Ventricular Fibrillation Zone Research Articles

Inappropriate therapies in modern implantable cardioverter-defibrillators: A propensity score–matched comparison between single- and dual-chamber discriminators in single-chamber devices THe sINGle lead Study (THINGS Study)

BackgroundIn patients with implantable cardioverter-defibrillators (ICDs), inappropriate therapies (ITs) are often caused by supraventricular tachyarrhythmias (SVTs). ObjectiveWe aimed to estimate the incidence of IT in modern single-lead ICDs. MethodsThe THINGS study enrolled patients with single-lead ICDs with 2 SVT discrimination modalities: dual chamber (DC) with an atrial floating dipole or single chamber (SC) with morphology criterion. All devices were programmed with 2-zone therapy: ventricular tachycardia (VT) zone from 170 beats/min with ≥15 seconds (≥36 beats) detection time and SVT discriminators; and ventricular fibrillation (VF) zone from 214 beats/min with ≥7 seconds (≥24 beats) detection time. The primary end point was the first occurrence of IT, adjudicated by an independent board. ResultsA total of 526 patients (median age, 66 years; 83% male), 183 (34.8%) with DC and 343 (65.2%) with SC discrimination, were observed for a median of 2.2 years. The incidence rate of IT was 4.2% (95% confidence interval [CI], 2.7%–6.4%) at 1 year and 7.1% (95% CI, 5.0%–9.9%) at 2 years. Younger age (adjusted hazard ratio, 0.97; 95% CI, 0.95–0.99; P = .013) and history of atrial fibrillation (adjusted hazard ratio, 2.67; 95% CI, 1.30–5.46; P = .007) were significantly associated with increased IT risk. In a propensity score–matched comparison, DC discrimination showed a trend toward reduced IT rates compared with SC discrimination in the VT zone (1-year incidence, 1.8% vs 3.5%; P = .105). ConclusionHigh-rate VF cutoff and prolonged detection time programming resulted in a low IT rate in single-lead ICD patients with modern SVT discriminators. A trend favoring the DC system was observed in the VT zone.

Safety and feasibility concerns of radiotherapy in the presence of subcutaneous implantable cardioverter-defibrillator

Abstract Introduction Radiotherapy (RT) in patients with cardiac implantable electronic devices (CIED) is performed increasingly more frequently. Currently, there is no evidence, whether RT in patients with subcutaneous implantable cardioverter-defibrillator (sICD) is feasible and safe. Purpose To perform the first in-vitro analyses using a model of left lung cancer treated with stereotactic body radiotherapy (SBRT) with the presence of an sICD. Methods Three functional sICDs explanted from patients following the heart transplant underwent RT. In one device (No º3), the lead had to be cut during explantation at ~ 3 cm from the tip. A computed tomography-based SBRT plan was calculated for a left lung tumor (located 3.5 cm from the sICD). Three fractions of 18 Gy with a nominal energy of 6 MV were delivered, and the maximum dose calculated for the sICD was 3.5 Gy. Each sICD and lead were placed on an anthropomorphic phantom in the nominal location. The intervals between fractions were 7 days. The next step was a direct irradiation of the sICD with an open-field RT with 25 fractions of 2 Gy, then 2 of 20 Gy, 1 of 40 Gy, and a final fraction of 100 Gy. Before and after each fraction, the devices were interrogated, and to verify whether RT affects the devices in the possibly least optimistic clinical scenario, high-voltage therapies were turned on for each fraction and off for the intervals between them. Results A major depletion in the battery percentage (from 88% to 16%) between the first and second fraction of RT in device No. 2 was observed, while in two other devices, major reductions in the device battery longevity were observed after the third fraction of RT (from 38% to 14% and from 60% to 15%, respectively). The estimated doses for sICDs in those stages of RT were respectively 1.2 Gy, 3.5 Gy, and 3.5 Gy. Due to a significant drop of the battery longevity in device No 2º, only two remaining sICD underwent the open-field RT. During the direct irradiation, an unannounced shock was delivered during the interrogation directly after the 14th fraction of 2 Gy, in a device with a macroscopically intact lead. An external interference was demonstrated, which was interpreted as an arrhythmia in the ventricular fibrillation zone. The complete device reset occurred in both devices after having received approximately 195 Gy. Conclusions The presented findings strongly indicate an association between RT and the malfunction of the sICD occurring in the anthropomorphic phantom model of left lung tumor, as well as the risk of inappropriate shocks during the open-beam direct radiation on the devices.Battery longevities before and after RT

Right ventricular function is a predictor for sustained ventricular tachycardia requiring anti-tachycardic pacing in arrhythmogenic ventricular cardiomyopathy: insight into transvenous vs. subcutaneous implantable cardioverter defibrillator insertion.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) patients develop ventricular arrhythmias (VAs) responsive to anti-tachycardia pacing (ATP). However, VA episodes have not been characterized in accordance with the device therapy, and with the emergence of the subcutaneous implantable cardioverter defibrillator (S-ICD), the appropriate device prescription in ARVC remains unclear. Study aim was to characterize VA events in ARVC patients during follow-up in accordance with device therapy and elicit if certain parameters are predictive of specific VA events. This was a retrospective single-centre study utilizing prospectively collated registry data of ARVC patients with ICDs. Forty-six patients were included [54.0 ± 12.1 years old and 20 (43.5%) secondary prevention devices]. During a follow-up of 12.1 ± 6.9 years, 31 (67.4%) patients had VA events [n = 2, 6.5% ventricular fibrillation (VF), n = 14], 45.2% VT falling in VF zone resulting in ICD shock(s), n = 10, 32.3% VT resulting in ATP, and n = 5, 16.1% patients had both VT resulting in ATP and ICD shock(s). Lead failure rates were high (11/46, 23.9%). ATP was successful in 34.5% of patients. Severely impaired right ventricular (RV) function was an independent predictor of VT resulting in ATP (hazard ratio 16.80, 95% confidence interval 3.74-75.2; P < 0.001) with a high predictive accuracy (area under the curve 0.88, 95%CI 0.76-1.00; P < 0.001). VA event rates are high in ARVC patients with a majority having VT falling in the VF zone resulting in ICD shock(s). S-ICDs could be of benefit in most patients with ARVC with the absence of severely impaired RV function which has the potential to avoid consequences of the high burden of lead failure.

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

Ventricular arrhythmia detection for contemporary Biotronik and Abbott implantable cardioverter defibrillators with markedly prolonged detection in Biotronik devices.

Implantable cardioverter defibrillators (ICDs) are typically programed with both ventricular tachycardia (VT) and ventricular fibrillation (VF) treatment zones. Biotronik and Abbott ICDs do not increment the VT counter when the tachycardia accelerates to the VF zone, which could result in a prolonged delay in tachycardia detection. Patients with Biotronik and Abbott ICDs receiving care at Veterans Affairs facilities in Northern California were identified. Patient information and device tracings for patients with any ICD therapies were examined to assess for possible delayed tachycardia detection. Among 52 patients with Biotronik ICDs, 8 (15%) experienced appropriate ICD therapy over a median follow-up of 29months. Among 68 patients with Abbott ICDs, 26 (38%) experienced appropriate ICD therapy over a median follow-up of 83months. Three of the patients with Biotronik ICDs who received appropriate therapy experienced a delay in VT/VF detection due to the tachycardia rate oscillating between the VT and VF treatment zones (longest 31.2s on detection), compared with four of the patients with Abbott ICDs (longest 4.1s on the detection and 8s on redetect). One of the patients with a Biotronik ICD experienced recurrent syncope associated with delayed detection and another died on the day of delayed detection. One of the patients with an Abbott ICD experienced syncope. Because contemporary Biotronik and Abbott ICDs freeze the VT counters when tachycardia is in the VF zone, ICD therapies can be markedly delayed when the tachycardia oscillates between the VT and VF zone.

Impact of programming in a large cohort of implantable cardioverter-defibrillator patients with long-term follow-up: findings from the UMBRELLA study

Abstract Background Data about the penetration of current ICD programming recommendations in a real-life setting are lacking. Purpose To assess how modern-era ICD patients are programmed and to study the relationship between programming and ICD therapies in large cohort of Spanish patients. Methods UMBRELLA (NTC01561144) is a prospective, multicentre, nationwide study of ICD patients followed by remote monitoring. ICD programming was performed according to regular clinical practice at each site and it was automatically stored through the remote monitoring system. Arrhythmic events were also automatically stored and reviewed in a blinded process performed by a committee of experts. The study outcomes were appropriate ICD therapies and inappropriate shocks (IS). Results The study population consisted of 4296 patients implanted with an ICD from 2005 to 2017 (61.9±12.9 years, ischaemic cardiomyopathy in 50% and dilated cardiomyopathy in 22.7% of population). Primary prevention (PP) was the main indication (64.2%). At implant, 66.4% of patients had LVEF ≤35% and 18.9% had LVEF &amp;gt;50%. Majority of patients (52.4%) presented with narrow QRS (&amp;lt;120 ms), while QRS width was &amp;gt;150 ms in 26.7% of population. Single-chamber, dual-chamber and cardiac resynchronization therapy-defibrillator (CRT-D) devices were implanted in 47.2%, 22.6% and 30.2% of population, respectively. At first remote transmission, single zone detection programming was only enabled in 43.2% of population (52.6% among PP patients), while the remaining patients (56.8%) had a ventricular tachycardia zone enabled, despite the ventricular fibrillation (VF) zone (73.8% among secondary prevention patients). Delayed high-rate detection programming (detection interval &amp;lt;320 ms and NID ≥30/40 within the VF zone) was only enabled in 39.7% of population. Adherence to programming recommendations significantly increased through the study period (Table). During a mean follow-up of 46.6±27.3 months, 16,067 episodes of sustained ventricular arrhythmia (SVA) occurred. An appropriate ICD therapy was delivered to 85.7% (n=13,767) episodes of SVA in 1173 patients (event rate: 27.3%). In multivariate analysis, delayed high-rate detection in PP patients (HR: 0.76, 95% CI: 0.61–0.94) (Figure) and single-zone programming (HR: 0.69, 95% CI: 0.59–0.81) were associated to lower risk of appropriate ICD therapies. At follow-up, 257 patients (6% of population) experienced an IS. The incidence of IS did not differ according to type of device (6.4% vs. 6.2% vs. 5.2% for single-, dual-chamber, and CRT-D, respectively, p=0.321). In multivariate analysis single-zone programming (HR: 0.71, 95% CI: 0.51–0.97) was the only ICD setting independently related to a lower risk of IS. Conclusions Implementation of current programming recommendations is required in modern-era ICD patients. Funding Acknowledgement Type of funding sources: None. Figure 1Table 1

Single- vs dual-chamber ICDs to prevent from inappropriate shocks: the debate is still alive

Abstract Background The efficacy of dual-chamber implantable cardioverter defibrillators (ICDs) in preventing from inappropriate shocks (IS) is still a matter of debate. Purpose To compare the risk of IS among single- and dual-chamber ICDs in a cohort of heart failure (HF) patients carrying a prophylactic device. We aimed to focus on the relationship between programming and discriminators, and the risk of IS in a large cohort. Methods All HF patients with left ventricle ejection fraction &amp;lt;35% undergoing a prophylactic ICD-only implant were collected from the multicentre, prospective and nationwide UMBRELLA study. ICD programming was performed according to regular clinical practice at each site and. ICD setting and arrhythmic events occurring during the study period were automatically stored through the remote monitoring system. An experts committee analysed in a blinded manner all electrograms coming from the arrhythmic events. Results From 2006 to 2015, 782 patients implanted with an ICD were analysed (537 patients (68.7%) with single-chamber ICDs and 245 patients (31.3%) with dual-chamber ICDs). During a mean follow-up of 4.35±2 years, 109 IS were delivered in 49 patients. IS occurred in 7.8% (n=42) of patients carrying single-chamber ICDs and in 2.9% (n=7) of dual-chamber carriers (p=0.001). A propensity score matched analysis was performed. The matched cohort was composed by 110 well-balanced (regarding baseline characteristics and programming) patients. In the weighted sample, dual-chamber ICDs were related to lower rates of IS (Figure 1) as compared to single-chamber devices (0.9% vs. 11.8%, p≤0.001). Among programming the following ICD settings correlated to lower risk of IS: ≥30 of 40 intervals detection within ventricular fibrillation (VF) zone (HR=0.47; p=0.018), a programmed ATP-capable zone enabled through VF zone (HR=0.54; p=0.038), morphology discriminator (Wavelet®) (HR=0.42; p=0.032), and the specific dual-chamber discriminator (PR Logic®) (HR=0.28; p=0.004). After multivariable Cox regression analysis including clinical variables and device settings, PR Logic® discriminator was the only programming parameter independently related to a lower risk of IS (HR=0.18, CI 0.06–0.48, p=0.001). Conclusions In our nationwide cohort of primary prevention ICD-only patients, dual-chamber devices were associated with a lower risk of IS. ICDs equipped with PR Logic® discriminator might be useful to prevent from IS. Funding Acknowledgement Type of funding sources: None. Programming in the matched populationFigure 1

Impact of an adaptive CRT optimization algorithm on the risk of life-threatening ventricular arrythmias of heart failure patients

Abstract Introduction Adaptive cardiac resynchronization therapy (aCRT) algorithm provides ambulatory CRT optimization and synchronized left-ventricular pacing instead of conventional biventricular pacing. Purpose To analyze the impact of aCRT on the risk of life-threatening ventricular arrythmia (VA) in patients with concomitant defibrillator therapy. Methods Symptomatic HF patients, in sinus rhythm, with LVEF ≤35% and QRS complex ≥130 ms undergoing first CRT-defibrillator (CRT-D) implant were collected from the multicentre, prospective and nationwide UMBRELLA study (2012–2017). All device information was automatically stored and collected through the remote monitoring system. An experts committee analysed in a blinded manner all electrograms. The endpoint was first appropriate therapy (AT) delivered within ventricular fibrillation zone at 12-months follow-up. Results 206 patients were collected (66.1±8.7 years; 73.3% male). Fifty nine patients composed the aCRT group and 147 composed the non-aCRT group. At implant, LBBB was present in 93% of patients, functional class III or IV in 69.9%, non-ischemic HF in 63.1% of patients and mean LVEF was 26.5±5.6%. Optimal medical treatment was achieved in a majority (B-blockers in 92%; RAASi in 89% and MRA in 72.2%). The percentage of ventricular pacing through 12 months was 96.1±9.4% in non-aCRT patients and 97.5±2.7% in aCRT patients (p=0.261). At 1-year of follow-up, 16 patients were delivered an AT (event rate: 7.8%). Most of these episodes (n=14) were due to sustained monomorphic ventricular tachycardia while the rest were caused by sustained polymorphic ventricular tachycardia/VF. A lower incidence of AT was observed in aCRT patients (3.4%) compared to non-aCRT patients (9.5%) but with no statistical differences (OR=0.33, CI 0.07–1.51, p=0.155). Conclusions In patients undergoing CRT provided by aCRT algorithm the risk of malign VA after 1-year of follow-up was low. Randomized studies are needed to clarify the impact of this dynamic algorithm on the arrhythmic risk of HF patients. Funding Acknowledgement Type of funding source: None

SVT discrimination algorithms significantly reduce the rate of inappropriate therapy in the setting of modern-day delayed high-rate detection programming.

Contemporary implantable cardioverter-defibrillator (ICD) programming involving delayed high-rate detection and use of supraventricular tachycardia (SVT) discriminators has significantly reduced the rate of inappropriate shocks. The extent to which SVT algorithms alone reduce inappropriate therapies is poorly understood. PainFree SST enrolled 2770 patients with a single- or dual-chamber ICD or cardiac resynchronization defibrillator. Patients were followed for 22 ± 9 months with SVT discriminators on in 96% of patients. Sustained ventricular tachyarrhythmias and SVT episodes were adjudicated by an independent physician committee. For this analysis, all episodes were subjected to postprocessing computer simulation with SVT discriminators off with and without delayed high-rate detection criteria (ventricular fibrillation zone only, 30/40 at 320 ms). There were 3282 adjudicated SVT episodes of which 115 resulted in an ICD shock and 113 received only ATP (2-year inappropriate shock and therapy rates of 3.1% and 4.1%). Therapy was appropriately withheld for the remaining 3054 SVT episodes. With both SVT discriminators and delayed high-rate detection simulated off, the 2-year inappropriate therapy rate would have been 22.9% (hazard ratio [HR] = 6.24; 95% confidence interval [CI]: 5.20-7.49). With SVT discriminators simulated off and delayed high-rate detection simulated on in all patients, the 2-year rate would have been 6.4% (HR = 1.63; CI: 1.44-1.85). The use of SVT discriminators has a significant role in reducing the rate of inappropriate ICD therapy even in the setting of delayed high-rate detection settings. Deactivating SVT discriminators would have resulted in an overall increase in the inappropriate ICD therapy rate by 63% and 524% with and without delayed high-rate detection programming, respectively.

Analysis of arrhythmic episodes in patients with implanted cardioverter defibrillators and a high risk of sudden cardiac death

Aim. To analyze arrhythmic events, according to the programming data of implanted cardioverter defibrillators (ICD), with the view of minimizing shock effects. Material and methods. The study included examination materials of 207 patients with implanted ICD/cardiac resynchronization therapy (CRT) devices. Patients were divided according to the types of implanted devices: 65 patients (31%) — CRT, 75 patients (36%) — single-chamber ICD, 67 patients (33%) — dual-chamber ICD. In the patient structure there were 168 patients (81%) with primary and 39 patients (19%) with secondary prevention of sudden cardiac death (SCD). In order to minimize the amount of shock effects applied, the following defibrillator programming techniques were used: prolongation of the duration of tachycardia detection in the ventricular fibrillation (VF) zone from the nominal parameters and changing the plan of applying antitachycardia stimulation (ATS) in VF zone (the number of stimuli in the exposure pack was increased and the stimulation interval was shortened by 10-20% in comparison with the initial parameters). To stop hemodynamically insignificant monomorphic ventricular tachycardia, shocks in the stopping pattern were disabled and only ATS was activated. Statistical processing of the obtained data was carried out using the “IBM SPSS Statistics 20” software. Results. The probability of shock and ATS effects in patients from the primary SCD prophylaxis group significantly increases in the presence of: ischemic cardiomyopathy (p=0,006) and severe ventricular extrasystoles (p=0,029).The absence of amiodarone therapy significantly increases the risk of shock effects in patients with implanted ICD for primary (p=0,002) and secondary prevention of SCD (p=0,02). In the vast majority of cases, appropriate shock effects were inflicted on patients with coronary artery disease and a history of myocardial infarction. On the contrary, in patients with dilated cardiomyopathy, clinically inappropriate shocks prevailed, most often performed on atrial fibrillation ( р &lt;0,001). In all cases of life-threatening ventricular arrhythmias, the effects of ICD and CRT were effective for their relief. There were no suddenly dead patients in the study. There were no negative effects of the proposed programming techniques. Against the background of increased tachycardia detection time, 48% of all arrhythmias stopped on their own without worsening. In patients with CRT devices, founded and unfounded responses were significantly less common than among patients with ICD. The main causes of inappropriate responses were: atrial arrhythmias in the VF detection zone ( р &lt;0,001), standard detection time in the VF zone ( р &lt;0,001) restrictions on the use of atrial ventricular arrhythmias discriminator ( р &lt;0,018). Conclusion. The prolongation of the tachycardia detection duration in the VF zone and the optimization of ATS lead to a decrease in shock ICD effects.

Taquicardias ventriculares rápidas en pacientes con desfibrilador implantable: reducción de choques mediante terapia antitaquicárdica antes y durante la carga

Introduction and objectivesFast ventricular tachycardias in the ventricular fibrillation zone in patients with an implantable cardioverter-defibrillator are susceptible to antitachycardia pacing (ATP) termination. Some manufacturers allow programming 2 ATP bursts: before charging (BC) and during (DC) charging. The aim of this study was to describe the safety and effectiveness of ATP BC and DC for fast ventricular tachycardias in the ventricular fibrillation zone in patients with an implantable cardioverter-defibrillator in daily clinical practice. MethodsData proceeded from the multicenter UMBRELLA trial, including implantable cardioverter-defibrillator patients followed up by the CareLink monitoring system. Fast ventricular tachycardias in the ventricular fibrillation zone until a cycle length of 200ms with ATP BC and/or ATP DC were included. ResultsWe reviewed 542 episodes in 240 patients. Two ATP bursts (BC/DC) were programmed in 291 episodes (53.7%, 87 patients), while 251 episodes (46.3%, 153 patients) had 1 ATP burst only DC. The number of episodes terminated by 1 ATP DC was 139, representing 55.4% effectiveness (generalized estimating equation-adjusted 60.4%). There were 256 episodes terminated by 1 or 2 ATP (BC/DC), representing 88% effectiveness (generalized estimating equation-adjusted 79.3%); the OR for ATP effectiveness BC/DC vs DC was 2.5, 95%CI, 1.5-4.1; P <.001. Shocked episodes were 112 (45%) for ATP DC vs 35 (12%) for ATP BC/DC, representing an absolute reduction of 73%. The mean shocked episode duration was 16seconds for ATP DC vs 19seconds for ATP BC/DC (P=.07). ConclusionsThe ATP DC in the ventricular fibrillation zone for fast ventricular tachycardia is moderately effective. Adding an ATP burst BC increases the overall effectiveness, reduces the need for shocks, and does not prolong episode duration.Full English text available from: www.revespcardiol.org/en

Prospective Randomized Evaluation of Implantable Cardioverter‐Defibrillator Programming in Patients With a Left Ventricular Assist Device

BackgroundVentricular arrhythmias are common in patients with left ventricular assist devices (LVADs) but are often hemodynamically tolerated. Optimal implantable cardioverter defibrillator (ICD) tachy‐programming strategies in patients with LVAD have not been determined. We sought to determine if an ultra‐conservative ICD programming strategy in patients with LVAD affects ICD shocks.Methods and ResultsAdult patients with an existing ICD undergoing continuous flow LVAD implantation were randomized to standard ICD programming by their treating physician or an ultra‐conservative ICD programming strategy utilizing maximal allowable intervals to detection in the ventricular fibrillation and ventricular tachycardia zones with use of ATP. Patients with cardiac resynchronization therapy (CRT) devices were also randomized to CRT ON or OFF. Patients were followed a minimum of 6 months. The primary outcome was time to first ICD shock. Among the 83 patients studied, we found no statistically significant difference in time to first ICD shock or total ICD shocks between groups. In the ultra‐conservative group 16% of patients experienced at least one shock compared with 21% in the control group (P=0.66). There was no difference in mortality, arrhythmic hospitalization, or hospitalization for heart failure. In the 41 patients with CRT ICDs fewer shocks were observed with CRT‐ON but this was not statistically significant: 10% of patients with CRT‐ON (n=21) versus 38% with CRT‐OFF (n=20) received shocks (P=0.08).ConclusionsAn ultra‐conservative programming strategy did not reduce ICD shocks. Programming restrictions on ventricular tachycardia and ventricular fibrillation zone therapy should be reconsidered for the LVAD population. The role of CRT in patients with LVAD warrants further investigation.Clinical Trial RegistrationURL: https://www.clinicaltrials.gov. Unique identifier: NCT01977703.

Shock Reduction With Antitachycardia Pacing Before and During Charging for Fast Ventricular Tachycardias in Patients With Implantable Defibrillators

Introduction and objectivesFast ventricular tachycardias in the ventricular fibrillation zone in patients with an implantable cardioverter-defibrillator are susceptible to antitachycardia pacing (ATP) termination. Some manufacturers allow programming 2 ATP bursts: before charging (BC) and during (DC) charging. The aim of this study was to describe the safety and effectiveness of ATP BC and DC for fast ventricular tachycardias in the ventricular fibrillation zone in patients with an implantable cardioverter-defibrillator in daily clinical practice. MethodsData proceeded from the multicenter UMBRELLA trial, including implantable cardioverter-defibrillator patients followed up by the CareLink monitoring system. Fast ventricular tachycardias in the ventricular fibrillation zone until a cycle length of 200ms with ATP BC and/or ATP DC were included. ResultsWe reviewed 542 episodes in 240 patients. Two ATP bursts (BC/DC) were programmed in 291 episodes (53.7%, 87 patients), while 251 episodes (46.3%, 153 patients) had 1 ATP burst only DC. The number of episodes terminated by 1 ATP DC was 139, representing 55.4% effectiveness (generalized estimating equation-adjusted 60.4%). There were 256 episodes terminated by 1 or 2 ATP (BC/DC), representing 88% effectiveness (generalized estimating equation-adjusted 79.3%); the OR for ATP effectiveness BC/DC vs DC was 2.5, 95%CI, 1.5-4.1; P <.001. Shocked episodes were 112 (45%) for ATP DC vs 35 (12%) for ATP BC/DC, representing an absolute reduction of 73%. The mean shocked episode duration was 16seconds for ATP DC vs 19seconds for ATP BC/DC (P=.07). ConclusionsThe ATP DC in the ventricular fibrillation zone for fast ventricular tachycardia is moderately effective. Adding an ATP burst BC increases the overall effectiveness, reduces the need for shocks, and does not prolong episode duration.

Spectrum and Outcome of Patients Who Have Undergone Implantation of an Implantable Cardioverter Defibrillator After Aborted-Sudden Cardiac Arrest

Most of implantable cardioverter defibrillator (ICD) secondary prevention studies have been published 2 decades ago. We aimed to describe a contemporary cohort of patients who have undergone implantation of an ICD after an aborted-sudden cardiac arrest (SCA). We retrospectively evaluated consecutive patients referred to our centers between 2005 and 2013. Predictors of overall mortality or heart transplant were analyzed using Cox proportional hazards models. A total of 250 patients (76.4% male, 48.7 ± 16.7 years) were included (mean follow-up = 49.6 ± 35 months). The presence of a structural heart disease (SHD) was considered as the primary cause of the aborted-SCA in 160 patients (64%). In 90 patients (36%), no SHD was observed, with patients much younger (40.9 ± 16.2 years vs 53.0 ± 15.5 years in the SHD group, p < 0.0001). The 5-year estimated rates of death or heart transplant were 14.3% and 5.2% in the group with and without SHD, respectively (hazard ratio = 4.65, 95% confidence interval 1.40 to 15.6, p = 0.014). The 5-year estimated rates of appropriate ICD therapy in the ventricular fibrillation zone were 16.7% and 25.1% in patients without and with SHD (p = 0.24), respectively. Only left ventricular ejection fraction remained independently associated with mortality or heart transplant (hazard ratio = 0.94, 95% confidence interval 0.90 to 0.97, p = 0.0004). Overall, 69 patients (27.6%) experienced at least 1 ICD-related complication. In conclusion, compared with secondary prevention pivotal studies, the current patients who have undergone implantation of an ICD after aborted-SCA are younger, with a high proportion of structurally normal hearts. Compared with patients without SHD, who depicted a relatively favorable outcome, patients with SHD present a fourfold higher risk of death during follow-up. Reduced left ventricular ejection fraction remains the major influencing factor.

Initial Clinical Experience With a New Automated Antitachycardia Pacing Algorithm: Feasibility and Safety in an Ambulatory Patient Cohort.

Antitachycardia pacing (ATP) in implantable cardioverter-defibrillators (ICD) decreases patient shock burden but has recognized limitations. A new automated ATP (AATP) based on electrophysiological first principles was designed. The study objective was to assess the feasibility and safety of AATP in ambulatory ICD patients. Enrolled patients had dual chamber or cardiac resynchronization therapy ICDs, history of ≥1 ICD-treated ventricular tachycardias (VT)/ventricular fibrillation episode, or a recorded, sustained monomorphic VT. Detection was set to ventricular fibrillation number of intervals to detect=24/32, VT number of intervals to detect≥16, and a fast VT zone of 240 to 320 ms. AATP prescribed the components and delivery of successive ATP sequences in real time, using the same settings for all patients. ICD datalogs were uploaded every ≈3 months, at unscheduled visits, exit, and death. Episodes and adverse events were adjudicated by separate committees. Results were adjusted (generalized estimating equations) for multiple episodes. AATP was downloaded into the ICDs of 144 patients (121 men), aged 67.4±11.9 years, left ventricular ejection fraction 33.1±13.6% (n=137), and treated 1626 episodes in 49 patients during 14.5±5.1 months of follow-up. Datalogs permitted adjudication of 702 episodes, including 669 sustained monomorphic VT, 20 polymorphic VT, 10 supraventricular tachycardia, and 3 malsensing episodes. AATP terminated 39 of 69 (59% adjusted) sustained monomorphic VT in the fast VT zone, 509 of 590 (85% adjusted) in the VT zone, and 6 of 10 in the ventricular fibrillation zone. No supraventricular tachycardias converted to VT or ventricular fibrillation. No anomalous AATP behavior was observed. The new AATP algorithm safely generated ATP sequences and controlled therapy progression in all zones without need for individualized programing.

Antitachycardia pacing programming in implantable cardioverter defibrillator: A systematic review.

Implantable cardioverter defibrillator (ICD) programming involves several parameters. In recent years antitachycardia pacing (ATP) has gained an increasing importance in the treatment of ventricular arrhythmias, whether slow or fast. It reduces the number of unnecessary and inappropriate shocks and improves both patient’s quality of life and device longevity. There is no clear indication regarding the type of ATP to be used, except for the treatment of fast ventricular tachycardias (188 bpm-250 bpm) where it has been shown a greater efficacy and safety of burst compared to ramp; 8 impulses in each sequence of ATP appears to be the best programming option in this setting. Beyond ATP use, excellent clinical results were obtained with programming standardization following these principles: extended detection time in ventricular fibrillation (VF) zone; supraventricular discrimination criteria up to 200 bpm; first shock in VF zone at the maximum energy in order to reduce the risk of multiple shocks. The MADIT-RIT trial and some observational registries have also recently demonstrated that programming with a widespread use of ATP, higher cut-off rates or delayed intervention reduces the number of inappropriate and unnecessary therapies and improves the survival of patients during mid-term follow-up.

Very high rate programming in primary prevention patients with reduced ejection fraction implanted with a defibrillator: Results from a large multicenter controlled study

Programming implantable cardioverter-defibrillators (ICDs) with a high-rate therapy strategy has proven to be effective in reducing shocks and is associated with a reduced mortality. We sought to determine the impact of a very high rate cutoff programming strategy on outcomes in patients with a primary indication for an ICD due to reduced left ventricular ejection fraction. Using data from the multicenter French DAI-PP registry, this cohort-controlled study compared outcomes in 500 patients programmed with a very high rate cutoff (VH-RATE group: monitor zone 170-219 beats/min; ventricular fibrillation zone ≥220 beats/min with 13 ± 4 detection intervals) with 1500 matched control patients programmed with 1 or 2 therapy zone. All ICDs were implanted for primary prevention in patients with systolic dysfunction. Risks of events were compared after propensity score matching of sex, age, ejection fraction, New York Heart Association class, cardiomyopathy, atrial fibrillation, and type of device. After a mean follow-up of 3.6 ± 2.3 years, VH-RATE programming was associated with a reduction of appropriate therapy risk (hazard ratio [HR] 0.40; 95% confidence interval [CI] 0.31-0.51; P < .0001) and inappropriate shock (HR 0.42; 95% CI 0.27-0.63; P < .0001). It was also associated with a decreased risk of sudden cardiac death (HR 0.43; 95% CI 0.17-0.99; P = .04) as compared with patients programmed with 2 therapy zones. There was no significant difference in overall survival between the groups. In patients implanted with an ICD in primary prevention with left ventricular dysfunction, very high rate cutoff programming (single therapy zone ≥220 beats/min) was associated with a 60% reduction of appropriate therapies as well as inappropriate shocks, without affecting mortality.

Implantable cardioverter-defibrillator programming and electrical storm: Results of the OBSERVational registry On long-term outcome of ICD patients (OBSERVO-ICD)

Electrical storm (ES) is defined as 3 or more episodes of ventricular fibrillation (VF) or ventricular tachycardia (VT) within 24 hours and is associated with increased cardiac and all-cause mortality. The purpose of this study was to test whether aggressive implantable cardioverter-defibrillator (ICD) programming can be associated with ES. The OBSERVational registry On long-term outcome of ICD patients (OBSERVO-ICD) is a multicenter, retrospective registry enrolling all consecutive patients undergoing ICD implantation from 2010 to 2012 in 5 Italian high-volume arrhythmia centers. Clinical history and risk factors were collected for all patients, as were ICD therapy-related variables such as detection zones and delays. The total number of arrhythmic episodes and therapies delivered by the ICD were collected through out-of-hospital visits and remote monitoring. The registry enrolled 1319 consecutive patients, of whom 62 (4.7%) experienced at least 1 ES during follow-up (median 39 months). Patients who experienced ES had a significantly lower VF detection zone (P = .002), more frequently had antitachycardia pacing therapies programmed off during capacitor charge (P = .001), and less frequently had an ICD set with delayed therapies for VT zones (P = .042) and VF zone (P = .036). Patients who experienced ES had a significantly higher incidence of death and heart failure-related death compared to patients with no ventricular arrhythmias and patients with unclustered VTs/VFs (P = .025 and P <.001, respectively). Patients with ES had a more aggressive ICD programming setup, including lower VF detection rates, shorter detection times, and no antitachycardia pacing therapies during capacitor charge. This kind of ICD programming potentially could increase the likelihood of ES and the related risk of death.

Safety and efficacy of high-rate cutoff and long detection interval ICD programming in secondary prevention patients.

Several trials demonstrated that a long detection interval and a high-rate cutoff reduced implantable cardioverter-defibrillator (ICD) therapy in primary prevention patients. However, only a few data are available for secondary prevention (SP) patients. The aim of this study was to evaluate whether these ICD programming would be effective in reducing ICD therapies in SP patients. We enrolled 65 SP patients under ICD or cardiac resynchronization therapy with the defibrillator programmed with the same setting (conventional setting). During follow-up, we changed detection rates in each zone; cycle length (CL) ≤400 to ≤370ms for ventricular tachycardia (VT) zone, CL ≤350 to ≤320ms for fast VT zone, CL ≤300 to ≤270ms for ventricular fibrillation (VF) zone, and number of intervals to detect ventricular tachyarrhythmia in VF zone: 12-24. We retrospectively compared the incidences of ICD therapies, syncope, and hospitalization due to slow VT under the detection rate between both settings. Median follow-up periods were 5.0 (interquartile range 2.5-7.8) and 2.5years (interquartile range 2.3-2.7) in conventional and strategic settings, respectively. The incidence of appropriate ATP and shock significantly decreased in strategic setting (conventional and strategic settings: 21.2 and 4.8 ATPs per year, respectively, OR 0.18, 95% CI 0.06-0.54, p=0.002, 26.1 and 7.8 shocks per year, respectively, OR 0.29, 95% CI 0.09-0.88, p=0.03). The incidence of overall inappropriate therapy significantly decreased (conventional and strategic settings: 17.6 and 2.8 therapies per year, respectively, OR 0.14, 95% CI 0.05-0.44, p=0.01). The incidence of syncope and slow VT was not significantly different between both settings. In conclusion, ICD programming-combined long detection interval with high-rate cutoff was effective in reducing appropriate shock and inappropriate therapy without increasing the incidence of syncope and slow VT in SP patients.

Relation between detection rate and inappropriate shocks in single versus dual chamber cardioverter-defibrillator--an analysis from the OPTION trial.

The programming of implantable cardioverter-defibrillators (ICDs) influences inappropriate shock rates. The aim of the study is to analyse rates of patients with appropriate and inappropriate shocks according to detection zones in the OPTION trial. All patients received dual chamber (DC) ICDs randomly assigned to be programmed either to single chamber (SC) or to DC settings including PARAD+ algorithm. In a post-hoc analysis, rates of patients with inappropriate and appropriate shocks were calculated for shocks triggered at heart rates ≥170 bpm (ventricular tachycardia zone) and at rates ≥200 bpm (ventricular fibrillation zone). In the SC group, higher rates of patients with total and inappropriate shocks were delivered at heart rates ≥170 bpm than at rates ≥200 bpm (total shocks: 21.1% vs. 16.6%; p = 0.002; inappropriate shocks: 7.6% vs. 4.5%, p = 0.016; appropriate shocks: 15.2% vs. 13.5%; p = n.s.). No such differences were observed in the DC group (total shocks: 14.3% vs. 12.6%; p = n.s.; inappropriate shocks: 3.9% vs. 3.6%; p = n.s.; appropriate shocks: 12.2% vs. 10.4%; p = n.s.). The higher frequency of patients with total shocks with SC settings than with DC settings that benefit from PARAD+ was driven by a higher percentage of patients with inappropriate shocks in the VT zone (170–200 bpm) in the SC population.