Influence of clinical and procedural predictors on ventricular tachycardia ablation outcomes: an analysis from the substrate mapping and ablation in Sinus Rhythm to Halt Ventricular Tachycardia Trial (SMASH-VT)

Acute post-procedural inducibility is a poor predictor of clinical outcomes in high-risk patients (PAINESD > 17) undergoing scar-related ventricular tachycardia ablation

AIMS

Ventricular tachycardia (VT) non-inducibility in response to programmed ventricular stimulation (PVS) is a widely used procedural endpoint for VT ablation despite inconclusive evidence with respect to clinical outcomes in high-risk patients. The aim is to determine the utility of acute post-ablation VT inducibility as a predictor of VT recurrence, mortality, or mortality equivalent in high-risk patients.

METHODS AND RESULTS

We conducted a retrospective analysis of high-risk patients (defined as PAINESD > 17) who underwent scar-related VT ablation at our institution between July 2010 and July 2022. Patients' response to PVS (post-procedure) was categorized into three groups: Group A, no clinical VT or VT with cycle length > 240 ms inducible; Group B, only non-clinical VT with cycle length > 240 ms induced; and Group C, all other outcomes (including cases where no PVS was performed). The combined primary endpoint included death, durable left ventricular assist device placement, and cardiac transplant (Cox analysis). Ventricular tachycardia recurrence was considered a secondary endpoint (competing risk analysis). Of the 1677 VT ablation cases, 123 cases met the inclusion criteria for analysis. During a 19-month median follow-up time (interquartile range 4-43 months), 82 (66.7%) patients experienced the composite primary endpoint. There was no difference between Groups A and C with respect to the primary [hazard ratio (HR) = 1.21 (0.94-1.57), P = 0.145] or secondary [HR = 1.18 (0.91-1.54), P = 0.210] outcomes. These findings persisted after multivariate adjustments. The size of Group B (n = 13) did not permit meaningful statistical analysis.

CONCLUSION

The results of post-ablation PVS do not significantly correlate with long-term outcomes in high-risk (PAINESD > 17) VT ablation patients.

Ventricular Tachycardia Ablation Endpoints: Moving Beyond Noninducibility

In patients with structural heart disease and ventricular tachycardia (VT) undergoing catheter ablation, the response to programmed electrical stimulation (PES) at the end of the procedure has been traditionally used to evaluate the acute success and predict long-term outcomes. Although noninducibility at PES has been extensively investigated and validated in clinical trials and large multicenter registries, its performance in predicting long-term freedom from VT is suboptimal. In addition, PES has inherent limitations related to the influence of background antiarrhythmic drug therapy, periprocedural use of anesthesia, and the heterogeneity in PES protocols. The increased utilization of substrate-based ablation approaches that focus on ablation of abnormal electrograms identified with mapping in sinus or paced rhythm has been paralleled by a need for additional procedural endpoints beyond VT noninducibility at PES. This article critically appraises the relative merits and limitations of different procedural endpoints according to different ablation techniques for catheter ablation of scar-related VT.

Machine-Learning-Based Prediction of 1-Year Arrhythmia Recurrence after Ventricular Tachycardia Ablation in Patients with Structural Heart Disease

BACKGROUND

Ventricular tachycardia (VT) recurrence after catheter ablation remains a concern, emphasizing the need for precise risk assessment. We aimed to use machine learning (ML) to predict 1-month and 1-year VT recurrence following VT ablation.

METHODS

For 337 patients undergoing VT ablation, we collected 31 parameters including medical history, echocardiography, and procedural data. 17 relevant features were included in the ML-based feature selection, which yielded six and five optimal features for 1-month and 1-year recurrence, respectively. We trained several supervised machine learning models using 10-fold cross-validation for each endpoint.

RESULTS

We observed 1-month VT recurrence was observed in 60 (18%) cases and accurately predicted using our model with an area under the receiver operating curve (AUC) of 0.73. Input features used were hemodynamic instability, incessant VT, ICD shock, left ventricular ejection fraction, TAPSE, and non-inducibility of the clinical VT at the end of the procedure. A separate model was trained for 1-year VT recurrence (observed in 117 (35%) cases) with a mean AUC of 0.71. Selected features were hemodynamic instability, the number of inducible VT morphologies, left ventricular systolic diameter, mitral regurgitation, and ICD shock. For both endpoints, a random forest model displayed the highest performance.

CONCLUSIONS

Our ML models effectively predict VT recurrence post-ablation, aiding in identifying high-risk patients and tailoring follow-up strategies.

[Catheter ablation of ventricular tachycardia-Update 2023]

The management of ventricular tachycardias (VT), which are often associated with severe cardiac disease, is a challenging clinical task. The structural damage to the myocardium associated with cardiomyopathy is crucial to the occurrence of VT and plays a fundamental role in arrhythmia mechanisms. The goal of catheter ablation is to develop an accurate understanding of the patient-specific arrhythmia mechanism as a first procedural step. As a second step, the ventricular areas that maintain the arrhythmia mechanism can be ablated and thereby electrically inactivated. Catheter ablation thereby enables causal therapy of VT by modifying the areas of the affected myocardium in such a way that VT can no longer be triggered. The procedure is an effective treatment option for affected patients.

Complications of catheter ablation for ventricular tachycardia

With the increasing literature demonstrating benefits of catheter ablation for ventricular tachycardia (VT), the number of patients undergoing VT ablation has increased dramatically. As VT ablation is being performed more routinely, operators must be aware of potential complications of VT ablation. This review delves deeper into the practice of VT ablation with a focus on periprocedural complications.

The prognostic value of J-wave pattern for recurrence of ventricular tachycardia after catheter ablation in patients with myocardial infarction

BACKGROUND

J-waves and fragmented QRS (fQRS) on surface ECGs have been associated with the occurrence of ventricular tachyarrhythmias. Whether these non-invasive parameters can also predict ventricular tachycardia (VT) recurrence after radiofrequency catheter ablation (RFCA) is unknown. Of interest, patients with a wide QRS-complex have been excluded from clinical studies on J-waves, although a J-wave like pattern has been described for wide QRS.

METHODS

We retrospectively included 168 patients (67 ± 10 years; 146 men) who underwent RFCA of post-infarct VT. J-wave pattern were defined as J-point elevation ≥ 0.1 mV in at least two leads irrespective of QRS width. fQRS was defined as various RSR` pattern in patients with narrow QRS and more than two R wave in those with wide QRS. The primary endpoint was VT recurrence after RFCA up to 24 months.

RESULTS

J-wave pattern and fQRS were present in 27 and 28 patients, respectively. Overlap of J-wave pattern and fQRS was observed in nine. During a median follow-up of 20 (interquartile range 9-24) months, 46 (27%) patients had VT recurrence. Kaplan-Meier curves revealed that both J-wave pattern and fQRS were associated with VT recurrence. Multivariate Cox regression analysis demonstrated that the presence of J-wave pattern (hazard ratio [HR] 2.84; 95% confidence interval [CI] 1.45-5.58; P = .002) and greater number of induced VT (HR 1.29; 95% CI 1.15-1.45; P < .001) were the independent predictors of VT recurrence.

CONCLUSIONS

A J-wave pattern-but not fQRS-is independently associated with an increased risk of post-infarct VT recurrence after RFCA irrespective of QRS width. This simple non-invasive parameter may identify patients who require additional treatment.

Prophylactic Catheter Ablation of Ventricular Tachycardia in Ischemic Cardiomyopathy: a systematic review and meta-analysis of randomized controlled trials Electrophysiology Collaborative Consortium for Metaanalysis - ELECTRAM Investigators

Aims

Catheter ablation is an effective strategy for drug-refractory ventricular tachycardia (VT) in ischemic cardiomyopathy. We aimed to perform a systematic review and meta-analysis of outcomes of prophylactic catheter ablation (PCA) of Ventricular Tachycardia (VT) in ischemic cardiomyopathy patients.

Methods

We performed a comprehensive literature search through February 10, 2020, for all eligible randomized controlled trials that compared "PCA" versus "No PCA" for VT. Primary efficacy outcomes included - appropriate ICD therapy (composite of anti-tachycardia pacing and ICD shock), appropriate ICD shocks, electrical storm, cardiac mortality, and all-cause mortality. The primary safety outcome was any adverse events.

Results

Four randomized controlled trials (N = 505) met inclusion criteria. Prophylactic catheter ablation was associated significant reduction in appropriate ICD therapies (RR 0.70; 95% CI 0.55 - 0.89, p = 0.004), appropriate ICD shocks (RR 0.57 95% CI 0.40 - 0.80, p = 0.001) with a trend towards reduced risk of electrical storm (RR 0.64; CI 0.39 - 1.05; p = 0.075) compared to "No PCA". There was no significant difference in cardiac mortality (RR 0.66, 95% CI 0.31 - 1.43, p = 0.29) and all-cause mortality (RR 0.98, 95% CI 0.52 - 1.82, p = 0.94) with similar adverse events (RR 1.46, 95% CI 0.73 - 2.95, p = 0.29) between two groups.

Conclusions

Prophylactic catheter ablation in ischemic cardiomyopathy patients was associated with a lower risk of ICD therapies, including ICD shocks and VT storm with no difference in cardiac and all-cause mortality.

How personalized heart modeling can help treatment of lethal arrhythmias: A focus on ventricular tachycardia ablation strategies in post-infarction patients

Precision Cardiology is a targeted strategy for cardiovascular disease prevention and treatment that accounts for individual variability. Computational heart modeling is one of the novel approaches that have been developed under the umbrella of Precision Cardiology. Personalized computational modeling of patient hearts has made strides in the development of models that incorporate the individual geometry and structure of the heart as well as other patient-specific information. Of these developments, one of the potentially most impactful is the research aimed at noninvasively predicting the targets of ablation of lethal arrhythmia, ventricular tachycardia (VT), using patient-specific models. The approach has been successfully applied to patients with ischemic cardiomyopathy in proof-of-concept studies. The goal of this paper is to review the strategies for computational VT ablation guidance in ischemic cardiomyopathy patients, from model developments to the intricacies of the actual clinical application. To provide context in describing the road these computational modeling applications have undertaken, we first review the state of the art in VT ablation in the clinic, emphasizing the benefits that personalized computational prediction of ablation targets could bring to the clinical electrophysiology practice. This article is characterized under: Analytical and Computational Methods > Computational Methods Models of Systems Properties and Processes > Organ, Tissue, and Physiological Models Translational, Genomic, and Systems Medicine > Translational Medicine.

[Catheter ablation of ventricular tachycardia : Clinical outcome]

Catheter-based ablation of ventricular tachycardia (VT) is increasingly used in clinical practice. The reported success rates are especially high in idiopathic VT. In randomized controlled clinical trials like VANISH, ablation of scar-associated VT was superior in terms of mortality when compared to antiarrhythmic therapy. Treatment at experienced centers, e.g., using state-of-the-art electroanatomical mapping systems, is a promising option for these complex and often multimorbid patients.

Role of 3-Dimensional Architecture of Scar and Surviving Tissue in Ventricular Tachycardia: Insights From High-Resolution Ex Vivo Porcine Models

BACKGROUND

An improved knowledge of the spatial organization of infarct structure and its contribution to ventricular tachycardia (VT) is important for designing optimal treatments. This study explores the relationship between the 3-dimensional structure of the healed infarct and the VT reentrant pathways in high-resolution models of infarcted porcine hearts.

METHODS

Structurally detailed models of infarcted ventricles were reconstructed from ex vivo late gadolinium enhancement and diffusion tensor magnetic resonance imaging data of 8 chronically infarcted porcine hearts at submillimeter resolution (0.25×0.25×0.5 mm³). To characterize the 3-dimensional structure of surviving tissue in the zone of infarct, a novel scar-mapped thickness metric was introduced. Further, using the ventricular models, electrophysiological simulations were conducted to determine and analyze the 3-dimensional VT pathways that were established in each of the complex infarct morphologies.

RESULTS

The scar-mapped thickness metric revealed the heterogeneous organization of infarct and enabled us to systematically characterize the distribution of surviving tissue thickness in 8 hearts. Simulation results demonstrated the involvement of a subendocardial tissue layer of varying thickness in the majority of VT pathways. Importantly, they revealed that VT pathways are most frequently established within thin surviving tissue structures of thickness ≤2.2 mm (90th percentile) surrounding the scar.

CONCLUSIONS

The combination of high-resolution imaging data and ventricular simulations revealed the 3-dimensional distribution of surviving tissue surrounding the scar and demonstrated its involvement in VT pathways. The new knowledge obtained in this study contributes toward a better understanding of infarct-related VT.

Personalized virtual-heart technology for guiding the ablation of infarct-related ventricular tachycardia

Ventricular tachycardia (VT), which can lead to sudden cardiac death, occurs frequently in patients with myocardial infarction. Catheter-based radiofrequency ablation of cardiac tissue has achieved only modest efficacy, owing to the inaccurate identification of ablation targets by current electrical mapping techniques, which can lead to extensive lesions and to a prolonged, poorly tolerated procedure. Here we show that personalized virtual-heart technology based on cardiac imaging and computational modelling can identify optimal infarct-related VT ablation targets in retrospective animal (5 swine) and human studies (21 patients) and in a prospective feasibility study (5 patients). We first assessed in retrospective studies (one of which included a proportion of clinical images with artifacts) the capability of the technology to determine the minimum-size ablation targets for eradicating all VTs. In the prospective study, VT sites predicted by the technology were targeted directly, without relying on prior electrical mapping. The approach could improve infarct-related VT ablation guidance, where accurate identification of patient-specific optimal targets could be achieved on a personalized virtual heart prior to the clinical procedure.

Prophylactic catheter ablation of ventricular tachycardia in ischemic cardiomyopathy: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Catheter ablation is proven to be an effective strategy for drug refractory ventricular tachycardia (VT) in ischemic cardiomyopathy. However, the appropriate timing of VT ablation and identifying the group of patients that may receive the greatest benefit remains uncertain. There is limited data on the effect on prophylactic catheter ablation (PCA) in the prevention of implantable cardioverter defibrillator (ICD) therapy, electrical storm, and mortality.

METHODS

We performed a comprehensive literature search through November 1, 2017, for all eligible studies comparing PCA + ICD versus ICD only in eligible patients with ischemic cardiomyopathy. Clinical outcomes included all ICD therapies including ICD shocks and electrical storm. Additional outcomes included all-cause mortality, cardiovascular mortality, and complications.

RESULTS

Three randomized controlled trials (RCTs) (N = 346) met inclusion criteria. PCA was associated with a significantly lower ICD therapies (OR 0.49; CI 0.28 to 0.87; p = 0.01) including ICD shocks [OR 0.38; CI 0.22 to 0.64; p = 0.0003) and electrical storm (OR 0.55; CI 0.30 to 1.01; p = 0.05) when compared with ICD only. There was no significant difference in all-cause mortality (OR 0.77; CI 0.41 to 1.46; p = 0.42), cardiovascular mortality (OR 0.49; CI 0.16 to 1.50; p = 0.21), and major adverse events (OR 1.45; CI 0.52 to 4.01; p = 0.47) between two groups.

CONCLUSION

These results suggest prophylactic catheter ablation decreases ICD therapies, including shocks and electrical storm with no improvement in overall mortality. There is a need for future carefully designed randomized clinical trials.

High-Density Mapping in Ventricular Tachycardia Ablation: A PentaRay® Study

Background

High-density mapping of ventricular tachycardia (VT) with PentaRay^® (Biosense-Webster) provides high resolution with discrimination of local abnormal electrograms and slow conducting channels. We evaluate the feasibility of PentaRay^® to characterize the anatomical substrate and assume an influence of the outcome despite limitations.

Methods

Over a 24-month period, 26 endocardial and four epicardial maps were obtained of 26 VT patients (18 ischemic cardiomyopathy (ICM, 69.2%) and 8 non-ischemic cardiomyopathy (NICM, 30.8%), age 65 ± 9 years). Catheter ablation (CA) was performed with the aim of transecting the isthmus. The endpoint was non-inducibility of any VT. Manual review of the maps was performed and focused on evaluating scarring, bipolar electrograms, and procedure times.

Results

In 55.6 ± 34.4 min, 1,085.9 ± 726.2 points were created. The mean ablation time was 50.8 ± 30.1 min. The endpoint was achieved in 12 patients (46.2%). The mean dense scar area and the mean patchy scar area were 49.4 ± 51.8 cm² (range 0 - 190 cm²) and 14.7 ± 14.9 cm² (range 0 - 110 cm²), respectively. Analyzing the learning curve, we found a tendency in decreasing procedure times. During the course of follow-up treatment averaging a 14-month period, device interrogation showed that 17 patients (65.4%) had remained free of any arrhythmia recurrence.

Conclusion

The high-density maps with PentaRay^® were safely created in a short period of time. Our manual review of the maps reveals limitations of current annotation criteria; nevertheless, medium-term outcomes were encouraging. Further prospective studies are required to validate our findings in a larger cohort of patients.

Non-invasive programmed stimulation to identify high-risk patients with implanted cardioverter defibrillator (the NIPS-ICD study): study protocol for a randomized controlled trial

Background

The use of an implantable cardioverter defibrillator (ICD) is a widely used and effective therapy, which reduces the risk of cardiac death in many cardiac diseases, both implanted for secondary and primary prevention. However, recurrent arrhythmias and ICD discharges have adverse prognostic significance. Additional parameters that would identify patients who are at increased risk of arrhythmias and appropriate ICD interventions would be of clinical value. Modern ICDs are relatively complex devices with a number of functions, including the possibility to perform noninvasive programmed stimulation (NIPS) with an implanted electrode located in the right ventricle.

Methods/Design

The aim of the study is to evaluate the usefulness of NIPS in determining the likelihood of life-threatening arrhythmic events in patients with ICD. The study will include 150 consecutive patients with an ICD implanted both for primary and secondary prevention, regardless of etiology, who are followed in the outpatient clinic of our center and do not meet the exclusion criteria. A 12-step St. George’s Hospital NIPS protocol using ICD will be performed. The endpoint is to induce sustained ventricular arrhythmia (VT lasting more than 30 seconds or hemodynamically unstable VT/VF) or the end of the protocol. In case of serious and/or hemodynamically unstable heart rhythm disorders resistant to treatment with a low-energy antiarrhythmic pacing (ATP), the patient receives a short-term intravenous general anesthesia, and internal or external defibrillation is performed. Outpatient follow-up will be conducted during the pre-scheduled ICD control visits. An analysis of records of a registered memory device will be collected, a patient will be interviewed, and physical examination will be carried out. The follow-ups will be held every 3 months for 1 year. The primary endpoint of the follow-up will be appropriate intervention of ICD or sudden cardiac (arrhythmic) death; the secondary, appropriate ICD intervention, or death from cardiovascular causes; and the tertiary, appropriate ICD intervention, death or hospitalization for cardiovascular causes.

Discussion

It is expected that appropriate ICD interventions during follow-up will occur more often in patients who had sustained ventricular arrhythmias induced during NIPS.

Clinical trials registry

ClinicalTrials.gov, NCT02373306, date of registration: 26 February 2015.

Catheter ablation of drug refractory electrical storm in patients with ischemic cardiomyopathy: A single center experience

Objective:

Electrical storm (ES) is a life-threatening pathology that requires immediate and effective treatment due to increased morbidity and mortality. Catheter ablation (CA) is an effective therapeutic option, particularly in patients with drug resistant ventricular arrhythmia episodes. These procedures should only be performed in highly specialized and experienced centers. Here we aimed to assess safety and efficacy of CA in a relatively large cohort with ES in our tertiary center hospital.

Methods:

A total of 44 patients (90.9% male; mean age: 59.7±10.3 years) with ischemic cardiomyopathy undergoing CA for drug-refractory ES were prospectively evaluated. Procedures were performed using non-contact and electro-anatomic mapping systems. Long-term follow-up analysis addressed the predictors of ES recurrence and cardiac mortality.

Results:

Acute success rates for clinical and non-clinical VTs were 90.8% and 55.5%, respectively. A mean follow-up at 28±11 months revealed cardiac mortality in 8 (18%) patients, 39 (88.6%) patients were free from the ES, and 24 (55%) patients remained free from both ES and paroxysmal VT episodes. In multivariate regression analysis, recurrence of ES (OR=3.11, 95% CI: 1.65-4.62, p=0.001), LVEF, and serum creatinine were found as independent predictors of cardiac mortality. In addition, substrate based ablation, implantation of ICD for secondary prophylaxis, LVEF, and serum creatinine were good predictors of ES recurrence.

Conclusion:

Catheter ablation for ventricular arrhythmias in the course of ES in patients with ischemic cardiomyopathy is safe with an acceptable success rate. (Anatol J Cardiol 2016; 16: 159-64)

Freedom from recurrent ventricular tachycardia after catheter ablation is associated with improved survival in patients with structural heart disease: An International VT Ablation Center Collaborative Group study

BACKGROUND

The impact of catheter ablation of ventricular tachycardia (VT) on all-cause mortality remains unknown.

OBJECTIVE

The purpose of this study was to examine the association between VT recurrence after ablation and survival in patients with scar-related VT.

METHODS

Analysis of 2061 patients with structural heart disease referred for catheter ablation of scar-related VT from 12 international centers was performed. Data on clinical and procedural variables, VT recurrence, and mortality were analyzed. Kaplan-Meier analysis was used to estimate freedom from recurrent VT, transplant, and death. Cox proportional hazards frailty models were used to analyze the effect of risk factors on VT recurrence and mortality.

RESULTS

One-year freedom from VT recurrence was 70% (72% in ischemic and 68% in nonischemic cardiomyopathy). Fifty-seven patients (3%) underwent cardiac transplantation, and 216 (10%) died during follow-up. At 1 year, the estimated rate of transplant and/or mortality was 15% (same for ischemic and nonischemic cardiomyopathy). Transplant-free survival was significantly higher in patients without VT recurrence than in those with recurrence (90% vs 71%, P<.001). In multivariable analysis, recurrence of VT after ablation showed the highest risk for transplant and/or mortality [hazard ratio 6.9 (95% CI 5.3-9.0), P<.001]. In patients with ejection fraction <30% and across all New York Heart Association functional classes, improved transplant-free survival was seen in those without VT recurrence.

CONCLUSION

Catheter ablation of VT in patients with structural heart disease results in 70% freedom from VT recurrence, with an overall transplant and/or mortality rate of 15% at 1 year. Freedom from VT recurrence is associated with improved transplant-free survival, independent of heart failure severity.

Contemporary Mapping Techniques of Complex Cardiac Arrhythmias - Identifying and Modifying the Arrhythmogenic Substrate

Cardiac electrophysiology has moved a long way forward during recent decades in the comprehension and treatment of complex cardiac arrhythmias. Contemporary electroanatomical mapping systems, along with state-of-the-art technology in the manufacture of electrophysiology catheters and cardiac imaging modalities, have significantly enriched our armamentarium, enabling the implementation of various mapping strategies and techniques in electrophysiology procedures. Beyond conventional mapping strategies, ablation of complex fractionated electrograms and rotor ablation in atrial fibrillation ablation procedures, the identification and modification of the underlying arrhythmogenic substrate has emerged as a strategy that leads to improved outcomes. Arrhythmogenic substrate modification also has a major role in ventricular tachycardia ablation procedures. Optimisation of contact between tissue and catheter and image integration are a further step forward to augment our precision and effectiveness. Hybridisation of existing technologies with a reasonable cost should be our goal over the next few years.

A Questionable Indication For ICD Extraction After Successful VT Ablation

Sustained ventricular tachyarrhythmias represent a kind of complication shared by a number of clinical presentations of heart disease, sometimes leading to sudden cardiac death. Many efforts have been made in the fight against such a complication, mainly being represented by the implantable cardioverter defibrillator (ICD). In recent years, catheter ablation has grown as a means to effectively treat patients with sustained ventricular arrhythmias, in the contest of different cardiac substrates. Since carrying an ICD is associated with a potential risk deriving from its possible infective or malfunctioning complications, and given the current effectiveness of lead extraction procedures, it has been thought not to be unreasonable to ask ourselves about how to deal with ICD patients who have been successfully treated by means of ablation of their ventricular arrhythmias. To date, no control data have been published on transvenous lead extraction in the setting of VT ablation. In this paper we will review the current evidence about ICD therapy, catheter ablation of ventricular arrhythmias and lead extraction, trying to outline some considerations about how to face this new clinical issue.

Combined analysis of unipolar and bipolar voltage mapping identifies recurrences after unmappable scar-related ventricular tachycardia ablation

AIMS

Scars causing ventricular tachycardia can extend deep to and beyond bipolar low-voltage areas (LVAs) and they may be a reason for endocardial ablation failure. Analysis of endocardial unipolar voltage maps has been used to detect scar transmurality and epicardial scar. We hypothesized that endocardial unipolar LVA around the overlying bipolar LVA may predict endocardial ablation recurrence in patients with structural heart disease undergoing substrate modification.

METHODS AND RESULTS

Twenty consecutive patients with structural heart disease (11 ischaemic and 9 non-ischaemic cardiomyopathy) and undergoing substrate modification due to unmappable ventricular tachycardia (VT) (18 males, 51 ± 11 age, LVEF: 36 ± 7%) were retrospectively reviewed. Bipolar LVA defined as <1.5 mV and unipolar LVA defined as <8.3 mV, respectively, on electro-anatomic mapping system. Peripheral unipolar LVA (pUni-LVA) surrounding bipolar LVA was measured and compared patients with and without VT recurrence at 6-month follow-up period. : Mean unipolar voltage and mean bipolar voltage was 6.26 ± 4.99 and 1.90 ± 2.30 mV, respectively. Bipolar voltage and unipolar voltage in corresponding points were correlated (r = 0.652, P = 0.0001). In all patients, unipolar LVAs were larger than the bipolar LVAs. Bipolar LVA (91.1 ± 93.5 vs. 87.5 ± 47.5 cm(2), P = 0.91) and unipolar LVA (148.1 ± 96.3 vs. 104.7 ± 44.2 cm(2), P = 0.21) were similar in patients with and without VT recurrence, respectively. Peripheral unipolar LVA was significantly larger in patients with VT recurrence than without (57.0 ± 40.4 vs. 17.2 ± 12.9 cm(2), P = 0.01).

CONCLUSION

In patients with structural heart disease and unmappable VT, pUni-LVA surrounding bipolar scar predicts recurrence of VT ablation. The results of this pilot study highlight the importance of intramural/epicardial substrate on endocardial VT ablation outcome.

Prophylactic catheter ablation of ventricular tachycardia before cardioverter-defibrillator implantation in patients with non-ischemic cardiomyopathy: Clinical outcomes after a single endocardial ablation

BACKGROUND

Outcomes related to prophylactic catheter ablation (PCA) for ventricular tachycardia (VT) before implantable cardioverter-defibrillator (ICD) implantation in non-ischemic cardiomyopathy (NICM) are not well characterized. We assessed the efficacy of single endocardial PCA in NICM patients.

METHODS

We retrospectively analyzed 101 consecutive NICM patients with sustained VT. We compared clinical outcomes of patients who underwent PCA (ABL group) with those who did not (No ABL group). Successful PCA was defined as no inducible clinical VT. We also compared the clinical outcomes of patients with successful PCA (PCA success group) with those of the No ABL group. Endpoints were appropriate ICD therapy (shock and anti-tachycardia pacing) and the occurrence of electrical storm (ES).

RESULTS

PCA was performed in 42 patients, and it succeeded in 20. The time to ES occurrence was significantly longer in the ABL group than in the No ABL group (p=0.04). The time to first appropriate ICD therapy and ES occurrence were significantly longer in the PCA success group than in the No ABL group (p=0.02 and p<0.01, respectively).

CONCLUSION

Single endocardial PCA can decrease ES occurrence in NICM patients. However, high rates of VT recurrence and low success rates are issues to be resolved; therefore, the efficacy of single endocardial PCA is currently limited.

VT ablation: New Developments and Approaches

OPINION STATEMENT

Over the past decade, catheter ablation has emerged as an important therapeutic option for ventricular tachycardia (VT) in both patients with and without structural heart disease. In patients without structural heart disease, catheter ablation serves as sole therapy for the treatment of VT. For those with structural heart disease, VT ablation has generally been reserved for patients who experience ICD therapies, and particularly those who fail antiarrhythmic agents. With the growing number of patients with implantable devices as well as improvements in heart failure therapy resulting in improved survival among ICD patients, the overall number of patients needing therapy for VT continues to increase. The past years have witnessed significant advances in our understanding of the arrhythmic substrate in various cardiomyopathies, resulting in substrate-based approaches for targeted VT ablation. Further, the growth in better technologies and techniques for VT ablation, such as the use of percutaneous epicardial ablation, the innovation of multielectrode catheters for rapid mapping, the use of intracardiac echocardiography (ICE) for mapping unusual sites, and activation and entrainment mapping of previously unmappable VTs assisted by mechanical circulatory support devices, has overcome the limitations and greatly improved the success rates of catheter ablation. This review summarizes recent advances and novel approaches in both technology and techniques for catheter ablation of ventricular tachycardia.

Predictors of success in ablation of scar-related ventricular tachycardia

During ablation of re-entrant ventricular tachycardia (VT) 3-dimensional mapping systems are now used to properly delineate the scar tissue and aid ablation of scar-related VT. The aim of our study was to outline how the mode of ablation predicts success and recurrence in large scar-related VT. When comparing patients with recurrence and patients with no recurrence, univariate analysis showed that number of ablation lesions (28 ± 8 vs. 12 ± 8, P = 0.01) and more linear ablation lesions rather than focal lesions (P = 0.03) were associated with long-term success. We demonstrated that more extensive ablation lesions and creation of linear lesions is associated with better success rate and lower recurrence rate during ablation of large scar-related ventricular tachycardia.

Myocardial structural associations with local electrograms: a study of postinfarct ventricular tachycardia pathophysiology and magnetic resonance-based noninvasive mapping

BACKGROUND

The association of scar on late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) with local electrograms on electroanatomic mapping has been investigated. We aimed to quantify these associations to gain insights regarding LGE-CMR image characteristics of tissues and critical sites that support postinfarct ventricular tachycardia (VT).

METHODS AND RESULTS

LGE-CMR was performed in 23 patients with ischemic cardiomyopathy before VT ablation. Left ventricular wall thickness and postinfarct scar thickness were measured in each of 20 sectors per LGE-CMR short-axis plane. Electroanatomic mapping points were retrospectively registered to the corresponding LGE-CMR images. Multivariable regression analysis, clustered by patient, revealed significant associations among left ventricular wall thickness, postinfarct scar thickness, and intramural scar location on LGE-CMR, and local endocardial electrogram bipolar/unipolar voltage, duration, and deflections on electroanatomic mapping. Anteroposterior and septal/lateral scar localization was also associated with bipolar and unipolar voltage. Antiarrhythmic drug use was associated with electrogram duration. Critical sites of postinfarct VT were associated with >25% scar transmurality, and slow conduction sites with >40 ms stimulus-QRS time were associated with >75% scar transmurality.

CONCLUSIONS

Critical sites for maintenance of postinfarct VT are confined to areas with >25% scar transmurality. Our data provide insights into the structural substrates for delayed conduction and VT and may reduce procedural time devoted to substrate mapping, overcome limitations of invasive mapping because of sampling density, and enhance magnetic resonance-based ablation by feature extraction from complex images.

Three-dimensional mapping of cardiac arrhythmias - string of pearls -

The evolution of 3-dimensional (D) mapping systems has contributed to improved procedures for ablation of complex tachyarrhythmia in terms of providing detailed anatomical information along with the ability to integrate with pre-acquired computed tomography/magnetic resonance imaging/intracardiac echocardiography images, reducing the radiation exposure, and producing activation and substrate maps. 3-D mapping systems are categorized as magnetic based vs. impedance based according to the catheter location technology, and are also classified as contact based vs. non-contact based according to the data collection technology. Contact-based mapping systems are used widely, in which a series of electrograms is taken sequentially in contact with the heart, thus requiring a relatively stable and sustained arrhythmia to create an activation map. Non-contact mapping systems, however, allow a beat-to-beat analysis of the activation even in non-sustained, polymorphic, or hemodynamically intolerant tachycardia. In this article, the clinical utility of 3-D mapping systems is discussed based on the literature and on experience, with particular emphasis on the non-contact mapping system.