The functional and molecular imaging characteristics of ischemic ventricular tachycardia (VT) substrate are incompletely understood. Our objective was to compare regional 18F-FDG PET tracer uptake with detailed electroanatomic maps (EAMs) in a more extensive series of postinfarction VT patients to define the metabolic properties of VT substrate and successful ablation sites. Methods: Three-dimensional (3D) metabolic left ventricular reconstructions were created from perfusion-normalized 18F-FDG PET images in consecutive patients undergoing VT ablation. PET defects were classified as severe (defined as <50% uptake) or moderate (defined as 50%-70% uptake), as referenced to the maximal 17-segment uptake. Color-coded PET scar reconstructions were coregistered with corresponding high-resolution 3D EAMs, which were classified as indicating dense scarring (defined as voltage < 0.5 mV), normal myocardium (defined as voltage > 1.5 mV), or border zones (defined as voltage of 0.5-1.5 mV). Results: All 56 patients had ischemic cardiomyopathy (ejection fraction, 29% ± 12%). Severe PET defects were larger than dense scarring, at 63.0 ± 48.4 cm2 versus 13.8 ± 33.1 cm2 (P < 0.001). Similarly, moderate/severe PET defects (≤70%) were larger than areas with abnormal voltage (≤1.5 mV) measuring 105.1 ± 67.2 cm2 versus 56.2 ± 62.6 cm2 (P < 0.001). Analysis of bipolar voltage (23,389 mapping points) showed decreased voltage among severe PET defects (n = 10,364; 0.5 ± 0.3 mV) and moderate PET defects (n = 5,243; 1.5 ± 0.9 mV, P < 0.01), with normal voltage among normal PET areas (>70% uptake) (n = 7,782, 3.2 ± 1.3 mV, P < 0.001). Eighty-eight percent of VT channel or exit sites (n = 44) were metabolically abnormal (severe PET defect, 78%; moderate PET defect, 10%), whereas 12% (n = 6) were in PET-normal areas. Metabolic channels (n = 26) existed in 45% (n = 25) of patients, with an average length and width of 17.6 ± 12.5 mm and 10.3 ± 4.2 mm, respectively. Metabolic channels were oriented predominantly in the apex or base (86%), harboring VT channel or exit sites in 31%. Metabolic rapid-transition areas (>50% change in 18F-FDG tracer uptake/15 mm) were detected in 59% of cases (n = 33), colocalizing to VT channels or exit sites (15%) or near these sites (85%, 12.8 ± 8.5 mm). Metabolism-voltage mismatches in which there was a severe PET defect but voltage indicating normal myocardium were seen in 21% of patients (n = 12), 41% of whom were harboring VT channel or exit sites. Conclusion: Abnormal 18F-FDG uptake categories could be detected using incremental 3D step-up reconstructions. They predicted decreasing bipolar voltages and VT channel or exit sites in about 90% of cases. Additionally, functional imaging allowed detection of novel molecular tissue characteristics within the ischemic VT substrate such as metabolic channels, rapid-transition areas, and metabolism-voltage mismatches demonstrating intrasubstrate heterogeneity and providing possible targets for imaging-guided ablation.

AIMSAtrial fibrillation (AF) is the most common sustained arrhythmia and an important risk factor for stroke and heart failure. We aimed to conduct a systematic review of the literature and summarize the performance of mobile health (mHealth) devices in diagnosing and screening for AF.METHODS AND RESULTSWe conducted a systematic search of MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials. Forty-three studies met the inclusion criteria and were divided into two groups: 28 studies aimed at validating smart devices for AF diagnosis, and 15 studies used smart devices to screen for AF. Evaluated technologies included smartphones, with photoplethysmographic (PPG) pulse waveform measurement or accelerometer sensors, smartbands, external electrodes that can provide a smartphone single-lead electrocardiogram (iECG), such as AliveCor, Zenicor and MyDiagnostick, and earlobe monitor. The accuracy of these devices depended on the technology and the population, AliveCor and smartphone PPG sensors being the most frequent systems analysed. The iECG provided by AliveCor demonstrated a sensitivity and specificity between 66.7% and 98.5% and 99.4% and 99.0%, respectively. The PPG sensors detected AF with a sensitivity of 85.0-100% and a specificity of 93.5-99.0%. The incidence of newly diagnosed arrhythmia ranged from 0.12% in a healthy population to 8% among hospitalized patients.CONCLUSIONAlthough the evidence for clinical effectiveness is limited, these devices may be useful in detecting AF. While mHealth is growing in popularity, its clinical, economic, and policy implications merit further investigation. More head-to-head comparisons between mHealth and medical devices are needed to establish their comparative effectiveness.

Capítulo 14. Utilidad del mapeo tridimensional en la

BACKGROUND:Left ventricular (LV) lead implantation for CRT can be challenging. We describe the technique of wire externalisation to enable posterolateral (PL) LV lead placement and give case examples to illustrate its use. METHODS:The technique includes: The externalised guidewire provides excellent support for antegrade or retrograde advancement of the LV lead. RESULTS:Wire externalisation has been used to overcome PL branch tortuosity, persistent left SVC or acute angulation of the CS ostium. Antegrade delivery or retrograde delivery is possible but there may be an additional need for balloon angioplasty to facilitate lead advancement. There have been no complications at implant or 30-day follow-up. CONCLUSIONS:The wire externalisation technique can facilitate optimal LV lead placement in difficult CRT cases.

Catheter ablation for ventricular tachycardia (VT) in ischemic heart disease is considered standard therapy in patients with recurrent, sustained monomorphic ventricular tachycardia, usually after failed antiarrhythmic therapy. Many centers worldwide use pre-procedural imaging with cardiac magnetic

A 59-year-old woman with a non-ischaemic cardiomyopathy was bought forward for a cardiac resynchronization therapy defibrillator device. Coronary sinus venography revealed a single posterior-lateral target branch and left ventricular (LV) lead placement proved challenging with the only trackable lead (4 F unipolar) placed …

AIMS:Previous studies have reported the defibrillation testing during implantable cardioverter defibrillator (ICD) implantation is associated with elevated cardiac biomarkers and ST-segment electrocardiogram (ECG) changes suggesting that shocks during testing may cause harm. However, the effects of testing have not been isolated from the implant procedure itself, where lead deployment may cause myocardial damage. This prospective study examined high sensitivity troponin T (hs-TnT) levels and ECG changes during ICD implanting alone, ICD implantation with testing and device testing as a stand-alone procedure.METHODS AND RESULTS:We examined hs-TnT at baseline, and 6-8 h post procedure and 12 lead ECG at baseline, and 30 s, 5 min, and 10 min post right ventricle lead deployment and post defibrillation. There was no significant change in hs-TnT levels in a group of patients (n = 11) undergoing defibrillation testing alone, while hs-TnT was significantly elevated in patients undergoing implantation alone (n = 13, median increase 96%, P = 0.005) and in patients undergoing implantation and testing (n = 13, median increase 161%, P = 0.005). There was a significant correlation between the number of lead deployments and the percentage change in hs-TnT (r = -0.51, P = 0.01), but no correlation between either the number of shocks (r = 0.26, P = 0.25) or the total delivered energy (r = 0.24, P = 0.30) and percentage change in hs-TnT.CONCLUSION:Implantation of ICD leads was associated with release of troponin, but we did not observe any evidence that ICD shocks alone cause myocardial injury.

HomeCirculation: Arrhythmia and ElectrophysiologyVol. 8, No. 2Closing the Knowledge Gaps Free AccessEditorialPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessEditorialPDF/EPUBClosing the Knowledge Gaps Alejandro Jimenez, MD and Timm M. Dickfeld, MD, PhD Alejandro JimenezAlejandro Jimenez From the Heart and Vascular Institute, Cleveland Clinic Abu Dhabi, Abu Dhabi, United Arab Emirates (A.J.); and University of Maryland Medical Center, VA Baltimore and Maryland Arrhythmia and Cardiac Imaging Group (MACIG) (T.M.D.). and Timm M. DickfeldTimm M. Dickfeld From the Heart and Vascular Institute, Cleveland Clinic Abu Dhabi, Abu Dhabi, United Arab Emirates (A.J.); and University of Maryland Medical Center, VA Baltimore and Maryland Arrhythmia and Cardiac Imaging Group (MACIG) (T.M.D.). Originally published1 Apr 2015https://doi.org/10.1161/CIRCEP.115.002783Circulation: Arrhythmia and Electrophysiology. 2015;8:252–255Radiofrequency ablation for atrial fibrillation (AF) has become a widely accepted therapy, but despite technological and procedural advances, long-term freedom from AF remains modest.1 The most common approach is the electric isolation of pulmonary veins (PV) via circular ablation lines around the PV ostia or antra. In some centers, additional linear lesions are placed along the left atrial (LA) roof and mitral isthmus especially in patients with persistent AF. Despite successful acute PV isolation and conduction block along ablation lines, failure to maintain sinus rhythm is commonly seen during follow-up2. Mechanistically, electric PV reconnection represents the predominant cause for the ablation failure and has been reported in 54% to 71% of patients at 5-year follow-up.3,4 Reversible edema rather than permanent radiofrequency-induced tissue necrosis is thought to result in gaps within the ablation lines leading to PV reconnection.5 Indeed, tissue temperatures >45°C result in a marked decrease in conduction velocity and transient conduction block. However, full-tissue recovery occurs up to the heat-induced tissue necrosis during the course of 1 to 4 weeks.6 Identification of such gaps by noninvasive techniques, such as cardiac magnetic resonance imaging (CMR), would have high clinical utility.7–11Article see p 270In this issue, Harrison et al12 present data on 20 patients with a prior AF ablation who underwent a redo ablation because of recurrence of AF or atrial tachycardia. Index lesion sets consisted of wide area encirclement with optional stepwise CAFE (complex atrial fractionated electrogram) ablation and linear lesions along the LA roof, mitral, and cavotricuspid isthmus for persistent AF. End point of the repeat procedure was electric PV isolation and electrically confirmed block of any prior linear lesion set. A CMR was performed before the repeat ablation in all patients, but was unavailable to the treating electrophysiologist. After the repeat ablation, the point-by-point Carto 3 electroanatomical maps (averaging 342 points per LA) were coregistered with the 3-dimensional (3D) CMR reconstructed data sets using custom-made software. First, the investigators compared the unipolar/bipolar voltages of the resulting 6767 mapping points with the corresponding late gadolinium (LGE) signal intensities to assess the correlation between decreasing voltage and increasing CMR scar. They found a surprisingly weak correlation (weighted means of −0.17 to −0.21), even when including surrounding 2.5- and 5-mm LGE areas. Discouragingly, neither the traditionally used threshold of <0.05 mV nor the cut-off of <0.3 mV derived from animal work by the same investigators11 performed well in predicting CMR-defined scar. Second, the authors compared the mean and minimum LGE signal intensity along a 20-mm wide path of the prior linear ablation lesions around the PV antra, LA roof, and mitral isthmi. The mean signal intensity was analyzed as a measure of total scar burden, whereas the minimum signal intensity was measured to identify the weakest link within the line, representing the possible site of electric reconnection. At repeat ablation, 50% of the PVs and 36% of LA roof/mitral isthmus lines demonstrated electric reconnection. Neither the mean nor minimum LGE signal intensity was different between isolated/reconnected PVs or the blocked/unblocked linear lines. Interestingly, in the 13 PVs with a single discrete electric gap, the minimum LGE intensity correlated in only 1 case with the electric breakthrough site. Moreover, the average LGE intensity at the breakthrough sites was actually 4× higher than the measured minimum LGE signal.This carefully conducted study by Harrison et al12 highlights the challenges that still exist in the field of atrial ablation imaging. Since Peters et al13 first demonstrated the feasibility of LA scar imaging, a variety of publications have examined the clinical applicability of LA fibrosis imaging. However, attempts to detect conducting gaps by CMR have shown conflicting results (Table).Table. CMR Studies Assessing Lesion Gaps Post AF AblationStudyNo. of Patients (n)Atrial Scar Threshold (mV)LGE Threshold MethodScanner Type/Timing of Scan After First AblationLA Endocardial Mapping/Ablation MethodVoxel Size (mm3)ConclusionsHarrison et al1220<0.3 mVMinimum/mean LGE signal intensity in preablated areas of LA1.5T, 32-channel cardiac phased array coil/not specifiedPoint-by-point, >300 points per LA, 3.5-mm irrigated catheter1.3×1.3×4Poor correlation between LGE CMR and LA voltage (correlation coefficient of −0.17). LGE signal intensity at sites of PV reconnection was greater than the overall lower LGE signal intensity (3.08 vs 0.76)Bisbal et al715NA40±5 of the maximum voxel signal intensity in LA, derived from an automated pixel SI-based algorithm3.0T, 12-element phased array coil/15 mo postPoint-by-point, >800 points per LA, 3.5-mm irrigated contact sensing catheter1.4×1.4×1.4PV reconnection match of 79% between LGE CMR and LA voltage. Median voltage for LGE CMR scar areas was 0.21 mVSpragg et al810<0.5 mVVisually estimated LGE hyperenhancement1.5T, 12-channel phased array coil/16 mo postPoint-by-point, >100 points per LA, 3.5-mm irrigated catheter1.3×1.3×2Poor correlation between LGE CMR and LA voltage PV reconnections. Good correlation between LA voltage and LGE CMR scar (0.84). Mean LA voltage in LGE CMR scar areas was 0.39 mVBadger et al913<0.1 mVBimodal distribution of pixel intensity in the LA scar defined as 3 SD above normal mean tissue pixel intensity values1.5T, phased array coil/3 mo postPoint-by-point, >100 points per LA, 3.5-mm irrigated catheter1.25×1.25×2.5Positive quantitative correlation between LGE CMR and PV antral voltage scar (R 2=0.57). Qualitative correlation between gaps on LGE CMR and EAM in 7/7 patients after second AF ablationTaclas et al1019<0.05 mVVisually estimated LGE hyperenhancement and manually selected ROI (LA and PV ostia)1.5T, 5-element cardiac coil/3 mo postPoint-by-point, number of LA points not specified, 3.5-mm irrigated and 8-mm nonirrigated catheters1.3×1.3×4Visual quantitative correspondence between voltage map and LGE CMR post ablation of 80%. Qualitative good EAM/LGE CMR correlation for gap visualizationAF indicates atrial fibrillation; CMR, cardiac magnetic resonance imaging; EAM, electroanatomic mapping; LA, left atrial; LGE, late gadolinium; PV, pulmonary veins; and ROI, region of interest.Although LA scar imaging developed as an extension of the well-established LV fibrosis imaging, its technical complexity remains high and may well explain some of the discrepant results. Similar to LV scar imaging, a Look-Locker T1 mapping sequence must be applied to null the myocardium rendering normal myocardium black and fibrotic myocardium white. Compared with the thick LV myocardium, most investigators feel that the LA wall thickness of only 1 to 4 mm does not allow a direct application in the LA myocardium and therefore use surrogate measurements of the LV or even the LA blood pool instead. Indeed, an accurate delineation of the myocardial LA boundary is challenging even to the experienced imaging specialist. However, the inclusion of blood pool with high signal intensity may result in false-positive scar or inversely assigning high signal areas to extramyocardial structures may eliminate true LA fibrosis. To compensate for the high degree of technical complexity, various centers have developed center-specific imaging acquisition and processing protocols (Table). Despite those improvements, an important number of LA CMR studies are deemed of insufficient diagnostic quality even in highly experienced centers.13Both topics investigated by Harrison et al,12 namely the atrial voltage cut-off for scar and gap imaging, are of high clinical importance for electrophysiologists. The commonly used threshold of 0.05 mV to define LA scar in many studies lacks histopathologic validation. Recent animal and human CMR studies have suggested new cut-off values for atrial endocardial bipolar voltages: 0.3 mV from the animal data and 0.25 mV at the LA/PV junction in human atria.11,14 However, application of the cut-off of 0.3 mV derived from the animal scar model of the same investigators did not perform well in this study. Differences between right and LA tissue, porcine versus human myocardium and variable imaging quality may explain some of the differences. The ability to perform gap visualization post ablation remains an issue of ongoing debate, and in this study similar to the study by Sprague et al,8 CMR was not able to reliably identify conducting gaps. In contrast, studies by Bisbal et al,7 Badger et al,9 and Taclas et al10 showed good correlation between electroanatomic mapping and LGE CMR to predict gap location (Table). Some reasons may be technical and the different image acquisition protocols, scar reconstruction algorithms, LGE and electroanatomic mapping threshold values, scan resolution and magnetic resonance imaging scan timing make a comparison difficult. However, this study highlights the difficulties that still exist today with this challenging application. In addition, modeling experiments have shown that conduction block can exist despite presence of small gaps in ablation lesions (1.4–4 mm) as long as reduced tissue conductivity is maintained.15 A scenario of incomplete ablation line and electric isolation is therefore possible.Despite its rigorous methodology, the study by Harrison et al12 is not without limitations. The CMR area assigned to each mapping point taken with a 3.5-mm tip can be argued, but the investigators also assessed 2.5- and 5-mm radius areas without improving correlation between voltage and CMR intensity. A 10-mm radius assigned to each location along the ablation lines may incorporate too much nonenhanced myocardium and limit the value of the minimum LGE intensity measurement. A minimum LGE is susceptible to the inclusion of extramyocardial low intensity tissue, but this would likely have only affected a small amount of studies. Finally, the study was performed before the advent of contact force-sensing catheters, which may have introduced mapping errors because of imperfect tissue contact.Ultimately however, this study is important precisely because of their negative findings, which may allow us to step back and reassess. Electrophysiologists have witnessed incredible advances and improvements in the diagnostic and treatment capabilities. In some cases, the desire to think may have preceded our necessary mechanistic understanding leading to disappointing results (eg, renal denervation). The results from Harrison et al remind us that clinical implementation of novel technology is often a hard-won token. Joint and collaborative efforts toward standardization and validation of LA imaging protocols are needed and underway. A recent study by Karim et al16 offered a challenge to compete for the best magnetic resonance imaging LA fibrosis algorithm with participation of 7 leading centers in the field assessing 8 imaging algorithms. Sixty magnetic resonance imaging scans were used to compare the performance of each center's scar segmentation algorithm(s). Interestingly, all of the algorithms performed similarly, showing room for further collaboration and synergistic improvement to arrive at a generally agreed reference standard. The 2012 expert consensus on catheter ablation for AF17 stated that the technical aspects of magnetic resonance–based imaging of atrial fibrosis and ablation lesions make it difficult to adapt these techniques for clinical use today. Three years on we still have work to do.DisclosuresDr Dickfeld receives grant funding from Biosense Webster and GE Healthcare and is a consultant for Biosense Webster. Dr Jimenez reports no conflicts.FootnotesThe opinions expressed in this article are not necessarily those of the editors or of the American Heart Association.Correspondence to Timm M. Dickfeld, MD, PhD, University of Maryland Medical Center, 22 S. Greene St, Rm N3W77, Baltimore, MD 21201. E-mail [email protected]References1. Camm AJ, Kirchhof P, Lip GY, Schotten U, Savelieva I, Ernst S, Van Gelder IC, Al-Attar N, Hindricks G, Prendergast B, Heidbuchel H, Alfieri O, Angelini A, Atar D, Colonna P, De Caterina R, De Sutter J, Goette A, Gorenek B, Heldal M, Hohloser SH, Kolh P, Le Heuzey JY, Ponikowski P, Rutten FH; European Heart Rhythm Association; European Association for Cardio-Thoracic Surgery. Guidelines for the management of atrial fibrillation: the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC).Eur Heart J. 2010; 31:2369–2429.CrossrefMedlineGoogle Scholar2. Verma A, Kilicaslan F, Pisano E, Marrouche NF, Fanelli R, Brachmann J, Geunther J, Potenza D, Martin DO, Cummings J, Burkhardt JD, Saliba W, Schweikert RA, Natale A.Response of atrial fibrillation to pulmonary vein antrum isolation is directly related to resumption and delay of pulmonary vein conduction.Circulation. 2005; 112:627–635. doi: 10.1161/CIRCULATIONAHA.104.533190.LinkGoogle Scholar3. Ouyang F, Tilz R, Chun J, Schmidt B, Wissner E, Zerm T, Neven K, Köktürk B, Konstantinidou M, Metzner A, Fuernkranz A, Kuck KH.Long-term results of catheter ablation in paroxysmal atrial fibrillation: lessons from a 5-year follow-up.Circulation. 2010; 122:2368–2377. doi: 10.1161/CIRCULATIONAHA.110.946806.LinkGoogle Scholar4. Weerasooriya R, Khairy P, Litalien J, Macle L, Hocini M, Sacher F, Lellouche N, Knecht S, Wright M, Nault I, Miyazaki S, Scavee C, Clementy J, Haissaguerre M, Jais P.Catheter ablation for atrial fibrillation: are results maintained at 5 years of follow-up?J Am Coll Cardiol. 2011; 57:160–166. doi: 10.1016/j.jacc.2010.05.061.CrossrefMedlineGoogle Scholar5. Arujuna A, Karim R, Caulfield D, Knowles B, Rhode K, Schaeffter T, Kato B, Rinaldi CA, Cooklin M, Razavi R, O'Neill MD, Gill J.Acute pulmonary vein isolation is achieved by a combination of reversible and irreversible atrial injury after catheter ablation: evidence from magnetic resonance imaging.Circ Arrhythm Electrophysiol. 2012; 5:691–700. doi: 10.1161/CIRCEP.111.966523.LinkGoogle Scholar6. Simmers TA, de Bakker JM, Wittkampf FH, Hauer RN.Effects of heating with radiofrequency power on myocardial impulse conduction: is radiofrequency ablation exclusively thermally mediated?J Cardiovasc Electrophysiol. 1996; 7:243–247.CrossrefMedlineGoogle Scholar7. Bisbal F, Guiu E, Cabanas-Grandío P, Berruezo A, Prat-Gonzalez S, Vidal B, Garrido C, Andreu D, Fernandez-Armenta J, Tolosana JM, Arbelo E, de Caralt TM, Perea RJ, Brugada J, Mont L.CMR-guided approach to localize and ablate gaps in repeat AF ablation procedure.JACC Cardiovasc Imaging. 2014; 7:653–663. doi: 10.1016/j.jcmg.2014.01.014.CrossrefMedlineGoogle Scholar8. Spragg DD, Khurram I, Zimmerman SL, Yarmohammadi H, Barcelon B, Needleman M, Edwards D, Marine JE, Calkins H, Nazarian S.Initial experience with magnetic resonance imaging of atrial scar and co-registration with electroanatomic voltage mapping during atrial fibrillation: success and limitations.Heart Rhythm. 2012; 9:2003–2009. doi: 10.1016/j.hrthm.2012.08.039.CrossrefMedlineGoogle Scholar9. Badger TJ, Daccarett M, Akoum NW, Adjei-Poku YA, Burgon NS, Haslam TS, Kalvaitis S, Kuppahally S, Vergara G, McMullen L, Anderson PA, Kholmovski E, MacLeod RS, Marrouche NF.Evaluation of left atrial lesions after initial and repeat atrial fibrillation ablation: lessons learned from delayed-enhancement MRI in repeat ablation procedures.Circ Arrhythm Electrophysiol. 2010; 3:249–259. doi: 10.1161/CIRCEP.109.868356.LinkGoogle Scholar10. Taclas JE, Nezafat R, Wylie JV, Josephson ME, Hsing J, Manning WJ, Peters DC.Relationship between intended sites of RF ablation and post-procedural scar in AF patients, using late gadolinium enhancement cardiovascular magnetic resonance.Heart Rhythm. 2010; 7:489–496. doi: 10.1016/j.hrthm.2009.12.007.CrossrefMedlineGoogle Scholar11. Harrison JL, Jensen HK, Peel SA, Chiribiri A, Grøndal AK, Bloch LØ, Pedersen SF, Bentzon JF, Kolbitsch C, Karim R, Williams SE, Linton NW, Rhode KS, Gill J, Cooklin M, Rinaldi CA, Wright M, Kim WY, Schaeffter T, Razavi RS, O'Neill MD.Cardiac magnetic resonance and electroanatomical mapping of acute and chronic atrial ablation injury: a histological validation study.Eur Heart J. 2014; 35:1486–1495. doi: 10.1093/eurheartj/eht560.CrossrefMedlineGoogle Scholar12. Harrison JL, Sohns C, Linton NW, Karim R, Williams SE, Rhode KS, Gill J, Cooklin M, Rinaldi CA, Wright M, Schaeffter T, Razavi RS, O'Neill MD.Repeat left atrial catheter ablation: cardiac magnetic resonance prediction of endocardial voltage and gaps in ablation lesion sets.Circ Arrhythm Electrophysiol. 2015; 8:270–278. doi: 10.1161/CIRCEP.114.002066.LinkGoogle Scholar13. Peters DC, Wylie JV, Hauser TH, Kissinger KV, Botnar RM, Essebag V, Josephson ME, Manning WJ.Detection of pulmonary vein and left atrial scar after catheter ablation with three-dimensional navigator-gated delayed enhancement MR imaging: initial experience.Radiology. 2007; 243:690–695. doi: 10.1148/radiol.2433060417.CrossrefMedlineGoogle Scholar14. Kapa S, Desjardins B, Callans DJ, Marchlinski FE, Dixit S.Contact electroanatomic mapping derived voltage criteria for characterizing left atrial scar in patients undergoing ablation for atrial fibrillation.J Cardiovasc Electrophysiol. 2014; 25:1044–1052. doi: 10.1111/jce.12452.CrossrefMedlineGoogle Scholar15. Ranjan R, Kato R, Zviman MM, Dickfeld TM, Roguin A, Berger RD, Tomaselli GF, Halperin HR.Gaps in the ablation line as a potential cause of recovery from electrical isolation and their visualization using MRI.Circ Arrhythm Electrophysiol. 2011; 4:279–286. doi: 10.1161/CIRCEP.110.960567.LinkGoogle Scholar16. Karim R, Housden RJ, Balasubramaniam M, Chen Z, Perry D, Uddin A, Al-Beyatti Y, Palkhi E, Acheampong P, Obom S, Hennemuth A, Lu Y, Bai W, Shi W, Gao Y, Peitgen HO, Radau P, Razavi R, Tannenbaum A, Rueckert D, Cates J, Schaeffter T, Peters D, MacLeod R, Rhode K.Evaluation of current algorithms for segmentation of scar tissue from late gadolinium enhancement cardiovascular magnetic resonance of the left atrium: an open-access grand challenge.J Cardiovasc Magn Reson. 2013; 15:105. doi: 10.1186/1532-429X-15-105.CrossrefMedlineGoogle Scholar17. Calkins H, Kuck KH, Cappato R, Brugada J, Camm AJ, Chen SA, Crijns HJ, Damiano RJ, Davies DW, DiMarco J, Edgerton J, Ellenbogen K, Ezekowitz MD, Haines DE, Haissaguerre M, Hindricks G, Iesaka Y, Jackman W, Jalife J, Jais P, Kalman J, Keane D, Kim YH, Kirchhof P, Klein G, Kottkamp H, Kumagai K, Lindsay BD, Mansour M, Marchlinski FE, McCarthy PM, Mont JL, Morady F, Nademanee K, Nakagawa H, Natale A, Nattel S, Packer DL, Pappone C, Prystowsky E, Raviele A, Reddy V, Ruskin JN, Shemin RJ, Tsao HM, Wilber D; Heart Rhythm Society Task Force on Catheter and Surgical Ablation of Atrial Fibrillation. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design: a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation. Developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC) and the European Cardiac Arrhythmia Society (ECAS); and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). Endorsed by the governing bodies of the American College of Cardiology Foundation, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, the Asia Pacific Heart Rhythm Society, and the Heart Rhythm Society.Heart Rhythm. 2012; 9:632–696.e21. doi: 10.1016/j.hrthm.2011.12.016.CrossrefMedlineGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetails April 2015Vol 8, Issue 2 Advertisement Article InformationMetrics © 2015 American Heart Association, Inc.https://doi.org/10.1161/CIRCEP.115.002783PMID: 25900986 Originally publishedApril 1, 2015 Keywordsatrial fibrillationablation techniquesgadoliniumEditorialsPDF download Advertisement SubjectsCatheter Ablation and Implantable Cardioverter-DefibrillatorComputerized Tomography (CT)Electrophysiology

Background Intracardiac echocardiography (ICE) is increasingly used to guide complex ablation procedures. This study aimed to assess the scar substrate of ventricular tachycardia (VT) by ICE in patients undergoing VT ablation. Methods In 22 patients undergoing VT ablation (10 ischemic, 12 nonischemic), the Biosense CARTOSOUND module (Biosense Webster, Diamond Bar, CA, USA) was used for three‐dimensional reconstruction of the ventricles. The characteristics and appearance with ICE imaging of voltage‐defined scar zones (bipolar voltage <0.5 mV), border zones (0.5–1.5 mV), and normal myocardium (>1.5 mV) on electroanatomic maps were evaluated. The standard image analysis software Image J (National Institutes of Health, Bethesda, MD, USA) was used to analyze signal intensity (mean pixel signal intensity unit [SIU]) and heterogeneity (standard deviation of signal intensity in analyzed area) on ICE images. Results A total of 83 myocardial areas were analyzed from two‐dimensional ICE images (15 scars, 31 border zones, and 37 normal). Voltage‐defined scar zones had increased signal intensities compared to border zones (149 SIU vs 104 SIU, P < 0.0001) and normal myocardium (88 SIU, P < 0.0001). Border zones were more likely to have heterogeneous densities compared to normal myocardium (standard deviation of signal intensity 20 SIU vs 12 SIU, P < 0.0001). In receiver‐operator characteristic analyses, signal intensity ≥137 SIU differentiated scar from nonscar zones (area under curve 0.91, P < 0.0001). Software‐based color enhancement of areas with signal intensity ≥137 SIU allowed identification of the VT substrate in all 15 patients with voltage‐defined scar zones. Conclusions ICE provides important information about the VT anatomical substrate and may have potential to identify areas of scarred myocardium.

BackgroundCardiac magnetic resonance imaging (CMRI) is the gold standard for myocardial scar evaluation. Although ideal for substrate assessment in ventricular tachycardia (VT), most patients have an implantable cardioverter-defibrillator (ICD) at presentation for ablation. This study evaluates the ICD artifact burden during standard late gadolinium enhancement CMRI (LGE-CMRI) evaluation of myocardial scar in VT patients with ICDs.MethodsThirty-one patients with ICD and cardiomyopathy underwent LGE-CMRI using 1.5-T magnetic resonance scanner before VT ablation. Using the American Heart Association (AHA) 17-segment model, short-axis LGE series were analyzed for artifact burden localization and assessment.ResultsPreablation CMRI was performed in 31 patients with single chamber (n = 13), dual chamber (n = 11), and biventricular (n = 7) ICDs. Pre- and post-MRI ICD parameters were unchanged. All patients had susceptibility artifact and 51.6% (256 of 496) of segments were affected by artifact. The artifact area (178136cm(2)) resulted in an artifact burden of 54 +/- 21% of the LV myocardial area (327 +/- 15cm(2)). The anterior wall was most affected by artifact (89%) compared with 52%, 49%, and 23% in the lateral, septal, and inferior walls, respectively (P<0.0001). The apical segments had more artifact burden (66%) than the mid (49%) and basal (44%) segments (P = 0.0005). Artifact area correlated with ICD-heart distance on anteroposterior chest radiograph (r = 0.42, P = 0.021) and body mass index (r = -0.48, P = 0.008).ConclusionsCurrent clinical LGE-CMRI scar imaging protocols produce ICD artifacts that affect >50% of the LV myocardium and correlate with the ICD-heart distance. This significantly limits the application of CMRI for image-guided VT ablation.

Cardiac SarcoidosisObjectivesThe objectives of this study were to identify the predictors of life-threatening ventricular arrhythmias in patients with cardiac sarcoidosis (CS) and to evaluate the role of the implantable cardioverter-defibrillator (ICD) in this patient population.BackgroundICD implantation is a class IIA recommendation for patients with CS. However, some indications for ICD implantation in CS patients are still unclear and not enough data are available to establish predictors of malignant ventricular tachyarrhythmias in this group of patients.MethodsWe retrospectively identified all consecutive patients who were diagnosed with CS, during the period from March 2002 to April 2010. Cardiac rhythm devices were regularly interrogated and clinical data recorded during follow-up visits.ResultsThirty-three patients (17 male) with CS were identified. The mean age was 53 11. The mean left ventricular ejection fraction (LVEF) was 41 +/- 18%. Thirty patients received an ICD. Twelve patients (36.3%) had sustained ventricular arrhythmias. Eleven patients received appropriate therapies and 9 patients received inappropriate shocks, representing 36.7% and 30.0% of the ICD population, respectively. Patients who received appropriate ICD therapies were younger with mean age 47.4 +/- 7.8, and had a lower mean LVEF 33.0 +/- 12.0 compared to those who did not receive ICD therapies (P = 0.0301 and 0.0341, respectively). There were no other demographic, clinical, electrocardiographic, electrophysiological, or imaging markers that predicted the future occurrence of appropriate ICD therapies in our cohort of patients.ConclusionsCS is strongly associated with malignant ventricular arrhythmias. No specific predictors of such tachyarrhythmias emerged, other than young age and low LVEF.

IntroductionDuring mapping and ablation procedures, the movement of large ferromagnetic items (i.e., fluoroscopic equipment) introduce heterogeneities in the electromagnetic field, which may affect the accuracy of electromagnet‐based navigation. We aimed to assess the impact of common periprocedural fluoroscopic equipment movement on the accuracy of an electromagnet‐based navigation system.Methods and ResultsThe impact of fluoroscopic equipment movement on the accuracy of the Carto® 3 System (Biosense Webster, Inc., Diamond Bar, CA, USA) was assessed both in vitro (n = 20 patients, phantom model) and in vivo (n = 18 patients). Location recordings were obtained with unchanged catheter position for fluoroscopic equipment rotational movements (RMs) and maximal to closest distance (MD to CD) to phantom/patient. The effects of both single‐ and biplane fluoroscopy were assessed. In vitro, the movement of fluoroscopic equipment resulted in an average catheter location estimation error of 0.8 mm (interquartile range 0.3–1.3). The maximal location estimation errors with MD to CD movement and RM were 2.3 mm and 1.3 mm, respectively. Changing from single‐plane to biplane setup resulted in an average location estimation change of 1.5 mm (maximum 2.1). Larger location changes were observed in vivo (2.9 mm vs 0.8 mm, P < 0.0001) with 28.7% of these exceeded 4 mm versus none of the in vitro measurements (P < 0.0001).ConclusionAlthough fluoroscopy manipulation affected the accuracy of the Carto® 3 System, the in vitro data suggest that these inaccuracies are likely of limited clinical consequences. The larger in vivo inaccuracies are most likely due to nonferromagnetic interferences, such as respiratory or cardiac movements.

AIMS Identification of patients most likely to benefit from implantable cardioverter defibrillator (ICD) implant remains a complex challenge. This study aimed to investigate the utility of measures derived from standard 10 s 12-lead electrocardiogrphy (ECG) without complex signal processing in predicting appropriate therapy in an ICD population. METHODS AND RESULTS We examined 108 ICD patients for primary (n = 32) and secondary prevention (n = 76). Baseline clinical data and characteristics of QRS complex, T-wave, and heart rate from standard 12-lead ECG were examined and related to the occurrence of subsequent appropriate therapy. Over a mean follow-up of 29 ± 11 months, 44% of patients received appropriate therapy. Patients with depressed heart rate variability (HRV) (≤6.5%) were 2.68 [95% confidence interval (CI) 1.21-5.90, P = 0.015] times more likely to receive appropriate therapy than patients with HRV >6.5%. In patients with bundle branch block (BBB), large QRS dispersion of >39 ms was associated with 2.88 times risk (95% CI 1.24-6.71, P = 0.014) of experiencing appropriate therapy than those with QRS dispersion <39 ms. In patients without BBB, reduced maximum T-wave amplitude (<0.4 mV) were 3.82 times (95% CI 1.63-8.93, P = 0.002) more likely to receive appropriate therapy compared with those with maximum T-wave amplitude >0.4 mV. History of atrial arrhythmia [hazard ratio (HR) = 2.30, 95% CI 1.29-4.12, P = 0.005] and secondary prevention (HR = 2.55, 95% CI 1.14-5.71, P = 0.022) were also predictive of device therapy. CONCLUSION Measurements from standard 12-lead ECG were predictive of appropriate therapy in a heterogeneous ICD population. Incorporation of 12-lead ECG parameters such as these into risk stratification models may improve our ability to select patients for ICD implantation.