Ventricular Tachycardia Burden Research Articles

Dynamic voltage mapping of the ventricular tachycardia substrate

Abstract Background Substrate mapping techniques that predict ventricular tachycardia (VT) isthmus components in sinus or paced rhythm are necessary as mapping during VT is often not possible. Voltage maps lack accuracy in differentiating scar, traditionally displayed as tissue <0.50mV, from bordering arrhythmogenic substrate. We developed a practical technique aiming to improve the utility of a voltage map during VT ablation, termed ‘Dynamic Voltage Mapping’ (DVM). Methods Consecutive patients with post-infarct VT at our centre underwent left ventricle (LV) voltage mapping (mean 4762 points) with Carto3 v.7® and a PentaRay®, or Ensite X® and a HD Grid mapping catheter. Both mapping systems offer algorithms that allow substrate activation maps to be superimposed and analysed on the surface of a voltage display (i.e. Carto Ripple Maps, or Ensite X activation vectors). DVM is a process that sequentially adjusts the voltage display to highlight scar tissue in areas devoid of Ripple bars, or in areas where activation vectors point in multiple unfathomable directions (‘vector disarray’). This approach is summarised in Figures 1 & 2 and was retrospectively performed in all cases. This alternative scar voltage limit was termed the ‘DVM scar threshold’ (mV). Tissue below this threshold was termed ‘DVM-scar’, and tissue immediately surrounding (up to 0.5mV) was termed "DVM-Borderzone (BZ)". Results Twenty-five patients (mean age 64.4±11.0 years, 88% male, LV ejection fraction 31.8±6.9%, 16.4±8.5 years since infarct) were studied (n=15 Carto; n=10 EnSite). Across all cases, the mean shell area with voltage <0.50 mV was 36.8±20.3 cm2. The mean DVM scar threshold was 0.24±0.07 mV (Carto: 0.22±0.07 mV [range 0.12–0.35 mV]; EnSite: 0.26±0.08 [range 0.18–0.50 mV]). The mean DVM-scar area was 18.4±14.3 cm2, significantly smaller than the traditional 0.50mV value (p=0.0002). In the 8 patients where stable VT was mapped, the VT isthmus sites co-located within the DVM-BZ in all cases, exemplified in the figures. Pace-mapping at the DVM-BZ matched the remaining unmappable VT morphologies. Ablation lesions were retrospectively superimposed onto the DVM map and generally co-located within the DVM-BZ. No ablation was delivered in tissues >0.5mV. At median follow-up of 8.8 months, VT burden significantly reduced (median 3 episodes in 3-months pre vs. 0 post; p<0.001), with 76% of patients VT-free. Conclusion DVM appears to improve the delineation of the post-infarct VT substrate, and is feasible using two commercially-available mapping systems. The mean voltage threshold that differentiated DVM-Scar from BZ tissue was significantly lower than the traditional 0.50 mV scar definition, at 0.24mV, though ranged widely, suggesting that scar thresholds require individualised substrate definition. Targeted ablation of DVM-BZ may be effective at reducing future VT, though requires prospective validation.Figure 1Figure 2

Impact of repeat ablation of ventricular tachycardia in patients with structural heart disease.

Recurrences of ventricular tachycardia (VT) after initial catheter ablation is a significant clinical problem. In this study, we report the efficacy and risks of repeat VT ablation in patients with structural heart disease (SHD) in a tertiary single centre over a 7-year period. Two hundred ten consecutive patients referred for repeat VT ablation after previous ablation in our institution were included in the analysis (53% ischaemic cardiomyopathy, 91% males, median age 65 years, mean left ventricular ejection fraction 35%). After performing repeat ablation, the clinical VTs were acutely eliminated in 82% of the patients, but 46% of the cohort presented with VT recurrence during the 25-month follow-up. Repeat ablation led to a 73% reduction of shock burden in the first year and 61% reduction until the end of follow-up. Similarly, VT burden was reduced 55% in the first year and 36% until the end of the study. Fifty-two patients (25%) reached the combined endpoint of ventricular assist device implantation, heart transplantation, or death. Advanced New York Heart Association functional class, anteroseptal substrate, and periprocedural complication after repeat ablation were associated with worse prognosis independently of the type of cardiomyopathy. While complete freedom from VT after repeat ablation in SHD was difficult to achieve, ablation led to a significant reduction in VT and shock burden. Besides advanced heart failure characteristics, anteroseptal substrate and periprocedural complications predicted a worse outcome.

Abstract 18088: Survival After Ventricular Tachycardia Onset in Left Ventricular Assist Device Recipients

Introduction: Left Ventricular Assist Devices (LVADs) revolutionized the care of patients with heart failure. However, the burden of ventricular tachycardia (VT) increases after LVAD insertion. The role of ablation in treating VT in LVAD recipients is unclear. Hypothesis: The incidence of VT following LVAD insertion is associated with worse survival, but this association is ameliorated by VT ablation. Methods: This is a single-center retrospective review of 549 LVAD recipients. LVADs implanted elsewhere, LVADs prior to 2011, and patients with inadequate follow up were excluded. Endpoints were transplantation, explantation, and last date of follow up. Event failure was defined as patient death. Cox and Kaplan-Meier survival analysis was performed with STATA and reported as hazard ratio with 95% confidence interval (HR [95% CI]). Results: Pre-LVAD VT was seen in 52% of patients: 33% had a prior ICD shock and 12% had a prior VT ablation. At study conclusion, 57% had died, 22% were transplanted, 9% were explanted, and 12% remained alive. Regardless of VT incidence, worse survival was seen in ischemic cardiomyopathy (HR 2.0 [1.5-2.7]), RV failure necessitating RVAD (HR 2.6 [1.9-3.6]), and pre-LVAD ICD shocks (HR 1.3 [1.0-1.7]). While post-LVAD VT overall was not associated with worse survival (HR 1.1 [0.8-1.3]), VT within 1 year of LVAD insertion demonstrated worse survival (HR 1.9 [1.3-2.6]; Figure 1). Incremental years between LVAD insertion and VT onset improved survival (HR 0.8 [0.7-0.9]). Among those with post-LVAD VT, ablation was not associated with a survival difference (IRR 0.9 [0.6-1.4]) regardless of the timing of ablation or VT onset. Conclusions: The incidence of VT within 1 year of LVAD insertion is associated with worse survival. However, mortality was not improved by VT ablation. This study is limited by its retrospective design, and further prospective studies would better determine the impact of VT ablation on survival in LVAD recipients.

Abstract 13943: Comparison of the Frequency and Time to True Ventricular Tachycardia Among Patients in the Cardiac, Medical/Surgical and Neurologic Intensive Care Units

Introduction: Continuous ECG monitoring is the non-invasive gold standard used to identify ventricular tachycardia (VT), yet 87% of current bedside monitor VTs could be false. Therefore, knowing the burden of true VT is essential to guide treatment to those at greatest risk of poor outcomes. Hypothesis: When stratifying by intensive care unit (ICU) (cardiac, medical/surgical, neurological), there will be differences in: 1) demographic and clinical characteristics of patients with true VT; and 2) frequency and time to first true VT. Methods: Retrospective cohort study of adults admitted to an academic medical center ICU, 9/13-4/15. Potential VTs among 5,679 consecutive ICU patients were manually annotated by clinicians as true/false. Patient-level data were extracted from the health record. We used Kaplan-Meier and Cox proportional hazards methods to calculate time to first true VT and 60-day VT rate by ICU type. Results: There were differences in all characteristics examined (p<0.0001)(Table) and frequency of true VT, stratified by ICU type (log-rank p<0.0001)(Figure). After adjustment for age, gender, and risk factors (Table), CICU patients had a 42% increased rate (HR 1.42, 95% CI 1.16-1.74) and NICU patients had a 28% decreased rate of VT (HR 0.72, 95% CI 0.59-0.89) compared to M/SICU patients. Conclusion: Patients in the CICU experienced true VT much earlier (1.5 days) after admission than patients in the M/SICU and NICU. In addition, CICU patients had a higher rate of true VT and associated VT risk factors as compared to M/SICU and NICU patients. As expected, known cardiac risk factors are associated with true VT, but may be hidden among false alarms during bedside monitoring.

One-year outcomes after stereotactic body radiotherapy for refractory ventricular tachycardia

BackgroundCardiac stereotactic body radiotherapy (SBRT) has emerged as a promising noninvasive treatment for refractory ventricular tachycardia (VT). ObjectiveThe purpose of this study was to describe the safety and effectiveness of SBRT for VT in refractory to extensive ablation. MethodsAfter maximal medical and ablation therapy, patients were enrolled in a prospective registry. Available electrophysiological and imaging data were integrated to generate a plan target volume. All SBRTs were planned with a single 25 Gy fraction using respiratory motion mitigation strategies. Clinical outcomes at 6 weeks, 6 months, and 12 months were analyzed and compared with the 6 months prior to treatment. VT burden (implantable cardioverter-defibrillator [ICD] shocks and antitachycardia pacing sequences) as well as clinical and safety outcomes were the main outcomes. ResultsFifteen patients were enrolled and underwent planning. Fourteen (93%) underwent treatment, with 12 (80%) surviving to the end of the 6-week period and 10 (67%) surviving to 12 months. From 6 week to 12 months, there was recurrence of VT, which resulted in either appropriate antitachycardia pacing or ICD shocks in 33% (4 of 12). There were significant reductions in treated VT at 6 weeks to 6 months (98%) and at 12 months (99%) compared to the 6 months before treatment. There was a nonsignificant trend toward lower amiodarone dose at 12 months. Four deaths occurred after treatment, with no changes in ventricular function. ConclusionFor a select group of high-risk patients with VT refractory to standard therapy, SBRT is associated with a reduction in VT and appropriate ICD therapies over 1 year.

One Year Follow-up and Toxicity Review in a Series of 6 Patients Receiving Stereotactic Arrhythmia Radioablation for Ventricular Tachycardia

Stereotactic body radiation therapy (SBRT) to arrhythmogenic scar regions defined by noninvasive cardiac mapping has recently been described for patients with treatment refractory ventricular tachycardia (VT). Long-term outcomes and both intra- and extra-cardiac toxicities are not well described in this patient population. We report the outcomes following at least 1-year post-treatment along with toxicity for 6 patients treated with this technique in our institution. A total of 6 patients treated between 2019 and 2022 with refractory VT with previously failed ablations and at least one anti-arrhythmic drug was treated at our institution. All were treated with 25 Gy in a single fraction to the suspected arrhythmogenic scar. Cardiac microstructure contouring was done following the atlas by Duane et al. 2017. Implantable cardioverter defibrillator (ICD) interrogation was performed regularly by the treating cardiologist to assess the number of VT and ICD events, and, patients were seen immediately following SBRT, and at 3, 6, and 12 months respectively. Computed tomography of the chest was done at 3 months to assess for radiation induced pneumonitis and transthoracic echocardiograms were done as per the cardiologist's discretion. Radiation toxicity was evaluated using CTCAE v5.0. The median follow-up time for the 6 evaluated patients is 24 months. Three patients (50%) remained VT free during the one-year period post SBRT. Two of these patients remain VT free and are either on reduced or discontinued anti-arrhythmic drugs, while another failed at 24 months in an area of the arrhythmogenic substrate that was intentionally not irradiated due to organ at risk safety concerns. Among those that failed, the median time to failure was 4 months (range 3-5 months). All 6 patients tolerated treatment with no immediate acute side effects. Three (50%) of patients had no acute clinical or radiographic side effects. Grade 1 esophagitis, grade 1 fatigue, and grade 1 cough was reported in 1 (17%) patient each (all different patients), and 1 patient required hospitalization 4 months after SBRT for a heart failure exacerbation (potentially SBRT related). One patient (17%) died within 3 months following treatment but their death was not attributed to radiation treatment. No cardiac microstructure toxicity has been reported to date. Despite increasing reports in the literature, there are no established criteria to predict success for SBRT in the context of treatment-refractory VT, or the optimal treatment dose for success, making it difficult to identify optimal patients. Current limited evidence suggests that this technique may be a relatively safe approach to provide an acute reduction in VT burden for those refractory to standard of care and has an acceptable acute toxicity profile however longer term follow-up is required. Long term toxicity, specifically to cardiac microstructures, and dose optimization is currently are the focus of ongoing study.

Recurrences of ventricular tachycardia after stereotactic arrhythmia radioablation arise outside the treated volume: analysis of the Swiss cohort.

Stereotactic arrhythmia radioablation (STAR) has been recently introduced for the management of therapy-refractory ventricular tachycardia (VT). VT recurrences have been reported after STAR but the mechanisms remain largely unknown. We analysed recurrences in our patients after STAR. From 09.2017 to 01.2020, 20 patients (68 ± 8 y, LVEF 37 ± 15%) suffering from refractory VT were enrolled, 16/20 with a history of at least one electrical storm. Before STAR, an invasive electroanatomical mapping (Carto3) of the VT substrate was performed. A mean dose of 23 ± 2 Gy was delivered to the planning target volume (PTV). The median ablation volume was 26 mL (range 14-115) and involved the interventricular septum in 75% of patients. During the first 6 months after STAR, VT burden decreased by 92% (median value, from 108 to 10 VT/semester). After a median follow-up of 25 months, 12/20 (60%) developed a recurrence and underwent a redo ablation. VT recurrence was located in the proximity of the treated substrate in nine cases, remote from the PTV in three cases and involved a larger substrate over ≥3 LV segments in two cases. No recurrences occurred inside the PTV. Voltage measurements showed a significant decrease in both bipolar and unipolar signal amplitude after STAR. STAR is a new tool available for the treatment of VT, allowing for a significant reduction of VT burden. VT recurrences are common during follow-up, but no recurrences were observed inside the PTV. Local efficacy was supported by a significant decrease in both bipolar and unipolar signal amplitude.

Cryothermal energy demonstrates shorter ablation time and lower complication rates compared with radiofrequency in surgical hybrid ablation for recurrent ventricular tachycardia

Recurrent ventricular tachycardia (VT) after prior endocardial catheter ablation(s) presents challenges in the setting of prior cardiac surgery where percutaneous epicardial access may not be feasible. The purpose of this study was to compare the outcomes of cryothermal vs radiofrequency ablation in direct surgical epicardial access procedures. We performed a retrospective study of consecutive surgical epicardial VT ablation cases. Surgical cases using cryothermal vs radiofrequency ablation were analyzed and outcomes were compared. Between 2009 and 2022, 43 patients underwent either a cryothermal (n = 17) or a radiofrequency (n = 26) hybrid epicardial ablation procedure with direct surgical access. Both groups were similarly matched for age, sex, etiology of VT, and comorbidities with a high burden of refractory VT despite previous endocardial and/or percutaneous epicardial ablation procedures. The surgical access site was lateral thoracotomy (76.5%) in the cryothermal ablation group compared with lateral thoracotomy (42.3%) and subxiphoid approach (38.5%) in the radiofrequency group, with the remainder in both groups performed via median sternotomy. The ablation time was significantly shorter in those undergoing cryothermal ablation vs radiofrequency ablation (11.54 ± 15.5 minutes vs 48.48 ± 23.6 minutes; P < .001). There were no complications in the cryothermal ablation group compared with 6 patients with complications in the radiofrequency group. Recurrent VT episodes and all-cause mortality were similar in both groups. Hybrid surgical VT ablation with cryothermal or radiofrequency energy demonstrated similar efficacy outcomes. Cryothermal ablation was more efficient and safer than radiofrequency in a surgical setting and should be considered when surgical access is required.

Stereotactic management of arrhythmia - radiosurgery in treatment of ventricular tachycardia (SMART-VT). Results of a prospective safety trial

Background and purposeDespite its increasing popularity, there are limited prospective data on stereotactic arrhythmia radioablation (STAR). In this trial, we assessed the safety and efficacy of STAR in patients with ventricular tachycardia (VT), focusing on early treatment-related grade ≥ 3 adverse events (AE). Materials and methodsThis prospective trial was designed for adults with VT recurrence following catheter ablation (CA) despite adequate pharmacotherapy, or contraindications to CA. A single dose of 25 Gy was delivered to the arrhythmia substrate defined on electro-anatomic mapping and cardiac-gated CT. The primary endpoint was safety, defined as two or fewer treatment-related grade ≥ 3 AEs during the first three months in 11 patients. Additional endpoints included treatment efficacy, clinical and biological markers of cardiac injury, and quality of life. ResultsEleven patients with a median age of 67 years, structural heart disease, and a clinically significant recurrence of VT despite adequate pharmacotherapy and 1–4 previous CAs were enrolled between 2020/09 and 2022/10. Following the treatment, one patient developed a possibly treatment-related grade ≥ 3 AE, a grade 4 heart failure exacerbation at 87 days, which resolved after conservative treatment. There was a total 84.3% reduction in VT burden in 10 evaluable patients; however, VT recurrence was eventually observed in eight, and three patients required additional CAs. Three deaths due to unrelated causes were recorded. ConclusionsSTAR appears to be safe and efficient. It is a promising treatment for selected patients; however, long-term outcomes remain to be evaluated, and controlled trials comparing STAR with standards of care are missing.

Radiosurgery for ventricular tachycardia (RAVENTA): interim analysis of a multicenter multiplatform feasibility trial

BackgroundSingle-session cardiac stereotactic radiation therapy (SBRT) has demonstrated promising results for patients with refractory ventricular tachycardia (VT). However, the full safety profile of this novel treatment remains unknown and very limited data from prospective clinical multicenter trials are available.MethodsThe prospective multicenter multiplatform RAVENTA (radiosurgery for ventricular tachycardia) study assesses high-precision image-guided cardiac SBRT with 25 Gy delivered to the VT substrate determined by high-definition endocardial and/or epicardial electrophysiological mapping in patients with refractory VT ineligible for catheter ablation and an implanted cardioverter defibrillator (ICD). Primary endpoint is the feasibility of full-dose application and procedural safety (defined as an incidence of serious [grade ≥ 3] treatment-related complications ≤ 5% within 30 days after therapy). Secondary endpoints comprise VT burden, ICD interventions, treatment-related toxicity, and quality of life. We present the results of a protocol-defined interim analysis.ResultsBetween 10/2019 and 12/2021, a total of five patients were included at three university medical centers. In all cases, the treatment was carried out without complications. There were no serious potentially treatment-related adverse events and no deterioration of left ventricular ejection fraction upon echocardiography. Three patients had a decrease in VT episodes during follow-up. One patient underwent subsequent catheter ablation for a new VT with different morphology. One patient with local VT recurrence died 6 weeks after treatment in cardiogenic shock.ConclusionThe interim analysis of the RAVENTA trial demonstrates early initial feasibility of this new treatment without serious complications within 30 days after treatment in five patients. Recruitment will continue as planned and the study has been expanded to further university medical centers.Trial registration numberNCT03867747 (clinicaltrials.gov). Registered March 8, 2019. Study start: October 1, 2019.

Stereotactic Arrhythmia Radioablation (STAR) for refractory ventricular tachycardia (VT) - A preliminary report from the German multicenter RAVENTA study

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): The multicenter RAdiosurgery for VENtricular TAchycardia (RAVENTA) study (NCT03867747) is part of the STOPSTORM.eu consortium project Background Stereotactic Arrhythmia Radioablation (STAR) has been shown to be a promising treatment option for refractory ventricular tachycardia (VT) in initial reports of monocentric clinical studies and case series. Methodology The multicenter RAdiosurgery for VENtricular TAchycardia (RAVENTA) study is part of the STOPSTORM.eu consortium project and investigates STAR with 25 Gy in one session for patients with refractory VT without further treatment options. The primary endpoint is to evaluate the feasibility and safety of the procedure with an incidence of ≤ 5% of severe (grade ≥ 3) treatment-related side effects within 30 days after therapy. We now present an analysis after enrolment of 10 of the 20 planned patients. Results Ten patients were included in the RAVENTA study at four treatment centers between 10/2019 and 10/2022. STAR was performed without complications in all patients. To date, there were no acute (≤ 30 days) or late (&amp;gt; 30 days up to one year) grade ≥ 3 side effects which were possibly treatment-associated. Significant reduction in VT burden and ICD interventions was observed in most patients. In 7/10 (70%) of the patients, sustained freedom from VT was achieved up until last follow-up. Conclusion RAVENTA is the world's first multicenter study for STAR of refractory VT. We did not observe any treatment-related severe side effects in the current analysis. Most patients benefited from significant reductions in VT burden.

Recurrences of ventricular tachycardia after stereotactic arrhythmia radioablation arise outside the treated volume: analysis of the Swiss cohort

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): The project is part of the STOPSTORM.eu consortium and has partially received funding from the European Union’s horizon 2020 research and innovation program Background 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 largely unknown. Purpose We analyzed recurrences in the Swiss Cohort after STAR for refractory VT in order to assess their location related to the irradiated volume. Methods From 09.2017 to 01.2020, 20 patients (68±8y, LVEF 37±15%) suffering from refractory VT were enrolled. The underlying cardiopathy was ischemic in 6, inflammatory in 4, neoplastic in 1 and idiopathic in 9 patients. Sixteen out of 20 patients had a history of at least 1 electrical storm. Before STAR, an invasive electro-anatomical mapping (Carto3) of the VT substrate was performed. A mean dose of 23±2Gy was delivered to the planning target volume (PTV). Results The median ablation volume was 26 ml (range 14-115) and involved the interventricular septum (IVS) in 75% of patients. During the first 6 months after STAR, VT burden decreased by 92% (median value, from 108 to 10 VT/semester, p&amp;lt;0.005). After a median follow-up of 25 months, 12/20 (60%) developed a recurrence with 14 sustained VTs and underwent a redo CA. VT recurrence was located in proximity of the treated arrhythmogenic substrate in 9 cases, occurred remote from the PTV in 3 cases and involved a larger substrate over ≥3 LV segments in 2 cases. No recurrences occurred inside the PTV. The estimated dose delivered at sites of VT recurrence was very heterogeneous, ranging from 0.11 to 28.37 Gy, and less than 15 Gy in 12/14 cases. Voltage measurements showed a significant decrease in both bipolar and unipolar signal amplitude. Conclusion STAR is a precious new tool available for the treatment of therapy-refractory VT, allowing for a significant reduction of VT burden. VT recurrences are common during follow-up, but no recurrences were observed inside the PTV. Local efficacy was supported by a significant decrease in both bipolar and unipolar signal amplitude.

A method to identify which patients will have VT substrate ablation targets prior to ablation procedure

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Dr Nanthakumar is a recipient of the Mid-career Investigator Award from the Heart &amp; Stroke Foundation of Ontario Background Recent trials in ventricular tachycardia (VT) ablation suggest that early ablation could reduce VT burden. A method to predict which patients will have substrate ablation targets based on non-invasive testing prior to the procedure does not exist and could be of value in selecting ideal patients for early VT substrate ablation. Decrement-evoked potential (DeEP) mapping is used to identify VT substrate ablation targets.1 A method for predicting which patients would have DeEP targets on a pre-ablation 12-lead ECG has not yet been developed. Objective To develop a metric to predict the presence of physiological substrate VT ablation targets from the 12-lead ECG. Method 22 electrophysiology (EP) lab VT cases that had undergone DeEP mapping were extracted from the CARTO® 3 system and were analysed retrospectively. For each case, DeEP was calculated by subtracting last component of the nearfield evoked response in the pacing train (S1) from the latest component of the nearfield evoked decremented response of the extra stimulus (S2). By inference, 12-lead ECG prediction was calculated by subtracting the width of the 12-lead surface ECG envelope of S1 from the width of the 12-lead ECG envelope of S2. Cases were divided into three categories: - Cases displaying intracardiac DeEP between 0-10ms – no ablation targets - Cases displaying intracardiac DeEP between 10-50ms – DeEP positive - Cases displaying intracardiac DeEP &amp;gt;50ms – prominent DeEP present Results Out of the 22 cases, 8 were characterised as no ablation targets, 12 as DeEP positive, and 2 as prominent DeEP present. The 12-lead surface ECG measurement means were 3.5±4.6ms for the no ablation target group, 23.2±9.1ms for positive DeEP group, and 80.9±8.1ms for prominent DeEP group. The surface ECG decrement was significantly different P&amp;lt;0.0001 between the three groups. Consequently, we propose that ECG QRS widening of envelope width of 20ms or more may indicate the presence of DeEP targets during invasive mapping. Conclusion It may be possible to detect which patients will have substrate ablation targets based on 12-lead ECG, prior to the VT ablation procedure. Additionally, this prediction rule, based on its association with arrhythmogenic potentials, may be able to predict which ambulatory patients who have not had manifest VT, may be prone to develop VT thus help identify early VT ablation candidates. This concept should be validated in larger data sets and is ideal for training and testing using surface ECG envelopes with artificial intelligence algorithms.

PO-05-063 MORTALITY IN LEFT VENTRICULAR ASSIST DEVICE RECIPIENTS WITH VT REQUIRING ABLATION

Left Ventricular Assist Devices (LVADs) improve survival in patients with heart failure. However, an increased burden of ventricular tachycardia (VT) can occur following LVAD implantation. The role of ablation in the treatment of VT for LVAD recipients and the timing of when ablation should occur is unclear. To determine mortality in LVAD recipients with VT who required an ablation We retrospectively reviewed all patients who received a ventricular ablation from January 2014 to February 2021 and included those who underwent VT ablation after LVAD placement. The composite endpoints included transplant, lost to follow up, or last date of data collection. Event failure was defined as patient death. Survival rates were calculated with Kaplan-Meier analysis. Rate of event failure was calculated as per patient-year incident death rate (IR) and was compared between treatment groups by incident rate ratio with 95% confidence intervals (IRR [95% CI]). Survival analysis was performed using STATA. 36 patients underwent VT ablation after LVAD placement. Of those, 21 (58%) had documented VT prior to LVAD placement and 14 (42%) had de novo VT after LVAD placement. Within 30 days, one patient died (IR 0.339 over 2.95 patient-years); within one year, four patients died (IR 0.128 over 31.1 patient-years); within two years, ten patients died (IR 0.183 over 54.5 patient-years); and within eight years, twenty patients died (IR 0.217 over 92.2 patient-years). At a study endpoint of 2 years (the time interval between the most recent LVAD placement and the last date of data collection), a significantly higher death rate per patient-year was found in patients with VT onset within 7 days of LVAD placement (IRR 5.19 [1.08-21.87]), with a trend towards significantly higher death rate seen in patients with ischemic cardiomyopathy (ICM) (IRR 4.12 [0.82-39.9]) (Table 1). All patients who died underwent a VT ablation within 90 days of VT onset (Figure 1). Mortality in LVAD recipients was highest in the immediate post-operative period, especially when VT occurred within 7 days of LVAD placement. A higher death rate was also seen when ablation was performed within 90 days of VT onset. Further comparison to matched LVAD recipients without VT requiring ablation is needed to better understand the impact of VT on mortality in LVAD recipients.Tabled 1Table 1. IRRs of Patient Mortality Stratified by Presence or Absence of Specific Risk FactorsAbsentPresentIRR95% CIp-valueIschemic Cardiomyopathy0.0720.2984.12[0.82-39.9]0.059LVAD as Destination Therapy0.1100.2572.32[0.53-13.93]0.223HeartWare LVAD Placed0.1450.2241.55[0.37-7.47]0.516VT Prior to LVAD Placement0.1150.2462.14[0.49-12.80]0.283VT Ablation Prior to LVAD Placement0.2020.1680.83[0.14-3.64]0.825VT Within 7 Days of LVAD Placement0.1240.6455.19[1.08-21.87]0.023Ablation of VT Within 90 Days of VT Onset00.260------0.031Multiple Ablations Performed for Recurrent VT0.2180.0760.35[0.08-2.50]0.322 Open table in a new tab

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