Author + information
- Received November 12, 2016
- Revision received January 26, 2017
- Accepted February 21, 2017
- Published online April 24, 2017.
- Pasquale Santangeli, MD, PhDa,∗ (, )
- David S. Frankel, MDa,
- Roderick Tung, MDb,
- Marmar Vaseghi, MDc,
- William H. Sauer, MDd,
- Wendy S. Tzou, MDd,
- Nilesh Mathuria, MDe,
- Shiro Nakahara, MDf,
- Timm M. Dickfeldt, MDg,
- Dhanunjaya Lakkireddy, MDh,
- T. Jared Bunch, MDi,
- Luigi Di Biase, MD, PhDj,k,
- Andrea Natale, MDj,
- Venkat Tholakanahalli, MDl,
- Usha B. Tedrow, MDm,
- Saurabh Kumar, BSc(Med), MBBS, PhDm,
- William G. Stevenson, MDm,
- Paolo Della Bella, MDn,
- Kalyanam Shivkumar, MD, PhDc,
- Francis E. Marchlinski, MDa,
- David J. Callans, MDa,
- International VT Ablation Center Collaborative Group
- aCardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
- bUniversity of Chicago Medicine, Pritzker School of Medicine, Chicago, Illinois
- cUCLA Cardiac Arrhythmia Center, UCLA Health System, Los Angeles, California
- dUniversity of Colorado, Aurora, Colorado
- eBaylor St. Luke's Medical Center/Texas Heart Institute, Houston, Texas
- fDokkyo Medical University Koshigaya Hospital, Saitama, Japan
- gUniversity of Maryland Medical Center, Baltimore, Maryland
- hUniversity of Kansas Medical Center, Kansas City, Kansas
- iIntermountain Heart Institute, Intermountain Medical Center, Murray, Utah
- jTexas Cardiac Arrhythmia Institute, St. David’s Medical Center, Austin, Texas
- kAlbert Einstein College of Medicine at Montefiore Hospital, New York, New York
- lUniversity of Minnesota Medical Center, Minneapolis VA Medical Center, Minneapolis, Minnesota
- mBrigham and Women’s Hospital, Boston, Massachusetts
- nHospital San Raffaele, Milan, Italy
- ↵∗Address for correspondence:
Dr. Pasquale Santangeli, Electrophysiology Section, Cardiovascular Division, Hospital of the University of Pennsylvania, 9 Founders Pavilion–Cardiology, 3400 Spruce Street, Philadelphia, Pennsylvania 19104.
Background In patients referred for radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) in the setting of structural heart disease, early post-procedural mortality (EM) has not been previously investigated.
Objectives The purpose of this study was to evaluate EM after catheter ablation of scar-related VT.
Methods Associations between clinical and procedural variables and EM (within 31 days of the procedure) were tested in patients with structural heart disease undergoing RFCA of VT at 12 international centers.
Results Of 2,061 patients (mean age 62 ± 13 years; left ventricular ejection fraction [LVEF] 34 ± 13%; 53% ischemic etiology), EM occurred in 100 (5%; 95% confidence interval [CI]: 4% to 6%). A total of 54 (3%) patients died before hospital discharge (median 9 days after the procedure; 25% for refractory VT), including 12 (0.6%) after a major procedure-related complication. In multivariable analysis, the following factors were found to be significantly associated with EM: LVEF (odds ratio [OR] per percent decrease: 1.12; 95% CI: 1.05 to 1.20; p < 0.001), chronic kidney disease (OR: 2.73; 95% CI: 1.10 to 6.80; p = 0.030), presentation with VT storm (OR: 3.61; 95% CI: 1.37 to 9.48; p = 0.009), and presence of unmappable VTs (OR: 5.69; 95% CI: 1.37 to 23.69; p = 0.017). Recurrent VT was also associated with an increased risk of subsequent death (hazard ratio: 7.19; 95% CI: 5.57 to 9.28; p < 0.001) and EM (hazard ratio: 11.45; 95% CI: 7.47 to 17.59; p < 0.001).
Conclusions In a contemporary cohort of patients with scar-related VT undergoing RFCA, EM occurred in 5% of cases. Clinical and procedural variables indicating poorer clinical status (low LVEF, chronic kidney disease, VT storm, and unmappable VTs) and post-procedural VT recurrence may predict EM. Identification of such features may prompt early consideration for hemodynamic support or other care to help mitigate later potential complications.
Radiofrequency catheter ablation (RFCA) has an established therapeutic role in managing recurrent, drug-refractory, scar-related ventricular tachycardia (VT) (1). Typically, patients with scar-related VT have complex underlying substrates, concomitant heart failure, and a high burden of associated comorbidities; these factors contribute to significant morbidity and mortality (2,3). Although VT recurrence has been the primary and most studied outcome in trials assessing RFCA of scar-related VT (1), the competing risk of mortality related to concomitant advanced heart failure and associated comorbidities, or linked to unsuccessful RFCA with early post-procedural VT recurrence, has not been adequately investigated. In-hospital and early (within 1 month) mortality (EM) have been used extensively as important outcome measures for invasive cardiology procedures, including interventional coronary procedures and cardiac surgery (4–6). To the best of our knowledge, no previous study has evaluated the incidence of EM after RFCA of scar-related VT or the clinical and procedural variables associated with EM. Proper identification of subjects at increased risk of EM after RFCA of VT would have important implications, not only for identifying therapeutic strategies to potentially improve survival but also for allowing appropriate pre-procedural counseling of patients and families.
The purpose of the present study was to investigate the incidence of EM after RFCA of scar-related VT, as well as its clinical and procedural correlates, using data from a large, multicenter VT ablation registry.
The International VT Ablation Center Collaborative Group is a shared retrospective multicenter database that incorporates procedural and outcome data of 12 international sites that specialize in VT management. The detailed database structure, with a list of participating centers and principal investigators, has been published previously (7). In brief, the International VT Ablation Center Collaborative Group database includes data from a retrospective review of consecutive VT ablation procedures between 2002 and 2013 in patients with the following inclusion criteria: 1) structural heart disease with ischemic cardiomyopathy (ICM) and/or nonischemic cardiomyopathy with left ventricular ejection fraction (LVEF) <55% (LVEF >55% was included in cases of right ventricular and hypertrophic cardiomyopathy); 2) RFCA for monomorphic VT; 3) evidence of myocardial scar, as identified with predefined criteria at electroanatomic voltage mapping (7–9); and 4) clinical follow-up for VT recurrence, transplant, and mortality.
As previously reported (7), the diagnosis of ICM was established according to history of myocardial infarction with focal wall-motion abnormality or fixed perfusion defect correlated with coronary stenosis or previous coronary intervention. Patients with nonischemic cardiomyopathy included those with arrhythmogenic right ventricular, hypertrophic, valvular, sarcoidosis, toxin-induced, myocarditis, congenital, chagasic, and idiopathic dilated cardiomyopathy. The institutional review boards of the participating centers approved the collection of data.
Electrophysiology study and catheter ablation
Patients presented to the cardiac electrophysiology laboratory in the fasting state. Conscious sedation or general anesthesia was used for patient comfort at the discretion of the operator. The main strategy for RFCA of VT across participating centers was a substrate-based ablation approach guided by electroanatomic mapping, as previously reported (7). Epicardial mapping and ablation were performed at the discretion of the operator; access to the pericardial space was obtained by using the percutaneous technique described by Sosa et al. (10). In cases of previous cardiac surgery or adhesions that impaired the ability to map the epicardium, surgical access was used to perform epicardial mapping and ablation (11). Hemodynamic support devices (extracorporeal membrane oxygenation, percutaneous mechanical hemodynamic support with the Impella device [Abiomed, Danvers, Massachusetts] or intra-aortic balloon pump) were used at the discretion of the operator. Programmed stimulation with up to 2 sites, with 2 drive trains and triple extrastimuli (minimum of 200-ms coupling interval or ventricular refractory period), was performed for VT induction. Electroanatomic maps were created during sinus or paced rhythm by using the CARTO (Biosense Webster, Diamond Bar, California) or NavX (St. Jude Medical, Minneapolis, Minnesota) three-dimensional mapping systems; standard voltage cutoff criteria were used to define scar (8,9). For hemodynamically tolerated VTs, entrainment mapping was performed within the low-voltage area at sites exhibiting diastolic activity to identify critical sites of the VT re-entrant circuit.
A critical site that was an appropriate target for ablation was defined as a site showing entrainment with concealed QRS fusion and return cycle within 30 ms of the VT cycle length, with matching stimulus–QRS and electrogram–QRS intervals (12) or where VT terminated during pacing without global capture (13). For hemodynamically unstable VTs, substrate modification was performed, targeting sites identified by pace mapping and split and late potentials, as previously described (7). Elimination of sustained monomorphic VT was the common desired procedural endpoint, and programmed stimulation was performed after ablation, unless hemodynamic instability or procedural duration was prohibitive. RFCA was performed by using a standard nonirrigated catheter (Navi-Star; Biosense Webster), an open-irrigated catheter (ThermoCool, ThermoCool SF, or NaviStar RMT 3.5-mm, Biosense Webster), or a closed-loop irrigated catheter (Chilli, Boston Scientific, Natick, Massachusetts) with a power of 30 to 50 W and a temperature limit of 42°C to 45°C.
The primary study endpoint was early post-procedural mortality (EM), which was defined as death occurring within 31 days from the index procedure. As a secondary endpoint, recurrent VT/ventricular fibrillation was reported. This outcome was defined as documented sustained VT and/or ventricular fibrillation, or any appropriate implantable cardioverter-defibrillator therapy, including antitachycardia pacing. Data and follow-up information from the most recent ablation were reported for patients who underwent multiple procedures.
Continuous data are reported as mean ± SD or median (25th to 75th percentile) for skewed distributions. Categorical data are reported as number and percentages. The unpaired Student t test or Mann-Whitney U test, when appropriate, was used to determine differences between groups for continuous variables. The chi-square test was used to compare differences across groups for categorical variables. Univariate and multivariable logistic regression analyses were applied for assessment of the association of baseline clinical and procedural variables with occurrence of EM. A backward reduction approach was performed by sequential exclusions from the model of variables with p > 20%. The impact of VT recurrence on subsequent overall mortality and EM was also evaluated by using Cox proportional hazards regression with VT recurrence as a time-dependent covariate.
Relative risk estimates for EM were reported as odds ratios (ORs) and 95% confidence intervals (CIs) or as hazard ratios and 95% CIs. In addition, the PAINESD risk score (Online Figure 1, Central Illustration), which was derived from a previous independent cohort of patients with structural heart disease undergoing VT ablation (14), was used to summarize differences in clinical risk profile between groups. A p level <0.05 was considered to indicate statistical significance. Statistical analyses were conducted by using Stata version 14.1 (Stata Corporation, College Station, Texas).
Clinical characteristics and procedural data
The baseline clinical characteristics and procedural data of the study patients are presented in Tables 1 and 2. A total of 2,061 patients (mean age 62 ± 13 years; 87% men) were included in the analysis; 1,095 (53%) patients had ICM. The mean LVEF was 34 ± 13%, with 647 (34%) patients presenting with severe heart failure symptoms (New York Heart Association functional class III/IV). A total of 684 (35%) patients presented with VT storm, defined as ≥3 separate, sustained episodes of VT in the 24 h before ablation (15), including 8 (0.4%) patients who presented with incessant VT. Pre-procedural antiarrhythmic medications included amiodarone in 1,020 (55%) patients, sotalol in 240 (13%), a Class 1A agent in 43 (2%), a Class 1C agent in 81 (4%), and a combination of at least 2 antiarrhythmic drugs in 338 (18%) patients. During the index ablation procedure, a median of 2 VTs per patient (range 1 to 3 per patient) were induced. A total of 773 (56%) patients had at least 1 unmappable VT induced during the procedure. Periprocedural hemodynamic support was used in 6% of cases.
At the end of the procedure, VT noninducibility at programmed electrical stimulation was achieved in 67% of patients; in 85 (4%) cases, repeat programmed stimulation was not performed. Procedural-related complications occurred in 127 (7%) cases. One-month follow-up data were available in all patients. Complete follow-up data through 1 year were available for 79% of the cohort, with censoring of 444 patients before 1 year.
Incidence of EM and comparison with late mortality
A total of 100 patients (5%; 95% confidence interval [CI]: 4% to 6%) died early after the procedure (Tables 1, 2, 3, and 4). Cumulative EM versus time is presented in Figure 1. Overall, mortality was 13% at 1 year. A comparison of clinical and procedural data between patients who died early post-procedure and those who had late mortality is presented in Table 3. Overall, patients who died early post-procedure had lower LVEF and higher rates of VT storm and chronic kidney disease. With regard to procedural data, patients who died early had higher requirements for periprocedural hemodynamic support, worse acute procedural outcomes (higher rates of acute procedural failure), and a higher rate of periprocedural complications. In addition, the PAINESD risk score (Online Figure 1) was significantly higher in patients who died early post-procedure compared with those who died later (16 ± 7 vs. 14 ± 6; p = 0.006) or those who survived throughout the study follow-up (16 ± 7 vs. 9 ± 6; p < 0.001).
EM and mode of death
Of the 100 EM cases, 48 (48%) patients had early recurrent VT preceding death (Figure 2), although the time course from time of first VT recurrence to death was highly variable. Refractory VT was the cause of death in 22% of cases, with another 39% dying of other cardiac causes (most commonly advanced heart failure). Information on the mode of death was not available in 28% of cases (Central Illustration).
Of the 100 patients with EM, 54 (54%) died before hospital discharge after a median of 9 days (range 3 to 17 days) from the index ablation procedure (13 [25%] of 52 due to refractory VT; 28 [54%] of 52 for cardiac causes different from VT; 11 [21%] of 52 for noncardiac causes; and 2 patients for unknown reasons). Among the 54 patients who died while in the hospital, 12 (0.6%) patients died after a major procedure-related complication (Table 5). These complications included major bleeding events (pericardial effusion, intracranial bleeding, and retroperitoneal hemorrhage), thromboembolic events (stroke and pulmonary embolism), and procedural death in 2 cases. Both procedural deaths were due to cardiogenic shock. In 1 case, rescue was attempted with emergent initiation of veno-arterial extracorporeal membrane oxygenation, which failed. In the other case, the cardiogenic shock was associated with disseminated intravascular coagulopathy.
An additional 4 (0.2%) patients died outside of the hospital (nursing facility or home) after a major procedure-related complication. The mode of death in these cases did not seem directly related to the procedure complication and included recurrent refractory VT (n = 1), pulseless electrical activity (n = 1), acute kidney failure leading to refractory heart failure (n = 1), and advanced heart failure (n = 1) (Online Table 1). Finally, 6 (0.3%) patients underwent heart transplantation within the first month post-ablation, with an average time between the index procedure and the transplant of 13 ± 7 days. These patients survived beyond 1 month post-procedure and were included in the control group.
Clinical and procedural correlates of EM
Compared with the rest of the study group, patients who had EM were older (67 ± 12 years vs. 62 ± 13 years; p = 0.001), had a higher prevalence of diabetes (38% vs. 21%; p < 0.001) and chronic kidney disease (55% vs. 28%; p < 0.001), had more severe heart failure symptoms (New York Heart Association functional class III/IV: 67% vs. 32%; p < 0.001) and lower LVEF (22 ± 8% vs. 34 ± 13%; p < 0.001), presented more often with VT storm (66% vs. 34%; p < 0.001) and history of implantable cardioverter-defibrillator shocks (80% vs. 65%; p = 0.004), and were treated more commonly with amiodarone (66% vs. 55%; p = 0.033), and ≥2 antiarrhythmic drugs (30% vs. 18%; p = 0.003).
As mentioned, EM cases had significantly higher PAINESD scores compared with patients who survived beyond 31 days post-procedure. Among procedural data (Table 2), the EM group had a higher number of induced (>3 in 52% vs. 37%; p = 0.018) and unmappable (73% vs. 55%; p = 0.001) VTs with slower cycle lengths (slowest cycle length: 454 ± 102 ms vs. 407 ± 108 ms; p < 0.001), higher use of mechanical hemodynamic support (25% vs. 5%; p < 0.001), longer procedure times (305 ± 117 min vs. 283 ± 117 min; p = 0.048), lower rates of VT noninducibility at post-procedural programmed stimulation (43% vs. 68%; p < 0.001), and higher rates of procedural-related complications (19% vs. 6%; p < 0.001). Year of enrollment did not seem to be associated with EM (Online Figure 2).
In multivariable analysis (Table 4), the following characteristics remained independently associated with EM: LVEF (OR per percent decrease: 1.12; 95% CI: 1.05 to 1.20; p < 0.001), chronic kidney disease (OR: 2.73; 95% CI: 1.10 to 6.80; p = 0.030), presentation with VT storm (≥3 appropriate implantable cardioverter-defibrillator interventions within 24 h; OR: 3.61; 95% CI: 1.37 to 9.48; p = 0.009), and presence of unmappable VTs (OR: 5.69; 95% CI: 1.37 to 23.69; p = 0.017). Recurrent VT was also associated with increased risk of subsequent death (hazard ratio: 7.19; 95% CI: 5.57 to 9.28; p < 0.001) and EM (hazard ratio; 11.45; 95% CI: 7.47 to 17.59; p < 0.001). Overall, periprocedural complications were associated with an increased risk of EM at univariate analysis (Tables 2 and 4). This outcome seemed driven by thrombotic and other complications different from periprocedural bleeding (Online Appendix, Online Tables 2 and 3).
To the best of our knowledge, this study is the largest to assess the incidence and the clinical and procedural correlates of post-procedural EM in patients undergoing RFCA of scar-related VT. In this multicenter registry, EM occurred in 5% of patients and was associated with clinical and procedural factors indicating poorer clinical status and worse procedural results. These factors include low LVEF, chronic kidney disease, VT storm, unmappable VTs, and post-procedural VT recurrence (Central Illustration).
Post-procedural EM has been adopted as a key outcome metric in various cardiology procedures, including percutaneous coronary interventions (PCIs) and coronary artery bypass graft (CABG) surgery (5,16). The clinical importance of EM relies on its strong association with the baseline clinical profile of patients and procedural risks, together with quality of hospital care and transition to the outpatient setting. Our study systematically describes the occurrence of post-procedural EM in patients undergoing RFCA of scar-related VT, and it is essential for understanding the rates of in-hospital and early post-discharge mortality in this complex patient population, allowing for direct comparison with similar indicators developed for other interventional and surgical cardiac procedures (5,16–18). For instance, recent estimates of EM associated with PCI and CABG range from 1.5% to 3%, respectively (5,16,17). These estimates seem substantially lower than the 5% rate of EM found in our study, and they suggest the presence of significant competing mortality risks in patients undergoing RFCA of scar-related VT, and possibly higher periprocedural risks compared with PCI or CABG. However, the EM rate found in our study is in line with what has been shown for interventional and surgical procedures in patients with severe heart disease (19,20).
As expected, the clinical profile of patients who died early post-procedure indicated more severe clinical status, with poorer left ventricular systolic function, presence of chronic kidney disease, presentation with VT storm, and unmappable VTs. Many of these variables are known predictors of survival in patients with heart failure, and they have been incorporated into clinical risk scores (e.g., the Seattle Heart Failure Model) that predict survival in different clinical scenarios, including after catheter ablation procedures (21).
Although these factors cannot be fully modified with specific therapeutic interventions, procedural outcomes were also found to have a profound impact on subsequent EM. Unsuccessful VT ablation with early post-procedural VT recurrence was also associated with EM, with 48% of EM cases experiencing VT recurrence before death. This outcome is in line with previous observational studies on smaller patient cohorts (22), and it would support the notion that more aggressive treatment of VT and/or heart failure in patients who experience early post-procedural recurrence may translate into a mortality benefit. In this regard, more comprehensive substrate-based ablation approaches that target abnormal electrograms within the scar (e.g., “scar homogenization”), avoiding attempts at VT induction, have been suggested to improve short- and long-term VT-free survival compared with more limited ablation strategies (23). However, in high-risk patients with large substrates and/or advanced heart failure status and limited cardiac reserve, extensive substrate ablation methods that target all abnormal electrograms may be suboptimal and have a negative impact on the limited cardiac reserve and function. In these patients, a more focused strategy (targeting the regions of the scar that are responsible for the clinical VT) may be the preferred approach. The latter may also be associated with reduced procedural time, which, in our study, was found to be associated with adverse outcomes at univariate analysis.
The remaining 52% of study patients with EM did not experience early recurrent VT before death. In these subjects, presentation with VT was likely just a marker of progressive clinical deterioration leading to EM. Future studies are necessary to better identify this specific subgroup, in whom attempts to achieve VT control with RFCA procedures might be more limited. In this regard, a proper identification of patients at risk of pump failure after effective elimination of VT may also prompt more intensive management of heart failure in these patients, including hemodynamic stabilization and support before and after the procedure, and possibly consideration for more advanced heart failure therapies, including permanent left ventricular assist device implantation or heart transplantation.
In-hospital mortality accounted for more than one-half of the EM cases, with non-VT–related mortality (mostly heart failure related) accounting for the majority of the in-hospital deaths. Of note, in 12% of EM cases (0.6% of the total patient cohort), in-hospital death followed a major procedure-related complication (Table 5). Overall, periprocedural complications (particularly thrombotic and other complications different from periprocedural bleeding) were significantly more common in patients who died early post-procedure (Online Tables 2 and 3). These results highlight the importance of minimizing procedural-related complications as an important outcome of VT ablation procedures, as this factor may have a potential favorable impact on subsequent mortality. Because complications tend to decline with operator and center experience (24,25), these data also suggest that these procedures should be performed in VT ablation specialty centers as a means to further reduce EM (25).
This study was a retrospective analysis from a large registry that included data from specialized tertiary referral centers. As such, the results on EM may represent the “best case scenario,” given the expertise of the participating institutions in catheter ablation of VT, and the results may not be generalizable to lower volume centers. The nonrandomized design is a limitation. However, the substantially larger sample size compared with any other published randomized trial is a major strength.
In addition, multiple ablations were performed, with reporting of the last ablation. Given the retrospective data collection, some potentially important clinical and procedural (e.g., type of left ventricular access) characteristics were not available for analysis. Given the overall small number of events and high number of covariates, multivariable statistical analyses may be affected by overfitting and should be viewed as hypothesis generating, rather than conclusive (26). Complete follow-up through 1 year was available for 79% of the cohort, although 1-month follow-up data were available in all patients. In this regard, we extended the time period to define EM to 31 days (instead of the typical 30-day period used in PCI and CABG studies) to increase the number of EM cases and potentially enhance the statistical power to detect differences between groups. Of note, 6 (6%) of 100 early death events occurred exactly at day 31 after the index procedure. Finally, we reported all-cause mortality as a measure of outcome, rather than only VT-related and procedure-related mortality (which are more directly affected by the results of RFCA) for several reasons. In many cases, the cause of death was not available and, in some cases, may have been misclassified, given the lack of implantable cardioverter-defibrillator interrogation at the time of death.
In a contemporary cohort of patients with scar-related VT undergoing RFCA, early post-procedural mortality occurred in 5% of cases, with more than one-half of the events occurring in-hospital. Early mortality may be predicted by clinical and procedural variables indicating poorer clinical status and worse procedural outcomes. These variables include low LVEF, chronic kidney disease, presentation with VT storm, presence of unmappable VTs, and post-procedural VT recurrence. Further studies are necessary to identify the best therapeutic strategies to reduce EM in these patients.
COMPETENCY IN MEDICAL KNOWLEDGE: In patients with structural heart disease and recurrent VT undergoing catheter ablation, early post-procedural mortality occurred in 5% and was associated with poorer pre-procedural clinical status and worse procedural outcomes.
TRANSLATIONAL OUTLOOK: Further prospective studies are necessary to evaluate therapeutic strategies that reduce EM in patients undergoing catheter ablation of scar-related VT.
For supplemental figures and tables, please see the online version of this article.
This trial was an unfunded, investigator-initiated collaborative study. Dr. Santangeli has received honoraria from Biosense Webster, Baylis Medical, Boston Scientific, and Medtronic; and is a consultant for Biosense Webster and Baylis Medical. Dr. Shivkumar is supported by National Heart, Lung, and Blood Institute grant R01HL084261. Dr. Tzou has received speaker honoraria from Boston Scientific. Dr. Di Biase is a consultant for Stereotaxis, Biosense Webster, and St. Jude Medical; and has received speaker honorarium/travel reimbursement from Biotronik, Medtronic, Boston Scientific, Janssen, Pfizer, and Epi EP. Dr. Natale is a consultant for Stereotaxis, Biosense Webster, and St. Jude Medical; and has received speaker honorarium/travel reimbursement from Biotronik, Medtronic, Boston Scientific, Janssen, Pfizer, and Epi EP. Dr. Tholakanahalli has received grants from St. Jude Medical Foundation. Dr. Tedrow has received honoraria from Medtronic, Boston Scientific, Biosense Webster, and St. Jude Medical; and research grants from Biosense Webster and St. Jude Medical. Dr. Burkhardt is a consultant to Biosense Webster. Dr. Dickfeldt has received a research grant from and is a consultant to Biosense Webster. Dr. Weiss is a consultant to Stereotaxis. Dr. Stevenson is the recipient of a patent for needle ablation consigned to Brigham and Women’s Hospital. Dr. Marchlinski is a consultant to Biosense Webster, Medtronic, and Boston Scientific. Dr. Della Bella is a consultant to St. Jude Medical; and has received honoraria for lectures from Biosense Webster, St. Jude Medical, and Biotronik. Dr. Callans has served as a consultant for Biosense Webster and St. Jude Medical. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Abbreviations and Acronyms
- coronary artery bypass graft
- confidence interval
- early mortality
- ischemic cardiomyopathy
- left ventricular ejection fraction
- odds ratio
- percutaneous coronary intervention
- radiofrequency catheter ablation
- ventricular tachycardia
- Received November 12, 2016.
- Revision received January 26, 2017.
- Accepted February 21, 2017.
- 2017 American College of Cardiology Foundation
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