 6 months including pacemaker utilization were assessed. METHODS AND RESULTS: All cardiac operations (n = 5950) were screened for CIED implantation following surgery, during the same admission, from 2015 to 2018. Data collection included patient, operative, and device characteristics; pacing utilization and complications at 6 months. A total of 250 (4.2%) implants occurred; 232 (3.9%) for bradycardia. Advanced age, infective endocarditis, left ventricle systolic impairment, and valve surgery were independent predictors for CIED implants (P < 0.0001). Relative risk (RR) of CIED implants and proportion of AVB increased with valve numbers operated (single-triple) vs. non-valve surgery: RR 5.4 (95% CI 3.9-7.6)-21.0 (11.4-38.9) CIEDs. Follow-up pacing utilization data were available in 91%. Significant utilization occurred in 82% and underutilization (<1% A and V paced) in 18%. There were no significant differences comparing utilization rates in early (≤day 5 post-operatively) vs. late implants (P = 0.55). CONCLUSION: Multi-valve surgery has a particularly high incidence of CIED implants (14.9% double, 25.6% triple valve). Age, left ventricle systolic impairment, endocarditis, and valve surgery were independent predictors of CIED implants. Device underutilization was infrequent and uninfluenced by implant timing. Early implantation (≤5 days) should be considered in AVB post-multi-valve surgery.

Empowerment of athletes with cardiac disorders: a new paradigm.

Athletes with cardiac disorders frequently pose an ethical and medical dilemma to physicians assessing their eligibility to participate in sport. In recent decades, patient empowerment has been gaining increasing recognition in clinical decision-making. Empowerment is a process through which people are involved over the decisions and actions that affect their own lives. In the context of a cardiac disorder, empowerment means giving an athlete the chance to participate in the decision about whether or not to remain active in competition. Three models of treatment decision-making are described in this article, with progressive levels of empowerment: the paternalistic model (the athlete has a passive role), the shared-decision making model (both athlete and physician participate in the decision), and the informed-decision making (the decision is made by the athlete while the role of the physician is solely to provide information). This article critically discusses the issues involved in disqualification of athletes with cardiovascular disorders and suggests possible ways of incorporating patient empowerment in potentially career-ending decisions. The authors propose a model of empowerment, which gives patients the opportunity to choose how much, and if, they would like to be involved in the decision-making process.

Percutaneous left atrial appendage occlusion using different technologies in the United Kingdom: A multicenter registry.

OBJECTIVES: This study aimed at assessing the feasibility and long-term efficacy of left atrial appendage occlusion (LAAO) in a "real world" setting. BACKGROUND: Although LAAO has recently emerged as an alternative to oral anticoagulants in patients with atrial fibrillation for the prevention of thromboembolic stroke, "real world" data about the procedure with different devices are lacking. METHODS: Eight centers in the United Kingdom contributed to a retrospective registry for LAAO procedures undertaken between July 2009 and November 2014. RESULTS: A total of 371 patients (72.9 ± 8.3 years old, 88.9% males) were enrolled. The overall procedure success was 92.5%, with major events in 3.5% of cases. The device choice was Watchman in 63% of cases, Amplatzer Cardiac Plug in 34.7%, Lariat in 1.7%, and Coherex WaveCrest in 0.6%. A significant improvement in procedure success (from 89.2% to 95.7%; P = 0.018) and reduction of acute major complications (from 6.5% to 0.5%; P = 0.001) were observed between procedures in the first and the second half of the recruitment time. An annual 90.1% relative risk reduction (RRR) for ischemic stroke, an 87.2% thromboembolic events RRR, and a 92.9% major bleeding RRR were observed, if compared with the predicted annual risks based on CHADS2, CHA2DS2-Vasc, and HAS-BLED scores, respectively, over a follow-up period of 24.7 ± 16.07 months. CONCLUSIONS: LAAO can be performed safely in a real world setting with good implant success rates and procedural outcomes. The long-term benefits of the procedure are reassuring in terms of both ischemic events and avoidance of severe bleeding associated with anticoagulation in this patient group. © 2016 Wiley Periodicals, Inc.

Dual-site right ventricular pacing in patients undergoing cardiac resynchronization therapy: Results of a multicenter propensity-matched analysis.

BACKGROUND: Dual-site right ventricular pacing (Dual RV) has been proposed as an alternative for patients with heart failure undergoing cardiac resynchronization therapy (CRT) with a failure to deliver a coronary sinus (CS) lead. Only short-term hemodynamic and echocardiographic results of Dual RV are available. We aimed to assess the long-term results of Dual RV and its impact on survival. METHODS: Multicenter retrospective assessment of all CRT implants during a 12-year period. Patients with failed CS lead implantation, treated with Dual RV, were followed and assessed for the primary endpoint of all-cause mortality and/or heart transplant. A control group was obtained from contemporary patients using propensity matching for all available baseline variables. RESULTS: Ninety-three patients were implanted with Dual RV devices and compared with 93 matched controls. During a median of 1,273 days (interquartile range 557-2,218), intention-to-treat analysis showed that all-cause mortality and/or heart transplant was higher in the Dual RV group (adjusted hazard ratio [HR] = 1.66, 95% confidence interval [CI] 1.12-2.47, P = 0.012). As-treated analysis yielded similar results (HR = 1.97, 95% CI 1.31-2.96, P = 0.001). Cardiac device-related infections occurred seven times more frequently in the Dual RV site group (HR = 7.60, 95% CI 1.51-38.33, P = 0.014). Among Dual RV nonresponders, four had their apical leads switched off, five required an epicardial LV lead insertion, a transseptal LV lead was implanted in two, and in nine patients, after reviewing the CS venogram, a new CS lead insertion was successfully attempted. CONCLUSION: Dual RV pacing is associated with worse clinical outcomes and higher complication rates than conventional CRT.

Ventricular stimulus site influences dynamic dispersion of repolarization in the intact human heart.

The spatial variation in restitution properties in relation to varying stimulus site is poorly defined. This study aimed to investigate the effect of varying stimulus site on apicobasal and transmural activation time (AT), action potential duration (APD) and repolarization time (RT) during restitution studies in the intact human heart. Ten patients with structurally normal hearts, undergoing clinical electrophysiology studies, were enrolled. Decapolar catheters were placed apex to base in the endocardial right ventricle (RVendo) and left ventricle (LVendo), and an LV branch of the coronary sinus (LVepi) for transmural recording. S1-S2 restitution protocols were performed pacing RVendo apex, LVendo base, and LVepi base. Overall, 725 restitution curves were analyzed, 74% of slopes had a maximum slope of activation recovery interval (ARI) restitution (Smax) > 1 (P < 0.001); mean Smax = 1.76. APD was shorter in the LVepi compared with LVendo, regardless of pacing site (30-ms difference during RVendo pacing, 25-ms during LVendo, and 48-ms during LVepi; 50th quantile, P < 0.01). Basal LVepi pacing resulted in a significant transmural gradient of RT (77 ms, 50th quantile: P < 0.01), due to loss of negative transmural AT-APD coupling (mean slope 0.63 ± 0.3). No significant transmural gradient in RT was demonstrated during endocardial RV or LV pacing, with preserved negative transmural AT-APD coupling (mean slope -1.36 ± 1.9 and -0.71 ± 0.4, respectively). Steep ARI restitution slopes predominate in the normal ventricle and dynamic ARI; RT gradients exist that are modulated by the site of activation. Epicardial stimulation to initiate ventricular activation promotes significant transmural gradients of repolarization that could be proarrhythmic.

Ventricular Arrhythmia Burden in Patients With Heart Failure and Cardiac Resynchronization Devices: The Importance of Renal Function.

BACKGROUND: Chronic kidney disease (CKD) is a risk factor for arrhythmias in patients with heart failure (HF). However, the effects of CKD on ventricular arrhythmia (VA) burden in patients with cardiac resynchronization therapy and defibrillator (CRT-D) devices in a primary prevention setting are unknown. OBJECTIVE: To determine whether baseline CKD is associated with increased risk of VA in patients implanted with primary prevention CRT-D devices. METHODS AND RESULTS: In this retrospective study, 199 consecutive primary prevention CRT-D recipients (2005-2010) were stratified by estimated glomerular filtration rate (eGFR) levels prior to device implantation with 106 (53.2%) ≥CKD III (eGFR < 60 mL/min/1.73 m2 ) (CKD group). CKD group patients were significantly older (70.0 ± 10 years vs. 61.3 ± 12 years, P < 0.05) with higher prevalence of ischemic cardiomyopathy (56.2% vs. 40.2%, P < 0.05). Detected ventricular tachycardia (VT)/ventricular fibrillation (VF) episodes resulting in device therapy occurred significantly more frequently in the CKD group [40/106(37.8%)] than controls [24/93(25.8%)], (odd ratio [OR] = 1.74, 95% confidence interval [CI] = 1.01-3.2, P = 0.05). At 5-year follow-up, interval censored data analysis showed 41% VT/VF incidence in the CKD group compared to 24% incidence in controls (P < 0.05). Cox proportional hazards model identified CKD > III as the only predictor of sustained VA in this group (adjusted hazard ratio [HR] 2.92, CI = 1.39-6.1, P = 0.004). CONCLUSION: Baseline CKD is a strong independent risk factor for VA in primary prevention CRT-D recipients. Further understanding of the underlying arrhythmogenic mechanisms relating to CKD may be of interest to allow appropriate correction and prevention. Device programming in this cohort may need to reflect this increased risk.

An 8-year single-centre experience of cardiac resynchronisation therapy: procedural success, early and late complications, and left ventricular lead performance.

AIMS: Despite the increasing number of device implants worldwide, little is known about the early and late complications of cardiac resynchronisation therapy (CRT) or the incidence of these complications in patients with different heart failure aetiologies. We aim to determine procedural success and early and late complications in CRT patients. METHODS AND RESULTS: All early (<90 days) and late (>90 days) complications occurring over 490 consecutive CRT procedures in 402 patients, from a large single-centre registry between 2000 and 2009 were analysed. Mean follow-up duration was 1012 ± 610 days. In addition, procedural data and long-term left ventricular (LV) lead performance were examined. The mean age of patients was 65 ± 15 years, 31% were female. The majority of devices (70%) were CRT-defibrillators. Left ventricular lead implantation was achieved after one or more than one attempt in 96.7% of patients (first procedure was successful in 95.1%). The incidence of early and late complications was 9.4% and 6.1% respectively. Infection and lead displacement were the most common complications. Dilated cardiomyopathy (DCM) was associated with significantly more complications than ischaemic cardiomyopathy (P = 0.01) and these occurred later in the DCM population. Long-term LV lead performance was comparable with that of right atrial and ventricular leads. CONCLUSION: Transvenous implantation of the LV lead is safe and achievable for CRT with high procedural success rates. For the first time we describe the late complications from CRT in different heart failure populations. This group of patients must be kept under surveillance, not only for heart failure events but also for device-related issues. The reasons for higher complication rates in DCM patients require further evaluation.

An overview of heart rhythm disorders and management in myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is the most common adult form of muscular dystrophy, presenting with a constellation of systemic findings secondary to a CTG triplet expansion of the noncoding region of the DMPK gene. Cardiac involvement is frequent, with conduction disease and supraventricular and ventricular arrhythmias being the most prevalent cardiac manifestations, often developing from a young age. The development of cardiac arrhythmias has been linked to increased morbidity and mortality, with sudden cardiac death well described. Strategies to mitigate risk of arrhythmic death have been developed. In this review, we outline the current knowledge on the pathophysiology of rhythm abnormalities in patients with myotonic dystrophy and summarize available knowledge on arrhythmic risk stratification. We also review management strategies from an electrophysiological perspective, attempting to underline the substantial unmet need to address residual arrhythmic risks for this population.

Does adenosine response predict clinical recurrence of atrial fibrillation after pulmonary vein isolation?

BACKGROUND: Approximately 30% of patients undergoing pulmonary vein isolation (PVI) for atrial fibrillation (AF) have clinical recurrence of AF, and a great majority of these patients have recovery of vein conduction. Adenosine can be associated with acute recovery of conduction to the pulmonary veins immediately after isolation. However, it is not known whether this is prognostic for permanent recovery of conduction or recurrence of AF. METHODS: Patients with paroxysmal AF underwent PVI, with administration of adenosine after electrical isolation. Those with transient conduction recovery (TCR+) underwent no further ablation and were compared to those without (TCR-) for clinical AF recurrence and conduction recovery at second procedure. RESULTS: Seventy-two consecutive PVI patients were studied (mean age 56.7 ± 9.2, 61 male). Twenty-five (35%) patients had transient recovery of conduction with adenosine. After 1 year, 18 patients (25%) had symptomatic recurrence of AF. In this group of 18 patients, 6 were TCR+ at initial ablation (sensitivity 33%, NPV = 74%). In the remaining group of 54 patients free from AF recurrence, 35 patients (65%) were TCR- at initial ablation (specificity 65%, PPV = 24%). All 18 patients with recurrent AF underwent repeat procedure and had at least 1 pulmonary vein with recurrent conduction. The initial adenosine test correctly predicted 13 out of 36 (36%) veins, with positive predictive value 90% and negative predictive value 15%. CONCLUSIONS: Adenosine testing for TCR does not appear to predict recurrence of clinical AF. TCR- veins remain susceptible to conduction recovery, as determined at the follow-up procedure.

Predictors of recurrence following radiofrequency ablation for persistent atrial fibrillation.

AIMS: To establish clinical factors affecting success in persistent atrial fibrillation (AF) ablation. METHODS AND RESULTS: Wide area circumferential ablation with linear and electrogram-based left atrial (LA) ablation was performed in 191 consecutive patients for persistent AF. After mean follow-up of 13.0 ± 8.9 months, overall success was 64% requiring a mean of 1.5 procedures. Single procedure success rate was 32%. Left atrial size was a univariate predictor of recurrence after a single procedure (P =0.04). Only LA size [hazard ratio (HR) 1.05/mm with 95% confidential interval (CI) 1.02-1.08] was an independent predictor of recurrence after a single procedure. Only LA size was a univariate predictor of recurrence after multiple procedures (P < 0.01). Left atrial size (HR 1.07/mm with 95% CI 1.02-1.11) and hypertrophic cardiomyopathy (HCM; HR 2.42 with 95% CI 1.06-5.55) were independent predictors of recurrence after multiple procedures. Ablation strategy did not affect success after a single procedure. Left atrial size of <43 mm predicted long-term success with a sensitivity of 92%, specificity 52%, positive predictive value 49%, and negative predictive value 93%. With LA size >43 mm, HCM (HR 3.09 with 95% CI 1.70-7.5) and AF duration (HR 1.07/year with 95% CI 1.00-1.13) were independent predictors of recurrence. CONCLUSION: Left atrial size is the major independent determinant of AF recurrence after ablation for persistent AF. This has important implications for patient selection for persistent AF ablation and the evaluation of AF ablation clinical trial results.

The use of a novel nitinol guidewire to facilitate transseptal puncture and left atrial catheterization for catheter ablation procedures.

AIMS: An increasing number of transseptal punctures (TSPs) are performed worldwide for atrial ablations. Transseptal punctures can be complex and can be associated with potentially life threatening complications. The purpose of the study was to evaluate the safety and efficacy of a novel transseptal guidewire (TSGW) designed to facilitate TSPs. METHODS AND RESULTS: Transseptal punctures were performed using a SafeSept TSGW passed through a standard TSP apparatus. Transseptal punctures were performed by standard technique with additional use of a TSGW allowing probing of the interatrial septum without needle exposure and penetration of the fossa into the left atrium (LA). Transseptal puncture using the TSGW was performed in 210 patients. Left atrial access was achieved successfully in 205 of 210 patients (97.6%) and in 96.3% of patients undergoing repeat TSP. Left atrial access was achieved with the first pass in 81.2% (mean 1.4 ± 0.9 passes, range 1-6) using the TSGW. No serious complications were attributable to the use of the TSGW, even in cases of failed TSP. CONCLUSIONS: The TSGW is associated with a high success rate for TSP and may be a useful alternative to transoesophageal or intracardiac echocardiogram-guided TSP.

A Normal Electrocardiogram Does Not Exclude Infra-Hisian Conduction Disease in Patients With Myotonic Dystrophy Type 1.

OBJECTIVES: This study aimed to identify electrocardiographic (ECG) predictors of a prolonged His-ventricular (HV) interval in patients with type 1 myotonic dystrophy (DM1). BACKGROUND: Patients with DM1 have an increased risk of sudden cardiac death. The presence of His-Purkinje system disease/prolonged HV interval (≥70 ms) is associated with a higher risk of potentially life-threatening bradyarrhythmic events. METHODS: Electrophysiology studies (EPSs) were performed in all DM1 patients referred to 2 tertiary centers for routine cardiac assessment. In a subgroup of patients, the EPS was repeated at varying intervals. RESULTS: A total of 154 patients (mean age: 43.7 ± 13.3; 58.1% male) underwent 202 diagnostic EPSs. HV ≥70 ms was found on 58 EPSs (28.7%); 9 of 59 patients (15.2%) with PR <200 ms and QRS interval <110 ms on baseline ECG had an HV ≥70 ms on EPS. Among those with PR ≥200 ms and/or QRS interval ≥100 ms, only 33.9% had an HV ≥70 ms on EPS. There were 38 patients who underwent repeated EPS, in which 28.8% demonstrated a prolongation of the HV interval overall compared with baseline. QRS duration demonstrated the most powerful discriminative capacity for HV ≥70 ms (area under the receiver operating characteristic curve: 0.76; 95% confidence interval [CI]: 0.68 to 0.84; p < 0.001). On multivariate analysis, QRS interval ≥112 ms had the highest predictive value for HV ≥70 ms (odds ratio: 7.94; 95% CI: 3.85 to 16.37. CONCLUSIONS: ECG parameters have a poor predictive value for infra-Hisian conduction block in DM1 patients. QRS and PR intervals are normal in up to 15.2% of DM1 patients with prolonged HV, and 66.1% of those with PR ≥200 ms and/or QRS ≥100 ms do not have advanced His-Purkinje conduction system disease on EPS. Electrophysiology testing should be a mandatory part of screening for all patients to guide prophylactic pacemaker implantation.

Incidence of left atrial thrombus prior to atrial fibrillation ablation: is pre-procedural transoesophageal echocardiography mandatory?

AIMS: The exact role of transoesphageal echo (TOE) prior to atrial fibrillation (AF) ablation remains unclear. This study examines the incidence and predictors of left atrial (LA) thrombus in patients undergoing AF ablation. METHODS AND RESULTS: Patients were treated with warfarin for at least 4 weeks prior to ablation. This was substituted with therapeutic dalteparin 3 days before the procedure. All patients underwent TOE to exclude LA thrombus. Six clinical risk factors for thrombus were defined, known to be risk factors for stroke in AF: age>75, diabetes, hypertension, valve disease, prior stroke, or transient ischaemic attack and cardiomyopathy. A total of 635 procedures were performed. The incidence of thrombus was 12/635 (1.9%) despite therapeutic anti-coagulation. Patients with thrombus had larger LA diameter, mean 50.6+/-6.2 mm vs. 44.2+/-7.6 (P=0.006). In univariate analysis, persistent AF [odds ratio (OR)=10.4 with 95% CI 1.8-19.1], hypertension [OR=11.7 with 95% CI 2.5-54.1], age>75 (OR=4.5 with 95% CI 1.2-17.2), and cardiomyopathy (OR 5.9 with 95% CI 1.8-19.1) were significantly associated with thrombus. In multivariate analysis, hypertension (OR=14.2 with 95% CI 2.6-77.5), age>75 (OR=8.1, 95% CI 1.5-44.9), and cardiomyopathy (OR=10.5 with 95% CI 2.6-77.5) were independently associated with thrombus. There was no thrombus in patients without clinical risk factors. CONCLUSION: In patients presenting for AF ablation, LA thrombus is only seen in those with clinical risk factors. TOE is indicated in this group but may be unnecessary in patients without clinical risk factors.

Effect of tricuspid regurgitation and right ventricular dysfunction on long-term mortality in patients undergoing cardiac devices implantation: >10-year follow-up study.

BACKGROUND: The long-term effect of tricuspid regurgitation (TR) after device implantation on long-term mortality remains unknown. In the present study, we sought to examine whether patients undergoing an implantable cardiac device procedure (pacemaker, cardiac defibrillator or cardiac resynchronisation therapy) have an increased risk of TR and to determine the effect of this on long-term survival. METHODS: A total of 304 patients who underwent device implant and had pre- and post-implant transthoracic echocardiogram were included in the analysis. All-cause mortality was the study endpoint over a follow-up period of median 11.6 years. RESULTS: New ≥ moderate tricuspid regurgitation post-device implantation developed in 66/304 (21.7%) patients. New right ventricular dysfunction post-device implantation occurred in 59/304 (19.4%) patients. Independent predictors of new RV dysfunction were ischaemic heart disease (OR 4.23, 95% CI 1.58 - 11.33, p = 0.004), left ventricular impairment (OR 2.74, 95% CI 5.41 - 30.00, p < 0.0001) and new ≥ moderate TR (OR 7.72, 95% CI 3.27 - 18.23, p < 0.001). Independent predictors of mortality were new ≥ moderate TR [HR: 3.14 (95% CI 1.29 - 7.63) p = 0.01] and new RV impairment [HR: 2.82 (95% CI 1.33 - 5.98) p = 0.01. CONCLUSIONS: Worsening TR and RV dysfunction post-device implantation is common. New post-implant ≥ moderate TR is associated with increased risk of new RV impairment and poor long term (>10 years) survival.

Differences in the upslope of the precordial body surface ECG T wave reflect right to left dispersion of repolarization in the intact human heart.

BACKGROUND: The relationship between the surface electrocardiogram (ECG) T wave to intracardiac repolarization is poorly understood. OBJECTIVE: The purpose of this study was to examine the association between intracardiac ventricular repolarization and the T wave on the body surface ECG (SECGTW). METHODS: Ten patients with a normal heart (age 35 ± 15 years; 6 men) were studied. Decapolar electrophysiological catheters were placed in the right ventricle (RV) and lateral left ventricle (LV) to record in an apicobasal orientation and in the lateral LV branch of the coronary sinus (CS) for transmural recording. Each catheter (CS, LV, RV) was sequentially paced using an S1-S2 restitution protocol. Intracardiac repolarization time and apicobasal, RV-LV, and transmural repolarization dispersion were correlated with the SECGTW, and a total of 23,946 T waves analyzed. RESULTS: RV endocardial repolarization occurred on the upslope of lead V1, V2, and V3 SECGTW, with sensitivity of 0.89, 0.91, and 0.84 and specificity of 0.67, 0.68, and 0.65, respectively. LV basal endocardial, epicardial, and mid-endocardial repolarization occurred on the upslope of leads V6 and I, with sensitivity of 0.79 and 0.8 and specificity of 0.66 and 0.67, respectively. Differences between the end of the upslope in V1, V2, and V3 vs V6 strongly correlated with right to left dispersion of repolarization (intraclass correlation coefficient 0.81, 0.83, and 0.85, respectively; P <.001). Poor association between the T wave and apicobasal and transmural dispersion of repolarization was seen. CONCLUSION: The precordial SECGTW reflects regional repolarization differences between right and left heart. These findings have important implications for accurately identifying biomarkers of arrhythmogenic risk in disease.

The use of a single chamber leadless pacemaker for the treatment of cardioinhibitory vasovagal syncope.

BACKGROUND: The use of pacemakers in the treatment of cardioinhibitory vasovagal syncope is controversial with a mixed message from the limited evidence base. Single chamber leadless pacemakers have been shown to be an effective alternative option to conventional pacemakers. OBJECTIVE: This study examines the use of leadless pacemakers in a cardioinhibitory vasovagal population in the United Kingdom. METHODS: Observational data on 32 patients implanted with the Micra Transcatheter Pacemaker System for vasovagal syncope are presented. Data was collected on implant indications, implant procedure and follow up data from 12 centres across the United Kingdom that had elected to use a Micra leadless pacemaker in this patient population. RESULTS: 32 patients aged 37 ±â€¯14 years (range 18 to 64 years) with 62% of the patients being female were recruited to the study. Vasovagal syncope was diagnosed clinically and with the support of Holter monitoring, tilt table testing and implantable loop recorders. The duration of symptoms was 8 ±â€¯8 yrs. with an average frequency of syncope being 4 ±â€¯6 times/year. The Micra pacemaker was successfully implanted in all patients with a major complication rate of 3.1%. Patients were followed up for 404 ±â€¯237 days (range 63-928 days). At follow up 28 (87%) patients were free from symptoms. CONCLUSIONS: This observational study suggests that the use of a single chamber leadless pacemaker in the treatment of cardioinhibitory vasovagal syncope might be a reasonable clinical option.