Inappropriate Antitachycardia Pacing Research Articles

Reduction in Inappropriate Therapy and Mortality through ICD Programming

BackgroundThe implantable cardioverter–defibrillator (ICD) is highly effective in reducing mortality among patients at risk for fatal arrhythmias, but inappropriate ICD activations are frequent, with potential adverse effects.MethodsWe randomly assigned 1500 patients with a primary-prevention indication to receive an ICD with one of three programming configurations. The primary objective was to determine whether programmed high-rate therapy (with a 2.5-second delay before the initiation of therapy at a heart rate of ≥200 beats per minute) or delayed therapy (with a 60-second delay at 170 to 199 beats per minute, a 12-second delay at 200 to 249 beats per minute, and a 2.5-second delay at ≥250 beats per minute) was associated with a decrease in the number of patients with a first occurrence of inappropriate antitachycardia pacing or shocks, as compared with conventional programming (with a 2.5-second delay at 170 to 199 beats per minute and a 1.0-second delay at ≥200 beats per minute).ResultsDuring an average follow-up of 1.4 years, high-rate therapy and delayed ICD therapy, as compared with conventional device programming, were associated with reductions in a first occurrence of inappropriate therapy (hazard ratio with high-rate therapy vs. conventional therapy, 0.21; 95% confidence interval [CI], 0.13 to 0.34; P<0.001; hazard ratio with delayed therapy vs. conventional therapy, 0.24; 95% CI, 0.15 to 0.40; P<0.001) and reductions in all-cause mortality (hazard ratio with high-rate therapy vs. conventional therapy, 0.45; 95% CI, 0.24 to 0.85; P=0.01; hazard ratio with delayed therapy vs. conventional therapy, 0.56; 95% CI, 0.30 to 1.02; P=0.06). There were no significant differences in procedure-related adverse events among the three treatment groups.ConclusionsProgramming of ICD therapies for tachyarrhythmias of 200 beats per minute or higher or with a prolonged delay in therapy at 170 beats per minute or higher, as compared with conventional programming, was associated with reductions in inappropriate therapy and all-cause mortality during long-term follow-up. (Funded by Boston Scientific; MADIT-RIT ClinicalTrials.gov number, NCT00947310.)

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.

Approximation of electrocardiogram T wave by using Gaussian mixtures and automatic measurement of QT interval

Results: Active fixation leads were used in 120 (90%) patients, and passive fixation leads were used in 14 (10%) patients. Local injury current was observed in 121 events (28.8%) and was detected more frequently after appropriate (43 [60.6%] events) and inappropriate (56 [64.4%] events) ICD shocks, as compared with appropriate (8 [9.2%] events) and inappropriate (3 [4.7%] events) antitachycardia pacing (ATP) or nonsustained ventricular tachycardia (11 [9.9%] events; analysis of variance, P ≤ .0001]. Appearance of LIC was a changeable phenomenon; that is, LIC was frequently observed after one, but not another, appropriate ICD shock in the same patient. Significant LIC was observed after 61% of events with single ICD shock, 83% of events with 2 shocks, 50% of events with 3 shocks, and 100% of events with 4 or more shocks (analysis of variance, P = .658). Type of ICD therapy (ICD shock vs ATP) was the most significant predictor of LIC (ATP:β-coefficient =−0.81; 95%confidence interval [CI], −1.19 to 0.44; P ≤ .0001), along with cycle length of tachycardia (β-coefficient = −0.0117; 95% CI, −0.0167 to −0.0068; P≤; .00001) and shock energy (β-coefficient = 0.024; 95% CI, 0.003–0.045; P = .025). Conclusion: Appropriate and inappropriate ICD shocks are frequently characterized by the development of LIC in patients with structural heart disease. Type of electrical ICD therapy, shock energy, and cycle length of ventricular arrhythmia are important determinants of LIC.

Arrhythmia rate distribution and tachyarrhythmia therapy in an ICD population: Results from the INTRINSIC RV trial

Appropriate implantable cardioverter-defibrillator (ICD) therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF) depends, in part, on the programming of tachycardia zones. We assessed events treated with ICD shocks or antitachycardia pacing (ATP) in the Inhibition of Unnecessary RV Pacing with AV Search Hysteresis in ICDs (INTRINSIC RV) trial. ATP and shock episodes from 1530 patients with dual-chamber ICDs were analyzed. For episodes in which electrograms were stored and adjudicated, ATP was delivered for 763 episodes (182 patients), shock-only was delivered for 300 episodes (146 patients), and shock following ATP was delivered for 81 episodes (56 patients). ATP was delivered appropriately for 507 episodes (130 patients), with 93% success, and inappropriately for 256 episodes (89 patients). For ATP episodes, appropriate (VT: 170 ± 28 bpm) and inappropriate (not VT: 165 ± 21 bpm) rates did not differ (P = .16). When the initial therapy was shock, onset rates were higher for appropriate therapy than for inappropriate therapy (224 ± 46 bpm vs 187 ± 31 bpm; P <.001). Inappropriate ATP was more likely to be followed by a shock (odds ratio 2.49; 95% confidence interval 1.56-3.97; P <.001). Fifty-eight percent (225 of 381) of shocked episodes had rates <200 bpm. For episodes between 200 and 250 bpm, 20% (23 of 113) were polymorphic VT or VF, 59% were monomorphic VT, 19% were supraventricular, and <1% was artifact. For episodes >250 bpm, 37% were VF, 28% polymorphic VT, 23% monomorphic VT, 7% supraventricular, and 5% artifact. In a general ICD population, ATP treated VT effectively or obviated the need for shock. Most ventricular arrhythmias <250 bpm were not VF. Proper zone programming may identify and treat VT without shock.

Impact of Accelerated Ventricular Tachyarrhythmias on Mortality in Patients with Implantable Cardioverter-Defibrillator

Background: Anti-tachycardia pacing (ATP) and shock delivery may induce or accelerate tachyarrhythmias in patients with implantable cardioverter defibrillator (ICD). Methods: We investigated the triggers and the clinical outcome of ventricular tachyarrhythmias accelerated by ATP or shock. Results: ICD were implanted in 1275 patients (age at implantation 59.7±14.0 years). Within a mean follow-up of 5.3±4.0 years, intracardiac electrograms were available in 1170 patients (91.8%). Overall 157 episodes of accelerated ventricular tachyarrhythmias were found in 100 of 1170 patients (8.5%). Termination of tachyarrhythmias was achieved by shock delivery in 153 episodes (96.8%). Triggers of accelerated tachyarrhythmias were appropriate ATP in 139 (88.5%) and inappropriate ATP in 14 (8.9%), as well as appropriate and inappropriate shocks in 2 (1.3%) episodes, respectively. Patients with accelerated ventricular tachyarrhythmia and shock therapy revealed higher all-cause mortality (47% versus 29.9%; p<0.001), and higher cardiac mortality (16% versus 6.5%; p<0.001), irrespectively of left ventricular function (LVF). Moreover, a trend was found towards a higher mortality in patients with preserved LVF and acceleration than in patients with reduced LVF without acceleration (p=0.070). Conclusions: ATP with arrhythmia acceleration and shock delivery is a frequent and serious complication of ICD therapy that predominantly occurs in patients with reduced LVF. Our data support the hypothesis that ICD shocks damage the heart and even may increase mortality.

Appropriate and Inappropriate Electrical Therapies Delivered by an Implantable Cardioverter-Defibrillator: Effect on Intracardiac Electrogram

Local injury current (LIC) seen after induced ventricular fibrillation rescue implantable cardioverter-defibrillator (ICD) shock predicts heart failure progression. We sought to determine the frequency of LIC after spontaneous events in patients receiving ICD therapies. Near-field (NF) right ventricular (RV) EGM during 10 seconds after delivered ICD therapy was compared with baseline EGM in 420 events that occurred in 134 patients (mean age 60.8 ± 14.8, 106 [79%] male). The magnitude of elevated or depressed potential immediately after the major fast EGM deflection was defined as LIC, and its ratio to the peak-to-peak EGM amplitude was defined as relative LIC. LIC of at least 1 mV or relative LIC of at least 15% was considered significant. LIC was observed in 121 events (28.8%) and was detected more frequently after appropriate (43 [60.6%] events) and inappropriate (56 [64.4%] events) ICD shocks, as compared with appropriate (8 [9.2%] events) and inappropriate (3 [4.7%] events) antitachycardia pacing (ATP) or nonsustained ventricular tachycardia (11 [9.9%] events) [ANOVA P < 0.0001]. Type of ICD therapy (ICD shock vs ATP) was the most significant predictor of LIC (ATP β coefficient -0.81; 95%CI-1.19 to 0.44); P < 0.0001), along with cycle length of tachycardia (β coefficient -0.0117; 95%CI -0.0167 to -0.0068, P < 0.00001) and shock energy (β coefficient 0.024; 95%CI 0.003-0.045, P = 0.025). Appropriate and inappropriate ICD shocks are frequently characterized by the development of LIC in patients with structural heart disease. Type of electrical ICD therapy, shock energy and cycle length of ventricular arrhythmia are important determinants of LIC.

Can linear triple-site atrial pacing reinforce the electrical treatment of atrial fibrillation?

This editorial refers to ‘Atrial activation time and pattern of linear triple-site vs. single-site atrial pacing after cardioversion in patients with atrial fibrillation’ by J.-I. Choi et al., on page 508. In their recent editorial commentary on the role of atrial pacing in prevention or interruption of atrial tachyarrhythmias, Janko and Hoffmann1 have concluded that today this treatment is of the arbitrary value and finished off with the statement ‘do we still need to talk about it?’ Indeed, despite more than a decade of significant intellectual investments and numerous clinical trials exploring a vast spectrum of pacing algorithms, pacing sites, and lead configurations, the majority of published data indicate unsatisfying short- or mid-term prevention or suppression of atrial fibrillation (AF) and atrial tachycardia (AT). The reasons for these poor results have been well documented and include: (i) the inability to adequately suppress predominantly left atrial sided triggers and/or penetrate the initial circulatory wave fronts, (ii) delayed interruption of AT/AF because of time needed for classifying and confirming the type of the already ongoing and nested atrial tachyarrhythmias, and (iii) incorrect pattern recognition. Most serious of all, adverse effects of inappropriate antitachycardia or overdrive pacing by provoking AT/AF instead of suppressing or preventing the arrhythmia due to incorrect or not timely diagnosis often emerge. Presently, classical sick sinus syndrome with a low incidence of paroxysmal AT/AF remains the best indication for this electrical therapy while patients with … *Corresponding author. Tel: +31 817559801; fax: +31 302516396, Email: n.m.vanhemel{at}hetnet.nl

Intraoperative defibrillation threshold testing during implantable cardioverter-defibrillator insertion: Do we really need it?

The assessment of defibrillation efficacy using a safety margin of 10 J has long been the standard of care for insertion of implantable cardioverter-defibrillator (ICD), but physicians are concerned about complications related to induction test. Therefore, the need for testing has been recently questioned. The aim of our study was to assess the impact of defibrillation threshold (DFT) testing of ICD on the efficacy of ICD therapy. We analyzed data obtained from follow-up visits of 122 consecutive patients who underwent ICD implantation at our institute from April 1996 to June 2008, with (n = 42) or without (n = 80) DFT testing. Patients in the DFT group were less likely to be men (83.3% vs 96.3%, P < .031) than those in the non-DFT group. Conversely, the 2 groups were similar in age, left ventricular ejection fraction at baseline, functional class, and underlying cardiovascular disease. Results during a 12-month follow-up, 13 (31.0%) and 30 (37.5%) ventricular tachyarrhythmic episodes were recorded in the DFT and non-DFT groups, respectively (P = .472). Antitachycardia pacing (ATP) terminated most of episodes, reducing the need of defibrillation at 7.7% in the DFT group and 3.3% in the non-DFT group (P = .533). Similar percentages of inappropriate ATP interventions (7.1% vs 3.8%, P = .413) and shock deliveries (2.4% vs 5.0%, P = .659) were recorded between DFT and non-DFT groups. At 1-year follow-up, the performance of DFT testing does not seem to add any significant efficacy advantage in patients undergoing ICD implantation. Prospective randomized trials and long-term follow-up are warranted to clarify whether routine DFT testing may be safely abandoned leading to a revision of current guidelines.

Implantable cardioverter-defibrillator therapy in adult patients with tetralogy of Fallot

Adults with repaired tetralogy of Fallot (TOF) are at risk of sudden cardiac death (SCD). ESC and AHA guidelines suggest the use of implantable cardioverter defibrillators (ICDs) to protect from this. Few data are available on the benefits of these devices in this population, and there are no randomized studies. We analysed outcomes with respect to death, ICD therapy delivery, and complications for 20 patients with repaired TOF and 39 dilated cardiomyopathy (DCM) patients followed up at a UK teaching hospital. All TOF patients had clinical ventricular tachycardia (VT), electrophysiological study-inducible VT, or previous arrest due to tachyarrhythmia and received dual-chamber devices with individualized atrial detection algorithms. Tetralogy of Fallot patients were younger than DCM patients, but follow-up duration was not different between the groups. Tetralogy of Fallot patients were more likely to have experienced oversensing (45 vs. 13%; P < 0.02), inappropriate anti-tachycardia pacing delivery (20 vs. 2%; P < 0.05), and inappropriate cardioversion (25 vs. 4%; P = 0.06) than DCM patients and less likely to receive appropriate therapies than DCM patients. The death rate in TOF patients was significantly lower than that in DCM patients (5 vs. 21%; P < 0.05). Tetralogy of Fallot patients have a higher risk of inappropriate therapies and other complications yet a lower incidence of appropriate therapies from their ICD than DCM patients. Further research into identification of factors predicting SCD in TOF and the benefits of ICD implantation is essential given the potential complications of ICD implantation in young congenital heart disease patients.

An unusual mechanism causing inappropriate implantable cardioverter defibrillator shocks: transient reduction in R-wave amplitude

Inappropriate shocks delivered by the implantable cardioverter defibrillator (ICD) are an increasingly recognized complication. The most frequent cause is related to supraventricular rhythms associated with fast conduction to the ventricles that are incorrectly detected as ventricular tachycardia leading to inappropriate antitachycardia pacing and/or shocks. Oversensing is a frequent cause of inappropriate shocks usually due to increased amplitude of the T-wave secondary to ischaemia or electrolyte disorders that lead to T-wave double counting. We describe an unusual case of T-wave double counting during sinus rhythm caused by transient reduction in R-wave amplitude with no changes in T-wave amplitude resulting in inappropriate shocks.

Endoscopy in patients with implanted electronic devices

Endoscopy in patients with implanted electronic devices

Abstracts for the British Congenital Cardiac Association Annual Meeting: The Barbican, London, 24–25 November 2005: Oral Presentations: Early and midterm outcomes of Implantable Cardioverter Defibrillator (ICD) implantation in patients with repaired Tetralogy of Fallot and pulmonary stenosis – a retrospective review

Introduction: Repair of Tetralogy of Fallot up until recent decades involved aggressive resection and annular enlargement through a right ventriculotomy. This resulted in ventricular scarring and pulmonary incompetence, with an increased risk of ventricular tachyarrhythmia and sudden death in young adulthood. Following the NICE guidelines, implantation of ICDs as primary prevention in patients with repaired Tetralogy is ever increasing. This study aims to determine the rate of appropriate and inappropriate discharges, the success rate of ICD therapy and the impact of ICD implantation on the use of anti-arrhythmic medication in this population of patients. Materials and Methods: This is a retrospective review of patients with repaired Tetralogy of Fallot (n = 18) and pulmonary stenosis (n = 2) with implantable cardioverter defibrillators managed at our tertiary centre. Patients were identified from our outpatient database, their notes and charts were examined and details regarding indication for ICD implantation, device specifications and complications following implantation were collected. Data was also collected on the incidence of appropriate and inappropriate therapies and the success rate of ICD therapy along with the impact of implantation on the usage of anti-arrhythmic medication in these patients. Results: Of the 20 patients, 18 had previous repair of Tetralogy of Fallot and 2 had pulmonary valvotomy and infundibular resection for pulmonary stenosis between 1969 and 1989. 70% (n = 14) of these patients required reoperation with 10 patients having pulmonary valve replacements (PVR), 3 having redo infundibular resections and 1 requiring aortic valve replacement. At the time of consideration for ICD implantation 80% had moderate to severe pulmonary incompetence and 60% had more than mild right ventricular dilatation on echocardiography. Indications for ICD implantation were symptomatic ventricular tachycardia requiring cardioversion (n = 8), ventricular tachycardia on 24 hr tape/Reveal or electrophysiological study (n = 8), ventricular fibrillation (VF)/pulseless ventricular tachycardia (VT) (n = 2) and syncope with an abnormal EPS other than VT (n = 2, high grade ventricular ectopics, sinus node dysfunction).The median age at implantation was 22 years (16.4–43 years). All our patients had dual chamber devices implanted with either dual (n = 13) or single coil (n = 6) ventricular leads. GEM3 AT (n = 5), Marquis DR (n = 8) and Maximo DR (n = 7) generators (Medtronic Inc.) were implanted in sub pectoral position and both anti-tachycardia pacing and cardioversion modes were programmed as part of individualised VT and VF protocols. Early post procedural complications included atrial lead displacement (n = 1) and pneumothorax requiring drainage (n = 1).During a median follow up of 1.6 years (0.03– 4.5 years) several episodes of inappropriate therapies were noted in 6 patients (30%) especially early after implantation. This was found to be mainly due to atrial tachyarrhythmia, double counting of T waves or inaccurate interpretation of varying PR intervals as AV dyssynchrony which were effectively dealt with by changes in device programming. There were 33 episodes of inappropriate anti-tachycardia pacing (ATP) in 4 patients and 19 episodes of inappropriate cardioversion in 5 patients. Appropriate ATP was instituted in 4 patients (25%) with successful termination of all 20 episodes (100% success rate) of ventricular tachycardia. One patient required cardioversion with successful termination of VF. One patient (5%) with troublesome tachyarrhythmia died suddenly of unknown cause, 10 months after AICD implantation having had no detections or therapies on his device.Prior to ICD implantation 8 patients were on amiodarone therapy. At the time of last follow up after AICD implantation all patients were established on anti-arrhythmic agents and of these 6 patients were on amiodarone with the others being effectively managed on beta-blockers and/or flecainide.Late complications of ICD implantation included lead failure in 1 patient requiring replacement 3.3 years after implantation and generator replacement in a patient who was pacemaker dependent a year after implantation due to an advisory issued by the manufacturer regarding the risk of sudden battery depletion. Conclusions: In our study we found a rate of 0.6 appropriate and 1.4 inappropriate therapies (0.9 episodes of inappropriate ATP and 0.5 episodes of inappropriate cardioversion) per patient-year of follow up following ICD implantation which is in keeping with published literature. The mortality in our study group was 5% which is acceptable given the high risk population. Implantation of an ICD allowed switching over from amiodarone to less toxic anti arrhythmic therapy in a proportion of patients. Anti-tachycardia pacing was very successful in terminating tachyarrhythmia in our population with 100% success in terminating ventricular tachycardia.

Far-field R wave oversensing in a dual chamber arrhythmia management device: predisposing factors and practical implications.

Initial experience with the Medtronic Jewel 7250, the ICD designed to detect and treat ventricular and supraventricular tachyarrhythmias, is very promising. Its effectiveness, however, depends on sensing performance, which has not yet been systematically examined. The aim of the study was to determine the incidence of, predisposing factors for, and practical implications of far-field R wave oversensing (FFRWOS) in this dual chamber ICD. During a total follow-up of 797 months in 48 patients who had the Jewel 7250, follow-up strip charts, 12-channel Holter recordings and, in particular cases, Holter recordings with intracardiac markers were analyzed for the presence of FFRWOS. FFRWOS was documented in ten (21.3%) patients. Compared to other lead locations, the right atrial appendage lead position was most frequently associated with FFRWOS (7/27 vs 3/21, P < 0.05). Patients with FFRWOS had significantly more treated and nontreated atrial episodes, many of which were judged to have been detected inappropriately. In one case, inappropriate atrial antitachycardia pacing due to R wave oversensing triggered sustained ventricular tachycardia, terminated eventually with a high energy shock. In dual chamber ICDs, FFRWOS may represent a frequent phenomenon possibly leading to serious consequences. For atrial leads, a lateral atrial wall position seems to be preferable. In most cases, FFRWOS can be eliminated by optimization of atrial sensing parameters. Given the possibility of ventricular proarrhythmia with atrial pacing therapy, the capability of ventricular backup defibrillation in respective devices is at least reassuring.

Significance of supraventricular tachyarrhythmias in patients with implanted pacing cardioverter defibrillators.

Eighty-six patients were treated with an implantable cardioverter defibrillator (ICD) because of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). In 27 patients an epicardial system was used, in 59 patients a transvenous system with a subcutaneous patch electrode was implanted. During a mean follow-up time of 17 +/- 9 months, inappropriate activations of the ICD due to supraventricular tachycardia were documented by Holter monitoring in 14 patients (16%). In 8 patients paroxysmal atrial fibrillation (AF), in 2 patients chronic AF, in 1 patient atrial flutter, and in 3 patients sinus tachycardia triggered antitachycardia pacing functions (12 patients) or internal defibrillation (2 patients). In 3 patients (5%) VT was induced by inappropriate antitachycardia pacing. In an additional 18 patients (21%) inappropriate activation of antitachycardia functions due to atrial tachyarrhythmias were suspected based on telemetry readouts or the patient's history. Inappropriate activation of ICD therapy triggered by intermittent supraventricular tachyarrhythmias is common. Further improvements of detection algorithms for supraventricular tachycardia are required in future device generations.