Atrial fibrillation burden: an update-the need for a CHA2DS2-VASc-AFBurden score.

Atrial fibrillation (AF) is an established independent risk factor for stroke. Current guidelines regard AF as binary; either present or absent, with the decision for anti-coagulation driven by clinical variables alone. However, there are increasing data to support a biological gradient of AF burden and stroke risk, both in clinical and non-clinical AF phenotypes. As such, this raises the concept of combining AF burden assessment with a clinical risk score to refine and individualize the assessment of stroke risk in AF-the CHA2DS2VASc-AFBurden score. We review the published data supporting a biological gradient to try and construct a putative schema of risk attributable to AF burden.

Multipolar mapping with the high-density grid catheter compared with conventional point-by-point mapping to guide catheter ablation for focal arrhythmias.

BACKGROUND: Multipolar catheters provide high-density mapping which may reduce the procedural duration and improve the success of catheter ablation (CA) for focal arrhythmias. The high-density grid (HDG) catheter is a 16 electrode mapping catheter with bipole recordings at orthogonal splines. The aim of this study is to compare the clinical and procedural features from a cohort who underwent CA for focal arrhythmias using multipolar mapping (MPM) with age and case-matched cohort using point-by-point (PbyP) mapping. METHODS: Consecutive patients undergoing CA for focal arrhythmias between October 2018 and January 2020 guided by MPM were compared with PbyP mapping with the ablation catheter over a similar period. Demographics, procedural features, and outcomes were compared. RESULTS: A total of 54 patients (27 in MPM vs. 27 in PbyP mapping) underwent CA for 68 focal arrhythmias (26 atrial and 42 ventricular). In the MPM group, the electrogram at the successful site was significantly earlier (39 ± 11 ms) than in the PbyP group (33 ± 7 ms; p = .02). In the MPM group, the mapping time (35 ± 24 vs. 53 ± 31 min in PbyP; p = .03) and procedural duration (126 ± 42 vs. 153 ± 39 min in PbyP; p = .02) were significantly shorter. There was no significant difference in radiofrequency and fluoroscopy times, acute procedural success, and arrhythmia recurrence. CONCLUSION: MPM with the HDG catheter for focal tachycardias identified earlier activation times and was associated with shorter mapping and procedure duration with equivalent success to PbyP mapping.

Endothelial dysfunction and glycocalyx shedding in heart failure: insights from patients receiving cardiac resynchronisation therapy.

To determine (a) whether chronic heart failure with reduced ejection fraction (HFrEF) is associated with increased glycocalyx shedding; (b) whether glycocalyx shedding in HFrEF with left ventricular dyssynchrony is related to inflammation, endothelial dysfunction and/or redox stress and is ameliorated by cardiac resynchronisation therapy. Glycocalyx shedding has been reported to be increased in heart failure and is a marker of increased mortality. Its role in dyssynchronous systolic heart failure and the effects of cardiac resynchronisation therapy (CRT) are largely unknown. Twenty-six patients with dyssynchronous HFrEF were evaluated before and 6 months after CRT insertion. Echocardiographic septal to posterior wall delay (SPWD) assessed intra-ventricular mechanical dyssynchrony, and quality of life, integrity of nitric oxide (NO) signalling, inflammatory and redox-related biomarkers were measured. Glycocalyx shedding was quantitated via plasma levels of the glycocalyx component, syndecan-1. Syndecan-1 levels pre-CRT were inversely correlated with LVEF (r = - 0.45, p = 0.02) and directly with SPWD (r = 0.44, p = 0.02), QOL (r = 0.39, p = 0.04), plasma NT-proBNP (r = 0.43, p = 0.02), and the inflammatory marker, symmetric dimethylarginine (SDMA) (r = 0.54, p = 0.003). On multivariate analysis, syndecan-1 levels were predicted by SPWD and SDMA (ß = 0.42, p = 0.009 and ß = 0.54, p = 0.001, respectively). No significant correlation was found between syndecan-1 levels and other markers of endothelial dysfunction/inflammatory activation. Following CRT there was no significant change in syndecan-1 levels. In patients with dyssynchronous HFrEF, markers of glycocalyx shedding are associated with the magnitude of mechanical dyssynchrony and elevation of SDMA levels and inversely with LVEF. However, CRT does not reverse this process.

Complications of cardiac implantable electronic device placement in public and private hospitals.

BACKGROUND: Few safety data exist comparing clinical outcomes in Australian public and private hospitals. We hypothesised that differences could exist between public and private hospitals due to differences in acuity and patient-level co-morbidities. AIMS: To report comparative complications of cardiac implantable electronic device (CIED) placement in public and private hospitals. METHODS: We conducted an observational cohort study of outcomes of patients aged >18 years from 2010 to 2015 undergoing a new permanent pacemaker (PPM), implantable cardioverter defibrillator (ICD) or cardiac resynchronisation therapy pacemaker or defibrillator (CRT-D/P) implant in NSW and Queensland public and private hospitals. The primary endpoint was major CIED-related complications occurring in-hospital or within 90 days of discharge. The independent effect of hospital sector was determined using multiple logistic regression, adjusting for covariates, including age, sex, co-morbidities and procedural acuity. RESULTS: A total of 32 364 new CIED implants (PPM 23 845, ICD 5361 and CRT-D/P 3158) were included (49% in private hospitals). Overall, 8.0% of private hospital procedures and 9.6% public hospital procedures experienced at least one complication. After adjustment, the overall risk of CIED complications was similar in private and public hospitals (OR: 0.92, 95% CI: 0.84-1.00, P = 0.06). In analysis of individual complications, adjusted all-cause in-hospital mortality was higher in private hospitals, (OR: 1.49, 95% CI: 1.03-2.16, P = 0.036) primarily driven by an excess mortality in acute cases. The adjusted risk of in-hospital generator operation (OR: 0.53, 95% CI: 0.30-0.94, P = 0.03) and post-discharge infection (OR: 0.61, 95% CI: 0.46-0.81, P < 0.001) was lower in private hospitals. CONCLUSIONS: These data identify important similarities and differences in safety outcomes of CIED implantation between Australian public and private hospitals.

Is Atrial Fibrillation a Stroke Risk Factor or Risk Marker? An Appraisal Using the Bradford Hill Framework for Causality.

Atrial fibrillation (AF) is strongly associated with stroke risk but association on its own does not necessarily imply causality. Is AF a cause (risk factor) of stroke? Would treatment that reduces AF burden also reduce the burden of stroke? Or, perhaps, AF is a risk marker associated with a vascular syndrome in which there is co-existing atrial structural and electrical remodelling that results in the clinical manifestation of AF and the risk of stroke in parallel. A number of recent studies appear to detach AF as a direct cause of stroke. Studies in which cardiac implantable devices have been used to collect AF data preceding stroke appear to show no immediate temporal relationship. The Global Anticoagulant Registry in the Field - Atrial Fibrillation (GARFIELD-AF) a large worldwide registry of non-valvular AF, has shown that the risk of death exceeds the risk of stroke and that mortality, together with stroke and bleeding risk, is predicted by other vascular risk factors, defined by the CHA2DS2VASc score. Sir Bradford Hill proposed criteria to assess whether two associated factors are causal, more than 50 years ago. This method of analysing cause and effect in a complex scenario could be applied to AF and stroke. This paper aims to clinically appraise the evidence for each criterion outlined by Bradford Hill to single out whether the collective data supports one or the other.

Transcatheter Transseptal Mitral Valve-in-Valve Replacement: An Early Australian Case Series and Literature Review.

BACKGROUND: Transcatheter mitral valve implantation for degenerated bioprostheses has recently emerged as an alternative to redo mitral valve surgery, particularly in patients at high risk for reoperative cardiac surgery. We sought to examine our early experience of transcatheter transseptal mitral valve-in-valve procedures. METHODS: Prospectively collected data was retrospectively reviewed in patients undergoing transcatheter transseptal mitral valve-in-valve implantation using the Edwards Sapien 3 balloon expandable bioprosthesis (Edwards Lifesciences, Irvine, CA, USA). RESULTS: Seven (7) patients underwent the procedure between December 2017 and November 2018. Three (3) patients were young Indigenous Australians (age range 33-41years) who were not suitable for mechanical prostheses; four patients were elderly (age range 82-92 years) and considered high risk for reoperative surgery. The median (maximum, minimum) EuroSCORE II of the group was 7.32 (4.81, 19.89). Procedural success was obtained in six of the seven patients; these six patients had no significant complications and had a median hospital stay of 3 days. In one patient, the device displaced towards the left ventricle on inflation, resulting in left ventricular outflow tract obstruction and haemodynamic instability. Urgent redo mitral valve surgery and explantation of the transcatheter prosthesis was undertaken, however, this patient died postoperatively of multi-organ failure. Of the successfully deployed valves, the median (maximum, minimum) gradient across the new mitral prosthesis was 5.5 mmHg (4, 7) and only one patient had mild mitral regurgitation, all others had no or trivial regurgitation. At 30 days, these six patients are well and all are in New York Heart Association (NYHA) Class I. CONCLUSIONS: Our early experience with transcatheter transseptal mitral valve-in-valve implantation demonstrates this procedure to be feasible in our institution with acceptable early results. Further follow-up is necessary to determine the longevity of valves implanted in this manner, especially in the younger population.

Clinical safety of the ProMRI implantable cardioverter-defibrillator systems during head and lower lumbar magnetic resonance imaging at 3 T: results of the ProMRI 3T ENHANCED Master study.

AIMS: There have been no published studies on the safety of magnetic resonance imaging (MRI) at 3 Tesla (3 T) in patients with MRI-conditional implantable cardioverter-defibrillators (ICDs). The aim of this study was to assess clinical safety of the Biotronik ProMRI ICD system during non-diagnostic head and lower lumbar scans under 3 T MRI conditions. METHODS AND RESULTS: The study enrolled 129 patients at 12 sites in Australia, Singapore, and Europe. Predefined head and lower lumbar MR scans (total duration ≈30 min) were performed in 112 patients. Three primary endpoints were evaluated from the pre-MRI to the 1-month post-MRI visit: (i) freedom from serious adverse device effects (SADEs) related to MRI (hypothesized to be >90%); (ii) pacing threshold invariance for all leads (geometric mean of the patient-wise ratios for 1 month vs. pre-MRI was hypothesized to be <1.07); and (iii) sensing amplitude invariance (geometric mean of the ratios was hypothesized to be >0.993). No MRI-related SADE occurred (SADE-free rate 100%, 95% confidence interval 95.98-100%). Pacing threshold and sensing amplitudes fulfilled the invariance hypotheses with high statistical significance (P < 0.0013). No threshold increase >0.5 V or sensing amplitude decrease by >50% was observed (secondary endpoints). Lead impedances, battery capacity, and detection and treatment of arrhythmias by ICDs were not affected by MRI scans. CONCLUSION: The head and lower lumbar scans under specific 3 T MRI conditions were safe in the investigated MR-conditional ICD systems. There was no evidence of harm to the patients or any negative influence of the MRI scan on the implanted systems.

Electrical remodelling post cardiac resynchronization therapy in patients with ischemic and non-ischemic heart failure.

BACKGROUND: The beneficial effects of cardiac resynchronization therapy (CRT) in heart failure are largely considered to be due to improved mechanical contractility. The contributory role of electrical remodelling is less clear. We sought to evaluate the impact of electrical remodelling in these patients. METHODS: 33 patients with conventional indications for CRT and with ischemic (ICM) (n = 17) and non-ischemic (NICM) (n = 16) aetiologies for heart failure were prospectively recruited. Functional parameters of peak exercise oxygen consumption (VO2max) and Minnesota quality of life (QOL) score, echocardiographic measures of LV functions and parameters of electrical remodelling, e.g. intrinsic QRS duration (iQRSD), intracardiac conduction times of LV pacing to RV electrocardiogram (LVp-RVegm), were measured at CRT implant and after 6 months. RESULTS: Only two electrical parameters predicted functional or symptomatic improvement. LVp-RVegm reduction significantly correlated with improvement in VO2max (r = -0.42, p = 0.03 while reduction in iQRSD significantly correlated with improvement in QOL score (r = 0.39, p = 0.04). The extent of changes in LVp-RVegm and iQRSD was significantly greater in NICM than in ICM patients (p = 0.017 and p = 0.042 for heterogeneity). There was also significant differential impact on QOL score in the NICM relative to the ICM group (p = 0.003) but none with VO2max. On multivariate analysis, only non-ischemic aetiology was a significant determinant of reduction in iQRSD. CONCLUSION: CRT induces potentially beneficial reduction in LVp-RVegm and iQRSD, which are seen selectively in NICM rather than ICM patients. The extent of improvement in these markers is associated with some functional and symptomatic measures of CRT efficacy.

Temporal stability and specificity of high bipolar electrogram entropy regions in sustained atrial fibrillation: Implications for mapping.

BACKGROUND: The potential utility of entropy (En) for atrial fibrillation (AF) mapping has been demonstrated in previous studies by multiple groups, where an association between high bipolar electrogram (EGM) entropy and the pivot of rotors has been shown. Though En is potentially attractive new approach to ablation, no studies have examined its temporal stability and specificity, which are critical to the application of entropy to clinical ablation. In the current study, we sought to objectively measure the temporal stability and specificity of bipolar EGM entropy in medium to long term recordings using three studies: i) a human basket catheter AF study, ii) a tachypaced sheep AF study and iii) a computer simulation study. OBJECTIVE: To characterize the temporal dynamics and specificity of Approximate, Sample and Shannon entropy (ApEn/SampEn/ShEn) in human (H), sheep (S), and computer simulated AF. METHODS: 64-electrode basket bi-atria sustained AF recordings (H:15 min; S:40 min) were separated into 5 s segments. ShEn/ApEn/SampEn were computed, and co-registered with NavX 3D maps. Temporal stability was determined in terms of: (i) global pattern stability of En and (ii) the relative stability the top 10% of En regions. To provide mechanistic insights into underlying mechanisms, stability characteristics were compared to models depicting various propagation patterns. To verify these results, cross-validation was performed across multiple En algorithms, across species, and compared with dominant frequency (DF) temporal characteristics. The specificity of En was also determined by looking at the association of En to rotors and areas of wave cross propagation. RESULTS: Episodes of AF were analysed (H:26 epochs, 6040 s; S:15 epochs, 14,160 s). The global pattern of En was temporally unstable (CV- H:13.42% ±â€¯4.58%; S:14.13% ±â€¯8.13%; Friedman- H: p > 0.001; S: p > 0.001). However, within this dynamic flux, the top 10% of ApEn/SampEn/ShEn regions were relatively temporally stable (Kappa >0.6) whilst the top 10% of DF regions were unstable (Kappa <0.06). In simulated AF scenarios, the experimental data were optimally reproduced in the context of an AF pattern with stable rotating waves surrounded by wavelet breakup (Kappa: 0.610; p < 0.0001). CONCLUSION: En shows global temporal instability, however within this dynamic flux, the top 10% regions exhibited relative temporal stability. This suggests that high En regions may be an appealing ablation target. Despite this, high En was associated with not just the pivot of rotors but also with areas of cross propagation, which suggests the need for future work before clinical application is possible.

Cardiovascular magnetic resonance-GUIDEd management of mild to moderate left ventricular systolic dysfunction (CMR GUIDE): Study protocol for a randomized controlled trial.

BACKGROUND: The majority of sudden cardiac death (SCD) in patients with heart failure occurs in those with mild-moderate left ventricular (LV) systolic dysfunction (LVEF 36-50%) who under current guidelines are ineligible for primary prevention implantable cardiac defibrillator (ICD) therapy. Recent data suggest that cardiac magnetic resonance (CMR) evidence of replacement fibrosis forms a substrate for malignant arrhythmia and therefore potentially identifies a subgroup at increased risk of SCD. Our hypothesis is that among patients with mild-moderate LV systolic dysfunction, a CMR-guided management strategy for ICD insertion based on the presence of scar or fibrosis is superior to a current strategy of standard care. METHODS/DESIGN: CMR GUIDE is a prospective, multicenter randomized control trial enrolling patients with mild-moderate LV systolic dysfunction and CMR evidence of fibrosis on optimal heart failure therapy. Participants will be randomized to receive either a primary prevention ICD or an implantable loop recorder (ILR). The primary endpoint is the time to SCD or hemodynamically significant ventricular arrhythmia (VF or VT) during an average 4-year follow-up. Secondary endpoints include quality of life assessed by Minnesota Living with Heart Failure Questionnaire, heart failure related hospitalizations, and a cost-utility analysis. Clinical trials.gov identifier NCT01918215. DISCUSSION: CMR GUIDE trial will add substantially to our understanding of the role of myocardial fibrosis and the risk of developing life-threatening ventricular arrhythmias. If the superiority of a CMR-guided approach over standard care is proven, it may change international clinical guidelines, with the potential to considerably increase survival in this growing patient population.

The impact of atrial fibrillation type on the risk of thromboembolism, mortality, and bleeding: a systematic review and meta-analysis.

AIMS: Thromboembolic risk stratification schemes and clinical guidelines for atrial fibrillation (AF) regard risk as independent of classification into paroxysmal (PAF) and non-paroxysmal atrial fibrillation (NPAF). The aim of the current study was to conduct a systematic review evaluating the impact of AF type on thromboembolism, bleeding, and mortality. METHODS AND RESULTS: PubMed was searched through 27 November 2014 for randomized controlled trials, cohort studies, and case series reporting prospectively collected clinical outcomes stratified by AF type. The incidence of thromboembolism, mortality, and bleeding was extracted. Atrial fibrillation clinical outcome data were extracted from 12 studies containing 99 996 patients. The unadjusted risk ratio (RR) for thromboembolism in NPAF vs. PAF was 1.355 (95% CI: 1.169-1.571, P < 0.001). In the study subset off oral anticoagulation, unadjusted RR was 1.689 (95% CI: 1.151-2.480, P = 0.007). The overall multivariable adjusted hazard ratio (HR) for thromboembolism was 1.384 (95% CI: 1.191-1.608, P < 0.001). The overall unadjusted RR for all-cause mortality was 1.462 (95% CI: 1.255-1.703, P < 0.001). Multivariable adjusted HR for all-cause mortality was 1.217 (95% CI: 1.085-1.365, P < 0.001). Rates of bleeding were similar, with unadjusted RR 1.00 (95% CI: 0.919-1.087, P = 0.994) and adjusted HR 1.025 (95% CI: 0.898-1.170, P = 0.715). CONCLUSION: Non-paroxysmal atrial fibrillation is associated with a highly significant increase in thromboembolism and death. These data suggest the need for new therapies to prevent AF progression and further studies to explore the integration of AF type into models of thromboembolic risk.

A Randomised Controlled Trial on the Effect of Nurse-Led Educational Intervention at the Time of Catheter Ablation for Atrial Fibrillation on Quality of Life, Symptom Severity and Rehospitalisation.

BACKGROUND: Atrial Fibrillation (AF) is a common condition associated with impaired quality of life (QOL) and recurrent hospitalisation. Catheter ablation for AF is a well-established treatment for symptomatic patients despite medical therapy. We sought to examine the effect of point specific nurse-led education on QOL, AF symptomatology and readmission rate post AF ablation. METHODS: Forty-one patients undergoing AF ablation were randomised to Nurse Intervention (NI) versus Control (C), n=22 vs. 19. Both groups were well matched with respect to age, sex and AF subtype. All patients completed SF36 and AF Symptom Checklist, Frequency and Severity Scale questionnaires at baseline and six months post ablation. The NI group underwent nurse education on admission, prior to discharge, and with telephone contact. RESULTS: Baseline SF-36 and AF Symptom Checklist, Frequency and Severity scores were similar. The NI group showed significant differences compared to Control with respect to higher QOL on the SF-36 score of Physical Functioning and Vitality at six months. There were significant improvements in seven components of the AF Symptom Checklist, Frequency and Severity at six months in the NI group with a trend in a further seven. There was no difference in AF related hospital readmissions at six months between C and NI groups (10.5% vs. 13.6%, p=ns). CONCLUSION: Nurse-led education at time of AF ablation is associated with improved QOL and reduced symptom frequency and severity compared to usual care.

Cardiac Implantable Electronic Devices and End-of-Life Care: An Australian Perspective.

Cardiac implantable electronic devices (pacemakers and defibrillators) are increasingly common in modern cardiology practice, and health professionals from a variety of specialties will encounter patients with such devices on a frequent basis. This article will focus on the subset of patients who may request, or be appropriate for, device deactivation and discuss the issues surrounding end-of-life decisions, along with the ethical and legal implications of device deactivation.

Condition-specific Streaming versus an Acuity-based Model of Cardiovascular Care: A Historically-controlled Quality Improvement Study Evaluating the Association with Early Clinical Events.

BACKGROUND: Ensuring optimal evidence translation is challenging when health-service design has not kept pace with developments in care. Differences in patient outcomes were evident when specific cardiac conditions were discordant with the subspecialty of the cardiologists managing their care. We prospectively explored the clinical and health service implications of a "condition-based" redesign in cardiac care delivery, rather than acuity-based, within a tertiary hospital. METHODS: Prospective evaluation of a disease-specific streaming model of care compared to propensity-matched historical controls, among cardiac patients admitted to a tertiary hospital cardiology unit was undertaken. The outcome measures of 30-day death, and readmission for myocardial infarction, cardiac arrhythmia, and heart failure were explored. RESULTS: In total, 2018 patients admitted subsequent to the implementation of the streaming model were compared with 1830 patients admitted prior. The median age was 68.9 years, and 39.5% were female. There was no significant difference in the overall proportion of patients admitted with an acute coronary syndrome, arrthythmia or heart failure, nor their Charlson index before and after streaming. Subsequent to the implementation, there was a reduction in the use of angiography (pre: 35.4% vs. post: 31.2%, p=0.007) and echocardiography (pre: 59.4% vs. post: 55.6%, p=0.007). A reduction in length of length-of-stay was observed in the entire cohort (pre: 2.7 (range: 1.2-5.0) days vs. post: 2.3 (range 1.0-4.5) days, p=0.0003). By 30 days, the propensity-adjusted hazard ratio for major adverse cardiac events and death or any cardiovascular admission was 0.76 (95% C.I. 0.59-0.97, p=0.026). CONCLUSION: Cardiac service redesign that streams cardiac patients by presenting diagnosis into teams designed to treat that condition may provide capacity and productivity gains for health services striving to improve outcome and efficiency.

Cardiac resynchronisation therapy in patients with atrioventricular nodal disease and reduced ejection fraction - can we afford it?

BACKGROUND: Recent pacing guidelines from the European Society of Cardiology recommend cardiac resynchronisation therapy (CRT) in patients with an atrioventricular (AV) nodal pacing indication and reduced ejection fraction (EF). However, concerns over added expenditure may limit its widespread implementation. We investigate the potential incremental cost of biventricular over right ventricular pacing if such a practice was adopted. METHODS: Retrospective analysis was performed of devices implanted over eight years. The database was analysed for device type, pacing indication and EF. Cost analysis was performed. RESULTS: 1751 devices were implanted over eight years at an averaged cost of AUD$1,369,125 per year. 172 with CRT were excluded. 25.4 (11.6%) patients per year had an EF≤50% and AV nodal disease. 18.4 were in sinus rhythm (SR) and 7.0 in atrial fibrillation (AF). Of these, 13.5 (6.2%) had EF≤45% (9.9 SR, 3.6 AF) and 8.2 (3.8%) had EF≤35% (5.6 SR, 2.6 AF). Based on an incremental cost of $4,000 per device, if all patients with EF≤50% received CRT, the total cost increment per year equates to $73,500 for SR patients or $101,500 if AF patients were included. In patients with EF≤35% and EF≤45%, this amounts to $22,500 and $39,500 per year for SR patients respectively or $33,000 and $54,000 per year if AF patients were included. Depending on the EF and rhythm, this represents a 1.6% to 7.4% increase per year in the pacing budget for an increased patient population of between 2.6% (EF≤35% in SR) to 11.6% (EF≤50%). CONCLUSION: A small proportion of additional patients will qualify for CRT based on the chosen cut-off and rhythm. Although the individual incremental cost for biventricular over right ventricular pacing is high in patients with AV nodal disease and reduced EF, overall this represents at most, a modest increase in the total pacing budget.

Assessment of oesophageal position by direct visualization with luminal contrast compared with segmentation from pre-acquired computed tomography scan-implications for ablation strategy.

AIMS: Atrio-oesophageal fistula is a rare but often fatal complication of catheter ablation for atrial fibrillation (AF). Various strategies are employed to evaluate the oesophageal position in relation to the posterior left atrium (LA). These include segmentation of the oesophagus from a pre-acquired computed tomography (CT) scan and direct, real-time assessment of the oesophageal position using contrast at the time of the procedure. METHODS AND RESULTS: One hundred and fourteen patients with drug-refractory AF underwent CT scanning prior to AF ablation. The LA and oesophagus were segmented from this scan. The oesophagus was deemed midline, ostial if it crossed directly behind any of the pulmonary vein (PV) ostia, or antral if it passed within 5 mm of a PV ostium. Under general anaesthesia at the time of ablation, the same patients were administered contrast via an oro-gastric tube to outline the oesophagus. Catheters were placed at the PV ostia and oesophageal position in relation to the PVs was established radiographically using a postero-anterior view. Oesophageal position assessed by real-time assessment correlated with the CT scan in only 59% of patients. In 34% the oesophagus was more right sided on direct visualization, while in 7% it was more left sided. CONCLUSION: Segmentation of the oesophagus from the CT scan did not correlate the real-time oesophageal position at the time of the procedure in over 40% of patients under general anaesthesia. Reliance on the determination of oesophageal position by previously acquired CT may be misleading at best and provide a false sense of security when ablating in the posterior LA.

Brugada ECG Pattern Unmasked by IV Flecainide in an Individual with Idiopathic Fascicular Ventricular Tachycardia.

A 45-year old man presents with stable monomorphic ventricular tachycardia. He had previously been diagnosed with idiopathic fascicular ventricular tachycardia. Intravenous flecainide results in termination of his tachycardia but unmasks a latent type 1 Brugada ECG pattern not seen on his resting ECG. We discuss his subsequent management and the need to consider an alternative diagnosis in individuals with a Brugada type ECG pattern who present with stable monomorphic ventricular tachycardia.

Vertebral artery dissection secondary to defibrillation threshold testing.

We report a case of vertebral artery dissection presenting 2 days after ICD implantation with defibrillation threshold testing in a 57-year-old man with ischemic cardiomyopathy. The association between vertebral artery dissection and neck trauma and the role of DFT testing in ICD implantation are discussed.

Tissue Doppler derived mechanical dyssynchrony does not change after cardiac resynchronization therapy.

BACKGROUND: Mechanical left ventricular (LV) dyssynchrony, as determined by tissue Doppler imaging (TDI), predicts response to cardiac resynchronization therapy (CRT). However, changes in TDI mechanical dyssynchrony after CRT implantation have only limited investigation. Our objective was to detect changes in the extent and location of TDI mechanical dyssynchrony pre- and post-CRT, and to explore their relationship in response to CRT. METHODS: Thirty-nine consecutive patients undergoing CRT implantation for chronic heart failure underwent TDI analysis pre-CRT and up to 12 months post-CRT. Regional dyssynchrony was determined by the time to systolic peak velocity of opposing LV walls. Dyssynchrony was defined as a difference in time to peak contraction of >105 msec. Two patients were excluded, as suitable coronary venous access was not available. RESULTS: Of the 37 patients, 28 (76%) had significant mechanical dyssynchrony pre-CRT. Of those with dyssynchrony, 18 (64%) had septal delay and 10 (36%) had LV free wall delay. Post-CRT, 29 (78%) patients had significant mechanical dyssynchrony, 17 (59%) with septal delay, and 12 (41%) with LV free wall delay. There was no difference in both the amount of dyssynchrony (P=0.8) or the location of the dyssynchrony (P=0.5), before and after CRT, even though 28 (76%) were considered responders based on symptomatic and echocardiographic parameters. CONCLUSION: The TDI-derived dyssynchrony does not change with CRT despite significant symptomatic and echocardiographic improvement in cardiac function. The TDI is of limited utility for monitoring response to CRT.