Efficacy Of Antitachycardia Pacing Research Articles

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).

Antitachycardia pacing at the His bundle is safer than conventional right ventricular antitachycardia pacing in a canine myocardial ischemic injury model.

Antitachycardia pacing (ATP) is used to terminate ventricular tachycardia (VT) by delivering rapid, low energy pacing to the right ventricle (RV). Unfortunately, ATP is not effective against all VT episodes and can result in adverse outcomes, such as VT acceleration and degeneration into ventricular fibrillation (VF). Improving ATP is therefore desirable. Our objective was to compare the efficacy and safety of ATP delivered at the His bundle to traditional ATP. Six dogs were anesthetized and pacing leads were implanted in the RV and His bundle. The left anterior descending artery was occluded for 2 h to create an ischemic injury. In a study 4-7 days later, a 128-electrode sock was placed snugly around the ventricles and VT was induced using rapid pacing. ATP was delivered from either the His bundle or RV lead, then attempted at the other location if unsuccessful. Success rates and instances of VT acceleration and degeneration into VF were calculated. We induced 83 runs of VT and attempted ATP 128 times. RV ATP was successful in 36% of attempts; His ATP was successful in 38% of attempts. RV ATP resulted in significantly more adverse outcomes. RV and His ATP induced VT acceleration in 9% and 3% of trains, respectively, and induced degeneration into VF in 5% and 1% of trains, respectively. His bundle ATP is safer, but not significantly more effective, than RV ATP.

PO-05-082 ANTITACHYCARDIA PACING IS MORE EFFECTIVE WHEN DELIVERED TO THE LEFT BUNDLE BRANCH COMPARED TO THE RIGHT VENTRICLE IN A CANINE ISCHEMIC VENTRICULAR TACHYCARDIA MODEL

Implantable cardioverter-defibrillators (ICDs) can terminate ventricular tachycardia (VT) with Antitachycardia pacing (ATP) delivered to a right ventricular (RV) pacing lead, thereby avoiding painful and damaging high-energy shocks. However, ATP efficacy is limited for fast VT, and ATP can accelerate VT or convert VT to ventricular fibrillation (VF). Physiological pacing delivered to the left bundle branch (LBB) has emerged as a clinically relevant target to minimize ventricular dyssynchrony and pacing-induced heart failure. ATP efficacy and safety delivered to the LBB are yet to be investigated. Evaluate the therapeutic efficacy and safety of ATP delivered to an LBB lead compared to ATP delivered to a conventional RV lead. In 6 anesthetized dogs, pacing leads from two ICDs (CobaltTM XT DR, Medtronic, Inc) were implanted at the RV apex (6947 Sprint Quattro SecureTM, Medtronic, Inc) and the LBB (3830 SelectSecureTM, Medtronic, Inc). A lateral thoracotomy procedure was performed, and a two-hour lateral anterior descending artery ischemia-reperfusion injury was caused. The thoracotomy was closed and on post-infarct day 4, dogs were anesthetized, and sustained VT episodes were induced by programmed electrical stimulation. ATP (up to 5 trains of 8 pulses at approximately 88% of the VT cycle length) was delivered to either the LBB or RV pacing site in a randomized fashion. The success rate of ATP in terminating the VT episodes and the rate of VT acceleration and degeneration into VF from both pacing locations were evaluated. In our canine ischemic VT model, VT was induced 80 times, with a mean VT cycle length of 178±35 ms. ATP was delivered and tested for each episode. For ATP delivered to the RV, the success rate for terminating VT was 54%. The success rate for terminating VT for ATP delivered to the LBB was 73% (Fig. A, p < 0.05). ATP resulted in VT acceleration for 10% and 5% of ATP attempts delivered to the RV and LV, respectively (Fig. B, p = Not Significant, NS). Degeneration to VF occurred for 5% of all ATP attempts delivered to the RV, and there was no such incident for ATP delivered to the LBB (Fig. B). Higher efficacy and lower incidence of VT acceleration were observed with ATP delivered to LBB compared to ATP delivered to the RV in this canine ischemic VT model. Improved performance of ATP delivered to LBB compared to RV provides additional incentive for expanded use of LBB leads for pacing and therapy delivery.

Optimization of anti-tachycardia pacing efficacy through scar-specific delivery and minimization of re-initiation: a virtual study on a cohort of infarcted porcine hearts.

Anti-tachycardia pacing (ATP) is a reliable electrotherapy to painlessly terminate ventricular tachycardia (VT). However, ATP is often ineffective, particularly for fast VTs. The efficacy may be enhanced by optimized delivery closer to the re-entrant circuit driving the VT. This study aims to compare ATP efficacy for different delivery locations with respect to the re-entrant circuit, and further optimize ATP by minimizing failure through re-initiation. Seventy-three sustained VTs were induced in a cohort of seven infarcted porcine ventricular computational models, largely dominated by a single re-entrant pathway. The efficacy of burst ATP delivered from three locations proximal to the re-entrant circuit (septum) and three distal locations (lateral/posterior left ventricle) was compared. Re-initiation episodes were used to develop an algorithm utilizing correlations between successive sensed electrogram morphologies to automatically truncate ATP pulse delivery. Anti-tachycardia pacing was more efficacious at terminating slow compared with fast VTs (65 vs. 46%, P = 0.000039). A separate analysis of slow VTs showed that the efficacy was significantly higher when delivered from distal compared with proximal locations (distal 72%, proximal 59%), being reversed for fast VTs (distal 41%, proximal 51%). Application of our early termination detection algorithm (ETDA) accurately detected VT termination in 79% of re-initiated cases, improving the overall efficacy for proximal delivery with delivery inside the critical isthmus (CI) itself being overall most effective. Anti-tachycardia pacing delivery proximal to the re-entrant circuit is more effective at terminating fast VTs, but less so slow VTs, due to frequent re-initiation. Attenuating re-initiation, through ETDA, increases the efficacy of delivery within the CI for all VTs.

Efficacy of antitachycardia pacing alert by remote monitoring of implantable cardioverter-defibrillators for out-of-hospital electrical storm.

Remote monitoring (RM) has been shown to reduce all-cause mortality in patients with implantable cardioverter-defibrillators or cardiac resynchronization therapy defibrillators (ICD/CRT-D). Not all devices transmit an alert for antitachycardia pacing (ATP) therapy, and it is unknown whether differences of RM alert affect the outcomes of electrical storm (ES). We enrolled 42 patients with ICD/CRT-D whose out-of-hospital ES were detected by RM between 2013 and 2020. We divided their 54 episodes into two groups (ATP-alert-on; 22, ATP-alert-off; 32), and clinical outcomes were compared between the two groups. In 35 of 54 episodes of ES, ventricular tachycardia (VT) could be terminated within 24h of ES onset just by ATP (ATP-alert-on: 14, ATP-alert-off: 21); however, many patients subsequently received shock delivery for VT. Among the 35 episodes, only in ATP-alert-on group, seven patients were prompted to visit our hospital without ICD shock through confirmation of ES by ATP-alert. Episodes that led to shock delivery 24h or longer after the ES onset were significantly less common in the ATP-alert-on group (ATP-alert-on: 1/14, ATP-alert-off: 9/21, p=.03). Although there were no significant differences in the number of shock deliveries between episodes in the two groups, the number of ATP deliveries were significantly fewer in the ATP-alert-on group (12[7-26] vs. 29[16-53] in ATP-alert-off group, p=.03). Multivariate logistic regression analyses showed that the only ATP-alert significantly reduced ATP deliveries (HR=0.14, 95%CI=0.04-0.57, p=.003). Remote monitoring with an ATP-alert function during electrical storm may reduce appropriate ICD therapy through prompting early review.

Anti-tachycardia pacing for non-fast and fast ventricular tachycardias in individual Japanese patients: From Nippon-storm study.

BackgroundAnti‐tachycardia pacing (ATP) delivered from an implantable device is a useful tool to terminate ventricular tachycardia (VT). But its real‐world efficacy for those patients having multiple VTs with varying VT rates has not been fully studied.MethodsUsing the Nippon‐storm study database, efficacy of patient‐by‐patient basis ATP programing for Japanese patients having both non‐fast (120‐187 bpm) and fast VT (≥188 bpm) was assessed. According to the useful criteria of ≥50% success termination by ATP, patients were divided into three subgroups; success ≥50% for both non‐fast and fast VT (both useful), ≥50% only for non‐fast VT (non‐fast VT useful), or ≥50% for neither non‐fast nor fast VT (neither useful).ResultsDuring a median follow‐up of 28 months, ATP terminated 184 of the 203 non‐fast VT episodes (91%) and 86 of the 113 fast VT episodes (76%) in all 41 patients. In the patient‐by‐patient analysis, efficacy of ATP was not different between non‐fast and fast VT in most of the patients (36/41 = 88%); 32 patients were in the both useful and four other patients in the neither useful. Neither ischemic nor non‐ischemic structural heart disease was associated with the ATP efficacy, whereas LVEF more than 37.0% and non‐prescribed amiodarone were characteristics of the patients classified into the both useful.ConclusionsATP well terminated both non‐fast and fast VT occurring in individual Japanese patients with various structural heart diseases in the real‐world device treatment and this finding further supports ATP programing for all device tachycardia detection zones in most patients with multiple VTs.

Efficacy of antitachycardia pacing for electrical storms in patients with implantable defibrillators.

Although antitachycardia pacing (ATP) is effective in terminating ventricular tachyarrhythmias in patients with implantable cardioverter defibrillators (ICDs), the efficacy of ATP during an electrical storm (ES) and the positive impact on all-cause mortality have not been fully elucidated. From 2010 to 2012, 1570 patients who underwent ICD implantation in 48 ICD centers in Japan were enrolled in the study and prospectively followed up. Patients with long QT syndrome, Brugada syndrome, and idiopathic ventricular fibrillation were excluded. The prevalence of shocks during ESs and impact on the all-cause mortality were evaluated. During a median follow-up of 28 months, there were 127 ESs in 84 patients. Of those 127 ESs, 80 ESs (63%) in 37 patients were treated by only ATP and the remaining 47 ESs in 47 patients required at least one shock. The lower ventricular rate of the initial arrhythmia during ES (odds ratio [OR]: 1.02 per unit; 95% confidence interval [CI]: 1.00-1.04; p = .02) and narrower QRS complex (OR: 1.03 per unit; 95% CI: 1.01-1.06; p < .01) were the independent predictors of ATP success during the ES. The patients treated with ATP alone tended to have lower all-cause mortality compared to those that required shocks during the ES (log-rank p = .10). ATP was effective in patients suffering from ESs as it avoided painful shocks in more than half of the cases. Patients who received only ATP during ES tended to have lower mortality compared to those who received the shock.

P2883VT/VF treatment in a contemporary population of single chamber ICD recipients: ATP efficacVF

Abstract Aim of the study to investigate the efficacy of ATP in consecutive, unselected ICD recipients implanted in 2014–2015. Methods All patients had a VT zone as 350 ms and a VF zone as 280 ms programmed, with a detection duration &gt;20 seconds and &gt;8 seconds respectively for VT and VF. Anti-tachycardia pacing (ATP) was available before/during charging in the VF zone, while at least 3 attempts with ATP were programmed in the VT zone. ATP efficacy was assed at the first ventricular arrhythmia episode for each patient. Overall ATP efficacy was also calculated on the burden of treated episodes. Results A total of 165 patients (median age 63 [48–72] years, male 79%, primary prevention 80%, ischemic 53%) implanted with a single chamber ICD were followed for a median period of 847 [666–1030] days: 44 (27%) had VT/VF episodes. Among a total of 706 VT/VF episodes, 623 were treated with ATP and/or shock. 7 patients were treated with shock as first delivered therapy (efficacy 100%), whereas 33 were treated with ATP (efficacy 55% of treated patients, 71% of episodes). The median cycle of the treated arrhythmias was 309 [280–324] ms. Efficacy at first attempt ALL Ischemic NICM Primary Secondary Per patient (first therapy occurrence) Shock (7/7) 100% (7/7) 100% – (6/6) 100% (1/1) 100% ATP (18/33) 55% (13/23) 57% (5/10) 50% (13/22) 59% (5/11) 45% Per episode Shock (14/14) 100% (14/14) 100% – (6/6) 59% (8/8) 100% ATP (432/609) 71% (245/362) 68% (187/247) 76% (127/201) 63% (305/408) 75% Conclusion ATP is quite effective is a contemporary cohort of single chamber ICD recipients in a fast arrhythmia range (average 190–220 bpm) with a long detection. This observation strengthen the value of ATP in ICD selection, and should be balancen when considering an S-ICD.

Safety and efficacy of anti-tachycardia pacing in patients with hypertrophic cardiomyopathy implanted with an ICD.

In hypertrophic cardiomyopathy (HCM) patients implanted with an implantable cardioverter defibrillator (ICD), clinical outcomes of antitachycardia pacing (ATP) have been poorly explored. In a retrospective analysis of a cohort of consecutive HCM patients implanted with an ICD, we aimed to assess the efficacy, safety, and clinical value of ATP. The cohort of HCM patients implanted with a transvenous ICD and followed in our center was assessed for device intervention from implantation to last clinical follow-up. Overall 77 patients (45 males; mean age: 46±16 years) were analyzed. After 67±41 months, 24 patients had 49 ventricular tachycardia/fibrillation (VT/VF) appropriately treated (5.8% per year). Among 39 monomorphic VTs, ATP was effective in 27 (success rate: 69%). Mean time from VT onset to ATP delivery was 9.1±4.9s. The only clinical variable improving ATP success was use of beta-blockers (81%vs 50%; P=.04). Out of 12 ineffectively treated VTs, one was immediately shocked, four self-terminated after 18±12s, and seven (18%) were accelerated to a new VT. ATP was also delivered for 27 of 42 inappropriately detected episodes and induced two de novo VTs (7%). In the per patient analysis, 14 out 77 (18%) patients had one or more appropriate and effective ATP (3.4% per year), and only six (8%; 1.4% per year) received more than one ATP. ATP is moderately effective for the treatment of monomorphic VTs in HCM patients. However, the rate of appropriate ATP therapies is low, ATP is often prematurely delivered, and ATP-induced arrhythmia degeneration is of concern.

Implantable cardioverter defibrillator therapy in grown-up patients with transposition of the great arteries-role of anti-tachycardia pacing.

Grown-up patients with surgically corrected dextro-transposition of the great arteries (dTGA) as well as patients with congenitally corrected transposition of the great arteries (ccTGA) carry a high risk of ventricular arrhythmias. Data regarding implantable cardioverter defibrillator (ICD) therapy and efficacy of anti-tachycardia pacing in these patients is limited. Clinical data from a contemporary cohort of ICD carriers with atrial switch-corrected dTGA and burdened right ventricle or with ccTGA were obtained retrospectively from hospital records and patients were followed for additional 25 months prospectively. Clinical characteristics and ICD episode data were analyzed. Fourteen ICD carriers (8 male) with dTGA or ccTGA were included in the analysis. Four patients received the ICD for primary prevention based on severely reduced systemic ventricular function. The remaining patients had an ICD indication for secondary prevention. Cumulative follow-up added up to 113.5 patient-years. One patient died suddenly due to massive pulmonary embolism. One patient received a ventricular assist device. There were no arrhythmic deaths during the prospective follow-up period. Nine patients (64%) experienced a total of 177 ventricular tachyarrhythmias. Anti-tachycardia pacing was highly effective with 80% success rate in termination of arrhythmias. Five patients (36%) suffered from a total of 28 inappropriate ICD shocks for supraventricular tachycardia. In a contemporary cohort of ICD carriers with dTGA and ccTGA we observed a high proportion of appropriate ICD therapies for ventricular tachyarrhythmias. Over a period of up to 15 years almost two thirds of the patients received appropriate therapies. ATP was highly effective in our cohort and should therefore be programmed whenever possible.

Different impact of long-detection interval and anti-tachycardia pacing in reducing unnecessary shocks: data from the ADVANCE III trial.

AimsA long-detection interval (LDI) (30/40 intervals) has been proved to be superior to a standard-detection interval (SDI) (18/24 intervals) in terms of reducing unnecessary implantable cardioverter defibrillator (ICD) therapies. To better evaluate the different impact of LDI and anti-tachycardia pacing (ATP) on reducing painful shocks, we assessed all treated episodes in the ADVANCE III trial.Methods and resultsA total of 452 fast (200 ms < cycle length ≤ 320 ms) arrhythmic episodes were recorded: 284 in 138 patients in the SDI arm and 168 in 82 patients in the LDI arm (106/452 inappropriate detections). A total of 346 fast ventricular tachycardias (FVT) were detected in 169 patients: 208 in 105 patients with SDI and 138 in 64 patients with LDI. Setting LDI determined a significant reduction in appropriate but unnecessary therapies [208 in SDI vs. 138 in LDI; incidence rate ratio (IRR): 0.61 (95% CI 0.45–0.83), P = 0.002]. Anti-tachycardia pacing determined another 52% reduction in unnecessary shocks [208 in SDI with hypothetical shock-only programming vs. 66 in LDI with ATP; IRR: 0.37 (95% CI 0.25–0.53, P < 0.001)]. The efficacy of ATP in terminating FVT was 63% in SDI and 52% in LDI (P = 0.022). No difference in the safety profile (acceleration/degeneration and death/cardiovascular hospitalizations) was observed between the two groups.ConclusionThe combination of LDI and ATP during charging is extremely effective and significantly reduces appropriate but unnecessary therapies. The use of LDI alone yielded a 39% reduction in appropriate but unnecessary therapies; ATP on top of LDI determined another 52% reduction in unnecessary shocks. The strategy of associating ATP and LDI could be considered in the majority of ICD recipients.

An Automatic Algorithm Based on Morphological Stability During Fast Ventricular Arrhythmias Predicts Successful Antitachycardia Pacing in ICD Patients: A Multicenter Study.

Different types of ventricular arrhythmias (monomorphic ventricular tachycardia [VT], polymorphic VT, or ventricular fibrillation) can be detected by implantable cardiac defibrillators (ICDs) in fast VT zone. The efficacy of antitachycardia pacing (ATP) depends on the type of the treated arrhythmia. We hypothesized that an automatic algorithm based on morphological affinity of ICD far-field electrograms during tachycardia can predict ATP success and the need of shock. The algorithm was evaluated on ventricular arrhythmias recorded in CareLink ICD remote monitoring system (Medtronic Inc., Minneapolis, MN, USA). Patients were selected if first ATP programmed was a burst of eight pulses at 88% coupling interval and if a far-field electrogram was available. The algorithm calculated a stability coefficient (SC) for all their stored ATP-treated fast ventricular arrhythmia (VA) episodes (LC 200-300 ms), analyzing the morphology homogeneity of the last eight recorded far-field electrograms before ventricular arrhythmias detection. Inclusion criteria were fulfilled by 717 patients from 29 centers. Three hundred and twenty fast VA were recorded in 103 patients. A higher SC was observed in episodes terminated with the first-ATP (0.78 [0.72-0.84] vs 0.74 [0.60-0.84]; P = 0.006). These differences were especially marked among the 62 episodes of very fast VA (CL ≤250 ms) (0.77 [0.74-0.85] vs 0.64 [0.51-0.8]; P = 0.006). In the multivariate analysis, a SC > 70% was independently associated with a higher likelihood of first-ATP success (odds ratio [OR] = 2.5; [95% confidence interval (CI) = 1.4-4.5], P = 0.001) and a lower need of shock (OR = 0.37; [95% CI = 0.2-0.7], P = 0.002). This automatic algorithm (stability coefficient) shows that ATP therapy response can be predicted in fast ventricular arrhythmias through morphology evaluation.

Ventricular antitachycardia pacing therapy in patients with heart failure implanted with a cardiac resynchronization therapy defibrillator device: Efficacy, safety, and impact on mortality

Cardiac resynchronization therapy defibrillator can terminate ventricular tachycardia (VT) and fast VT (FVT) via antitachycardia pacing (ATP). We evaluated efficacy and safety of ATP, whether ATP induces ventricular arrhythmias after inappropriate ATP or atrial fibrillation (AF) after appropriate ATP, and whether ATP is associated with mortality. A total of 1404 patients with a cardiac resynchronization therapy defibrillator were followed in a prospective multicenter observational research. All-cause mortality rates were estimated in patient subgroups in order to uncouple the trigger (VT/FVT or other rhythms causing inappropriate detections) from ATP therapy. Over a median follow-up of 31 months, 2938 VT/FVT episodes were treated with ATP in 360 patients. The adjusted ATP success rate was 63% (95% confidence interval [CI] 57%-69%) on FVTs and 68% (95% CI 62%-74%) on VTs. Acceleration occurred in 55 (1.87%) and syncope in 4 (0.14%) of all ATP-treated episodes. In 14 true VT/FVT episodes in 5 patients, AF followed ATP therapy. In 4 episodes in 2 patients, VT followed ATP inappropriately applied during AF. Death rate per 100 patient-years was 5.6 (95% CI 4.3-7.5) in patients with appropriate ATP and 1.5 (95% CI 0.4-6.1) in patients with inappropriate ATP (P = .045). ATP was effective in terminating VT/FVT episodes and displayed a good safety profile. ATP therapies by themselves did not increase death risk; prognosis was indeed better in patients without arrhythmic episodes, even if they received inappropriate ATP, than in patients with ATP on VT/FVT episodes. Adverse outcomes observed in patients receiving implantable cardioverter-defibrillator therapies are probably related to the arrhythmia itself, a marker of disease progression, rather than to adverse effects of ATP.

Antitachycardia pacemakers in congenital heart disease.

Many patients with congenital heart disease (CHD) acquire rhythm abnormalities related to their repair, most commonly intraatrial reentrant tachycardia (IART). Treatment of IART in CHD is often multifaceted, and may include medication, ablation, and pacing. Evidence regarding the use of antitachycardia pacing therapies is limited. The aim of the study is to define the use and efficacy of antitachycardia pacing in patients with CHD at a single center. Eighty implants were performed on 72 patients between 2000 and 2010. Follow-up data of more than 3 months were available for 56 patients; median follow-up time was 2.8 years. Twenty (36%) patients received successful antitachycardia pacing at a median 1.3 years postimplant. For those patients with IART after implant, antitachycardia pacing was successful in 57%. Patients with two-ventricle repairs were more likely to have successful antitachycardia pacing than those with one-ventricle palliation (45% vs. 17%, P = .04). Patients with documented IART had more successful antitachycardia pacing than those with no documented atrial tachycardia prior to implant (46% vs. 7%, P = .006). Early complications of antitachycardia pacemaker implant occurred in six patients (11%); late complications after implant occurred in three patients (5.6%). Of the initial 72 patients implanted, there were six deaths (8%). Antitachycardia pacing therapies were successful in the majority of CHD patients who had IART after implant. Patients without documented atrial tachycardia prior to implant were unlikely to require or receive successful therapy from antitachycardia pacemaker. Those patients postatrial switch procedure who had documented IART prior to implant had the highest incidence of successful antitachycardia pacing therapies. Antitachycardia pacemaker implantation is an adjunct to the management of IART in CHD patients, but may not benefit patients who have not yet demonstrated IART.

EFFICACY OF ANTI-TACHYCARDIA PACING IN THE TREATMENT OF VENTRICULAR ARRHYTHMIAS IN THE RAFT TRIAL

BackgroundAnti-tachycardia pacing (ATP) is a common initial treatment in the termination of ventricular arrhythmias in implantable cardioverter defibrillators (ICDs). We sought to assess the efficacy of burst and ramp ATP on ventricular arrhythmias at different tachycardia cycle lengths (TCL) in the RAFT trial.MethodsThe RAFT trial randomized patients with functional class II and III heart failure to ICDs ± cardiac resynchronization and had standardized programming; VT was treated with burst pacing (8 beats/ 88% TCL/ fixed rate), followed by ramp pacing (6 beats/88% TCL/10ms decrements) if burst pacing failed. All arrhythmia events were adjudicated.ResultsView Large Image Figure ViewerDownload (PPT)ConclusionIn the cohort of RAFT patients it appears that ATP therapy was most successful in treating VT between 150-200bpm. VT faster than 200bpm was more likely to accelerate after ATP therapy, however, they too were more likely to receive Ramp ATP. BackgroundAnti-tachycardia pacing (ATP) is a common initial treatment in the termination of ventricular arrhythmias in implantable cardioverter defibrillators (ICDs). We sought to assess the efficacy of burst and ramp ATP on ventricular arrhythmias at different tachycardia cycle lengths (TCL) in the RAFT trial. Anti-tachycardia pacing (ATP) is a common initial treatment in the termination of ventricular arrhythmias in implantable cardioverter defibrillators (ICDs). We sought to assess the efficacy of burst and ramp ATP on ventricular arrhythmias at different tachycardia cycle lengths (TCL) in the RAFT trial. MethodsThe RAFT trial randomized patients with functional class II and III heart failure to ICDs ± cardiac resynchronization and had standardized programming; VT was treated with burst pacing (8 beats/ 88% TCL/ fixed rate), followed by ramp pacing (6 beats/88% TCL/10ms decrements) if burst pacing failed. All arrhythmia events were adjudicated. The RAFT trial randomized patients with functional class II and III heart failure to ICDs ± cardiac resynchronization and had standardized programming; VT was treated with burst pacing (8 beats/ 88% TCL/ fixed rate), followed by ramp pacing (6 beats/88% TCL/10ms decrements) if burst pacing failed. All arrhythmia events were adjudicated. Results ConclusionIn the cohort of RAFT patients it appears that ATP therapy was most successful in treating VT between 150-200bpm. VT faster than 200bpm was more likely to accelerate after ATP therapy, however, they too were more likely to receive Ramp ATP. In the cohort of RAFT patients it appears that ATP therapy was most successful in treating VT between 150-200bpm. VT faster than 200bpm was more likely to accelerate after ATP therapy, however, they too were more likely to receive Ramp ATP.

Influence of cycle length variations on antitachycardia pacing effectiveness among ICD patients

Antitachycardia pacing (ATP) fails to terminate 5% to 25% of ventricular tachycardias (VTs) occurring in implantable cardioverter-defibrillator patients. We speculated that small fluctuations in VT cycle length (CL) may be related to the efficacy of subsequent ATP. The purpose of this study was to determine the relationship between the R-R variations of the last 12 R-R intervals before ATP and the efficacy of the first ATP attempt. We studied 551 VTs (CL 329±35 ms) occurring in 67 patients. We also analyzed the percentage of variation (P-RR), which was calculated by dividing the mean difference between each R-R interval and the next one by the CL (×100), and the acceleration index (AI), which was calculated by dividing the CL of the first 6 R-R intervals by the CL of the next 6. The effectiveness of the first ATP therapy was 81%, being higher in VTs with AI<1 (85% vs 64%; P<.001). After classifying the events according to the tertiles of P-RR, ATP efficiency was better in higher values of P-RR (VTs with AI<1): 99% (third tertile) vs 85% (second tertile) vs 76% (first tertile), P<.001; and for VTs with AI≥1: 94% vs 68% vs 42% (P<.001). By logistic regression, P-RR (%; odds ratio 2.37; P<.001), and AI<1 (odds ratio 4.17; P<.001) were found to be independent predictors of successful first ATP attempts. Small changes in CL increase the effectiveness of ATP significantly. VTs with lower degrees of R-R fluctuations, especially when the pattern is a progressive CL shortening, are infrequently terminated by ATP.

Antitachycardia pacing reduces appropriate and inappropriate shocks in children and congenital heart disease patients

Antitachycardia pacing (ATP) can reduce implantable cardioverter-defibrillator shocks, but its use in children and patients with congenital heart disease (CHD) is not well described. To review the efficacy of ATP in children and patients with CHD. We reviewed implantable cardioverter-defibrillator therapies in children and patients with CHD (aged 2-52 years) at our institution. Appropriate therapies were defined as those delivered for true ventricular tachycardia (VT) or ventricular fibrillation; other therapies were defined as inappropriate. During a median follow-up of 4 years (range 0.5-15 years), 17 of 79 patients (23%) received appropriate therapy and 14 received ATP for 100 episodes of VT. ATP was highly successful (88%) in terminating VT, and only 10 of 100 episodes required a shock. Shocks were effective in terminating VT/ventricular fibrillation in 21 of 24 episodes (87%). The outcomes of appropriate therapy were similar for ATP and shocks (success 88% vs 87%, failure 9% vs 8%, acceleration 3% vs 4% for ATP and shocks, respectively). Thirty-one patients (39%) received inappropriate therapy. Inappropriate ATP (without subsequent shocks) was delivered to 11 patients for the following: sinus tachycardia (19 episodes in 7 patients) with slowing of the rate after ATP, T-wave oversensing (2 episodes in 2 patients) with loss of oversensing after ATP, and reentrant supraventricular tachycardia (14 episodes in 2 patients) terminated with ventricular ATP. ATP is highly efficacious for VT in children and patients with CHD. In addition to reducing appropriate shocks, inappropriate shocks due to sinus or supraventricular tachycardia can be significantly reduced with ATP.

Prospective multicenter randomized trial of fast ventricular tachycardia termination by prolonged versus conventional anti-tachyarrhythmia burst pacing in implantable cardioverter-defibrillator patients-Atp DeliVery for pAiNless ICD thErapy (ADVANCE-D) Trial results

PurposeThe purpose of the trial was to quantify and compare the efficacy of two different sequences of burst anti-tachycardia pacing (ATP) strategies for the termination of fast ventricular tachycardia.MethodsThe trial was prospective, multicenter, parallel and randomized, enrolling patients with an indication for implantable cardioverter-defibrillator implantation.ResultsFrom February 2004, 925 patients were randomized and followed-up for 12 months. Eight pulses ATP terminated 64% of episodes vs. 70% in the 15-pulse group (p = 0.504). Fifteen pulses proved significantly better in patients without a previous history of heart failure (p = 0.014) and in patients with LVEF ≥ 40% (p = 0.016). No significant differences between groups were observed with regard to syncope/near-syncope occurrence.ConclusionIn the general population, 15-pulse ATP is as effective and safe as eight-pulse ATP. The efficacy of ATP on fast ventricular arrhythmias confirmed once more the striking importance of careful device programming in order to reduce painful shocks.

Abstract 5893: Biventricular Versus Right Ventricular Delivered Anti-Tachicardia Pacing for the Termination Of Ventricular Tachyarrhythmias in Heart Failure Patients Receiving a Biventricular ICD: Results from the ADVANCE CRT-D Trial

Aim: To investigate the efficacy and safety of anti-tachycardia pacing (ATP) simultaneously delivered from right and left ventricles (BIV) vs conventional right ventricular (RV) delivery in heart failure (HF) patients treated with a biventricular ICD (CRT-D). Methods : Multicenter, prospective, randomized, controlled trial of pts implanted with a Medtronic CRT-D device. Anti-tachycardia detections were programmed: VF detection set at NID 18/24 for ≥250 bpm; FVT (via VF) with NID 18/24 between 188–250 bpm; VT detected when 20 consecutive RR intervals ≥143 bpm. Randomization was 1:1 to either BiV or RV ATP (single burst 8 pulse, 88% coupling interval ). Pts were followed for 12 months. Stored EGM, used to classify all spontaneous episodes, as well as all adverse events (including death) were adjudicated by an independent committee adjusting for pts with multiple episodes. The primary end-point (PEP) compared the efficacy of first BiV vs RV to terminate any ventricular tachyarrhythmias (VTs). The secondary composite end-point (SEP) compared adverse events (accelerations+ syncope/pre-syncope) to assess safety. Results : In total, 526 patients were enrolled and randomized (BiV = 260, RV = 266). There were no baseline differences between groups. In total, 1077 detections in 178 patients were recorded: 634 were true VTs in 119 patients (69 VF [11%] in 18 pts, 202 FVT [32%] in 49 pts, and 363 VT [57%] in 92 pts). PEP: Efficacy of first ATP was comparable between BiV (65%) and RV (68%) (p=0.58). In VT zone, RV was better (62% vs 71%., p=0.24), while in FVT zone BIV proved better (71% vs. 61%, p=0.33). RV ATP was significantly less effective in ischemic (I) pts (81% vs 59%, p=0.005). SEP: BIV ATP was ineffective 20 times and 3 accelerations occurred, whereas RV ATP failed 41 times and 14 accelerations occurred (p=0.12). Syncope/pre-syncope events never occurred for BiV ATP, while 4 times (3%) in RV ATP(p=0.3). No difference in mortality was observed. Conclusion : This trial demonstrated that ATP is also effective in CRT-D recipients. No significant differences in overall ATP efficacy were found between BIV and RV, but RV was significantly less effective in I patients; BIV was effective across different etiologies and showed a trend for superior safety profile.

Abstract 2132: Beta-Blocker Therapy and Effectiveness of Antitachycardia Pacing among ICD Patients: A Dose-Dependent Effect

Beta-blockers (BB) increase the efficacy of antitachycardia pacing (ATP) in terminating slow and monomorphic ventricular tachycardias (MVT) in ICD patients. Whether this effect occurs in fast MVT and whether it is dose-dependent it is unknown. Our aim is to determine the relationship between the indexed dose equivalents (IDE) of beta-blockers (BB-IDE) with the effectiveness of ATP in terminating MVT. In this prospective study we included 200 ICD patients (LVEF: 31±11). Detection and ATP therapies for VT were programmed as follows: Fast-VT zone (Cycle Length [CL]: 250 –320 ms; 1 burst of 5 pulses at 84% of CL); slow-VT zone (CL: 321–390 ms; 3 bursts of 15 pulses at 91%). In each patient we determined the BB-IDE at MVT presentation. Dose equivalents (DE) were defined with atenolol used as reference. IDE were calculated by dividing DE by body surface area (mg*m2/day). During a follow-up of 602±368 days, 546 MVT (CL: 329±35 ms; 41% fast-VT; 22 % no BB treatment; median of BB-IDE: 26 mg*m2/day) were recorded. Success rate of APT was 87%. BB-IDE was higher in the cases of successful ATP (S-ATP): 22±18 vs. 15±16 (p=0.001). Classifying the events into three groups according to the BB-IDE: no BB, low IDE (BB-IDE&lt;median) and high IDE (BB-IDE≥median), the frequency of S-ATP increased with the BB-IDE: 78 vs. 84 vs. 94% (all MVTs; p&lt;0.001 for the trend) and 47 vs. 84 vs. 97% (fast-MVTs; p&lt;0.001, for the trend). In a multivariate analysis (logistic regression), BB-IDE (mg*m2/day) remained as a significant predictor of S-ATP: OR: 1.03 (95% CI: 1.01–1.05; p=0.001). The incidences of MVT-related symptoms and appropriate discharges were lower in higher values of BB-IDE. Table . Among ICD patients, BB therapy increases the likelihood of ATP terminating MVTs, especially in fast MVTs. This effect is dose-dependent: the higher the IDE, the more probable the S-ATP. Thus, BB improves MVT clinical tolerance. Frequencies of tachycardia-related symptoms and appropriate discharges with respect to BB-IDE