Author + information
- Received October 2, 2015
- Revision received January 21, 2016
- Accepted January 26, 2016
- Published online August 1, 2016.
- Chin-Yu Lin, MDa,b,
- John Silberbauer, MD(Res)c,d,
- Yenn-Jiang Lin, MD, PhDa,b,∗ (, )
- Men-Tzung Lo, PhDe,
- Chen Lin, PhDe,
- Hsiang-Chih Chang, PhDe,
- Shih-Lin Chang, MD, PhDa,b,
- Li-Wei Lo, MD, PhDa,b,
- Yu-Feng Hu, MD, PhDa,b,
- Fa-Po Chung, MDa,b,
- Jo-Nan Liao, MDa,b,
- Yun-Yu Chen, MPHa,
- Chun-Wang Chiou, MDa,b,
- Shih-Ann Chen, MDa,b and
- Paolo Della Bella, MDc,∗∗ ()
- aDepartment of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan
- bDivision of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
- cArrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy
- dRoyal Sussex County Hospital, Brighton, United Kingdom
- eInstitute of Translational and Interdisciplinary Medicine and Department of Biomedical Sciences and Engineering, National Central University, Taoyuan City, Taiwan
- ↵∗Reprint requests and correspondence:
Dr. Yenn-Jiang Lin, Taipei Veterans General Hospital, Department of Medicine, Division of Cardiology, No. 201, Section 2, Shipai Road, Beitou District, Taipei, Taiwan 112.
- ↵∗∗Dr. Paolo Della Bella, Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, via Olgettina 60, Milan, Italy.
Objectives This study sought to develop a novel automated technique, simultaneous amplitude frequency electrogram transformation (SAFE-T), to identify ventricular tachycardia (VT) isthmuses by analysis of sinus rhythm arrhythmogenic potentials (AP).
Background Substrate ablation is useful for patients with scar-related hemodynamically unstable VT; however, the accuracy of different approaches remains inadequate, varying from targeting late potentials to full scar homogenization.
Methods High-density ventricular mapping was performed in 3 groups: 1) 18 normal heart control subjects; 2) 10 ischemic patients; and 3) 8 nonischemic VT patients. In VT patients, isthmus sites were characterized using entrainment responses. Sinus rhythm right ventricle/left ventricle endocardial and epicardial electrograms underwent Hilbert-Huang spectral analysis and were displayed as 3-dimensional SAFE-T maps. AP and their relation to the VT isthmus sites were studied.
Results AP were defined by a cutoff value of 3.08 Hz mV using normal heart control subjects. Receiver-operating characteristics showed that VT isthmus sites were best identified using SAFE-T mapping (p < 0.001) as compared with bipolar and unipolar scar and late potential mapping with an optimal cutoff value of 3.09 Hz mV, allowing identification of 100% of the 34 mapped VT isthmuses, compared with 68% using late potentials. There was no significant difference between sinus rhythm and paced SAFE-T values. Abnormal SAFE-T areas involved about one-quarter of the scar total area.
Conclusions Automated electrogram analysis using 3-dimensional SAFE-T mapping allows rapid and objective identification of AP that reliably detect VT isthmuses. The results suggest that SAFE-T mapping is good alternative strategy to late potential mapping in identifying VT isthmuses and allows reduced ablation as compared to scar homogenization.
Radiofrequency catheter ablation (RFCA) is an effective treatment option in post-infarction or nonischemic cardiomyopathy patients with medically refractory ventricular tachycardia (VT) (1). Substrate ablation techniques are preferred in patients with VT due to hemodynamic instability and require a thorough point-by point acquisition of voltage information displayed on a 3-dimensional (3D) electroanatomic map (EAM). Abnormal voltage cutoff values are established and reflect damaged myocardial tissue or scar (2). High-density 3D pace-mapping, the presence of arrhythmogenic potentials (AP) (3,4), and cardiac magnetic resonance scar characteristics are techniques that enable VT isthmus identification without the need for activation and entrainment mapping (5–7). Of these, the targeting of AP during sinus rhythm (SR) in patients with scar-related VT has been most widely utilized (2,4,8,9). The classical procedural endpoint is abolition of inducible VT, targeting either the clinical VT or all inducible VT (10,11). Recent studies have demonstrated that the additional targeting of AP during SR is associated with reduced VT recurrence in patients with ischemic and nonischemic VT (8,9,11,12). Local and distant pacing maneuvers are used to demonstrate a long stimulus-to-QRS interval or multicomponent electrograms, indicative of poorly coupled myocardium; however, this is impractical in the setting of scar with hundreds of potential sites (8,11).
We propose a novel automated temporal frequency analysis method using the Hilbert-Huang transform (HHT) (13), interpreted within the 3D EAM, to accurately recognize AP during SR that colocate with VT isthmuses characterized by classical entrainment mapping.
From 2013 to 2015, 18 consecutive patients referred to our center for VT ablation, who underwent a detailed electrophysiological study using the CARTO 3 system (MEM version, UDM Module, Biosense Webster, South Diamond Bar, California) and had isthmus identification through entrainment of tolerated VT and successful isthmus-directed RFCA, were recruited. All patients had episodes of repetitive, sustained VT resistant to antiarrhythmic medication requiring external cardioversion or implantable cardioverter-defibrillator therapies. Baseline characteristics were assessed in detail. All patients provided written informed consent prior to participation. The procedures were all clinically indicated, and the human research committee approved data collection.
Electroanatomic substrate mapping
A standardized electrophysiological study was performed in the fasting state with conscious sedation or general anesthesia. Antiarrhythmic drugs were discontinued for a minimum of 5 half-lives before RFCA. In the absence of spontaneous VT, rapid ventricular pacing and programmed stimulation with up to 3 extra stimuli was performed with a catheter placed at the right ventricular (RV) apex. If VT was noninducible, intravenous isoprenaline 1 to 5 μg/min was infused to achieve at least 20% heart rate increment.
The VT QRS morphologies were compared with those of the documented VT. The left ventricular (LV) endocardium was accessed by transseptal or retrograde transaortic approach. Pericardial access was obtained by subxiphoid puncture if a previous endocardial ablation had failed, if an epicardial substrate was suspected, or if minimal or no endocardial scar was present. EAM was performed during SR using CARTO system. Mapping and RFCA were performed with an open-irrigated ablation catheter (Thermocool, Biosense Webster). The voltage maps were edited by manually eliminating intracavitary points. To avoid low-voltage recordings due to poor contact, the following criteria were used: 1) the signal had to satisfy 3 stability criteria automatically detected by the CARTO system in terms of cycle length, local activation time, and beat-to-beat difference of the location of the catheter; 2) both bipolar and unipolar signals were simultaneously acquired to confirm true catheter contact through the analysis of the local electrogram; and 3) in the presence of a low-voltage area, at least 3 additional points were acquired in the same site to confirm the reproducibility of the voltage measurement. Unipolar filtering was set at 2 to 240 Hz, and bipolar filtering set at 16 to 500 Hz. Wilson central terminal was assigned as the unipolar reference electrode. Intracardiac bipolar electrogram data were exported through the Carto UDM Module for HHT transformation. The products were reimported to Carto UDM Module for real-time analysis ensuring anatomic coregistration. Bipolar scar and low-voltage areas were defined as areas with a peak-to peak bipolar voltage <0.5 and <1.5 mV, RV and LV unipolar scar area as areas with a peak-to-peak unipolar voltage <5.5 and <8.3 mV, respectively (2). Late potentials were defined as local ventricular potentials occurring after the terminal portion of the surface QRS, whereas early arrhythmogenic potentials were defined as those inscribed within the QRS. The late potentials definition included either continuous fragmented activity, bridging from the main component within the QRS to the latest signal recorded, or isolated potentials recorded after the QRS offset, without a definite voltage cutoff (11). Regions of scar, low-voltage zone (LVZ), and late potentials were measured using the standard surface area measurement tool on the CARTO system. When multiple areas of confluent low voltage were present, the aggregate area from individual regions of interest was calculated.
VT mapping and catheter ablation
Induced VT were analyzed for cycle length and morphology using the electrophysiological recording system (LabSystem PRO EP Recording System, BARD, Inc., Lowell, Massachusetts). If an induced VT was hemodynamically tolerated, pacing from the mapping catheter at a cycle length 20 to 30 ms faster than the tachycardia cycle length was performed, observing the entrainment response. A site was considered a VT mid-isthmus only if it demonstrated the following: 1) concealed fusion on all 12 electrocardiographic leads during entrainment; 2) the post-pacing interval was within 30 ms of the VT cycle length; 3) the stimulus-electrogram interval was within 30 ms of the electrogram-QRS interval following entrainment; and 4) the local electrogram to QRS interval was between 30% and 70% of the VT cycle length. Confirmed VT isthmus sites were annotated on the map after VT termination in SR. RFCA was performed with power settings of 30 to 50 W. Only sites that resulted in VT termination with RFCA directed at the isthmus (entrance, central, or exit isthmuses) were included as true isthmus sites for this analysis. Remapping was performed after inducibility testing.
Simultaneous amplitude frequency electrogram transformation mapping
We propose an automated method to recognize abnormal high-frequency potentials during SR. Because these electrogram waveforms are intermittent and highly nonlinear, the traditional Fourier filter cannot easily separate out the far-field components (Online Appendix, Online Figures 1 and 2). The present method therefore used nonlinear strategies, mostly inspired from a novel signal processing tool for nonlinear and nonstationary signals called HHT (13).
Figure 1 demonstrates that the Hilbert-Huang spectrum can readily distinguish normal from abnormally fractionated electrograms within the high-frequency band. Inspection of the Hilbert-Huang spectrum allows identification of instantaneous frequencies of AP occupying the 70- to 180-Hz band for significant time durations during each beat. HHT then enabled quantification of AP by the product of the instantaneous frequency and its corresponding amplitude of the electrogram, providing a single clinically useful parameter to intensify the abnormal high-frequency ventricular potentials beneath the QRS electrogram. The AP value, as identified by the instantaneous frequency and amplitude product in each recording, namely the simultaneous amplitude frequency electrogram transformation (SAFE-T) value, was applied to a color-coded 3D EAM.
Normal heart reference values for SAFE-T
A total of 4,066 LV normal bipolar electrogram points were analyzed from 18 idiopathic VT patients (points with bipolar voltage >1.5 mV). Ninety percent of LV endocardial bipolar signals had a SAFE-T <3.08 Hz mV, and 95% had a SAFE-T <4.89 Hz mV (mean 0.94 ± 1.98); therefore a SAFE-T ≥3.08 Hz mV defined abnormal SAFE-T electrograms and a SAFE-T >4.89 Hz mV defined highly abnormal SAFE-T electrograms (Figure 2).
Patients were followed up with 12-lead electrocardiograms, 24-h Holter monitors, and echocardiography after RFCA every 3 months for the first year and every 6 months thereafter. Patients who were unable to attend follow-up at our institution were reviewed at local institutions and underwent telephone consultation for recurrent symptoms and arrhythmias. The medical reports were obtained from these institutions for review.
All analyses were performed using SPSS statistical software (version 20.0, IBM, Armonk, New York). Continuous data are expressed as mean ± SD and as percentages for categorical variables. All continuous data were tested using the 1-sample Kolmogorov-Smirnov test against a normal distribution. Continuous variables were compared using the independent Student t test. For comparison of dichotomous variables, the chi-square test was used. A p value of ≤0.05 was considered statistically significant. Receiver-operating characteristic curves and areas under receiver-operating characteristic curve were analyzed to determine the optimal cutoff point of SAFE-T for identification of true VT isthmuses. The generalized estimating equation was used to account for the variables (unipolar and bipolar voltage, late potential latency, and SAFE-T value) within subjects for a clustering effect of individual patient and mapping site when comparing electrophysiological characteristics of isthmus and nonisthmus areas.
This study evaluated the predictive performance by calculating the Pearson correlation coefficient and using scatter plots. Internal consistency of SAFE-T values between SR and premature ventricular beats were evaluated by Cronbach α coefficient, Cronbach α coefficient of 0.7 or above was considered satisfactory (14), and Bland–Altman plots (15). Substrate parameters including unipolar voltage, bipolar voltage, SAFE-T value, and late potential latency (the interval from the end of QRS complex to the end of the local electrogram) were compared at isthmus and nonisthmus sites.
Baseline characteristics of the 18 patients are listed in Table 1. Ten (57%) were diagnosed with ischemic cardiomyopathy and 8 with nonischemic cardiomyopathy, including 2 (11%) with dilated cardiomyopathy, 4 (22%) with hypertrophic cardiomyopathy, and 2 (11%) with arrhythmogenic RV cardiomyopathy. There was no significant difference in age, sex, comorbidity, previous RFCA history, clinical presentation, electrocardiography morphology, LV ejection fraction, and ventricular arrhythmia type. Clinical VT or implantable cardioverter-defibrillator therapy and previous amiodarone therapy was documented in all patients. RFCA was successful in all patients without complication with a median follow-up period of 349 days (interquartile range: 236 to 486 days).
Conventional substrate mapping in the population
The 18 patients with sustained VT underwent detailed endocardial LV and/or RV EAM (725 ± 409 points per patient) prior to RFCA. In 3 patients (17%)—1 with arrhythmogenic RV cardiomyopathy, 1 with ischemic heart disease, and 1 with hypertrophic cardiomyopathy—an epicardial approach was required because endocardial RFCA was unsuccessful. These 3 patients underwent detailed epicardial EAM (802 ± 370 points per patient). The procedure and substrate mapping details are summarized in Tables 2 and 3.
Electrophysiological study, VT mapping, and catheter ablation
The ablation strategies were based on entrainment and pace-mapping in all patients (100%), local AP (including early and late potential) elimination in 16 patients (88.9%), VT activation mapping in 5 patients (27.8%), and short-line ablation in 11 patients (61.1%) (16). Programmed ventricular stimulation induced 49 distinct nonsustained and sustained VT in the study cohort, 2.9 ± 1.7 per patient (range 1 to 6). Ten VT (from 7 patients) required defibrillation for hemodynamic instability. Seven VT were nonsustained. There were 34 VT with hemodynamic stability allowing characterization using entrainment (Table 4). Five VT entrance-isthmus sites were identified, all (100.0%) located within scar and abnormal SAFE-T areas and 3 (60%) within late potential areas. Central and exit isthmuses were identified in 34 VT. Thirteen (38.2%) central isthmuses were within scar, 21 (61.8%) were within in scar border zone, 34 (100.0%) were within abnormal SAFE-T areas, and 24 (70.6%) were within late potential areas. Seven (20.5%) exit isthmus sites were within scar, 24 (70.6%) were within scar border zone, 3 (8.8%) in normal voltage areas, 34 (100.0%) were within abnormal SAFE-T area, and 3 (8.8%) were within late potential areas.
The validation and cutoff SAFE-T value during SR
There were 631 points (243 from the septum and 388 from the free wall) from 13 patients (9 nonischemic cardiomyopathy and 4 ischemic cardiomyopathy) collected for SAFE-T value assessment during SR and extraventricular beats/RV pacing. The SAFE-T value was independent of the rhythm (Cronbach α = 0.897) (Figure 3A) (14). With respect to SR and extraventricular SAFE-T values, there was no significant difference in the mean value (p = 0.855) with a significant correlation (Pearson: 0.918, p < 0.001). Scatter plots of SR and extraventricular beat SAFE-T values at the same site are shown in Figure 3B. The Bland-Altman plot in Figure 3C shows that the mean of the difference in SAFE-T between SR and extraventricular beats falls close to the zero line, indicating that there is no bias and that the 2 methods are generally consistent (15).
Electrophysiological parameters were compared between nonisthmus and isthmus sites (Table 5). The bipolar voltage, unipolar voltage, late potential latency, and SAFE-T value were significantly different between isthmus and nonisthmus sites. SAFE-T value was higher within isthmus in comparison to nonisthmus area after multivariate adjustment. Receiver-operating characteristic curves were applied for the identification of true VT isthmuses based on bipolar voltage, unipolar voltage, local latency, and SAFE-T value (Figure 4). The SAFE-T value provides a good prediction of true isthmus sites with an optimal cutoff value of 3.09 Hz mV and an area under the curve of 0.96. The SAFE-T area under the curve was significantly larger than the other parameters (p < 0.01) (17).
Abnormal SAFE-T area analysis
Areas of abnormal SAFE-T value (≥3.09 Hz mV) were present in 18 of 18 patients (100%) with nonischemic or ischemic cardiomyopathy. The abnormal SAFE-T area occupied a mean endocardial area of 10.2 ± 7.8 cm2 (4.3 ± 2.8% of total endocardial surface area), which was significantly smaller than the unipolar LVZ (79.2 ± 82.2 cm2, 29.9 ± 29.2%), bipolar LVZ (55.8 ± 56.5 cm2, 21.1 ± 19.2%), and bipolar scar area (31.4 ± 46.2 cm2, 11.8 ± 16.4%). The late potential area occupied a mean endocardial area of 6.0 cm2 (2.4% of total endocardial surface area), which was nonsignificantly smaller than the high SAFE-T area (Figures 5A and 5B). High SAFE-T areas overlapped other areas as follows: 83.1 ± 37.4% with unipolar low-voltage areas, occupying 24.1 ± 42.8% of the unipolar low-voltage areas; 81.3 ± 39.8% with bipolar low-voltage areas, occupying 27.2 ± 44.5% of the bipolar voltage scar areas; and 35.4 ± 39.8% with bipolar scar areas, occupying 26.5 ± 44.2% of the bipolar voltage scar areas.
Relationship of VT circuit to areas of abnormal voltage and SAFE-T
Of the 34 isthmus sites identified, all (100%) were located within unipolar low-voltage areas, 32 (94.1%) were located within bipolar LVZ or bipolar scar areas, and 23 (67.6%) were located within a late potential area. Abnormal SAFE-T regions (≥3.09 Hz mV) could be identified in all conduction isthmuses (100%) (Figures 6 and 7). In ischemic cardiomyopathy patients, all isthmuses (100%, 19 of 19) were located within bipolar LVZ. In nonischemic cardiomyopathy patients, 13 isthmuses (87%) were within the bipolar LVZ, and 10 isthmuses (67%) were identified by late potentials. Within the isthmus sites (N = 626), high SAFE-T was identified in 89.9% and 91.8% in nonischemic and ischemic cardiomyopathy, respectively (p = 0.216). The ischemic isthmus sites had a lower unipolar and bipolar voltage than those of nonischemic cardiomyopathy (Table 3).
Of the overall 15,461 mapping points from 18 patients, there were 1,755 abnormal SAFE-T points and 574 (32.7%) were located within identified isthmus areas (Table 4). Among electrograms with abnormal SAFE-T values, points with lower unipolar voltage, lower bipolar voltage, and increased late potential latency were more related to isthmus sites.
Isthmus site characterization post-ablation
There were a total of 289 entrainment points in 34 isthmuses (mean: 8.8 ± 2.2 points/isthmus). After entrainment mapping, isthmus points were mapped within the isthmus, identified by the entrainment points, during SR. A total of 626 isthmus points were collected before RFCA and 426 points after RFCA (Online Table 1). The SAFE-T value normalized and the unipolar voltage, bipolar voltage, and late potential latency were all significantly reduced (p < 0.001).
Post-RFCA, VT was noninducible in 12 patients (75%) with clinical VT noninducible in all patients (100%). There was a higher rate of nonclinical VT inducibility in the ischemic group. Eight patients continued antiarrhythmic therapy. During follow-up, 1 patient required heart transplantation for a post-infarction ventricular septal defect. There were no recurrences of nonsustained VT, sustained VT, or implantable cardioverter-defibrillator therapies, and no patients died or required repeat RFCA procedures.
This study describes a new methodology for real-time automated displaying of abnormal fractionated scar electrogram characteristics on a 3D EAM. The main findings are as follow: 1) AP, as defined using SAFE-T mapping, were present in patients with ischemic and nonischemic cardiomyopathy and accurately predicted mapped VT isthmus sites; 2) AP were located within the scar border and thus present a safe target for RFCA; 3) AP elimination could be used as a procedural endpoint with post-RFCA SAFE-T remapping; 4) AP appear independent of ventricular location and thus may be a superior approach as compared to the late potential method, which may miss early-to-activate arrhythmogenic areas; 5) the SAFE-T method appears independent of the ventricular rhythm and thus may obviate the need for time-consuming local and remote pacing maneuvers; and 6) the area identified by SAFE-T mapping represents about one-quarter of the total scar, thus potentially providing an alternative ablation strategy that may reduce the burden of ablation as compared to a full scar homogenization approach.
Comparison with previous studies
Entrainment mapping has long been regarded as the gold standard for identification of VT isthmuses but has limitations (18,19), in particular the need for hemodynamic stability. Higher incidences of late potentials are found within VT circuits, especially at entrance and central isthmus sites (20). Isolated potentials occur at the majority of sites with shared common pathways (4). At exit sites, electrograms are typically earlier, between the QRS complexes, and present as isolated or split potentials (19). Pace-mapping is often combined with a voltage map during substrate mapping to define potential exits (21).
A recent study examined the usefulness of frequency and fragmentation analysis in identifying conduction isthmuses using an offline method (7). High-frequency components overlapped with 60% of the identified VT isthmus sites and sites of high frequency harbored electrograms with prolonged duration, more deflections, and lower voltage. These findings are compatible with previous qualitative data (22). However, it is difficult to identify critical components within multicomponent prolonged electrograms. Additionally, SR mapping can also employ the identification of conducting channels (23), which have been shown to relate to corridors of border zone as identified using magnetic resonance imaging (24), and the benefit of targeted dechanneling has been demonstrated (25). The SAFE-T maps identified larger areas than the late potentials areas. The abnormal potentials unmasked by SAFE-T mapping also contain early potentials, which were inscribed within the QRS and could not be identified by late potential maps, especially in septal areas (26). The additional area relates to the electrograms that have the delayed component superimposed or not much delayed with respect to the far field electrogram, which may be considered the “conducting channel entrance.” The visualized conducting channel entrance based on SAFE-T mapping could help operators characterize them automatically and more objectively. To the best of our knowledge, this is the first study demonstrating that automated SR SAFE-T mapping using Hilbert-Huang spectral analysis can identify areas in which VT isthmus sites are contained.
Advantages of SAFE-T mapping
AP in patients with scar-related VT are suggestive of arrhythmogenic areas. However, lateness of AP is affected to a large extent by location. The likelihood of detecting late AP increases when electrogram onset is later, specifically, laterally and epicardially. Substrate-based approaches directed at late AP may neglect critical early AP, particularly in the septum and other early-to-activate regions (27). We hypothesize that critical high-frequency electrogram components can be extracted from the far-field electrogram using HHT, allowing better definition and interpretation of AP using a novel real-time method that can be displayed on the 3D EAM. Additionally, the computational requirements are not high and the SAFE-T map can be obtained instantaneously during mapping in the same way that the rest of the EAM currently used are generated. A comparison with extraventricular beats indicates that AP, identified by SAFE-T, are independent of ventricular activation sequence, potentially simplifying the current substrate assessment process used for early AP by removing the requirement for local and remote pacing maneuvers (8,21). The inherent inconsistency with visual interpretation of fractionated signals is also overcome. These factors may explain why all VT isthmuses were identified using SAFE-T mapping in the present study. Furthermore, the AP area identified using SAFE-T mapping is about one-quarter of the total scar size. This “smaller target” may improve procedural safety by limiting ablation as compared to homogenization (28).
First, this is a retrospective study and ablation was not guided by SAFE-T mapping. Therefore, this is a hypothesis-generating study in terms of its usefulness for guiding VT substrate ablation. Second, this study focuses by design only on mappable VT. Third, the sample size was small, and a head-to head comparison with other substrate-based ablation techniques to define acute and long-term success rates is warranted. Patient-level statistical analyses are likely underpowered. Further prospective trials are needed to prove the hypothesis that this approach is clinically useful, reproducible, and generalizable to unmappable VT. Finally, nonischemic patients could have scar in the mid-myocardium or epicardium, which is not mappable from the endocardium. Further endo-epicardial and imaging-based studies for the application of this technique to intramural substrate are required.
Automated electrogram time-frequency analysis using 3D SAFE-T mapping allows objective identification of AP that reliably detect mappable VT isthmuses in patients with structural heart disease. The results of this study provide a good choice and useful alternative mapping/ablation strategy in addition to late potential mapping for the identification of VT isthmuses during SR and reducing ablation as compared to scar homogenization. The technique provides a clear and objective endpoint that is suitable for assessment by post-ablation remapping. Prospective evaluation of this novel automated approach to substrate ablation, empirically targeting regions of SR APs, is warranted.
COMPETENCY IN MEDICAL KNOWLEDGE: Automated electrogram time-frequency 3D SAFE-T mapping allows objective identification of mappable VT isthmuses in patients with structural heart disease. The technique also provides an alternative endpoint of VT ablation by post-ablation remapping.
TRANSLATIONAL OUTLOOK: Automated 3D SAFE-T mapping provides a good alternative choice for VT ablation in structural heart patients. Further head-to head comparison with other substrate-based ablation techniques in mappable and unmappable VT to define acute and long-term success rates is warranted.
For supplemental tables and figures, please see the online version of this paper.
This work was supported by Ministry of Science and Technology of Taiwan for National Yang-Ming University, Taipei Veterans General Hospital, and the Center for Dynamical Biomarkers and Translational Medicine, National Central University (MOST 103-2221-E-008-006-MY3, 103-2314-B-010-048-MY3, 103-2321-B-008-003, 104-3115-E-008-001, 104-2314-B-010-063-MY2); Grant of Taipei Veterans General Hospital (V104E7-001, V105C-122).
- Abbreviations and Acronyms
- arrhythmogenic potential(s)
- electroanatomic map(ping)
- Hilbert-Huang transform
- left ventricle
- low-voltage zone
- radiofrequency catheter ablation
- right ventricle
- simultaneous amplitude frequency electrogram transformation
- sinus rhythm
- ventricular tachycardia
- Received October 2, 2015.
- Revision received January 21, 2016.
- Accepted January 26, 2016.
- American College of Cardiology Foundation
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