HomeCirculation: Arrhythmia and ElectrophysiologyVol. 14, No. 10Interatrial Septal Fat Contributes to Interatrial Conduction Delay and Atrial Fibrillation Recurrence Following Ablation Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyRedditDiggEmail Jump toFree AccessLetterPDF/EPUBInteratrial Septal Fat Contributes to Interatrial Conduction Delay and Atrial Fibrillation Recurrence Following Ablation Rahul Samanta, MD, PhD, Christian P. Houbois, MD, Sophia Z. Massin, MSc, Michael Seidman, MD, PhD, Bernd J. Wintersperger, MD and Vijay S. Chauhan, MD Rahul SamantaRahul Samanta Division of Cardiology, Peter Munk Cardiac Centre, Toronto General Hospital, ON, Canada (R.S., S.Z.M., V.S.C.). , Christian P. HouboisChristian P. Houbois Joint Department of Medical Imaging, Toronto General Hospital, ON, Canada (C.P.H., B.J.W.). Department of Medical Imaging, University of Toronto, ON, Canada (C.P.H., B.J.W.). Institute for Diagnostic and Interventional Radiology, University Hospital, Cologne, Germany (C.P.H.). , Sophia Z. MassinSophia Z. Massin https://orcid.org/0000-0001-6611-4228 Division of Cardiology, Peter Munk Cardiac Centre, Toronto General Hospital, ON, Canada (R.S., S.Z.M., V.S.C.). , Michael SeidmanMichael Seidman https://orcid.org/0000-0002-9594-827X Laboratory Medicine Program, University Health Network and the Department of Laboratory Medicine and Pathobiology, University of Toronto (M.S.). , Bernd J. WinterspergerBernd J. Wintersperger https://orcid.org/0000-0001-5404-156X Joint Department of Medical Imaging, Toronto General Hospital, ON, Canada (C.P.H., B.J.W.). Department of Medical Imaging, University of Toronto, ON, Canada (C.P.H., B.J.W.). and Vijay S. ChauhanVijay S. Chauhan Correspondence to: Vijay Chauhan, MD, Gerrard Wing-3-522, Toronto General Hospital, 150 Gerrard St. W, Toronto, Ontario, Canada M5G 2C4. Email E-mail Address: [email protected] https://orcid.org/0000-0001-9264-5073 Division of Cardiology, Peter Munk Cardiac Centre, Toronto General Hospital, ON, Canada (R.S., S.Z.M., V.S.C.). Originally published29 Sep 2021https://doi.org/10.1161/CIRCEP.121.010235Circulation: Arrhythmia and Electrophysiology. 2021;14:e010235Obesity is growing epidemic and may contribute to the pathogenesis of atrial fibrillation (AF) by virtue of associated risk factors and modification of atrial substrate through epicardial fat infiltration and atrial fibrosis.1 Clinical studies have demonstrated an association between epicardial fat and AF burden as well as AF recurrence following catheter ablation.2 Epicardial fat is associated with localized conduction slowing and heterogeneity independent of the extent of atrial fibrosis.3 Interatrial septal (IAS) fat is an anatomic extension of epicardial fat and has been associated with AF; however, the mechanism has not been well defined. The quantification of IAS fat is not standardized with most clinical reports using IAS thickness as a surrogate measure of volume.4,5 Our aim was to evaluate the effect of IAS fat volume, IAS fibrosis, and epicardial fat volume on interatrial conduction in patients with AF undergoing pulmonary vein isolation, and to determine whether atrial arrhythmia recurrence postablation was associated with greater IAS fat volume.Patients with paroxysmal or persistent AF undergoing first-time pulmonary vein isolation were prospectively enrolled. ECG-synchronized, contrast-enhanced, cardiac computed tomography (CT) was performed with a 320-slice CT scanner (Aquilion ONE). High-resolution images were reconstructed with 1-mm slice thickness at 0.5 mm increments. IAS fat volume, IAS thickness, and epicardial fat volume were measured based on a density threshold for fat of −194 to −30 Hounsfield units.4,5 High-resolution, biatrial activation and bipolar voltage mapping were performed during high right atrial pacing at 750 ms using CARTO Confidence and a 20-electrode PentaRay catheter. Low-voltage, myopathic areas were defined based on local bipolar voltage <0.5 mV and expressed as a percentage of total atrial surface area after excluding the appendages, cava vein orifices, and valve orifices. To quantify IAS low-voltage, the sum of right and left septal low-voltage areas was divided by the sum of right and left septal areas and expressed as a percentage. Transseptal activation time was calculated as the difference in activation time between the earliest septal isochrone in the right atrium and the earliest septal isochrone in the left atrium (LA). P wave duration was measured from a 12-lead ECG during sinus rhythm. Following CT and biatrial mapping, pulmonary vein isolation was performed using a contact force-sensing catheter (Smartouch SF) and irrigated radiofrequency energy (25–35 W). Antiarrhythmic drugs were discontinued 3 months post-ablation. The clinical end point was atrial arrhythmia recurrence, including AF, flutter, or atrial tachycardia, for >30 seconds with or without antiarrhythmic drugs during 12 months prospective follow-up, excluding a 3-month blanking period. This study was approved by our IRB and study data are available upon reasonable request.Fifty-five patients were prospectively enrolled (age 57±12 years, 78% male, 33% persistent AF, LA volume 38±11 mL/m2). IAS fat volume was 1.5±1.1 mL, and the observer measurement variability was low (intraclass coefficient of variation, 0.91). Epicardial fat volume, IAS thickness, and IAS low-voltage area were 88±82 mL, 3.9±3.6 mm, and 9.3±2.8%, respectively. Global right atrium and LA low-voltage areas were 5.8±5.0% and 4.2±3.9%, respectively.IAS fat volume was greater in patients with obesity, hyperlipidemia, diabetes, and sleep apnea compared with those without these characteristics (P≤0.05). Body mass index correlated with IAS fat volume (Spearman r, 0.47; P<0.01), epicardial fat volume (r, 0.52; P<0.01), and IAS thickness (r, 0.46; P<0.01). IAS fat volume correlated with epicardial fat volume (r, 0.67; P<0.01). However, there was a weak correlation between IAS fat volume and IAS thickness (r, 0.31; P=0.04), and no correlation with IAS low-voltage areas. Furthermore, IAS fat volume correlated with transseptal activation time (r, 0.59; P<0.01), which is highlighted in the Figure for 2 representative patients. Epicardial fat volume also correlated with transseptal activation time (r, 0.48; P=0.02). In contrast, IAS thickness and IAS low-voltage area did not correlate with transseptal activation time. Patients with prolonged P wave ≥130 ms had greater IAS fat volume than those with P wave <130 ms (1.8±1.5 versus 0.9±0.7 mL, P=0.03), but there was no difference in epicardial fat volume, IAS thickness or IAS low-voltage area. On multivariable linear regression analysis, IAS fat volume (β=0.42, P=0.03) and LA low-voltage area (β=0.43, P=0.01) predicted P wave duration after adjusting for epicardial fat volume, IAS low-voltage area, IAS thickness, and LA volume index.Download figureDownload PowerPointFigure. Interatrial septum (IAS) fat volume assessed by multiplanar computed tomography (CT) and its relationship to IAS low-voltage area and transseptal activation time. Upper row shows 2 transverse (A and B) and 1 parasagittal (C) views of the IAS with segmented IAS fat highlighted in green (within selected threshold) in Patient 1 with low IAS fat volume (0.5 mL); (D) demonstrates the respective volume rendering of the segmented IAS fat in the anteroposterior view. Lower row (E–H) demonstrates similar orientations in Patient 2 with moderate IAS fat volume (3.0 mL). Below the CT images are shown the biatrial bipolar voltage maps and activation maps of the same 2 patients. Patient 1 has low IAS fat volume, but IAS low-voltage area is large (22%–34%). Despite this, transseptal activation time is normal at 10 ms. Patient 2 has moderate IAS fat volume, but minimal IAS low-voltage area (≤4%). Transseptal activation time is prolonged at 44 ms. LA indicates left atrium; and RA, right atrium.After 11±3 months follow-up, atrial arrhythmias recurred in 33% of patients. IAS fat volume (2.6±1.5 versus 1.5±1.4 mL, P=0.04) and LA volume index (43±10 versus 35±11 mL/m2, P=0.03) were greater in patients with atrial arrhythmia recurrence than those without, while epicardial fat volume (103±42 versus 82±31 mL, P=0.07) and LA low-voltage area (9.1±4.2 versus 4.2±5.4%, P=0.09) showed a trend toward being significantly different. In contrast, patients with and without atrial arrhythmia recurrence had similar IAS thickness.In summary, quantification of IAS fat volume using high-resolution CT provides novel insights into the relationship of IAS fat with abnormal atrial substrate, not apparent using IAS thickness. Visceral IAS fat is an extension of epicardial fat, which explains the associated with greater body mass index and epicardial fat. However, IAS fat is associated with prolonged transseptal conduction time and P wave duration independent of IAS low-voltage burden or epicardial fat. These findings may increase AF vulnerability in obese patients and heighten the risk of AF recurrence after pulmonary vein isolation, which warrants further study.Nonstandard Abbreviations and AcronymsCTcomputed tomographyIASinteratrial septumLAleft atriumSources of FundingThis study was supported by the Heart and Stroke Foundation of Ontario Career Award (MC 7577), the Heart and Stroke Foundation of Canada Grant-in-Aid (G-18-0022050), and the Pennycook Arrhythmia Research Fund to V.S. Chauhan.Disclosures None.Footnotes*B.J. Wintersperger and V.S. Chauhan contributed equally.For Sources of Funding and Disclosures, see page 967.Correspondence to: Vijay Chauhan, MD, Gerrard Wing-3-522, Toronto General Hospital, 150 Gerrard St. W, Toronto, Ontario, Canada M5G 2C4. Email vijay.[email protected]caReferences1. Samanta R, Pouliopoulos J, Thiagalingam A, Kovoor P. Role of adipose tissue in the pathogenesis of cardiac arrhythmias.Heart Rhythm. 2016; 13:311–320. doi: 10.1016/j.hrthm.2015.08.016CrossrefMedlineGoogle Scholar2. Wong CX, Ganesan AN, Selvanayagam JB. Epicardial fat and atrial fibrillation: current evidence, potential mechanisms, clinical implications, and future directions.Eur Heart J. 2017; 38:1294–1302. doi: 10.1093/eurheartj/ehw045MedlineGoogle Scholar3. Nalliah CJ, Bell JR, Raaijmakers AJA, Waddell HM, Wells SP, Bernasochi GB, Montgomery MK, Binny S, Watts T, Joshi SB, et al.. Epicardial adipose tissue accumulation confers atrial conduction abnormality.J Am Coll Cardiol. 2020; 76:1197–1211. doi: 10.1016/j.jacc.2020.07.017CrossrefMedlineGoogle Scholar4. Park YM, Park HC, Ban JE, Choi JI, Lim HE, Park SW, Kim YH. Interatrial septal thickness is associated with the extent of left atrial complex fractionated atrial electrograms and acute procedural outcome in patients with persistent atrial fibrillation.Europace. 2015; 17:1700–1707. doi: 10.1093/europace/euu403MedlineGoogle Scholar5. Hung CL, Yun CH, Lai YH, Sung KT, Bezerra HG, Kuo JY, Hou CJ, Chao TF, Bulwer BE, Yeh HI, et al.. An observational study of the association among interatrial adiposity by computed tomography measure, insulin resistance, and left atrial electromechanical disturbances in heart failure.Medicine (Baltimore). 2016; 95:e3912. doi: 10.1097/MD.0000000000003912CrossrefMedlineGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetails October 2021Vol 14, Issue 10Article InformationMetrics Download: 133 © 2021 American Heart Association, Inc.https://doi.org/10.1161/CIRCEP.121.010235PMID: 34583515 Originally publishedSeptember 29, 2021 Keywordsrisk factorsadipose tissuecatheter ablationobesityatrial fibrillationPDF download SubjectsClinical StudiesComputerized Tomography (CT)ElectrophysiologyCatheter Ablation and Implantable Cardioverter-DefibrillatorAtrial Fibrillation

Both fatty infiltration and fibrosis in the atrial free wall have been described in patients with atrial fibrillation (AF), which can be associated with prolonged P-wave duration. The relevance of interatrial septal fat (IAS) in AF is less well understood.

Background Obesity is associated with increased risk of cardiovascular disease. There is little known, however, about the influence of body mass index (BMI) on spontaneously occurring ventricular arrhythmias in patients with ischaemic heart disease. We sought to examine the effect of BMI on the ventricular arrhythmia (VA) recurrence and mortality in defibrillator recipients with ischaemic cardiomyopathy. Methods Consecutive patients (n = 123) with ischaemic cardiomyopathy (left ventricular ejection fraction (LVEF) <= 40%) and a primary or secondary prevention defibrillator were induded. Patients were classified according to their BMI as being normal (18.5-24.99, n =54/ 43.9%), overweight (2 -29.99, n =43/ 35%) or obese (>30, n = 26/20.3%). Results The primary combined endpoint of VA recurrence and mortality occurred in 36%, 5.4% and 11.5% of patients with normal, overweight and obese BMI (p = 0.001). When adjusting for risk factors such as ejection fraction, age and triple vessel disease, on multivariable analysis, normal BMI remained a significant predictor for the primary outcome (Hazard Ratio, Normal vs Overweight = 7.1, 95% CI 1.8-25, p = 0.002: Hazard Ratio, Normal vs Obese = 5.5, 95% CI 1.11-25, p = 0.033). There was a non-significant trend towards reduced survival in patients with normal weight in comparison to overweight and obese patients (p = 0.08). Conclusion In defibrillator recipients with ischaemic cardiomyopathy, BMI appears to be a significant predictor for the combined primary outcome of spontaneously occurring ventricular arrhythmias and mortality. Normal BMI, compared to overweight and obese patients had worse outcomes, suggesting the presence of the obesity paradox in ventricular arrhythrnogenesis late post infarction.

BACKGROUND:Left ventricular (LV) lead implantation for cardiac resynchronization therapy (CRT) may be confounded by contrast load during attempted cannulation and lead dislodgement during guiding catheter splitting. An LV lead implant system with a steerable single catheter that completely avoids the use of guiding catheters when needed, acquires atrioventricular electrograms, measures intracardiac pressures, permits CS angiography, and has the ability to direct a coronary angioplasty wire that will lead the final delivery of LV lead into a CS tributary, may help limit contrast use and avoid lead dislodgement at CS guide sheath removal.METHODS AND RESULTS:In this article as a proof of concept, we describe the use of this minimalist technique as a first line approach in six patients who had standard indications for CRT. The LV lead was successfully implanted in a target vein in all patients without acute complications. Contrast was not used in half the group and the LV lead was successfully implanted without guiding catheter in four patients. The implantation technique evolved through the series and in the final patient, no guiding sheath or contrast was used. Postimplant lead positions on chest X-ray and lead parameters were stable in all patients at follow-up.CONCLUSION:In proof of concept paper, we describe a technique of LV lead implantation potentially without the use of contrast and standard CS guiding catheters. Once familiar, this approach may provide a less complicated strategy.

Background Recent studies suggest an obesity paradox in individuals with myocardial infarction with better outcomes in obese relative to normal weight patients. We assessed the influence of body mass index (BMI) on early and long-term outcomes in patients with ST elevation myocardial infarction (STEW) and left ventricular (LV) dysfunction. Methods Outcomes were assessed according to BMI status in 478 consecutive patients with STEMI and LV dysfunction (ejection fraction [EF]<40%) admitted to Westmead Hospital between 1 January 2004 and 16 April 2014. Normal weight, overweight and obesity were defined as BMI < 25, 25-29.9, and >= 30 kg/m2, respectively. Results Obese patients were significantly younger (p = 0.01) and were more likely to have hypertension and diabetes (p = 0.04 and 0.001 respectively). In hospital outcomes and 30-day major adverse cardiac events (MACE) were similar in all three groups. There was no difference in recurrent myocardial infarction (MI) and target vessel revascularisation (TVR) during long-term follow-up (mean follow-up 809 days). Overall mortality following hospital discharge was significantly lower in overweight and obese patients. Adjusted hazard ratio for all-cause mortality in normal weight patients compared to overweight patients was 2.4 (95% C.I 1.1-5.3, p= -0.03). The adjusted hazard ratio for all-cause mortality in normal weight patients in comparison to obese patients was 2.7 (95% C.I, 1 -7.4, p = 0.05). Left ventricular ejection fraction (LVEF) and age were other predictors of all-cause mortality. Conclusions Normal weight, overweight and obese patients with STEMI and LV dysfunction had similar in hospital outcomes and 30-day outcomes. Long-term all-cause mortality was, however, higher in normal weight patients suggesting the presence of an obesity paradox in this cohort.

Patients with end-stage renal disease (ESRD) are predisposed to heart rhythm disorders resulting in significant morbidity and mortality. Bradyarrhythmia appears to be more prevalent than ventricular tachyarrhythmias. There is also a high incidence of sudden cardiac death (SCD) in this group of patients, which cannot be explained only by traditional cardiac risk factors. The reported incidence and prevalence of arrhythmias and SCD is quite variable mainly because of the different study populations and recording techniques. The mechanism of SCD in patients with ESRD is also not clear. Although traditionally the thinking has been that ventricular arrhythmias are the main contributor to SCD, recent studies with implantable loop recorders have highlighted the role of bradyarrhythmias. The pathophysiological processes resulting in arrhythmia and SCD in patients with ESRD are unique. Some of the risk factors, including dialysate composition, timing, and frequency, are modifiable and hence provide an option for interventions to potentially reduce SCD. In addition, there might be a relationship with the timing of dialysis with SCD tending to occur during the long interdialytic period. Patients with ESRD have a higher likelihood of requiring pacemaker implantation; however, they also have a higher risk of device-related complications. The limited data available regarding the role of the implantable cardioverter defibrillator to prevent SCD in patients with ESRD have shown conflicting results. Future research is needed to develop appropriate risk stratification tools to identify patients who will benefit from such interventions and to assess their safety and efficacy.

Background: There is limited data regarding long-term survival in patients who present with STEMI and out of hospital cardiac arrest (OHCA). Methods: We prospectively analysed outcomes in 3521 consecutive patients who were diagnosed with STEMI and underwent primary percutaneous coronary intervention (PPCI) or coronary artery bypass surgery from 2004 to 2017. They were divided into two groups according to the presence of cardiac arrest (group I, patients with cardiac arrest; n = 156 group II, patients without cardiac arrest; n = 3365). Results: Patients with OHCA had higher in hospital mortality (27.7% vs 2.9%, p < 0.01), sustained VT or VF (44.6% vs 4.3%, p < 0.01) and cardiogenic shock (22.9% vs 6.8%, p < 0.01). 30-day mortality (excluding death within first 24 h) was also higher in the OHCA group (24.6% vs 3.3%, p < 0.01). There was no significant difference in recurrent AMI, TVR, stroke, major bleeds or new onset heart failure. After a mean follow-up of 18.6 months, mortality was higher in patients with OHCA (7.9% vs 3.8%, p < 0.04). This was driven mainly by an increase in cardiac mortality (5% vs 1.1%, p < 0.01). OHCA was a significant predictor of mortality beyond 30 days (HR -2.5, 95% CI 0.99-6.3). Kaplan-Meier curves and the log-rank test revealed that patients with OHCA had significantly lower survival (p < 0.01). Conclusions: Patients with STEMI complicated by OHCA remain a high-risk group associated with high in hospital mortality. Beyond 30 days the occurrence of cardiac arrest was a significant predictor of all-cause and cardiac mortality. (c) 2018 The Authors. Published by Elsevier B.V.

Sotalol is a non-selective beta-adrenergic blocking agent without intrinsic sympathomimetic activity. It has the additional unique property of producing pronounced prolongation of the cardiac action potential duration. Sotalol therapy has been indicated for the management of supraventricular arrhythmias, refractory life threatening ventricular arrhythmias and atrial fibrillation/flutter. Until recently, sotalol was only available in the oral form, however, it was approved for intravenous administration by the US Food & Drug Administration (FDA). The current recommendations are for sotalol 75-150mg to be administered intravenously over 5hours. This rate of administration does not reflect the majority of the research that has been performed with regards to intravenous sotalol. Also, the safety of intravenous bolus dosing of 100mg over 1 and 5minutes has previously been demonstrated. The antiarrhythmic action of sotalol depends on its ability to prolong refractoriness in the nodal and extra nodal tissue. Hence, by giving a lower dose over a long duration, patients may not necessarily benefit from its anti-arrhythmic potential. The purpose of this article is to review the research that has been conducted with regards to dosage and safety of intravenous sotalol, its electrophysiological effects and finally the spectrum of arrhythmias in which it has been used to date.

Background: There is little known about the influence of obesity on ventricular electrical remodelling after myocardial infarction. The aim of our study was to assess the relationship between body mass index (BMI) and the primary outcome of inducible-VT and the secondary outcome of all-cause mortality in consecutive patients who presented with ST elevation myocardial infarction (STEMI) and LV-dysfunction (LVEF <= 40%). Methods and results: Consecutive patients (n = 380) with STEMI and LV-dysfunction (LVEF <= 40%) underwent electrophysiological (EP) studies for risk-stratification. Inducible-VT >= 200 ms cycle-length (CL) with one to four extra-stimuli (ES) was considered abnormal. Patients were classified according their body mass index (BMI) to be normal (18.5-24.9), overweight (25-29.9) or obese (>30). The primary outcome of inducible-VT occurred in 42.7%, 21.5% and 21% of normal weight, overweight and obese patients respectively (p < 0.001). When adjusting for ejection-fraction, hypertension and triple-vessel-disease, normal BMI remained a significant predictor for inducible-VT. All-cause mortality was higher in patients with normal weight (12.8%) when compared to overweight (3.2%) and obese (3.8%) patients (p = 0.002) and was mainly driven by increased cardiac-death (6.8%, 1.9% and 1.9% in normal, overweight and obese patients respectively, p = 0.05). After adjusting for age, EF, and hypertension, normal BMI remained a significant predictor of mortality. Conclusion: In patients presenting with STEMI and LV-dysfunction, BMI appears to be a significant predictor of inducible-VT and all-cause mortality, with worse outcomes for those with normal weight, when compared to overweight or obese individuals. These findings are consistent with the obesity-paradox. (c) 2018 Published by Elsevier B.V.

Background: Recent studies have demonstrated that intramyocardial adipose tissue (IMAT) may contribute to ventricular electrophysiological remodeling in patients with chronic myocardial infarction. Using an ovine model of myocardial infarction, we aimed to determine the influence of IMAT on scar tissue identification during endocardial contact mapping and optimal voltage-based mapping criteria for defining IMAT dense regions. Method and Results: In 7 sheep, left ventricular endocardial and transmural mapping was performed 84 weeks (15–111 weeks) post-myocardial infarction. Spearman rank correlation coefficient was used to assess the relationship between endocardial contact electrogram amplitude and histological composition of myocardium. Receiver operator characteristic curves were used to derive optimal electrogram thresholds for IMAT delineation during endocardial mapping and to describe the use of endocardial mapping for delineation of IMAT dense regions within scar. Endocardial electrogram amplitude correlated significantly with IMAT (unipolar r=−0.48±0.12, P<0.001; bipolar r=−0.45±0.22, P=0.04) but not collagen (unipolar r=−0.36±0.24, P=0.13; bipolar r=−0.43±0.31, P=0.16). IMAT dense regions of myocardium reliably identified using endocardial mapping with thresholds of <3.7 and <0.6 mV, respectively, for unipolar, bipolar, and combined modalities (single modality area under the curve=0.80, P<0.001; combined modality area under the curve=0.84, P<0.001). Unipolar mapping using optimal thresholding remained significantly reliable (area under the curve=0.76, P<0.001) during mapping of IMAT, confined to putative scar border zones (bipolar amplitude, 0.5–1.5 mV). Conclusions: These novel findings enhance our understanding of the confounding influence of IMAT on endocardial scar mapping. Combined bipolar and unipolar voltage mapping using optimal thresholds may be useful for delineating IMAT dense regions of myocardium, in postinfarct cardiomyopathy.

AIMS:Longer procedural time is associated with complications in radiofrequency atrial fibrillation ablation. We sought to reduce ablation time and thereby potentially reduce complications. The aim was to compare the dimensions and complications of 40 W/30 s setting to that of high-power ablations (50-80 W) for 5 s in the in vitro and in vivo models.METHODS AND RESULTS:In vitro ablations-40 W/30 s were compared with 40-80 W powers for 5 s. In vivo ablations-40 W/30 s were compared with 50-80 W powers for 5 s. All in vivo ablations were performed with 10 g contact force and 30 mL/min irrigation rate. Steam pops and depth of lung lesions identified post-mortem were noted as complications. A total of 72 lesions on the non-trabeculated part of right atrium were performed in 10 Ovine. All in vitro ablations except for the 40 W/5 s setting achieved the critical lesion depth of 2 mm. For in vivo ablations, all lesions were transmural, and the lesion depths for the settings of 40 W/30 s, 50 W/5 s, 60 W/5 s, 70 W/5 s, and 80 W/5 s were 2.2 ± 0.5, 2.3 ± 0.5, 2.1 ± 0.4, 2.0 ± 0.3, and 2.3 ± 0.7 mm, respectively. The lesion depths of short-duration ablations were similar to that of the conventional ablation. Steam pops occurred in the ablation settings of 40 W/30 s and 80 W/5 s in 8 and 11% of ablations, respectively. Complications were absent in short-duration ablations of 50 and 60 W.CONCLUSION:High-power, short-duration atrial ablation was as safe and effective as the conventional ablation. Compared with the conventional 40 W/30 s setting, 50 and 60 W ablation for 5 s achieved transmurality and had fewer complications.

Background The Magnetic Navigation System (MNS) catheter was shown to be stable in the presence of significant cardiac wall motion and delivered more effective lesions compared to manual control. This stability could potentially make AV junctional re-entrant tachycardia (AVNRT) ablation safer. The aim of this study is to describe the method of mapping and ablation of AVNRT with MNS and 3-D electro-anatomical mapping system (CARTO, Biosense Webster, Diamond bar, CA, USA) anatomical mapping, with a view to improve the safety of ablation. Methods The method of precise mapping and ablation with MNS is described. Consecutive AVNRT cases (n = 30) from 2012 January to 2015 November, in which magnetic navigation was used, are analysed. Results Ablation was successful in 27 (90%) out of 30 patients. In three cases, ablation was abandoned due to the proximity of the three-dimensional His image to the potential ablation site. No complications, including AV nodal injury, occurred. The distance from the nearest His position to successful ablation site in both LAO and RAO projections of CARTO images was 26.4 +/- 8.8 and 27 +/- 7.7 mm respectively. Only in two (9%) patients, ablation needed to be extended superior to the plane of coronary sinus ostium, towards the His bundle region, to achieve slow pathway modification. Conclusion AVNRT ablation with MNS allows for accurate mapping of the AV node and stable ablation at a safe distance, which could help avoid AV nodal injury. We recommend this modality for younger patients with AVNRT.

Aims:Remote magnetic navigation (RMN) is a safe and effective means of performing ventricular tachycardia (VT) ablation. It may have advantages over manual catheter ablation due to ease of manoeuvrability and catheter stability. We sought to compare the safety and efficacy of RMN vs. manual VT ablation.Methods and results:Retrospective study of procedural outcomes of 139 consecutive VT ablation procedures (69 RMN, 70 manual ablation) in 113 patients between 2009 and 2015 was performed. Remote magnetic navigation was associated with overall higher acute procedural success (80% vs. 60%, P = 0.01), with a trend to fewer major complications (3% vs. 9% P = 0.09). Seventy-nine patients were followed up for a median of 17.0 [interquartile range (IQR) 3.0-41.0] months for the RMN group and 15.5 (IQR 6.5-30.0) months for manual ablation group. In the ischaemic cardiomyopathy subgroup, RMN was associated with longer survival from the composite endpoint of VT recurrence leading to defibrillator shock, re-hospitalization or repeat catheter ablation and all-cause mortality; single-procedure adjusted hazard ratio (HR) 0.240 (95% CI 0.070-0.821) P = 0.023, multi-procedure HR 0.170 (95% CI 0.046-0.632) P = 0.002. In patients with implanted defibrillators, multi-procedure VT-free survival was superior with RMN, HR 0.199 (95% CI 0.060-0.657) P = 0.003.Conclusion:Remote magnetic navigation may improve clinical outcomes after catheter ablation of VT in patients with ischaemic cardiomyopathy. Further prospective clinical studies are required to confirm these findings.

Epicardial adipose tissue is present in normal healthy individuals. It is a unique fat depot that, under physiologic conditions, plays a cardioprotective role. However, excess epicardial adipose tissue has been shown to be associated with prevalence and severity of atrial fibrillation. In arrhythmogenic right ventricular cardiomyopathy and myotonic dystrophy, fibrofatty infiltration of the myocardium is associated with ventricular arrhythmias. In the ovine model of ischemic cardiomyopathy, the presence of intramyocardial adipose or lipomatous metaplasia has been associated with increased propensity to ventricular tachycardia. These observations suggest a role of adipose tissue in the pathogenesis of cardiac arrhythmias. In this article, we review the role of cardiac adipose tissue in various cardiac arrhythmias and discuss the possible pathophysiologic mechanisms.

A 67 year male was referred for an elective coronary angiogram after presenting with stable angina. Angiogram revealed an aberrant vessel arising from the right coronary artery dividing into two vessels one supplying the circumflex territory and the other supplying the LAD territory. There was a vestigial intermediate-like artery arising from a left coronary sinus. These findings were confirmed on CT coronary angiography. The patient was treated medically and remained well on one year's follow up. Lipton et al described the classification of single coronary artery. Shirani et al described a more comprehensive classification system. This case does not fit into the system described by Shirani et al It partially resembles Lipton sub class RII-A however the vestigial like intermediate makes this case unique. To our knowledge this variant has not been described before.

AIMS:To define the temporal characteristics of atrial lesion growth (lesion surface area), local electrogram amplitude attenuation, and circuit impedance decrement during in vivo radiofrequency (RF) ablation with direct endocardial visualization (DEV). METHODS AND RESULTS:A direct endocardial visualization catheter was used for real-time endoscopic visualization of atrial endocardial surface during RF ablation. Videos of lesion growth (surface area), circuit impedance, and local electrogram amplitude were recorded during ablation in 11 ovine. Fifty-two atrial ablations at 12 W, 14 W, and 16 W power for 30 seconds were analyzed. During 30-second RF ablation, the lesion matured (90% of final lesion dimension) in the first 23.0 ± 5.8 seconds. The local electrogram amplitude attenuation (80% decrement) and circuit impedance attenuation (20% decrement from initial) occurred 13.8 ± 8.2 seconds and 13.1 ± 7.9 seconds, respectively, before lesion maturity in a significant proportion of 30 second atrial ablations. CONCLUSION:The DEV observations suggest that in smooth atrial surface ablations with significant local electrogram and impedance decrement in the first 10 seconds, further extension of ablation for 10-15 seconds could deliver optimal surface dimensions; however, real-time measurement of depth was not possible.

Permanent pacemaker implantation via subclavian vein puncture is associated with a wide spectrum of complications. We describe a case of perforation of the left internal mammary artery (LIMA) Graft perforation as a complication of permanent pacemaker implantation and its successful treatment by percutaneous intervention. To our knowledge this is the first such case to be described in literature.

A 78 year-old female was admitted to hospital with abdominal pain. While in hospital she developed significant new 2 mm ST elevation in inferior leads and ST depression in antero lateral leads. Emergent coronary angiography (see Fig. 1A and B) revealed a single vessel originating from the right coronary sinus with a 60% stenosis at the origin. The right coronary artery was chronically occluded proximally. The aberrant artery coursed anteriorly and inferiorly around the right ventricle to reach the anterior interventricular sulcus. The vessel then branched superiorly and inferiorly to occupy the anatomic territory of the left anterior descending artery. After reaching the superior aspect of the anterior inter ventricular sulcus it then coursed laterally in the left atrioventricular groove thus occupying the anatomic territory of the left circumflex artery. The very distal left anterior descending artery had had a 90% stenosis. There was collateralisation from the left anterior descending artery to the right coronary artery. This described coronary artery anomaly was confirmed on CT coronary angiography (see Fig. 2A and B). She was referred for cardiovascular surgery but refused and opted for conservative management. Figure 2CT coronary angiogram demostrating single coronary artery arising from the right sinus of valsalva. RCA, right coronary artery; ACA, aberrant coursing artery; PA, pulmonary artery; LADE, left anterior descending equivelant; CE, circumflex equivelant. View Large Image Figure Viewer Download Hi-res image