Ventricular Tachycardia Burden Research Articles

PO-04-189 CLINICAL OUTCOMES OF VENTRICULAR TACHYCARDIA ABLATION IN CARDIAC SARCOIDOSIS

Cardiac sarcoidosis (CS) is a known cause of ventricular tachycardia (VT) and sudden death. CS-related ventricular tachycardia (VT) is a rare disorder, and the underlying substrate and response to ablation are poorly understood. We aimed to assess clinical outcomes after catheter ablation for VT in CS patients. The meta-analysis was performed using a meta-package for R version 4.0/RStudio version 1.2, and Freeman Tukey double arcsine transformation with Hartung-Knapp random effect model was used. Outcomes measured included – (1) acute procedure success (defined as non-inducible for any VT); (2) freedom from recurrent VT; (3) redo VT ablation; (4) procedure-related complication; and (5) all-cause mortality. Eight studies from 2006 to 2021 incorporating a total of 273 patients with CS with drug-refractory VT underwent VT ablation (67% were men, mean age 50.3 ± 11.4 years, mean left ventricular ejection fraction 43.3 ± 15.3%). 83% had inducible VT with a mean inducible VT per patient of 2.9 ± 2.6. 14.7% of patients underwent epicardial-endocardial ablation, while the rest underwent endocardial-only ablation. Overall, acute procedural success was 73.7% (95% CI 45-95.1), with a procedure-related complication rate of 4.7% (95% CI 2.6-7.2). During the follow-up period (3.3±3.4 years), the pooled incidence of freedom from recurrent VT was 46.4% (95% CI 26.9–66.5), while 27.1% (95% CI 16.9-38.5) underwent redo VT ablation. All-cause mortality was 8.1% (95% CI 3.3-14.2). Catheter ablation of VT in conjunction with antiarrhythmic drugs in CS patients is safe and effective in eliminating VT or reducing the VT burden; however, recurrences are common, probably due to the inflammatory disease phase.

A Meta-analysis of the Efficacy and Safety of Stereotactic Arrhythmia Radioablation (STAR) in Patients with Refractory Ventricular Tachycardia

AimsReports of stereotactic arrhythmia radioablation (STAR) in patients with refractory ventricular tachycardia after catheter ablation are limited to small series. Here, we carried out a systematic review and meta-analysis of studies to better determine the efficacy and toxicity of STAR for ventricular tachycardia. Materials and methodsFollowing the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) and the Meta-analyses Of Observational Studies in Epidemiology (MOOSE) guidelines, eligible studies were identified on Medline, Embase, Cochrane Library and the proceedings of annual meetings to 10 February 2023. Efficacy was defined as a ventricular tachycardia burden reduction >70% at 6 months; safety was defined as <10% of any grade ≥3 toxicity. ResultsSeven observational studies with a total of 61 patients treated were included. At 6 months, the ventricular tachycardia burden reduction was 92% (95% confidence interval 85–100%) and use of fewer than two anti-arrhythmic drugs was seen in 85% (95% confidence interval 50–100). Six months after STAR, an 86% reduction (95% confidence interval 80–93) in the number of implantable cardioverter-defibrillator shocks was observed. The rates for improved, unchanged and decreased cardiac ejection fraction were 10%, 84% and 6%, respectively. Overall survival at 6 and 12 months was 89% (95% confidence interval 81–97) and 82% (95% confidence interval 65–98). The cardiac-specific survival at 6 months was 87%. Late grade 3 toxicity occurred in 2% (95% confidence interval 0–5%) with no grade 4–5 toxicity. ConclusionSTAR demonstrated both satisfactory efficacy and safety for the management of refractory ventricular tachycardia and was also associated with a significant decline in anti-arrhythmic drugs consumption. These findings support the continued development of STAR as a treatment option.

Ventricular Tachycardia and ICD Therapy Burden With Catheter Ablation Versus Escalated Antiarrhythmic Drug Therapy

BackgroundCatheter ablation improves ventricular tachycardia (VT) event-free (time to event) survival in patients with antiarrhythmic drug (AAD)-refractory VT and previous myocardial infarction (MI). The effects of ablation on recurrent VT and implantable cardioverter-defibrillator (ICD) therapy (burden) have yet to be investigated. ObjectivesThis study sought to compare the VT and ICD therapy burden following treatment with either ablation or escalated AAD therapy among patients with VT and previous MI in the VANISH (Ventricular tachycardia AblatioN versus escalated antiarrhythmic drug therapy in ISchemic Heart disease) trial. MethodsThe VANISH trial randomized patients with previous MI and VT despite initial AAD therapy to either escalated AAD treatment or catheter ablation. VT burden was defined as the total number of VT events treated with ≥1 appropriate ICD therapy. Appropriate ICD therapy burden was defined as the total number of appropriate shocks or antitachycardia pacing therapies (ATPs) delivered. The Anderson-Gill recurrent event model was used to compare burden between the treatment arms. ResultsOf the 259 enrolled patients (median age, 69.8 years; 7.0% women), 132 patients were randomized to ablation and 129 patients were randomized to escalated AAD therapy. Over 23.4 months of follow-up, ablation-treated patients had a 40% lower shock-treated VT event burden and a 39% lower appropriate shock burden compared with patients who received escalated AAD therapy (P <0.05 for all). A reduction in VT burden, ATP-treated VT event burden, and appropriate ATP burden among ablation patients was only demonstrated in the stratum of patients with amiodarone-refractory VT (P <0.05 for all). ConclusionsAmong patients with AAD-refractory VT and a previous MI, catheter ablation reduced shock-treated VT event burden and appropriate shock burden compared with escalated AAD therapy. There was also lower VT burden, ATP-treated VT event burden, and appropriate ATP burden among ablation-treated patients; however, the effect was limited to patients with amiodarone-refractory VT.

Short-term and long-term effects of noninvasive cardiac radioablation for ventricular tachycardia: A single-center case series.

Noninvasive cardiac radioablation is reported to be effective and safe for the treatment of ventricular tachycardia (VT). This study aimed to analyze the acute and long-term effects of VT radioablation. Patients with intractable VT or premature ventricular contraction (PVC)-induced cardiomyopathy were included in this study and treated using a single-fraction 25-Gy dose of cardiac radioablation. To quantitatively analyze the acute response after treatment, continuous electrocardiography monitoring was performed from 24 hours before to 48 hours after irradiation and at the 1-month follow-up. Long-term clinical safety and efficacy were assessed 1-year follow-up. From 2019 to 2020, 6 patients were treated with radioablation for ischemic VT (n = 3), nonischemic VT (n = 2), or PVC-induced cardiomyopathy (n = 1). In the short-term assessment, the total burden of ventricular beats decreased by 49% within 24 hours after radioablation and further decreased by 70% at 1 month. The VT component decreased earlier and more dramatically than the PVC component (decreased by 91% and 57% at 1 month, respectively). In the long-term assessment, 5 patients showed complete (n = 3) or partial (n = 2) remission of ventricular arrhythmias. One patient showed recurrence at 10 months, which was successfully suppressed with medical treatment. The posttreatment PVC coupling interval was prolonged (+38 ms at 1 month). Ischemic VT burden decreased more markedly than nonischemic VT burden after radioablation. In this small case series of 6 patients, without a comparison group, cardiac radioablation appeared to decrease the intractable VT burden. A therapeutic effect was apparent within 1-2 days after treatment but was variable by etiology of cardiomyopathy.

Single Institution Experience with Stereotactic Arrhythmia Radioablation for Ventricular Tachycardia

<h3>Purpose/Objective(s)</h3> Ventricular tachycardia (VT) is characterized by electrical re-entry within patches of heterogeneous myocardial fibrosis leading to sustained consecutive ventricular beats at a rate > 100 per minute. Catheter ablation is the standard of care adjunctive therapy for patients who are refractory to medical therapy to destroy the pathways responsible for these arrhythmias. Recently, a novel treatment approach using ablative radiation with stereotactic body radiation therapy (SBRT) to the arrhythmogenic scar regions defined by noninvasive cardiac mapping has been described for patients refractory to standard-of-care therapies. We describe our experience with 6 patients treated with this technique in our institution. <h3>Materials/Methods</h3> All 6 patients had refractory VT with previously failed ablations and at least one anti-arrhythmic drug. Patients were simulated with 4D computed tomography (4D-CT) and targets were defined using the combined information from cardiac mapping, diagnostic and simulation imaging with cardiologists, medical physicists, and radiation oncologists for each patient. An internal target volume was created based on the cardiac and respiratory motion. An isotropic margin of 3 mm was added to create the planning target volume (PTV). The PTVs were prescribed 25 Gy in 1 fraction normalized so 95% of the PTV was covered by the 25 Gy isodose. Radiation was delivered using volumetric modulated arc therapy. Patients were evaluated immediately following treatment for acute side effects, and then at 6 weeks, 3 months, 6 months, and then yearly. Implantable cardioverter defibrillator (ICD) interrogation was performed regularly by the treating cardiologist to assess the number of VT and ICD events. <h3>Results</h3> All 6 patients tolerated treatment with no immediate acute side effects. One patient experienced mild esophagitis in the first 3 weeks following treatment which resolved. 4 of 6 patients had immediate significant reduction in the number of VT and ICD events in the first 6 months after treatment (>90%), however, one patient did not respond and required an extracorporeal membrane oxygenation assisted ablation 3 months later. The first two patients treated have had longer follow-up and one remains VT-free and has stopped anti-arrhythmic drugs, however, another has relapsed 2 years following radiotherapy in an area of the arrhythmogenic substrate that was intentionally not irradiated due to organ at risk safety concerns. <h3>Conclusion</h3> Despite increasing reports in the literature, there are no established criteria to predict success for this treatment, making it difficult to identify optimal patients. Current limited evidence suggests that this technique may be a relatively safe approach that provides an acute reduction in VT burden for those that have run out of conventional treatment options.

Recurrences after stereotactic arrhythmia radioablation for refractory ventricular tachycardia

Abstract Introduction Stereotactic arrhythmia radioablation (STAR) has been recently introduced for the management of ventricular tachycardia (VT) refractory to antiarrhythmic drugs (AADs) and catheter ablation (CA). VT recurrences were recently reported after STAR but the mechanisms remain poorly known. Purpose We analyzed VT recurrences after STAR for refractory VT in order to assess the characteristics and delivered dose at sites of VT relapse. Methods From 09.2017 to 01.2020, 12 consecutive patients (pts) (66±8y, LVEF 40±14%) suffering from refractory VT were enrolled. The underlying cardiopathy was ischemic in 3, inflammatory in 3 and idiopathic in 6 pts. Nine (75%) out of 12 pts had a history of at least 1 electrical storm. Before STAR, an invasive electro-anatomical mapping (Carto3) of the VT substrate (VT-sub) was performed. A mean dose of 22±2Gy was delivered to the VT-sub using the Cyberknife® system. Results The ablation volume was 24±7cc and involved the basal interventricular septum (IVS) in 10 (83%) pts. During the first 6 months after STAR, VT burden decreased by 93% (mean value, from 640 to 46 VT/semester). After a median follow-up of 32±11 months, 10/12 (83%) developed ≥1 recurrence as a sustained VT and underwent a redo CA. Two (17%) pts presented 2 distinct VT recurrences from clearly different areas. VT recurrence was located at the border zone (BZ) of the treated VT-sub in 6 (50%) cases, involved both the BZ and a larger substrate in 2 (17%) cases, and occurred remote from the VT-sub in 4 (33%) cases (see Table 1). The dose delivered at sites of VT recurrence was 8.4±8.6 Gy with a large heterogeneity ranging from 0.11 to 28.37 Gy, for some pts due to dose constraints near critical structures (coronary arteries). Voltage mapping showed a small but significant reduction in both unipolar and bipolar EGM voltage in the irradiated area after STAR (before vs after, Bipolar: 1.8±1.2 vs 1.1±1.2 mV and Unipolar: 4.4±2.0 vs 3.4±2.3 mV, p=0.02 and 0.01 respectively). Importantly no pts developed a high-grade AV block after STAR despite IVS irradiation. Conclusion STAR appears to be an efficient tool for the management of refractory VT, leading to a strong VT burden reduction and no new high-grade AV block. Recurrences were nevertheless common, often at the border zone of the irradiated volume. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): CHUV

Stereotactic Radioablation for Ventricular Tachycardia in the Setting of Electrical Storm.

Stereotactic body radiotherapy (SBRT) has been reported as a safe and efficient therapy for treating refractory ventricular tachycardia (VT) despite optimal medical treatment and catheter ablation. However, data on the use of SBRT in patients with electrical storm (ES) is lacking. The aim of this study was to assess the clinical outcomes associated with SBRT in the context of ES. This retrospective study included patients who underwent SBRT in the context of ES from March 2020 to March 2021 in one tertiary center (CHU Lille). The target volume was delineated according to a predefined workflow. The efficacy was assessed with the following end points: sustained VT recurrence, VT reduced with antitachycardia pacing, and implantable cardioverter defibrillator shock. Seventeen patients underwent SBRT to treat refractory VT in the context of ES (mean 67±12.8 age, 59% presenting ischemic heart disease, mean left ventricular ejection fraction: 33.7± 9.7%). Five patients presented with ES related to incessant VT. Among these 5 patients, the time to effectiveness ranged from 1 to 7 weeks after SBRT. In the 12 remaining patients, VT recurrences occurred in 7 patients during the first 6 weeks following SBRT. After a median 12.5 (10.5-17.8) months follow-up, a significant reduction of the VT burden was observed beyond 6 weeks (-91% [95% CI, 78-103]), P<0.0001). The incidence of implantable cardioverter defibrillator shock and antitachycardia pacing was 36% at 1 year. SBRT is associated with a significant reduction of the VT burden in the event of an ES; however, prospective randomized control trials are needed. In patients without incessant VT, recurrences are observed in half of patients during the first 6 weeks. VT tolerance and implantable cardioverter defibrillator programming adjustments should be integrated as part of an action plan defined before SBRT for each patient.

Stereotactic body radioablation therapy as an immediate and early term antiarrhythmic palliative therapeutic choice in patients with refractory ventricular tachycardia.

BackgroundStereotactic body radioablation therapy (SBRT) has recently been introduced with the ability to provide ablative energy noninvasively to arrhythmogenic substrate while reducing damage to normal cardiac tissue nearby and minimizing patients’ procedural risk. There is still debate regarding whether SBRT has a predominant effect in the early or late period after the procedure. We sought to assess the time course of SBRT’s efficacy as well as the value of using a blanking period following a SBRT session.MethodsEight patients (mean age 58 ± 14 years) underwent eight SBRT sessions for refractory ventricular tachycardia (VT). SBRT was given using a linear accelerator device with a total dose of 25 Gy to the targeted area.ResultsDuring a median follow-up of 8 months, all patients demonstrated VT recurrences; however, implantable cardioverter-defibrillator (ICD) and anti-tachycardia pacing therapies were significantly reduced with SBRT (8.46 to 0.83/per month, p = 0.047; 18.50 to 3.29/per month, p = 0.036, respectively). While analyzing the temporal SBRT outcomes, the 2 weeks to 3 months period demonstrated the most favorable outcomes. After 6 months, one patient was ICD therapy-free and the remaining patients demonstrated VT episodes.ConclusionsOur findings showed that the SBRT was associated with a marked reduction in the burden of VT and ICD interventions especially during first 3 months. Although SBRT does not seem to succeed complete termination of VT in long-term period, our findings support the strategy that SBRT can be utilized for immediate antiarrhythmic palliation in critically ill patients with otherwise untreatable refractory VT and electrical storm.

Racial disparities in ventricular tachycardia in young adults: analysis of national trends.

In the last two decades, risk factors, prevalence, and mortality due to coronary artery disease in young adults are on the rise. We sought to assess the prevalence, trends, and economic burden of ventricular tachycardia (VT) hospitalizations in young adults (< 45years), further stratified by race and gender. The Nationwide Inpatient Sample was explored for hospitalizations with VT in patients (< 45years) between 2005 and 2018 and divided among 3 groups of the quadrennial period using validated International Classification of Diseases (ICD) 9th and 10th revision Clinical Modification (CM) codes. The Pearson chi-square test and Wilcoxon rank-sum were used for categorical and continuous variables, respectively. We assessed the temporal trends of mortality in VT hospitalizations and trends of VT hospitalization stratified by age, sex, and race by using Joinpoint regression analysis. The primary outcome was in-hospital mortality trends. Secondary outcomes were trends of hospital stay in days, cost of care in US dollars, cardiac arrest, and discharge disposition. Out of 5,156,326 patients admitted with VT between 2005 and 2018, 309,636 were young adults. Among them, 102,433 were admitted between 2005 and 2009 (mean age 36.1 ± 6.99; 61% male, 58.5% White), 109,591 between 2010 and 2014 (mean age 35.5 ± 7.16; 59% male, 54.2% White), and 97,495 between 2015 and 2018 (mean age 35.4 ± 7.00; 60% male, 52.3% White) (p < 0.07). In the young adults with VT, all-cause mortality was 7.37% from 2005 to 2009, 7.85% from 2010 to 2014 (6.5% relative increase from 2005 to 2009), and 8.98% from 2015 to 2018 (relative increase of 14.4% from 2010 to 2014) (p < 0.0001). Similarly, risk of cardiac arrest was on the rise (6.15% from 2005 to 2009 to 7.77% in 2010-2014 and 9.97% in 2015-2018). Inflation-adjusted cost increased over the years [$12,177 in 2005-2009; $13,249 in 2010-2014; $15,807 in 2015-2018; p < 0.0001)]. VT hospitalizations and related all-cause mortality, and healthcare utilization costs in young adults are on the rise in the study period. Hospitalization burden related to VT and poor outcomes were more notable for Black adults. Further studies are required for targeted screening and preventative measures in young adults.

Impact of Sleep-Disordered Breathing Treatment on Ventricular Tachycardia in Patients with Heart Failure.

Background: Sleep-disordered breathing (SDB) is a highly common comorbidity in patients with heart failure (HF), and a known risk factor for ventricular tachycardia (VT) development. However, little is known about the impact of SDB treatment on VT burden in HF patients to date. Therefore, this study investigated VT burden, as well as implantable cardioverter-defibrillator (ICD) therapies in HF patients with SDB treatment, in comparison to untreated SDB HF patients. Methods: This retrospective study analyzed VT burden, rate of antitachycardia pacing (ATP), and the number of shocks delivered in a propensity score-matched patient cohort of patients with SDB treatment or control. Patients had moderate or severe SDB (n = 73 per each group; standardized mean difference of 0.08) and were followed for a minimum of one year. In addition, survival over 4 years was assessed. Results: Mean patient age was 67.67 ± 10.78 and 67.2 ± 10.10, respectively, with 15.06% and 10.95% of the patients, respectively, being female. Regarding SDB subtypes in the control and SDB treatment group, central sleep apnea was present in 42.46% and 41.09% of the patients, respectively, and obstructive sleep apnea was present in 26.02% and 31.50% of the patients, respectively. Mixed type sleep disorder was present in 31.50% and 27.40% of cases. Among the SDB treatment group, a significantly lower number of VTs (28.8% vs. 68.5%; p = 0.01), ATP (21.9% vs. 50.7%; p = 0.02), as well as a lower shock rate (5.5% vs. 31.5%; p < 0.01), was observed compared to the control group. Furthermore, the VT burden was significantly lower in the SDB treatment group when compared to the time prior to SDB treatment (p = 0.02). Event-free survival was significantly higher in the SDB treatment group (Log-rank p < 0.01). Conclusion: SDB treatment in HF patients with ICD leads to significant improvements in VT burden, ATP and shock therapy, and may even affect survival. Thus, HF patients should be generously screened for SDB and treated appropriately.

Orthogonal high-density mapping with ventricular tachycardia isthmus analysis vs. pure substrate ventricular tachycardia ablation: A case-control study.

BackgroundSubstrate-based ablation has become a successful technique for ventricular tachycardia (VT) ablation. High-density (HD) mapping catheters provide high-resolution electroanatomical maps and better discrimination of local abnormal electrograms. The HD Grid Mapping Catheter is an HD catheter with the ability to map orthogonal signals on top of conventional bipolar signals, which could provide better discrimination of the arrhythmic substrate. On the other hand, conventional mapping techniques, such as activation mapping, when possible, help to identify the isthmus of the tachycardia.AimThe purpose of this study was to compare clinical outcomes after using two different VT ablation strategies: one based on extensive mapping with the HD Grid Mapping Catheter, including VT isthmus analysis, and the other based on pure substrate ablation.MethodsForty consecutive patients undergoing VT ablation with extensive HD mapping method in the hospital clinic (November 2018–November 2019) were included. Clinical outcomes were compared with a historical cohort of 26 consecutive patients who underwent ablation using a scar dechanneling technique before 2018.ResultsThe density of mapping points was higher in the extensive mapping group (2370.24 ± 920.78 vs. 576.45 ± 294.46; p < 0.001). After 1 year of follow-up, VT recurred in 18.4% of patients in the extensive mapping group vs. 34.6% of patients in the historical control group (p = 0.14), with a significantly greater reduction of VT burden: VT episodes (81.7 ± 7.79 vs. 43.4 ± 19.9%, p < 0.05), antitachycardia pacing (99.45 ± 2.29 vs. 33.9 ± 102.5%, p < 0.001), and implantable cardioverter defibrillator (ICD) shocks (99 ± 4.5 vs. 64.7 ± 59.9%, p = 0.02).ConclusionThe use of a method based on extensive mapping with the HD Grid Mapping Catheter and VT isthmus analysis allows better discrimination of the arrhythmic substrate and could be associated with a greater decrease in VT burden.

Impact of early ventricular tachycardia ablation in patients with an implantable cardioverter-defibrillator: An updated systematic review and meta-analysis of randomized controlled trials

There is limited information on whether early catheter ablation (CA) for ventricular tachycardia (VT) is associated with better outcomes compared with alternative strategies in patients with implantable cardioverter-defibrillator (ICD). The purpose of this article was to assess the efficacy of early VT CA in patients with ICD. EMBASE, PubMed, and Cochrane were searched from inception to April 2022. Randomized controlled trials comparing the efficacy of early VT CA with control groups, both in patients with ICD, were included in the analysis. Data on effect estimates in individual studies were extracted and combined via random effects meta-analysis using the DerSimonian and Laird method, a generic inverse variance strategy. Nine randomized controlled trials with 1106 patients (n = 1018, 92.1% with ischemic cardiomyopathy and n = 88, 7.9% with nonischemic cardiomyopathy) were evaluated. VT CA was associated with reduced VT recurrences (odds ratio [OR] 0.64; P = .007), appropriate ICD shocks (OR 0.53; P = .002), ICD therapies (OR 0.54; P=.002), and cardiovascular hospitalization (OR 0.67; P=.004). However, no significant differences were observed in terms of mortality rate, heart failure hospitalization, and quality of life between the early VT CA and control groups. Early CA was beneficial in reducing VT burden and ICD therapies. However, it did not affect mortality rate and quality of life. Since most patients in the included studies presented with ischemic cardiomyopathy, further studies on nonischemic cardiomyopathy should be conducted to validate if early CA has similar outcomes.

Ventricular Arrhythmias in Patients with Implanted Cardiac Devices at High Risk of Obstructive Sleep Apnea.

Background and Objectives: Patients with pre-existing cardiac disease have a higher prevalence of Obstructive Sleep Apnea (OSA). OSA has been associated with an increased risk of supraventricular and ventricular arrhythmia. We screened subjects with implanted pacemakers and automated implantable cardioverter defibrillators (AICD) for OSA with the Berlin Questionnaire and compared the incidence of ventricular arrhythmias and automated implantable cardioverter defibrillator (AICD) firing between high and low OSA risk groups. Materials and Methods: We contacted 648 consecutive patients from our arrhythmia clinic to participate in the study and performed final analyses on 171 subjects who consented and had follow-up data. Data were abstracted from the electronic health record for the incidence of non-sustained ventricular tachycardia (NSVT), ventricular tachycardia (VT), ventricular fibrillation (VF) and AICD firing and then compared between those at high versus low risk of OSA using the Berlin Questionnaire and multivariate negative binomial regression. Results: The average follow-up period was 24.2 ± 4.4 months. After adjusting for age, gender and history of heart failure, those subjects at high risk of OSA had a higher burden of NSVT vs. those with a low risk of OSA (33.4 ± 96.2 vs. 5.82 ± 17.1 episodes, p = 0.003). A predetermined subgroup analysis of AICD recipients also demonstrated a significantly higher burden of NSVT in the high vs. low OSA risk groups (66.2 ± 128.6 vs. 18.9 ± 36.7 episodes, p = 0.033). There were significant differences in the rates of VT, VF or AICD shock burden between the high and low OSA risk groups and in the AICD subgroup analysis. Conclusions: There was increased ventricular ectopy among pacemaker and AICD recipients at high risk of OSA, but the prevalence of VT, VF or AICD shocks was similar to those with low risk of OSA.

Recurrences after stereotactic arrhythmia radioablation for refractory ventricular tachycardia

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Stereotactic arrhythmia radioablation (STAR) has been recently introduced for the management of ventricular tachycardia (VT) refractory to antiarrhythmic drugs and catheter ablation (CA). VT recurrences have been reported after STAR but the mechanisms remain poorly known. We analyzed recurrences in our patients (pts) after STAR for refractory VT. Methods From 09.2017 to 01.2020, 12 pts (66±8y, LVEF 40±14%) suffering from refractory VT were enrolled. The underlying cardiopathy was ischemic in 3, inflammatory in 3 and idiopathic in 6 pts. Nine out of 12 pts had a history of at least 1 electrical storm. Before STAR, an invasive electro-anatomical mapping of the VT substrate (VT-sub) was performed. A mean dose of 22±2Gy was delivered to the VT-sub using the Cyberknife system. Results The ablation volume was 24±7cc and involved the basal interventricular septum (IVS) in 10 pts. During the first 6 months after STAR, VT burden decreased by 95% (mean value, from 930 to 46 VT/semester). After a median follow-up of 14±10 months, 10/12 (83%) developed a recurrence as a sustained VT and underwent a redo CA. VT recurrence was located at the border zone (BZ) of the treated VT-sub in 6 cases, involved both the BZ and a larger substrate in 2 cases, and occurred remote from the VT-sub in 2 cases (see Table). The dose delivered at sites of VT recurrence was 9.9±8.6 Gy with a large heterogeneity ranging from 0.11 to 28.37 Gy, for some patients due to dose constraints near critical structures. Importantly no pts developed an AV block after STAR. Conclusion STAR appears to be an efficient tool for the management of IVS refractory VT, leading to a strong VT burden reduction and no AV block. Recurrences were nevertheless common, often at the border zone of the irradiated volume.

Stereotactic body radiotherapy for refractory ventricular tachycardia: the overall czech experience

Abstract Funding Acknowledgements Type of funding sources: None. Background Catheter ablation (CA) is a well-established treatment strategy for the management of drug-refractory ventricular tachycardia (VT) in patients with structural heart disease. Stereotactic body radiotherapy (SBRT) was proposed recently as a treatment option for cases of failed CA. Purpose This study reports overall experience with the SBRT from two Czech centers. Methods Since 2014, we enrolled consecutive patients who underwent at least one prior CA for recurrent scar-related VT and had subsequent VT recurrences due to inaccessible substrate. Single-session SBRT for VT was performed without the use of general anesthesia or sedation. A dose of 25 Gy was delivered. Results The study investigated 33 patients (3 women) with a mean age of 66 ± 9 years. Underlying heart disease was ischemic (58%) and nonischemic (39%) cardiomyopathy; one patient had large cardiac fibroma. The mean left ventricular ejection fraction was 31 ± 8%. Seventy-six percent of patients were on amiodarone. Before SBRT, they underwent a median of 2 (IQR: 1-3; range: 1-5) CA that included epicardial access in 42% of patients. Following SBRT with a planned target volume of 42.6 ± 22.8 ml, the immediate effect was not observed in any patient, VT burden gradually decreased over weeks or months. Seventeen (52%) patients died (2 of them suddenly) during the mean follow up of 29 ± 23 months mainly due to the progression of heart failure (Figure 1). One patient died due to bleeding associated with esophagopericardial fistula that developed 9 months after SBRT. Overall, the number of DC shocks after a single procedure decreased significantly from 0.9 ± 1.9 per month in the period of 6 months before SBRT to 0.1 ± 0.3 per month in the period of 6-12 months after SBRT (P=0.008, Figure 2). However, 14 patients (42%) had to undergo additional CA due to VT recurrences at a mean interval of 13 ± 14 months after SBRT. Three patients underwent repeated SBRT (after 3, 29, and 38 months), which was successful in 2 of them. Conclusions SBRT in patients with refractory VT is feasible but the long-term mortality after the procedure is high and reflects mainly the severity of the underlying disease. The treatment effect of SBRT is delayed and additional CA is often necessary for VT suppression. At present, SBRT should be offered as only a bailout procedure for otherwise intractable VT.

CA-531-04 CANADIAN EXPERIENCE WITH SALINE ENHANCED RADIOFREQUENCY NEEDLE TIP ABLATION FOR VENTRICULAR TACHYCARDIA (SERF VT CANADA TRIAL)

Endocardial catheter ablation for ventricular tachycardia (VT) may fail because of the inability to deliver transmural lesions. Saline-enhanced radiofrequency (SERF) ablation uses a needle tip catheter which is placed at varying depths into the myocardial tissue and heated saline is injected along with radiofrequency (RF) creating fully transmural lesions. We report the first in-human SERF ablation for VT in Canada. The purpose of this study is to describe the prospective outcomes on a seriesof patients undergoing first-in-human SERF ablation for VT in Canada under an Investigational Testing Authorization. Twenty-five patients with ischemic and non-ischemic cardiomyopathy, with recurrent monomorphic drug-refractory VT which had failed a prior catheter ablation underwent SERF ablation in 3 different centers in Canada. After a voltage map, the mapping catheter was replaced with the needle-tipped ablation catheter, which was located perpendicular to the myocardium and extended either 6 or 8 mm into the tissue. Sterile saline solution was infused with a flow rate of 10 ml/min and 60° C and 50 watts of RF was used. LVEF was 33.3% ± 8.6, mean age was 69.5 ± 6.4 years; 92% were male. From 43 clinical VT induced, 42 were attempted and 266 SERF lesions were delivered (10.6 ± 4.9 per patient). At the end of the case, 41 VT were non-inducible (98%) and 24 patients (96%) had their VT eliminated. At 6 months follow-up, VT burden was reduced by 87%. Complications included 2 strokes, 2 pericardial effusion and one patient had ischemic bowel and 1died. SERF ablation is feasible and permits control of symptomatic monomorphic VT in drug-refractory patients with a prior failed ablation.

CA-533-02 STANDARD CARDIAC RADIOABLATION DOSE (25 GRAY) DOES NOT CAUSE MYOCYTE INJURY OR NEW FIBROSIS

Noninvasive cardiac radioablation (CRA) is an emerging therapy for refractory ventricular tachycardia (VT). Focused radiation to the heart is expected to cause local myocardial destruction with replacement fibrosis (ablation effect). The extent this effect in humans is unknown. To measure the CRA ablation effect with serial serum biomarkers and late gadolinium enhanced cardiac MRI (LGE-CMR). Single-center, IRB-approved case series of patients with refractory VT (ENCORE-VT NCT02919618). Patients without contraindication underwent LGE-CMR and blood draws at three timepoints: before treatment, 3 days, and 3 months after treatment. Left ventricle (LV) scar burden was assessed using semi-automatic contouring (Medis, Netherlands), blinded to location of radioablation. Global and segmental scar burden (%) was compared across timepoints. Segments targeted for radioablation (25 Gray) were compared to surrounding and off-target segments. Blood samples were analyzed for high-sensitivity troponin-I (Tn-I, marker of myocyte injury) and galectin-3 (Gal3, marker of fibroblast activation and fibrosis). 7 patients were included for analysis: mean age 64 years, 14% female, 57% nonischemic cardiomyopathy, 86% with history of VT storm, mean LVEF 32% (range 19-58%). Mean number of cardiac segments targeted for radioablation was 4 (range 3-8), resulting in mean cardiac treatment volume (CTV) 29 cm3 and planning treatment volume (PTV) 114 cm3. Mean scar burden at baseline was 49% (range 29-68%). Changes in scar burden at 3 days and 3 months were -0.4% (IQR = 5.5%) and 3.3% (IQR = 3%). Segment-by-segment analysis (Figure 1) showed no significant scar progression in segments targeted for radioablation (mean 68% to 68% to 71%), segments surrounding the target (43% to 44% to 47%), or off-target segments (44% to 42% to 46%). Serum Tn-I and Gal3 were not significantly changed (Figure 2). Compared to VT burden before treatment, all 7 patients had substantial reduction 6 months after treatment (4 had > 95% burden reduction, 1 had resolution of incessant slow VT). Despite improvement in VT burden, there was no appreciable cardiac injury or replacement fibrosis after CRA with 25 Gray. The mechanism of early VT control with cardiac radioablation is not myocyte injury or fibrosis.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

CE-522-03 LONGITUDINAL PREDICTION OF VENTRICULAR ARRHYTHMIAS IN PATIENTS WITH ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY

The arrhythmogenic right ventricular cardiomyopathy (ARVC) risk calculator (https://www.arvcrisk.com) stratifies risk for ventricular arrhythmia (VA) at the time of ARVC diagnosis. However, the risk factors included in the ARVC calculator change with time, and how well it performs at follow up evaluations is unknown. To identify the temporal trends of VA risk factors and test the longitudinal performance of the ARVC calculator. This was a retrospective analysis of ARVC patients without prior VA (sustained ventricular tachycardia (VT), appropriate ICD therapy, sudden cardiac death/arrest) enrolled in the Johns Hopkins Hospital ARVC registry and Netherlands ACM registry. Risk factors for VA (age, sex, history of cardiac syncope, burden of PVC on 24-hour heart monitor, history of non-sustained VT, number of T-wave inversions on ECG, and right ventricular ejection fraction) were assessed at the time of ARVC diagnosis and upon repeat evaluations. The 5-year risk of VA was predicted longitudinally using 1) the ARVC calculator (baseline risk factors), 2) the ARVC calculator (updated risk factors), 3) time varying Cox regression. 408 patients (37±15 years old, 40% male) were followed for a median of 5.2 [2.8, 9.6] years, during which time 132 experienced a first VA (4.0% events/year). Comparison of risk factors at baseline versus at >5 years of follow up revealed decreases in 24-hour PVC Burden (3,560 vs 2,510) and prevalence of non-sustained VT on the most recent Holter (53% vs 27%), and an increase in number of T-wave inversions (3.4 vs 3.9 leads). Prevalence of right ventricular dysfunction was unchanged. When calculated using baseline risk factors, the ARVC calculator’s ability to predict 5-year VA risk worsened after 3 years of follow up (from ROC-AUC 0.82 at baseline to 0.69 by 5 years). When calculated using updated risk factors, the ARVC calculator (ROC-AUC 0.77) performed as well as time varying Cox regression (ROC-AUC 0.77) after 5 years of follow up (Figure). Risk factors for VA in ARVC change over time. Up-to-date assessment of these risk factors is warranted for VA risk stratification at evaluations beyond 3 years from the time of initial ARVC diagnosis.

Radiosurgery in Treatment of Ventricular Tachycardia – Initial Experience Within the Polish SMART-VT Trial

BackgroundStereotactic Arrhythmia Radioablation (STAR) is an emerging treatment modality for patients with sustained ventricular tachycardia (VT) and refractory to treatment with drugs and radiofrequency catheter ablation (RFA). It is believed that up to 12–17% of patients experience recurrence of VT within 1 year of follow-up; thus, novel therapeutic options are needed. The aim of this article is to present initial experience within a novel treatment modality for VT.Case SummaryTwo patients with a medical history of coronary artery disease and heart failure with reduced left ventricle (LV) ejection fraction, after implantation of cardioverter-defibrillator (ICD) and previous unsuccessful RFAs owing to sustained VT were admitted to the cardiology department due to recurrence of sustained VT episodes. With electroanatomical mapping (EAM), the VT substrate in LV has been confirmed and specified. In order to determine the target volume for radioablation, contrast-enhanced computed tomography was performed and the arrhythmia substrate was contoured using EAM data. Using the Volumetric Modulated Arc Therapy technique and three 6 MeV flattening filter-free photon beam fields, a single dose of 25 Gy was delivered to the target volume structure located in the apex and anterior apical segments of LV in the first patient and in the apex, anterolateral and inferior apical segments of the second patient. In both cases, volumes of the target structures were comparable. Interrogation of the implanted ICD at follow-up visits throughout 6 months after the treatment revealed no VT episodes in the first patient and sudden periprocedural increase in VT burden with a subsequent gradual decrease of ventricular arrhythmia to only two non-sustained episodes at the end of the follow-up period in case of the second patient. A significant reduction in premature ventricular contractions burden was observed compared to the pre-treatment period. No noticeable deterioration in LV function was noted, nor any adverse effects of radiosurgery associated with the implanted device.ConclusionThe early response to STAR can be unpredictable and probably does not reflect the final outcome of irradiation. Close monitoring of patients, especially in the early period after irradiation is crucial to properly handle potentially harmful early reactions to STAR.

Ventricular Tachycardia Burden and Mortality: Association or Causality?

Ventricular tachycardia (VT) is a potentially fatal cardiac rhythm disorder. Implantable cardioverter defibrillators (ICDs) are the primary management strategy for VT and have been shown to reduce the incidence of death but, ICDs do not reduce VT recurrences. Further, mounting evidence indicates that high VT burden, defined as the cumulative number of recurrent VTs or ICD shocks, is associated with an elevated risk of death; however, it is unclear if high VT burden is a cause of death or a marker of severe heart disease. Proposed mechanisms for a causal pathway suggest that multiple VT episodes or potential deleterious effects from ICDs might alter the myocardium of the ventricles to induce worsening heart disease, which might translate to an increased risk of mortality. In this review, we present the evidence to support association and causation hypotheses for the relationship between VT burden and risk of mortality and indicate potential gaps in evidence. Overall, there is insufficient evidence to prove causal hypotheses for the relationship between VT burden and mortality. Consistent definitions for VT burden, randomized controlled trials that assess the relationship between VT burden and mortality, and observational studies that capture VT burden are warranted to investigate if a potential causal relationship exists.