Ventricular Tachycardia Events Research Articles

Thoracic impedance during national holidays

Abstract Background Several studies have observed increased incidence of myocardial infarctions during Christmas and national holidays. Emotional stress, overindulgence in food and alcohol have been suggested as potential underlying mechanisms. Monitoring of thoracic impedance (TI) by cardiac implantable electronic devices (CIED) has been proposed as a tool for detection of fluid accumulation. We aimed to assess the relationship between TI and national holidays in patients treated with CIED with and without reduced left ventricular ejection fraction (LVEF). Method Consecutive patients with CIED capable of TI monitoring enrolled in the remote monitoring program at a tertiary care hospital in Sweden were screened. Full disclosure remote CIED monitoring database containing daily measurements of TI and device therapy delivery was accessed as the source of information for this retrospective cohort study. Patients were included if they had the monitoring data for at least one holiday (Christmas, New Year or Midsummer) between June 2015 and January 2020. TI during the holiday was compared with baseline values, defined as a mean value of three days preceding Christmas Eve and Midsummer. Clinical characteristics, LVEF, medical treatment and possible contact with healthcare during the holidays or the following week were obtained from medical records. A linear mixed model was used since dependent observations existed. Result In total, 96 patients (82 % men, age 69±10 years, 92 % ICD, 78 % CRT, 72 % with LVEF<40%) were included, which provided data for 255 patient-holidays. TI decreased by mean 1.3 Ohm (95% CI -1.9 to -0.6, p< 0.001) on the Christmas Day, 0.6 Ohm (95 % CI -1.4 to 0.1, p = 0.08) on New Years Day and 1.0 Ohm (95 %CI -1.7 to -0.3, p=0.005) on Midsummer Day. These TI changes were not related to age and did not differ between men and women. Holiday-related TI drop was observed regardless of LVEF: mean decrease on Christmas Day 1,1 vs 1,4 Ohm, New Years Day 0,2 vs 0,4 Ohm and Midsummer Day 1,2 vs 1,0 Ohm for LVEF <40% and >40% respectively. By the third day after a holiday, TI had reached the baseline level. Only one ventricular tachycardia event requiring shock therapy and hospital admission was documented. No other patients were seeking care during the holidays or the days afterwards. Conclusion A significant transient decrease in thoracic impedance was evident during Christmas Day and Midsummer Day in CIED treated patients with reduced and preserved LVEF. These holidays are therefore associated with both decrease in thoracic impedance and incidence of myocardial infarction and it is possible that decrease in thoracic impedance could contribute to the increased incidence of myocardial infarction during holidays.

Ventricular Arrhythmias After Primary Percutaneous Coronary Intervention for STEMI

Currently, mortality risk for patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI) with an uncomplicated postprocedure course is low. Less is known regarding the risk of in-hospital ventricular tachycardia (VT) and ventricular fibrillation (VF). To evaluate the risk of late VT and VF after primary PCI for STEMI. This cohort study included adults aged 18 years or older with STEMI treated with primary PCI between January 1, 2015, and December 31, 2018, identified in the US National Cardiovascular Data Registry Chest Pain-MI Registry. Data were analyzed from April to December 2020. Multivariable logistic regression was used to evaluate the risk of late VT (≥7 beat run of VT during STEMI hospitalization ≥1 day after PCI) or VF (any episode of VF≥1 day after PCI) associated with cardiac arrest and associations between late VT or VF and in-hospital mortality in the overall cohort and a cohort with uncomplicated STEMI without prior myocardial infarction or heart failure, systolic blood pressure less than 90 mm Hg, cardiogenic shock, cardiac arrest, reinfarction, or left ventricular ejection fraction (LVEF) less than 40%. A total of 174 126 eligible patients with STEMI were treated with primary PCI at 814 sites in the study; 15 460 (8.9%) had VT or VF after primary PCI, and 4156 (2.4%) had late VT or VF. Among the eligible patients, 99 905 (57.4%) at 807 sites had uncomplicated STEMI. The median age for patients with late VT or VF overall was 63 years (IQR, 55-73 years), and 75.5% were men; the median age for patients with late VT or VF with uncomplicated STEMI was 60 years (IQR, 53-69 years), and 77.7% were men. The median length of stay was 3 days (IQR, 2-7 days) for the overall cohort with late VT or VF and 3 days (IQR, 2-4 days) for the cohort with uncomplicated STEMI with late VT or VF. The risk of late VT or VF was 2.4% (overall) and 1.7% (uncomplicated STEMI). Late VT or VF with cardiac arrest occurred in 674 patients overall (0.4%) and in 117 with uncomplicated STEMI (0.1%). LVEF was the most significant factor associated with late VT or VF with cardiac arrest (adjusted odds ratio [AOR] for every 5-unit decrease ≤40%: 1.67; 95% CI, 1.54-1.85). Late VT or VF events were associated with increased odds of in-hospital mortality in the overall cohort (AOR, 6.40; 95% CI, 5.63-7.29) and the cohort with uncomplicated STEMI (AOR, 8.74; 95% CI, 6.53-11.70). In this study, a small proportion of patients with STEMI treated with primary PCI had late VT or VF. However, late VT or VF with cardiac arrest was rare, particularly in the cohort with uncomplicated STEMI. This information may be useful when determining the optimal timing for hospital discharge after STEMI.

Performance comparison of 6 in-hospital patient monitoring systems in the detection and alarm of ventricular cardiac arrhythmias

BackgroundPatient monitoring devices are critical in alerting potential cardiac arrhythmias during hospitalization; however, there are concerns of alarm fatigue due to high false alarm rates. ObjectiveTo evaluate sensitivity and false alarm rate of hospital-based continuous electrocardiographic (ECG) monitoring technologies. MethodsSix commonly-used multiparameter bedside monitoring systems available in the United States were evaluated: B125M (GE HealthCare), ePM10 and iPM12 (Mindray), Efficia and IntelliVue (Philips), and Life Scope (Nihon Kohden). Sensitivity was tested using ECG recordings containing 57 true ventricular tachycardia (VT) events. False positive rate testing used 205 patient-hours of ECG recordings containing no cardiac arrhythmias. Signals from ECG recordings were fed to devices simultaneously; high-severity arrhythmia alarms were tracked. Sensitivity to true VT events and false positive rates were determined. Differences were assessed using Fisher’s exact tests (sensitivity) and Z-tests (false positive rates). ResultsB125M raised 56 total alarms for 57 annotated VT events and had the highest sensitivity (98%, P<0.05), followed by iPM12 (84%), Life Scope (81%), Efficia (79%), ePM10 (77%), and IntelliVue (75%). B125M raised 20 false alarms, significantly lower (P<0.0001) than iPM12 (284), Life Scope (292), IntelliVue (304), ePM10 (324), and Efficia (493). The most common false alarm was VT, followed by non-sustained VT. ConclusionWe found significant performance differences among multiparameter bedside ECG monitoring systems using previously-collected recordings. B125M had the highest sensitivity in detecting true VT events and lowest false alarm rate. These results can assist in minimizing alarm fatigue and optimizing patient safety by careful selection of in-hospital continuous monitoring technology.

Learning feature representations from unlabeled data for volcano-seismic event classification

Accurately identifying and labeling seismic events is essential for understanding the internal dynamics of volcanoes and predicting volcanic eruptions. However, the manual labeling of seismic events is a labor-intensive and resource-demanding process that requires the expertise of highly skilled vulcanologist professionals. Unsupervised learning approaches provide an alternative solution by automatically discovering hidden structures in the data, thereby enabling the characterization of seismic events without requiring manual labeling. We compare two widely recognized unsupervised learning algorithms, k-means and the Gaussian mixture model (GMM), which employ different assignment strategies (i.e., hard assignment for k-means and soft assignment for GMM), to learn a feature representation from an unlabeled dataset collected from the Cotopaxi volcano. The learned feature representations are then evaluated on a supervised task to classify LP and VT events using labeled datasets from the Cotopaxi and Llaima volcanoes. Additionally, we compare our approach to a baseline composed of hand-crafted features engineered by domain experts over the years. Our findings highlight the effectiveness of unsupervised techniques in learning a wide range of relevant features that exhibit a high correlation with the baseline. Furthermore, when assessed in a classification task, our unsupervised approach achieves a statistically similar performance compared to the baseline features. Notably, the GMM feature representation outperforms the baseline features in effectively handling VT and LP noisy signals from the BREF station at Cotopaxi volcano.

Abstract 12810: Short-Term Hospital Outcomes of Elderly Patients With Mechanical vs. Bioprosthetic Heart Valves Admitted for NSTEMI

Introduction: Valvular heart disease(VHD) is a significant cause of morbidity and mortality among the elderly. While the use, merits, and demerits of mechanical heart valves (MHV) and bioprosthetic heart valves(BHV) to treat VHD are well-documented in the literature, there needs to be more data on the outcomes following events of NSTEMI. Methods: We explored the 2016-2020 National Inpatient Sample for patients ages≥60 years hospitalized for a primary diagnosis of NSTEMI via their ICD-10 codes. We further retained those with a presence of MHV or BHV, and differences in outcomes between the two groups were evaluated. Results: Our study found 32775 adults of age 60 and more hospitalized with NSTEMI, which included 23670 (72.2%) cases with MHV, while 9105 (27.8%) patients had a BHV. No differences in mean Charlson Comorbidity Index (CCI) scores were found between the two groups (mean CCI in MHV patients: 4.14 vs. 4.22 in those with BHV, p=0.233). Compared to cases with BHV, those with MHV showed higher odds of acute kidney injury (aOR 1.108, p&lt;0.01), atrial fibrillation (aOR 1.110, p&lt;0.01), supraventricular tachycardia (aOR 1.46, p&lt;0.01), and use of CABG (aOR 1.289, p=0.031). However, patients with MHV were less likely to undergo PCI for NSTEMI than those with BHV (aOR 0.781, p&lt;0.01). No differences between the two cohorts were found for events of ventricular tachycardia (aOR 0.907, p=0.072), ventricular fibrillation (aOR 1.021, p=0.80), cardiogenic shock (aOR 1.012, p=0.876), or death (aOR 0.928, p=0.187). Finally, those with MHV reported a slightly more extended stay (mean length of stay 4.41 days) than those with BHV (mean length of stay 4.02 days, p&lt;0.01). Conclusions: Patients with MHV showed higher odds of complications such as AKI, Atrial fibrillation, supraventricular tachycardia, and use of CABG following NSTEMI while reporting lower odds of PCI use than those with BHV.

Abstract 15656: Early Recurrence of Ventricular Tachycardia and the Impact of Radiofrequency Ablation on Success of ICD Therapy

The early success of radiofrequency ablation (RFA) and impact on ICD delivered therapy (including the need for antitachycardia pacing (ATP) or ICD shock) after the procedure, due to recurrent VT events, is still not clear. Hypothesis: Recurrences of VT during 12 months of follow up (FU) after RFA are associated with the need for ICD therapy (successful ATP or need for ICD shock) and related to pre-procedural ATP success or failure. Methods: We analyzed the data of 141 ventricular arrhythmia patients who underwent RFA during 2019 - 2022 by identifying 54 (38.3%) patients with monomorphic VT and implanted ICDs. Age - 69.54±10.04 years , 52 (96.3%) males, BMI - 29.1±6.2; 27 (50.0%) patients - ICM; 51 (94.4%) used antiarrhythmics and 40 (82.1%) have failed; beta-blockers use - 47 (87.0%). 20 (37.0%) had an ICD for primary prevention. LVEF - 39.2±13.8%, VT cycle - 350±80 ms. VT storm - in 46 (85.2%). Results: Out of 54 included patients, only 34 (63%) had no recurrent VT events during FU post-RFA procedure. 20 (37.0%) experienced recurrent VT events and needed ICD therapy: 8 (40.0%) responded to ATP, whereas 12 (60.0%) failed ATP and required an ICD shock. Patients’ response to ICD delivered therapy was compared between two groups of patients: 1) pre-ablation ATP failure (n=40) and 2) pre-ablation ATP success (n=14). In pre-ablation ATP failure group, 23 (57.5%) patients had no recurrent VT events, 5 (12.5%) successfully responded to ATP and 11 (27.5%) failed ATP requiring ICD shock. In the pre-ablation ATP success group, 9 (64.5%) patients had no recurrent VT, 3 (21.4%) responded to ATP, and only 1 (7.14%) required ICD shock and no VT storm episodes, whereas 12 (30%) of patients with pre-procedural ATP failure had VT storm (IQR= 0.0, 0.0, vs 1.0, 5.0 respectively; p=0.019). Patients with recurrent VT events had higher BMI then patients with no recurrent VT: 32.9±5.4 vs 28.0±6.0, p&lt; 0.033. The pre-ablation ATP failure group had a greater proportion of hemodynamically unstable VT induced during RFA (56.7% vs 23.1%; p=0.043). Conclusion: The success of ATP after RFA was associated with pre-procedural ATP response and patients with lower BMI had less recurrent VT events. Overall, pre-ablation ATP failure for VT termination may identify patients with increased risk of failure to ATP therapy.

A target definition based on electroanatomic maps for stereotactic arrhythmia radioablation

PurposeIdentifying the target region is critical for successfully treating ventricular tachycardia (VT) with single fraction stereotactic arrhythmia radioablation (STAR). We report the feasibility of target definition based on direct co-registration of electroanatomic maps (EAM) and radioablation planning images. Materials and methodsThe EAM consists of 3D cardiac anatomy representation with electrical activity at endocardium and is acquired by a cardiac electrophysiologist (CEP) during electrophysiology study. The CEP generates an EAM using a 3D cardiac mapping system anticipating radioablation planning. Our in-house software read these non-DICOM EAMs, registered them to a planning image set, and converted them to DICOM structure files. The EAM based target volume was finalized based on a consensus of CEPs, radiation oncologists and medical physicists, then expanded to ITV and PTV. The simulation, planning, and treatment is performed with a standard STAR technique: a single fraction of 25 Gy using volumetric-modulated arc therapy or dynamic conformal arc therapy depending on the target shape. ResultsSeven patients with refractory VT were treated by defining the target based on registering EAMs on the planning images. Dice similarity indices between reference map and reference contours after registration were 0.814 ± 0.053 and 0.575 ± 0.199 for LV and LA/RV, respectively. ConclusionsThe quality of the transferred EAMs on the MR/CT images was sufficient to localize the treatment region. Five of 7 patients demonstrated a dramatic reduction in VT events after 6 weeks. Longer follow-up is required to determine the true safety and efficacy of this therapy using EAM-based direct registration method.

Description of multiparametric targeting techniques for stereotactic arrhythmia radioablation in refractory ventricular tachycardia: A quaternary medical center experience

Background: Ventricular tachycardia (VT) is a potentially life-threatening arrhythmia which remains a major contributor to cardiac morbidity and mortality worldwide. Recently the use of stereotactic radiation has demonstrated efficacy, although standardization of methodology is lacking and variations in technique exist. In this paper, we discuss our outcomes as well as the various options available and the proposed indications for each.Methods: 12-lead EKGs and device-obtained tracings were used to approximately localize the arrhythmogenic origin and to define the arrhythmic mechanism. When feasible, electrophysiology studies (EPS) with 3-D electroanatomic (EA) mapping during which a 3-D electroanatomic substrate map was created to delineate cardiac structures, identify areas of low voltage scar and confirm arrhythmic circuits. A 4-D cardiac magnetic resonance imaging (cMRI) or cardiac computed tomography (cCT) was performed to delineate cardiac geometry and structures. The Stereotactic arrhythmia radioablation (STAR) treatment plans delivered a total dose of 25 Gy in a single treatment fraction covering the entire arrhythmogenic target.Results: Six of the nine patients showed a reduction in VT events at 6 weeks post STAR. One patient underwent cardiac transplantation two weeks following STAR. Excluding this patient from the analysis, all but one patient had a dramatic diminution in VT events (to 0) at 6 months post-procedure, including both patients with an LVAD. Six of the nine patients survived at least 4 months post procedure event free and 6 patients survive to date. The lone patient who did not respond died 13 months post procedure, however he had no further defibrillator discharges. Another patient died two months post procedure from uncontrolled multiple myeloma. One patient developed an asymptomatic pleural effusion, but no serious STAR-induced postoperative complications occurred.Conclusions: STAR appears to be an effective therapy for refractory ventricular tachycardia, although long term data are still developing. Additional clinical trials and techniques are in development and STAR programs should be encouraged for additional well-equipped centers with experienced multidisciplinary clinicians.

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.

Ventricular arrhythmias in patients with hypertrophic cardiomyopathy: Prevalence, distribution, predictors, and outcome

Hypertrophic cardiomyopathy (HCM) carries an increased risk of sudden cardiac death. Ventricular fibrillation (VF) is thought to be the common culprit arrhythmia. The purpose of this study was to describe the incidence and predictors of sustained ventricular arrhythmias (VTAs) in HCM patients. We retrospectively analyzed all patients with HCM and an implantable cardioverter-defibrillator (ICD) from a prospectively derived registry in 2 tertiary medical centers. Clinical, electrocardiographic, echocardiographic, ICD interrogation, and genetic data were collected and compared, first between patients with and without VTAs and then between patients with only VF and those with ventricular tachycardia (VT) with or without VF. Of the 1328 HCM patients, 207 (145 [70%] male; mean age 33 ± 16 years) were implanted with ICDs. Over a mean follow-up of 10 ± 6 years, 37 patients with ICDs (18%) developed sustained VTAs. These were associated with a family history of sudden cardiac death and a personal history of VTAs (P = .036 and P = .001, respectively). Sustained monomorphic VT was the most common arrhythmia (n = 26, 70%) and was linked to decreased left ventricular (LV) ejection fraction and increased LV end-systolic and end-diastolic diameters. Antitachycardia pacing (ATP) successfully terminated 258 (79%) of the 326 VT events. Mortality rates were comparable between patients with and without VTAs (4 [11%] vs 29 [17%]; P = .42) and between those with and without ICDs (24 [16%] vs 85 [20%]; P = .367). VT rather than VF is the most common arrhythmia in patients with HCM; it is amenable to ATP and is associated with lower LV ejection fraction and higher LV diameters. Therefore, ATP-capable devices may be considered in HCM patients with these LV features.

P105: Pre-Emptive Use of Mechanical Circulatory support in sudden cardiac death- A contrasting case series

Life-threatening ventricular tachycardia(VT) and fibrillation(VF) are the most important causes of sudden cardiac death(SCD). Patients who survive are often predisposed to recurrent VT secondary to scar tissue and require definitive ablation therapies. However given the unpredictable nature of arrhythmias, patients can degenerate into VT storm even as outpatient and become hemodynamically unstable which precludes ablation therapies. Using preemptive mechanical circulatory support in such patients as a bridge to ablation can be a game changer, especially in the event of a fresh VT. We present two contrasting cases, where preemptive use of Impella showed better outcomes in neurological status post cardiac arrest. Our patient is a 16-year-old competitive basketball player who suffered an out-of-hospital VT arrest during match practice requiring bystander CPR and multiple shocks. He was stabilized in an outside hospital and brought to us intubated, paralyzed, on multiple pressors and maintained on IV amiodarone and lidocaine. ECHO demonstrated a very large right ventricle (RV) with severe left ventricle(LV) dysfunction, ejection fraction(EF) 10-15% with basal RV diameter 6.8cm. Cardiac MRI(CMRI) showed an area of late gadolinium enhancement (LGE) of the RV-free wall near the apex. Endomyocardial biopsy, Cardiac catheterization, and CT angiogram were unremarkable. With improvement in volume status, he was weaned off all inotropes and antiarrhythmics, received an AICD, and maintained only on sotalol and lisinopril. On outpatient follow-up, repeat CMRI confirmed Arrhythmogenic RV dysplasia. Unfortunately, four months later, the patient had another episode of cardiac arrest secondary to a VT storm with 20 minutes of downtime. He was deemed too unstable for VT ablation and thus emergently underwent a stellate ganglion block. The patient remained encephalopathic post-cardiac arrest with very slow neurologic recovery. He subsequently underwent cardiac transplantation The second case is that of a 63-year-old male with a past medical history of nonischemic cardiomyopathy with LVEF of 10% status post-ICD placement, and VT on amiodarone who presented with episodes of monomorphic VT followed by ICD shocks and syncope. Heart catheterization showed diffuse three-vessel disease. Due to recurrent VT patients, he received an Impella CP as a bridge to VT ablation. Interestingly during ablation, the patient goes into cardiac arrest requiring CPR for 90 minutes. He had successful VT ablation and with no neurological deficit post-procedure. Multiple trials have shown an improved 30-day survival rate without neurological sequelae with early implantation of Impella during ongoing CPR for cardiac arrest. Impella has several favorable properties by unloading the LV which limits the infarct size and maintains cerebral perfusion during the arrest. Preemptive Impella use is often used as a bridge to transplant, however using it as a bridge to ablation is yet to gain prominence.

Inducibility of Multiple Ventricular Tachycardia's during a Successful Ablation Procedure Is a Marker of Ventricular Tachycardia Recurrence.

Even after a successful ventricular tachycardia ablation (VTA), some patients have recurrent ventricular tachycardia (VT) during their follow-up. We assessed the long-term predictors of recurrent VT after having a successful VTA. The patients who underwent a successful VTA (defined as the non-inducibility of any VT at the procedure's end) in 2014-2021 at our center in Israel were retrospectively analyzed. A total of 111 successful VTAs were evaluated. Out of them, 31 (27.9%) had a recurrent event of VT after the procedure during a median follow-up time of 264 days. The mean left ventricular ejection fraction (LVEF) was significantly lower among patients with recurrent VT events (28.9 ± 12.67 vs. 23.53 ± 12.224, p = 0.048). A high number of induced VTs (>two) during the procedure was found to be a significant predictor of VT recurrence (24.69% vs. 56.67%, 20 vs. 17, p = 0.002). In a multivariate analysis, a lower LVEF (HR, 0.964; p = 0.037) and a high number of induced VTs (HR, 2.15; p = 0.039) were independent predictors of arrhythmia recurrence. The inducibility of more than two VTs during a VTA procedure remains a predictor of VT recurrence even after a successful VT ablation. This group of patients remains at high risk for VT and should be followed up with and treated more vigorously.

Ventricular tachycardia predicts all-cause mortality and non-sudden cardiac death in non-ischaemic cardiomyopathy

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): The DCM-VT study was partially supported by an investigator-initiated grant (IIS-310) from Biosense Webster (a Johnson &amp; Johnson company). The DANISH study was supported by unrestricted grants from Medtronic, St. Jude Medical, TrygFonden, and the Danish Heart Foundation. Background Endstage heart failure, ventricular tachycardia (VT) and sudden cardiac death (SCD) are sequels of non-ischaemic cardiomyopathies (NICM). Implantable cardioverter defibrillators (ICDs) can terminate VT and prevent SCD but mortality benefit has been limited in recent trials suggesting that VT may also be associated with non-sudden cardiovascular death (NSCVD). Purpose To assess the effect of VT on all-cause mortality and NSCVD in NICM patients with ICDs. Methods Two multicenter cohorts of NICM patients were merged for analysis: (1) patients randomized to ICD in the DANISH trial, which included patients with NICM, LVEF ≤35% and no prior VT and (2) the DCM-VT study cohort, which included consecutive NICM patients with any LVEF referred for ablation of sustained VT. Predictors for the primary composite outcome of all-cause death and heart transplant (death/HTx) and for the secondary outcome of NSCVD were assessed. In addition, propensity score matching was performed using the parameters age, gender, LVEF and eGFR. Finally, survival following VT occurrence was compared between DANISH and DCM-VT patients. Results A total of 828 patients (556 DANISH, 272 DCM-VT) were followed for a median of 3.9 years (2.1 – 5.8). DANISH patients had a median LVEF of 25% (20 – 30) and DCM-VT patients 35% (27 – 43). A total of 148 patients (DANISH 16.4%, DCM-VT 21.0%) experienced death/HTx and NSCVD occurred in 78 patients (7.7%, 12.9%, respectively). In multivariable analysis history of VT at inclusion was a significant predictor of the primary outcome with an adjusted hazard ratio (HRa) of 3.81 (95% CI 2.33 - 6.24) as were age [HRa 1.02 per year (1.01 - 1.04)], LVEF [HRa 0.96 per 1% increase (0.94 - 0.98)] and reduced eGFR [HRa 1.71 (1.15 – 2.53 )]. History of VT predicted NSCVD with an HRa of 7.54 (3.97 - 14.33). After matching, history of VT still predicted death/HTx [HR 4.12 (2.48 - 6.82)] and NSCVD [HR 6.92 (3.30 - 14.52)]. Risk of death/HTx, as well as NSCVD, for DANISH patients was similar to DCM-VT patients after they experienced their first VT event [HRa 0.90 (0.48 - 1.69) and HRa 1.07 (0.56 - 2.06) resp.]. Conclusions VT occurrence appears to be an important predictor of non-sudden CV death as well as all-cause death in NICM patients independent of other markers of heart failure severity. VT may be a marker of progressive disease and remodelling that could be incorporated into risk-stratification to help predict deterioration and need for HTx.

Cardiovascular rehabilitation with a WCD

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): ZOLL Background The wearable cardioverter-defibrillator (WCD) is a temporary treatment option for patients at high risk for sudden cardiac death (SCD) in whom implantation of a cardioverter defibrillator (ICD) is temporarily not possible. Exercise training and rehabilitation has an IA recommendation in these patients. There are no data on safety and outcomes of patients with a WCD undergoing cardiac rehabilitation. Purpose The aim of this study is to evaluate the safety and feasibility of wearing a WCD while undergoing a cardiac rehabilitation program. Methods We performed a retrospective analysis of all patients with a successfully completed stationary rehabilitation program. Results 55/896 patients (6.1%) registered in the Austrian WCD registry completed a stationary rehab program (60±11 years, 1% female). Underlying cardiac disease was ischaemic cardiomyopathy (CMP) in 27/55 (49%), dilatative CMP in 15/55 (27%), inflammatory CMP in 10/55 (18%) patients. One patient had valvular CMP, one patient had tako tsubo CMP, one patient had a primary electrical disease (each 1,8%). The baseline LVEF at rehab start was 36% [12;80%], duration of rehab was 28 days [18;42] compared to a total prescription duration of 94 days [26;294]. 75.6% (41/55) patients completed a regular rehab duration with a WCD, 3.6% (2/55) got their WCD stopped during rehab due to recovery of the LV function, 21,8% (12/55) got a WCD prescribed during rehab. The daily wearing duration was 23.4h [12.6;23.9]. 2848 (mean 52±117/patient) automatic alarms and 340 (mean 6±9/patient) manual alarms were generated. Within this cohort 3,6% (2/55) patients had shocks for VT/VF during prescription: one patient for a VF event that was terminated with the first shock, another patient had three VT events that were also terminate with the first WCD shock. All events happened before rehabilitation, so no patient had a WCD treatment during rehab, neither appropriate, nor inappropriate. Two patient had recurrent stable VTs that were controlled with antiarrhythmic drugs during prescription, only one of them during rehab. 3 patients had a reported syncope during rehab, all of them associated with hypotension, one patient had an ambulatory check-up at the CIED clinic because of false automatic alarms due to artefacts. Following a relevant weight loss through rehab measurements, the fabric garment of the WCD had a poor fit and was adapted. The LVEF after rehab was 42% [23;73%]. At the end of WCD prescription 33/55 (60%) had a restitution of their cardiac function with no need for an ICD, 19/55 (35%) patients were implanted with an ICD. One patient (1,8%) had a heart transplantation, one patient (1,8%) had the desire to stop WCD prescription and one patient (1,8%) had a terminal non-cardiac disease. Conclusion Completing a cardiovascular rehabilitation program is feasible and safe for patients prescribed with a WCD and may contribute positively to the restitution of the cardiac function.

Impact of cardiac magnetic resonance channels to localize deceleration zones during VT ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac magnetic resonance has demonstrated to accurately identify voltage conduction channels and it is nowadays an important tool to analyze the arrhythmic substrate, to predict ventricular tachycardia (VT) events and to aid VT ablation. The characteristics of CMR channels (CMR-CCs) that predicts the presence of deceleration zone (DZ) have not been explored. Methods Forty-four consecutive patients with scar-related VT undergoing ablation after CMR (October 2018-July 2021) were included (medium age 64.8±11.6 years; 95.5% male; 70.5% ischemic heart disease, mean ejection fraction of 32.3±7.8). Characteristics of CMR-CCs were analyzed and correlation with DZs both in baseline maps and remaps were performed. Patients were prospectively followed for VT recurrence for one year. Results Overall, 129 automatically detected CMR-CCs were analyzed (2.89±1.83 per patient; length: 52.72±65.44mm (0.18–376.73), CC mass: 1.76±2.46grams (0.01–14.59); protectedness 19.02±24.51% (0.01–143.51)). Overall, 73.6% of CMR-CCs were associated with a DZ: 58.1% CMR-CCs in baseline map and 15.5% with a DZs not observed initially but in remaps. The univariate analysis showed that channels associated with DZs were longer (61.83±73.43 vs. 29.96±32.55, OR 1.01, p0.004), with higher border zone mass (2.02±2.75 vs. 1.09±1.44, OR 1.28, p0.031) and more protectedness (21.90±27.23 vs. 11.46±14.20, OR1.02, p0.036). VT recurrence after one-year follow up was 21.95%. Conclusions Pre ablation CMR can accurately identify channels that correlates with DZs that could be targets for ablation, especially those CMR-CCs with higher length, border zone mass and protectedness. Additionally, some channels not related with DZ in the first map have a clear DZ after abolishing the first region of slow conduction, suggesting a very useful role of CMR to detect potential DZs.

PO-04-170 AUTOMATED CT-BASED PREDICTION OF VENTRICULAR ARRHYTHMIA

Robust risk stratification of post-myocardial infarction (MI) ventricular tachycardia (VT) is desirable to overcome the limitations of left ventricular ejection fraction (LVEF), the currently used criterion for implanting cardiac defibrillator devices. We hypothesized, that a fully automated CT-based technology could predict VT in post-MI patients. A fully automated CT image processing pipeline was implemented including AI-based LV wall segmentation followed by joint analysis and quantification of wall thickness (WT), intramural fat, and myocardial calcification (Fig.1A). A cohort of 132 patients with prior MI (66±11 years, 37±10% LVEF) with implanted cardiac devices underwent CT scan, and were subsequently followed by remote monitoring over an average of 6.6 years (80 ± 31 months). We analyzed the relationship between CT markers (WT, fat, calcification) and VT events at follow-up. Analysis of the wall thickness layers showed the optimal WT-derived marker was the ratio between areas of WT < 3mm and WT< 5mm (no VT 0.57±0.45 vs. VT 0.89±0.55; p<0.01). The amount of myocardial calcification was also found higher in patients with VT (no VT 0.10±0.38ml vs. VT 0.47±1.57ml, p=0.039), while the amount of fat did not differ significantly between groups (no VT 1.14±1.38ml vs. VT 1.21±1.01ml, p=0.771). The optimal cut-off for the WT 3/5mm ratio was 0.3. On Kaplan Meier analysis, this WT ratio was a powerful predictor of VT-free survival (Fig.1B, log rank P<0.01). In contrast, a LVEF<35% was not found to significantly relate to VT-free survival (Fig.1C, P=0.77). Automated analysis of post-MI scar is doable from CT images, allowing for improved risk stratification of future VT. The area of severe wall thinning divided by the total area of thinning appears to be the best marker of risk.

PO-04-095 ACCURATE EAM-BASED TARGET DELINEATION IN STEREOTACTIC ARRHYTHMIA RADIOABLATION OF VT

Stereotactic Arrhythmia Radiotherapy (STAR) aided by precise image-guided delivery and respiratory motion management has been used successfully for experimental treatment of refractory VT. However, accurate target selection remains challenging. Current methods often rely on manual delineation and/or visual estimation of predefined cardiac segments. Develop a systematic process for registering VT targets from electroanatomic maps (EAM) to reference imaging coordinates of the planning CT (pCT) used for radiation treatment. The goal is to minimize potential variations in target site selection as well as treated volumes. In patients on antiarrhythmic treatment and undergoing a 2nd unsuccessful VT ablation, EA maps of the LV (and LA/RV when possible) and more focal maps of VT target sites were acquired (CARTO®3, Biosense-Webster, CA, USA) and exported. In-house software was used to register these to a planning image set and convert them to DICOM structure files (Fig 1). Dice similarity coefficients were calculated between ventricular mesh data and corresponding reference contours. Initial targets (GTV) were expanded to include internal target volumes (ITV) and planning target volumes (PTV) to account for respiratory and cardiac motion and residual uncertainties, with minor manual adjustments guided by consensus among electrophysiologists, radiation oncologists and medical physicists. STAR was delivered as a single fraction of 25 Gy using volumetric-modulated arc therapy or dynamic conformal arc therapy depending on the target shape. 7 patients with refractory VT were treated by defining targets based on registering individualized EAM maps on the planning images. Dice similarity indices between transferred reference map and reference contours were 0.83 ± 0.04 and 0.72 ± 0.04 for LV and LA/RV, respectively (table 1). The median clinical target was 22cc, with PTVs ranging from 62.4 to 199.6 cc. All patients demonstrated a significant reduction in VT events by 6 weeks post STAR. We have developed an effective methodology for direct registration of VT targets selected for STAR, based on direct anatomic registration of individualized EA maps acquired during ablation procedures. This process offers a way to efficiently delineate variable target boundaries in a semi-automated way, which is advantageous when unusual contours make standard segmentation inaccurate and visual estimation difficult. However, rigorous comparison with other approaches remains to be done.Tabled 1Patient-specific metrics1234567Dice, LV0.8680.8450.7910.8060.7210.8720.794Dice, LA/RV0.7520.6670.734N/A0.382N/A0.338GTV (cc)22.313.526.520.759.863.927.2ITV (cc)45.529.142.230.959.8127.829.6PTV (cc)98.662.488.275.5166.8199.672.8 Open table in a new tab

PO-04-122 IMPACT OF CARDIAC MAGNETIC RESONANCE CHANNELS TO LOCALIZE DECELERATION ZONES DURING VT ABLATION

Cardiac magnetic resonance has demonstrated to accurately identify voltage conduction channels and it is nowadays an important tool to analyze the arrhythmic substrate, to predict ventricular tachycardia (VT) events and to aid VT ablation. The characteristics of CMR channels (CMR-CCs) that predicts the presence of deceleration zone (DZ) have not been explored. To analyze the correlation between CMR-CCs and deceleration zones in isochronal late activation maps. Forty-four consecutive patients with scar-related VT undergoing ablation after CMR (October 2018-July 2021) were included (medium age 64.8±11.6 years; 95.5% male; 70.5% ischemic heart disease, mean ejection fraction of 32.3±7.8). Characteristics of CMR-CCs were analyzed and correlation with DZs both in baseline maps and remaps were performed. Patients were prospectively followed for VT recurrence for one year. Overall, 129 automatically detected CMR-CCs were analyzed (2.89±1.83 per patient; length: 52.72±65.44mm (0.18–376.73), CC mass: 1.76±2.46grams (0.01–14.59); protectedness 19.02±24.51% (0.01–143.51)). Overall, 73.6% of CMR-CCs were associated with a DZ: 58.1% CMR-CCs in baseline map and 15.5% with a DZs not observed initially but in remaps. The univariate analysis showed that channels associated with DZs were longer (61.83±73.43 vs. 29.96±32.55, OR 1.01, p0.004), with higher border zone mass (2.02±2.75 vs. 1.09±1.44, OR 1.28, p0.031) and more protectedness (21.90±27.23 vs. 11.46±14.20, OR1.02, p0.036). VT recurrence after one-year follow up was 21.95%. Pre ablation CMR can accurately identify channels that correlates with DZs that could be targets for ablation, especially those CMR-CCs with higher length, border zone mass and protectedness. Additionally, some channels not related with DZ in the first map have a clear DZ after abolishing the first region of slow conduction, suggesting a very useful role of CMR to detect potential DZs.Tabled 1Univariate analysis of channels characteristics and the primary endpoint (slow conduction properties) (PO-04-122)Total (n=129)Slow conduction (n=95)Non-slow conduction (n=34)ORpLength per channel (mm)52.72±65.44 (0.18–376.73)61.83±73.4329.96±32.551.01 (1-1.03)0.004Mass per channel (grams)1.76±2.46 (0.01–14.59)2.02±2.751.09±1.441.28 (0.97-1.7)0.031Width per channel (mm)4.94±1.91 (0.01–9.34)4.97±1.894.67±2.041.08 (0.88-1.31)0.465Protectedness per channel (mm)19.02±24.51 (0.01–143.51)21.90±27.2311.46±14.201.02 (1-1.05)0.036Layers:- Endocardium- Mesocardium- Epicardium- Endo/Meso- Meso/Epi- Transmural.48 (37.2%)7 (5.4%)26 (20.2%)21 (16.3%)8 (6.2%)19 (14.7%).3052215717.1824612.0.41 (0.18-0.91)0.89 (0.16-4.81)2.26 (0.72-7.12)0.88 (0.31-2.48)2.63 (0.31-22.16)3.49 (0.76-15.97).0.030.890.160.360.360.09Number of layers per channel3.05±2.32 (1–9)3.32±2.462.50±1.801.16 (0.96-1.4)0.104Number of AHA segments per channel2.28±1.20 (1–8)2.47±1.361.85±1.031.56 (1.01-2.4)0.028 Open table in a new tab

PO-05-078 SHOCK REDUCTION THROUGH EARLY DELIVERY OF ANTITACHYCARDIA PACING FOR FAST VENTRICULAR TACHYCARDIAS

Antitachycardia pacing (ATP) is a programmable therapy in implantable cardiac defibrillator (ICD) devices that has been demonstrated to effectively reduce the need for shocks. Limited data, however, exists on the potential benefits of early ATP delivery in the ventricular fibrillation (VF) zone. While ATP is programmed to be delivered as a first line of therapy for ventricular tachycardia (VT) events, it does so only once the episode meets detection criteria by the ICD. Newer generations of BIOTRONIK ICDs have the ability for earlier delivery of ATP, called Early ATP OneShot, to be programmed in the VF therapy zone. Early ATP is delivered when 12 out of 16 events, plus stability criteria, are met to target fast VTs detected in the programmed VF therapy zone. This option is available for patients with longer detection times (VF detection counters of 16 out of 20 or higher) and allows the device to deliver ATP before episode detection counter criteria is met, thus providing therapy earlier than traditional ATP. To compare the success rates of Early ATP OneShot (eATP) for episodes in the VF zone against traditional ATP OneShot (tATP) programming. Using BIOTRONIK’s real-world research database, CERTITUDE, 696 patients with eATP capable ICD devices with VF episodes transmitted via remote monitoring were divided into groups based on tATP (n=584) or eATP (n=112) programming for the VF therapy zone. Each device detected episode was evaluated to determine the therapy (ATP and/or shocks) delivered, whether therapy was successful, or if the episode self-terminated. Patients with detection zone counters lower than 16 out of 20 were excluded. eATP was successful in 69.4% of cases in terminating episodes in the VF zone whereas tATP was successful in 49.1% of cases (p<0.0001). Extrapolation of the eATP success rate to the tATP cohort results in 30.0% less shocks (203 avoided shocks out of 676 total shocks). Cohorts did not differ statistically in mean R-R interval at episode detection, nor in device programming for detection limit zone or counters. Episode duration was shorter in the eATP cohort (p<0.0001). As compared to traditional programming, use of Early ATP OneShot provides increased success rates to terminate fast VTs detected in the VF zone, potentially reducing unnecessary shocks.Tabled 1Table: Comparison of ATP Therapy Groups for Device Detected VF Episodes (PO-05-078)OutcomeEarly ATP OneShotTraditional ATP OneShotp value (difference)Patients with VF Event112584-ATP Therapy Success Rate (Successes/Attempts)69.4% (161/232)49.1% (491/1001)<0.0001Median VF Episode Duration (sec)1217<0.0001Mean R-R interval at VF Episode Detection (ms)2572530.17Mean Programmed Rate of VF Detection Limit (ms)2882910.20Median Programmed Detection Counters for Programmed VF Zone (X/Y criteria)18/2418/240.94 Open table in a new tab

PO-05-058 PROGNOSTIC EVALUATION OF PATIENTS WITH ICD IN A LATIN AMERICAN TERTIARY CENTER.

Despite advances in ICD, SCD remains a public health problem. Chagas disease, still prevalent in Brazil, is associated with higher VT and VF events and SCD when compared to other cardiopathies. Data are conflicting in correlating mortality reduction in chagasic patients and the ICD implantation. We aimed to evaluate the ICD receivers mortality after structuring arrhythmia service in a Latin American tertiary center. Evaluate if the mortality and VT/VF events decrease when patients who received ICD at different periods of time (2007-2010, 2011-2014, 2015-2018) are compared in a tertiary center; compare the prognosis of chagasic to non-chagasic patients in different periods. Retrospective observational study of patients with ICD implanted in the Hospital das Clínicas da Universidade Federal de Minas Gerais (HC-UFMG) between October 2007 and December 2018. The primary outcome was mortality, evaluated in the total sample and in each period. The secondary outcomes were the VT/VF events and the combined outcome of death and/or VT/VF, evaluated in the total sample and in each period. A total of 885 patients were included, 31% chagasic. Out of these, 254 (28%) died, 127 (14%) had VT/VF and 329 (37%) died and/or had VT/VF. The Kaplan-Meier curves showed that period 3 vs. 1 was the only variable associated with better death-free survival, p=0.007. For the VT/VF and the combined outcome free survival curves, Chagas disease was the only variable associated with higher rate of events; p<0.001 and p=0.009, respectively. In the cox's analysis adjusted for age, sex and Chagas, period 2 vs. 1 was protective for death (HR 0.715, 95%CI 0.539-0.948) and combined outcome (HR 0.713, 95%CI 0.537-0.945); period 3 vs. 1 was protective for death (HR 0.516, 95%CI 0.351-0.759) and combined outcome (HR 0.530, 95%CI 0.361-0.780). After adjusting for age and gender, Chagas was associated with VT/VF in periods 1 (HR 2.531, 95%CI 1.469-4.360) and 2 (HR 3.247, 95%CI 1.735-6.076). There was a gradual reduction in mortality and combined outcome for ICD receivers at periods 2011-2014 and 2015-2018 compared to the initial period 2007-2010. Chagas was associated with a higher VT/VF events in ICD receivers only in the first two periods. The improvement of results was concomitant with the incorporation of new modalities and technologies to treat patients with ICD. The better organization of care may be associated with reduction of overall mortality and arrhythmic events in this population.