Antitachycardia Pacing Therapy Research Articles

High-intensity interval training in patients with an implantable cardioverter defibrillator: a randomized controlled study

Abstract Background Exercise is an effective treatment in a broad spectrum of cardiovascular diseases. High-intensity interval training (HIIT) has shown superior effect on cardiorespiratory fitness and equal or superior effect on morbidity and quality of life (QoL) compared to moderate continuous exercise training. However, evidence of the efficacy and risks of HIIT in patients with increased risk of ventricular arrhythmia remains limited. Purpose To evaluate the effects of HIIT on exercise capacity, QoL and burden of ventricular arrhythmias in patients with an implantable cardioverter defibrillator (ICD) with or without cardiac resynchronization therapy. Methods Patients with ischemic or dilated cardiomyopathy and ICD were randomized to a supervised 12-week HIIT program or to a control group continuing their usual exercise routines. HIIT consisted of four 4-minute intervals aiming at 85-95% of maximum heart rate (HRmax), and 3-minute active recovery aiming at 60-70 % of HRmax in between intervals, 3 times a week for 12 weeks. Primary outcomes were exercise capacity measured as peak oxygen uptake (VO2 peak) and QoL assessed with the Short Form 36 (SF-36) questionnaire. Main secondary outcome was the burden of ventricular arrhythmias analysed from remote patient monitoring data. Results Fifty-six patients were included (table 1). Three patients in the HIIT group did not complete the intervention. Two withdrew due to a knee injury and due to fear of SARS-CoV-2 exposure, respectively. One experienced an appropriate shock during exercise and was excluded from further training after clinical consideration. Fifty-three patients completed all follow-up examinations. HIIT significantly increased VO2 peak with 7.0 %, with no changes in the control group (p=0.001) (figure 1A). There was a significant increase in the SF-36 subscale scores on physical functioning (p<0.05), general health (p<0.05) and health change (p=0.001) in the HIIT group compared to the control group (figure 1B). There were no significant differences between groups in number of non-sustained or sustained ventricular tachycardias, anti-tachycardia pacing therapy or ICD shocks. Conclusions In patients with ICD due to ischemic or dilated cardiomyopathy, a supervised 12-week HIIT-program significantly increased VO2 peak and QoL without increasing the burden of ventricular arrhythmias.Table 1:Patient characteristicsFigure 1:Peak oxygen uptake and QoL

Assessing the benefit of a replacement implantable cardioverter-defibrillator device for primary prevention of sudden cardiac death

Abstract Background Implantable cardioverter-defibrillators (ICDs) have been shown to reduce the burden of sudden cardiac death in at-risk populations. However, data reflecting contemporary device programming and medication would be valuable, particularly when evaluating patients for a replacement ICD when they did not receive therapy from their original device. Purpose This real-world analysis examined the incidence of ICD therapy after routine generator replacement due to battery depletion in patients who didn’t receive therapy from their first ICD. Methods Data were obtained from a query of a deidentified database from 2007 to present. The final analysis included patients that underwent a generator replacement after 2012 due to battery depletion and who had received no therapy from their first ICD. Patients were divided into two groups based on their ICD indication status (primary prevention [PP] or secondary prevention [SP]). The main endpoint was time to first appropriate shock therapy, antitachycardia pacing (ATP) therapy, or any therapy (ATP or shock) after ICD replacement. Time to first therapy was plotted using the Kaplan-Meier method. Appropriateness of therapy was modeled via LASSO regression using characteristics present in both our dataset and the adjudicated PainFree SST trial. The model was fit on episodes from 80% of PainFree SST patients and validated on the remaining 20% before applying it to our dataset. Results A total of 8,383 patients were identified who met the criteria outlined above. Of these patients, 7,299 (66.3 ± 12.6 years old; 30.3% female) had a PP indication for an ICD and 1,084 (64.2 ± 14.0 years old; 30.3% female) had an SP indication. The mean longevity of initial ICD implants before replacement was similar in PP and SP patients (91.4 ± 16.2 vs 90.9 ± 16.3 months). At 7 years post-replacement, the incidence of first shock, ATP, or any therapy received by PP patients who did not receive first-device therapy was 16%, 23% and 27% respectively. After applying the model to estimate appropriateness of therapy, the appropriate therapy rates were 14%, 22%, and 26%, respectively (Figure 1). Similarly, SP patients who received no first-device therapy had an incidence of modeled first appropriate shock, ATP, and any therapy 7 years after ICD replacement of 12%, 20%, and 25%, respectively. The modeled 7-year inappropriate shock rate post-replacement was 4% in all patients. Conclusion In this large, long-term, real-world evaluation of ICD PP patients who hadn’t experienced a treated event with their initial device, 1 in 4 eventually received appropriate therapy from their second device. The results suggest that the underlying risk persists in these patients and device replacement may be necessary to protect them from experiencing a deadly event.

Two-year outcomes of primary prophylactic use of defibrillators with ischemic and non-ischemic cardiomyopathy: propensity score-matched analysis from NIPPON STORM Study

Abstract Background In 2016, the DANISH study showed negative results regarding the efficacy of implantable cardioverter defibrillators (ICDs) for patients with non-ischemic cardiomyopathy (NICM) and reduced left ventricular ejection fraction (LVEF). Thus, the ESC guidelines downgraded the indication for primary ICD prophylaxis for NICM patients with reduced LVEF from Class I to IIa. However, the change might be felt somewhat improper in the real wolrd ICD therapy and decided to use the Nippon storm study, a prospective registry study in Japan, to determine whether the DANISH results are of equal value in the clinical setting. Objective To determine the efficacy of ICDs as primary prevention in patients with NICM, the incidence of ICD appropriate therapy in patients with NICM was compared with that in patients with ischemic cardiomyopathy (ICM) for which primary ICD efficacy is generally recognized as a Class I indication. Methods We selected 1274 patients with underlying cardiac disease from a total of 1548 patients enrolled in the Nippon storm study. We analyzed data of 451 patients with LVEF ≤35% owing to NICM or ICM who underwent ICD implantation of primary prophylaxis (men, 78%; age, 65±12 years; LVEF, 25±1.4%; cardiac resynchronization therapy, 20%; ICM, 33%). All patients were followed up for at least 2 years. Patient selection was performed by employing the propensity score matching method with a digit-matching algorithm for clinical factors, ie, age, sex, cardiac resynchronization therapy with a defibrillator, LVEF. After all propensity score matches had been performed, we compared baseline covariates between the 2 groups: 132 patients with NICM and 132 with ICM. The cumulative incidences of ICD therapies (including both anti-tachycardia pacing and shock therapies) were calculated using competing risk analysis, because death is a competing risk for loss to follow-up. Results In the matched cohort, the 2-year appropriate ICD therapy risks were 27.7% and 12.2% in NICM and ICM groups, respectively (HR = 0.390 [95% CI, 0.218–0.701; P = 0.002) (Figure A). Two-year appropriate ATP therapy risks were 25.5% and 11.4% in NICM and ICM groups, respectively (HR = 0.417 [95% CI, 0.226– 0.776; P = .005]) (Figure B), and appropriate shock therapy risks were 6.3% and 1.6% in NICM and ICM groups, respectively (HR = 0.230 [95% CI, 0.049–1.085; P = .063]) (Figure C). Conclusion The present subanalysis of the Nippon Storm Study revealed that the risk for appropriate ICD therapy was significantly higher in the patients with NICM than in those with ICM based on our propensity score–matching method.

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< 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.

Clinical course of hypertrophic cardiomyopathy patients implanted with a transvenous or subcutaneous defibrillator.

The implantable cardioverter-defibrillator (ICD) is a life-saving therapy in patients with hypertrophic cardiomyopathy (HCM) at risk of sudden cardiac death. Implantable cardioverter-defibrillator complications are of concern. The subcutaneous ICD (S-ICD) does not use transvenous leads and is expected to reduce complications. However, it does not provide bradycardia and anti-tachycardia pacing (ATP). The aim of this study was to compare appropriate and inappropriate ICD interventions, complications, disease-related adverse events and mortality between HCM patients implanted with a S- or transvenous (TV)-ICD. Consecutive HCM patients implanted with a S- (n = 216) or TV-ICD (n = 211) were enrolled. Propensity-adjusted cumulative Kaplan-Meier curves and multivariate Cox proportional hazard ratios were used to compare 5-year event-free survival and the risk of events. The S-ICD patients had lower 5-year risk of appropriate (HR: 0.32; 95%CI: 0.15-0.65; P = 0.002) and inappropriate (HR: 0.44; 95%CI: 0.20-0.95; P = 0.038) ICD interventions, driven by a high incidence of ATP therapy in the TV-ICD group. The S- and TV-ICD patients experienced similar 5-year rate of device-related complications, albeit the risk of major lead-related complications was lower in S-ICD patients (HR: 0.17; 95%CI: 0.038-0.79; P = 0.023). The TV- and S-ICD patients displayed similar risk of disease-related complications (HR: 0.64; 95%CI: 0.27-1.52; P = 0.309) and mortality (HR: 0.74; 95%CI: 0.29-1.87; P = 0.521). Hypertrophic cardiomyopathy patients implanted with a S-ICD had lower 5-year risk of appropriate and inappropriate ICD therapies as well as of major lead-related complications as compared to those implanted with a TV-ICD. Long-term comparative follow-up studies will clarify whether the lower incidence of major lead-related complications will translate into a morbidity or survival benefit.

A Pitfall of Non-Sustained Ventricular Tachycardia Alert in Remote Monitoring System : Misdiagnosis of Sustained VT as Non-Sustained VT and Failure of Anti-Tachycardia Pacing Therapy in Three Patients

A Pitfall of Non-Sustained Ventricular Tachycardia Alert in Remote Monitoring System : Misdiagnosis of Sustained VT as Non-Sustained VT and Failure of Anti-Tachycardia Pacing Therapy in Three Patients

Interference of cardiac implantable electronic devices and computed tomography imaging in the current era with a phantom model.

Cardiac implantable electronic devices are used in patients with cardiac rhythm disorders. Computed tomography irradiation is not prohibited for patients with cardiac implantable electronic devices, despite adverse events being reported. Hence, appropriate preparation and knowledge are required before computed tomography irradiation can be carried out in these patients. Since there is limited knowledge or literature about the influence of computed tomography irradiation in cases with recent cardiac implantable electronic devices, we aimed to evaluate the adverse events and elucidate the necessary and sufficient safety measures associated with this therapy. We placed cardiac implantable electronic devices on an anthropomorphic phantom model and observed their electrical activity in electrograms, while various protocols of computed tomography irradiation were implemented and adverse events evaluated. Oversensing with pauses of up to 3.2 s was observed in standard computed tomography protocols, but ventricular tachyarrhythmia or other clinically significant events could not be confirmed. Oversensing with pauses of up to 8.0 s was observed and ventricular tachyarrhythmia was detected in the maximum-dose protocols. However, treatments such as antitachycardia pacing or shock therapy for ventricular tachyarrhythmia were not observed because of their absence. Computed tomography irradiation for patients using cardiac implantable electronic devices is highly unlikely to cause clinically significant adverse events with the device settings and computed tomography protocols currently being used. Changing or monitoring the device settings routinely before computed tomography irradiation is not necessarily required for most patients.

Long term results of catheter ablation in patients presented with ventricular storm

Abstract Funding Acknowledgements Type of funding sources: None. Background and Objective Catheter ablation is a treatment option in patients with ventricular tachycardia (VT storm, especially when refractory to medical treatment. In this trial, we aimed to evaluate the long-term results of catheter ablation in patients with VT storm. Method Between January 2015 and January 2022T, we enrolled a total of 65 VT storm patients who underwent catheter ablation. All patients who have either documented episodes of VT or appropriate ICD shocks more than 3in the last 24 hours. Medical treatment with antiarrhythmic drugs was given to all patients before catheter ablation. After the procedure, all-cause mortality, hospitalization due to stroke/myocardial infarction/heart failure, ICD shocks, and anti-tachycardia pacing therapies were recorded during follow-up. Results Among the whole study population (the median age is 65 years (17-85); 56 (86.2%) males) 37 (56.9%) had ischemic CMP, 24 (36.9%) had non-ischemic CMP whose 8 were ARVD, and 3 (4.6%) HCMP. The median left ventricle ejection fraction was 30% (12 – 65%). Activation mapping was performed in 60 patients, and the critical isthmus was ablated in 60 patients whose 22 had more than one critical ablation site. In 3 patients, only substrate mapping was performed, and substrate homogenization was done. In 2 patients, premature ventricular ectopy, which inducted VT, ablation was performed. Epicardial mapping was performed in 23 patients (35.4%). The median follow-up duration was 23 months (1-94 months). During follow-up, 23 patients died, 43 were hospitalized, and four presented again with VS storm. In 13 patients, appropriate shock/pacing therapy was observed. After the index procedure, re-do catheter ablation of ventricular tachycardia was performed in 8 patients. The mean postprocedural VT-free survival time was estimated at 76.5 months (SE:5.0, 95% CI: 66.6-86.4). Conclusion Catheter ablation therapy is an effective option for both acute and long-term management of patients with VT storms. However, postprocedural mortality and morbidity remain high in long-term follow-up duration. Long-term results may be related to the comorbidities and nature of underlying cardiac disorders.

Appropriate and inappropriate therapies in remotely monitored patients with cardiac implantable devices long-term experiences of a tertiary centre

Abstract Funding Acknowledgements Type of funding sources: None. Background The evidence supporting the implantation of implantable cardioverter-defibrillator (ICD) in the primary prevention of sudden cardiac death (SCD) comes mostly from the times when optimal management of heart failure was not as effective as at present. Moreover, the detailed data on the long-term risk of arrhythmias in patients with ICD are scarce. Purpose To present the long-term results of the remote monitoring (RM) of patients with ICD from a large, tertiary cardiovascular centre registry. Methods The clinical data from the time of device implantation were derived from the COMMIT-HF registry, while the follow-up data were obtained from the investigator-initiated RM registry. In brief, the registry encompasses data regarding the types of the transmissions and their contents, with particular emphasis on the occurrence of arrhythmic episodes, device interventions, as well as the data on the causes of other alert transmissions. Results In total, 1,299 patients were included in the analysis. The median follow-up duration of RM was 4.4 years, and the primary indication for implantation was ischemic cardiomyopathy (60.3%). Appropriate antitachycardia pacing (ATP) and high-voltage therapy for ventricular arrhythmias occurred in respectively 25.3% and 26.1% of patients, while inappropriate ATP and HV in respectively 11.5% and 8.7%. The prevalence of AF was 40.8%. Conclusions In a large real-life cohort of continuously remotely monitored patients with ICDs, the percentage of patients with appropriate therapies for ventricular arrhythmias exceeded 25%. Further analyses are necessary to stratify the risk of ventricular arrhythmias in the contemporary practice.

PO-05-080 EFFICACY OF ANTI-TACHYCARDIA PACING IN LVAD PATIENTS WITH AHA SCIENTIFIC STATEMENT-DIRECTED TACHYTHERAPY ICD PROGRAMMING

Ventricular Arrhythmias (VA) and ICD shocks are a common complication in patients with advanced heart failure (AHF) both before and after left ventricular assist device (LVAD) placement. Conservative ICD programming and anti-tachycardia pacing (ATP) may reduce the need for ICD shocks after LVAD. However, the efficacy of ATP and safety of conservative ICD programming remains unclear in this population. We sought to assess the efficacy of ATP and conservative ICD programming in patients undergoing LVAD placement. Consecutive patients who underwent LVAD placement (2015-2019) were included. The majority of patients had AHA Scientific Statement concordant conservative ICD programming with prolonged detection time, high VF zones cutoffs (>240bpm) and aggressive ATP use (>10 episodes before shock). A total of 237 patients who underwent LVAD implant were reviewed. Of these, 198 were discharged after LVAD with an ATP-capable device (age 60.4 ± 14.2, 146 males, 68 ischemic cardiomyopathy, 99 with prior VA). 32 patients were excluded for no ICD and 7 for subcutaneous ICD. 55 had single-chamber ICD (28%), 42 had dual-chamber ICD (22%), and 98 had CRT-D (50%). A total of 78 (39%) patients experienced at least one episode of ATP and 69 (35%) patients received at least one shock. Overall, there were 1131 distinct VT sustained episodes leading to 198 distinctive shock episodes. ATP was successful in terminating VT in 834 episodes (93%) for VT<200bpm, while the remaining 60 (7%) required shock to terminate. ATP was equally effective in patients with and without VT prior to LVAD (84% vs 78% respectively). ATP was less successful but remained effective in conservative VF zones (bpm>200 and <240, 57% success). In patients with fast VT in VF zone (>240bpm), ATP during charge was successful in terminating VT in 20% of cases. Aggressive ATP use (defined at >4 ATP episodes before shock) was also effective with a 54% success rate. ATP episodes causing degeneration and acceleration of VA’s requiring at least one shock occurred in 41 shock episodes (21%). ATP therapy in patients with LVAD can be effective to terminate VT, reducing ICD shocks in patients after LVAD placement. ATP use was more successful in traditional VT zones, but our data supports the use of conservative ICD programming (aggressive ATP use >10 episodes pre-shock and VF zone > 240bpm).

PO-04-231 THERAPIES DELIVERED BEFORE AND AFTER NONINVASIVE CARDIAC RADIOABLATION: A SECONDARY ANALYSIS OF THE ENCORE-VT TRIAL

Noninvasive Cardiac RadioAblation (CRA) is a new therapy for refractory ventricular tachycardia (VT) that delivers focused radiation to VT-related myocardial scar. Because CRA reduced VT events, we hypothesize therapies will be reduced. To compare type and number of therapies delivered before and after cardiac radioablation in patients with scar-based VT. This was a retrospective analysis of ICD interrogations from the ENCORE-VT trial (NCT02919618), where patients with high-burden of VT were treated with 25 Gray/1 fraction to myocardial scar nearest the VT exit site. For each patient, all device-identified VT episodes which required therapy were reviewed for the 6-month period prior to CRA and 6-month period after (excluding 6-week blanking period). Episodes of non-sustained VT, non-treated VT, or VF were excluded. Type and number of therapies derived from device review were used for primary comparison. Of the 19 patients enrolled into the trial, 16 were included for analysis (excluded 2 patients treated for PVCs, 1 patient death in first 6 months). Cohort analysis (Top Figure) using Student’s t-test showed statistically significant reduction in VT episodes (P 0.0006) and antitachycardia pacing (ATP) therapies (P 0.0004) post therapy and a greater than 78% reduction in shocks. Compared to pre-treatment (Bottom Figure), by percentage, ATP terminated VT more often post-treatment with two or fewer sequences. Three of more ATP sequences were seen, by percentage, more often pre-treatment as compared to post-treatment. Compared to before cardiac radioablation, episodes of VT and number of therapies for VT were significantly reduced. In addition, when VT did recur post-treatment, it was more susceptible to termination by two or fewer ATP sequences.

PO-05-083 ICD THERAPY CHARACTERISTICS IN PATIENTS WITH ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY, BRUGADA SYNDROME, AND LONG QT SYNDROME

Arrhythmogenic right ventricular cardiomyopathy (ARVC), Brugada syndrome (BrS) and Long QT syndrome (LQTS) are inherited arrhythmia disorders that frequently result in sudden death in young populations. ARVC often presents with monomorphic VT amenable to antitachycardia pacing (ATP) therapy, whereas BrS and LQTS are traditionally characterized by polymorphic VT or torsade de pointes requiring shock therapy. To assess the rates of ATP and shock therapies in a cohort of patients with ARVC, BrS and LQTS. Patients with ICD indications for ARVC, BrS and LQTS from the ALTITUDE database (Boston Scientific, Natick, MA) between 2011-2021 were identified. ATP and shock-free survival rates were calculated by Kaplan-Meier (KM) method and hazard ratios were analyzed by the Cox proportional hazards model. A total of 103 ARVC, 218 BrS, and 509 LQTS patients were identified. Mean age (46.6 ± 17.4) did not differ between groups while LQT had more female (69.2%) compared to ARVC (34%) and BrS (30.7%). Mean follow-up was 3.7 years. A total of 47 (45.6%) ARVC patients, 39 (17.9%) BrS, and 136 (26.7%) LQTS patients received any therapies during the follow-up period. Episodes in ARVC patients were significantly less likely to result in a shock (71/402, 18%) compared to BrS (73/157, 47%) and LQTS (333/581, 57%) (p<0.001). Per 100 patient-years (Figure 1a), ARVC patients had arrhythmia episodes requiring only ATP therapy 4.7 times the frequency of episodes requiring shock therapy (89.0 versus 19.1), whereas BrS and LQTS patients had comparable rates of ATP only vs shocks (10.2 versus 8.8 in BrS and 13.5 vs 18.2 in LQTS). From KM curve analysis, three-year rate of an ATP-only event was 43.0% in ARVC, 10.3% in BrS and 18.0% in LQTS. As compared with ARVC, risk of ATP only events in BrS (HR 0.20, 95% CI 0.12-0.33, p<0.001) and LQTS (HR 0.44, 95% CI 0.30-0.65, p<.0.001) were significantly lower. Three-year rate of events requiring shock therapy was 33.4% in ARVC, 14.5% in BrS and 20.0% in LQTS. As compared with ARVC, risk of a shock in BrS (HR 0.33, 95% CI 0.20-0.54, p<0.001) and LQTS (HR 0.62, 95% CI 0.41-0.93, p=0.020) were also significantly lower. ARVC patients had more ventricular arrhythmia episodes. When therapy was triggered, episodes in ARVC were less likely to be treated with a shock compared to BrS and LQTS. This may help guide programming parameters and device type selection in high-risk individuals with inherited arrhythmia syndromes.

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

Clinical, electrocardiographic, and echocardiographic parameters associated with the development of pacing and implantable cardioverter-defibrillator indication in patients with transthyretin amyloid cardiomyopathy.

This study aimed to identify factors for attention leading to future pacing device implantation (PDI) and reveal the necessity of prophylactic PDI or implantable cardioverter-defibrillator (ICD) implantation in transthyretin amyloid cardiomyopathy (ATTR-CM) patients. This retrospective single-center observational study included consecutive 114 wild-type ATTR-CM (ATTRwt-CM) and 50 hereditary ATTR-CM (ATTRv-CM) patients, neither implanted with a pacing device nor fulfilling indications for PDI at diagnosis. As a study outcome, patient backgrounds were compared with and without future PDI, and the incidence of PDI in each conduction disturbance was examined. Furthermore, appropriate ICD therapies were investigated in all 19 patients with ICD implantation. PR-interval ≥220 msec, interventricular septum (IVS) thickness ≥16.9 mm, and bifascicular block were significantly associated with future PDI in ATTRwt-CM patients, and brain natriuretic peptide ≥35.7 pg/mL, IVS thickness ≥11.3 mm, and bifascicular block in ATTRv-CM patients. The incidence of subsequent PDI in patients with bifascicular block at diagnosis was significantly higher than that of normal atrioventricular (AV) conduction in both ATTRwt-CM [hazard ratio (HR): 13.70, P = 0.019] and ATTRv-CM (HR: 12.94, P = 0.002), whereas that of patients with first-degree AV block was neither (ATTRwt-CM: HR: 2.14, P = 0.511, ATTRv-CM: HR: 1.57, P = 0.701). Regarding ICD, only 2 of 16 ATTRwt-CM and 1 of 3 ATTRv-CM patients received appropriate anti-tachycardia pacing or shock therapy, under the number of intervals to detect for ventricular tachycardia of 16-32. According to our retrospective single-center observational study, prophylactic PDI did not require first-degree AV block in both ATTRwt-CM and ATTRv-CM patients, and prophylactic ICD implantation was also controversial in both ATTR-CM. Larger prospective, multi-center studies are necessary to confirm these results.

Third-generation subcutaneous implantable cardioverter defibrillator and intermuscular two-incision implantation technique in patients with Arrhythmogenic cardiomyopathy: 3-year follow-up

BackgroundLong-term data on the potential advantages of combining the third-generation subcutaneous implantable cardioverter defibrillator (S-ICD) with modern software upgrade including the “SMART Pass”, modern programming strategies and the intermuscular (IM) two-incision implantation technique in arrhythmogenic cardiomyopathy (ACM) with different phenotypic variants are lacking. In this study we evaluated the long-term outcome of patients with ACM who underwent third-generation S-ICD (Emblem, Boston Scientific) and IM two-incision technique. MethodsThe study population included 23 consecutive patients [70% male, median age 31 (24–46) years] diagnosed with ACM with different phenotypic variants who received third-generation S-ICD implantation with the IM two-incision technique. ResultsDuring a median follow-up of 45.5 months [16–65], 4 patients (17.4%) received a at least one inappropriate shock (IS), with median annual event rate of 4.5%. Extra-cardiac oversensing (myopotential) during effort represented the only cause of IS. No IS due to T-wave oversensing (TWOS) were recorded. Only one patient (4.3%) experienced device-related complication consisting of premature cell battery depletion requiring device replacement. No device explantation because of need for anti-tachycardia pacing or ineffective therapy occurred. There was no significant difference between patients who did and did not experienced IS with regard to baseline clinical, ECG and technical characteristics. Five patients (21.7%) received appropriate shocks on ventricular arrythmias. ConclusionsAccording to our findings, although the third-generation S-ICD implanted with the IM two-incision technique appears to be associated with a low risk of complications and IS due to cardiac oversensing, the risk of IS due to myopotential mainly during effort should be considered.

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.

Antitachycardic Therapy of ICD in Patients with Multiple Morphologies of Monomorphous Ventricular Tachycardia Refractory to Therapy

The article presents a description of a clinical case of a patient with structural myocardial pathology (postinfarction cardiosclerosis) with recurrent paroxysmal sustained monomorphic ventricular tachycardia (VT) refractory to the nominal recommended ICD (implantable cardioverter defibrillator) settings; as well as discusses the shortcomings of existing standard algorithms for antitachycardia pacing (ATP) of implantable cardioverter defibrillators and potential ways to increase its efficiency. The refractoriness of recurrent paroxysms of ventricular tachycardia to ATP therapy increases the risk of repeated ICD shocks.&#x0D; Despite the existence of universal recommendations for ICD programming and ATP therapy, there is a need in clinical practice for individualized ATP programming in patients refractory to nominal settings. Increasing the number of ATP series and changing algorithms enables to increase the efficiency of ATP up to 8089%. Refractoriness to standard ATP settings may be also overcome by using alternative ATP pacing algorithms (Ramp, Burst-plus, or Ramp-plus instead of Burst), changing the pacing interval, ATP sequence duration, pacing type, and even adding 12 extra stimuli, as well as using data from the previous intracardiac electrophysiological heart test.&#x0D; The presented clinical case of a patient with postinfarction cardiosclerosis and paroxysmal stable monomorphic VT (SM-VT) of several morphologies demonstrates that the arrhythmogenic substrate after myocardial infarction changes for a long time without new stenoses in large coronary arteries and without new episodes of acute coronary syndrome, as well as generates several different morphologies of VT from one scar (with different heart rates) and the effect on hemodynamics. The efficiency of early ATP pacing may differ for VT of various morphologies, which makes it reasonable to use alternative pacing algorithms (in addition to the standard Burst sequences recommended by the 2019 Consensus on ICD programming) and testing possible ATP algorithms during ablation of monomorphic VT, including during preventive VT ablation before ICD implantation.

Cardioverter-defibrillator reduces mortality risk in eligible ischemic and non-ischemic cardiomyopathy patients: Sub-analysis of the multi-center Improve SCA study

Background & ObjectiveDespite the burden of sudden cardiac arrest (SCA) worldwide, implantable cardioverter-defibrillators (ICDs) are underutilized, particularly in Asia, Latin America, Eastern Europe, the Middle East, and Africa. The Improve SCA trial demonstrated that primary prevention (PP) patients in these regions benefit from an ICD or a cardiac resynchronization therapy defibrillator (CRT-D). We aimed to compare the rate of device therapy and mortality among ischemic and non-ischemic cardiomyopathy (ICM and NICM) PP patients who met guideline indications for ICD therapy and had an ICD/CRT-D implanted. MethodsImprove SCA was a prospective, non-randomized, non-blinded multicenter trial that enrolled patients from the above-mentioned regions. All-cause mortality and device therapy were examined by cardiomyopathy (ICM vs NICM) and implantation status. Cox proportional hazards methods were used, adjusting for factors affecting mortality risk. ResultsOf 1848 PP NICM patients, 1007 (54.5%) received ICD/CRT-D, while 303 of 581 (52.1%) PP ICM patients received an ICD/CRT-D. The all-cause mortality rate at 3 years for NICM patients with and without an ICD/CRT-D was 13.1% and 18.3%, respectively (HR 0.51, 95% CI 0.38–0.68, p < 0.001). Similarly, all-cause mortality at 3 years in ICM patients was 13.8% in those with a device and 19.9% in those without an ICD/CRT-D (HR 0.54, 95% CI 0.33–.0.88, p = 0.011). The time to first device therapy, time to first shock, and time to first antitachycardia pacing (ATP) therapy were not significantly different between groups (p ≥ 0.263). ConclusionsIn this large data set of patients with a guideline-based PP ICD indication, defibrillator device implantation conferred a significant mortality benefit in both NICM and ICM patients. The rate of appropriate device therapy was also similar in both groups. Clinical trial registrationClinicalTrials.gov ID: NCT02099721.

Abstract 13576: Stereotactic Cardiac Radiotherapy Reduces Structural Heart Disease Associated Refractory Ventricular Tachycardia - A Metaanalysis

Introduction: Cardiac stereotactic body radiotherapy (SBRT) is a paradigm changing treatment for refractory ventricular tachycardia (VT) in patients with structural heart disease. We sought to review the effectiveness of SBRT reported in published studies. Hypothesis: There is a reduction in VT events after cardiac SBRT. Methods: We performed a comprehensive literature search in PubMed, Embase and Google Scholar including all studies on cardiac SBRT for VT till May 2022. Efficacy was evaluated as random-effects pooled rate ratios (RR) of VT episodes, antitachycardia pacing (ATP) therapies and implantable cardioverter-defibrillator (ICD) shocks post-SBRT (after 6-week blanking) vs. during 3-12 months pre-SBRT, with patients serving as their own controls. Results: We included 12 single-arm studies on cardiac SBRT (90 patients) published 2017-2022 with median follow-up ranging 6-28 months. The pooled RR of VT episodes, ATP therapies and ICD shocks post- vs. pre-SBRT were 0.11 (95% CI 0.06-0.21, p&lt;0.001), 0.09 (95% CI 0.04-0.20, p&lt;0.001), and 0.10 (95% CI 0.05-0.19, p&lt;0.001) as shown in Figure 1. There was significant heterogeneity in results (p&lt;0.00001 for all 3 endpoints). The combined 1- and 2-year overall patient survival was 69% and 56% respectively (Figure 2). Conclusions: Cardiac SBRT reduces recurrent VT episodes and ICD shocks in patients with VT refractory to medical therapy and catheter ablation. There is heterogeneity in results from different studies, likely related to differences in patient selection and treatment techniques. The overall patient survival in this high-risk population compares favorably to data from catheter ablation trials.

Clinical Predictors of Successful Anti-tachycardia Pacing for Ventricular Arrhythmia Termination

Background: Anti-tachycardia pacing (ATP) is a fast and safe method for terminating ventricular tachycardia (VT). Implantable cardioverter defibrillator (ICD) shocks are unpleasant, stressful experiences that have been associated with higher mortality rates than ATP. Determining the factors enhancing the efficacy of ATP therapies can minimize the appropriate ICD shocks. Objectives: In this study, we investigated the factors anticipating the success rate of ATP. Methods: This descriptive cross-sectional study was carried out among 60 patients referring to our center for regular ICD device analysis. These patients had at least one episode of appropriate ATP therapy in their analysis. The VT morphologic characteristics were obtained from stored far-field intracardiac electrogram (EGM). The VT episodes and native QRS were classified into non-Q or Q categories based on their EGM morphologies. Results: ATP was successful in 38 (63.3%) cases. Age, sex, history of ischemic heart disease and diabetes, type of device and cardiomyopathy (ischemic or dilated), antiarrhythmic drugs, left ventricular ejection fraction, and EGM characteristics did not predict ATP success. Conclusions: It seems that neither the demographic factors nor the morphologic characteristics of VT EGMs can predict the efficacy of ATP therapy.