Cardioverter-defibrillator Therapy Research Articles

Efficacy of an implantable cardioverter-defibrillator in patients with diabetes and heart failure and reduced ejection fraction

BackgroundThe effect of implantable cardioverter-defibrillator (ICD) therapy in patients with heart failure with reduced ejection fraction (HFrEF) and diabetes is not fully elucidated.MethodsWe examined the effect of ICD therapy on sudden cardiac death, cardiovascular death and all-cause mortality, according to diabetes status at baseline in the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT). The outcomes were analyzed by use of cumulative incidence curves and Cox regressions models.ResultsOf the 1676 patients randomized to an ICD or placebo, 540 (32%) had diabetes at baseline. Patients with diabetes were slightly older (61 vs 58 years) and were more often in NYHA class III (37% vs 28%). ICD therapy did not reduce the risk of sudden cardiac death in HFrEF patients with diabetes (HR = 0.85; 95% CI 0.52–1.40); even though these patients had a higher risk of sudden cardiac death compared to patients without diabetes (HR = 1.73 95% CI 1.22–2.47). By contrast, ICD therapy did reduce sudden cardiac death in HFrEF patients without diabetes (HR = 0.26; 95% CI 0.15–0.46); Pinteraction=0.002. The findings for cardiovascular and all-cause death were similar.ConclusionICD therapy did not reduce the risk of sudden cardiac death (or, as a consequence, all-cause death) in HFrEF patients with diabetes. Conversely, an ICD reduced the risk of sudden death in patients without diabetes, irrespective of etiology.

Clinical Course of Dual-Chamber Implantable Cardioverter-Defibrillator Recipients followed by Cardiac Remote Monitoring: Insights from the LION Registry.

Patients receiving dual-chamber implantable cardioverter-defibrillator (DR-ICD) therapy are at risk of developing atrial arrhythmia because of the increased rate of ventricular pacing and the progression of heart failure. Remote monitoring (RM) may identify the patients at highest risk of adverse events such as atrial arrhythmias. A total of 283 patients with 91,632 remote transmissions during a 15-month follow-up (FU) period enrolled in the LION registry were analysed. The parameters retrieved included the pacing mode, lower rate limit, percentage of atrial (%AP) and ventricular pacing (%VP), and percentage of atrial arrhythmia burden (%AB). In 92.7% of patients, the devices were initially programmed in DDD(R) or DDI(R), with changes of the pacing mode in 19.3% only. The lower rate limit remained stable in 80.4% of patients. At the first transmission, 8.7% of patients suffered from RM-detected atrial arrhythmia, which reached 36% during FU. The %AP was not associated with increased AB (p = 0.67), but the %VP was different in patients developing RM-detected atrial arrhythmia (26.9% vs. 13.7%, p < 0.00001). The %VP increased in 105 patients (significance level of α = 0.05), and 11 patients crossed the border of 50% VP. The LION substudy supports the concept of using RM in a real-world DR-ICD population. Remote monitoring of DR-ICDs allows for the quantification of the course of the pacing parameters and AB. Based on these observations, device parameters can be adjusted and optimized.

Mechanistic implication of decreased plasma atrial natriuretic peptide level for transient rise in the atrial capture threshold early after ICD or CRT-D implantation.

Despite the use of steroid-eluting leads, a transient but not persistent rise in the atrial/ventricular capture threshold (TRACT/TRVCT) can occur early after pacemaker implantation in patients with sick sinus syndrome. This study aimed to assess the prevalence, predictors, and mechanisms of TRACT/TRVCT in patients with heart failure undergoing implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy (CRT) implantation. One hundred twenty consecutive patients underwent ICD (N = 70) or CRT (N = 50) implantation. Capture threshold was measured at implantation, 7-day, 1-month, and 6-month post-implantation. TRACT/TRVCT was defined as a threshold rise at 7days by more than twice the height of the threshold at implantation, with full recovery during follow-up. Atrial and brain natriuretic peptide (ANP and BNP) levels were measured before implantation. TRACT and TRVCT were observed in 13 (11%) and 10 (8%) patients, respectively. Patients with TRACT had lower ANP level (median 72 [42-105] vs. 99 [49-198] pg/mL, P = 0.06), lower ANP/BNP ratio (0.29 [0.20-0.36] vs. 0.50 [0.33-0.70], P < 0.01), lower atrial sensing amplitude (2.0 ± 0.8 vs. 2.7 ± 1.3mV, P = 0.02), and lower left ventricular ejection fraction (32 ± 12 vs. 40 ± 14%, P = 0.04) than those without TRACT. TRACT recovered within 1month, whereas TRVCT recovered within 6months. In multivariable analysis, ANP/BNP ratio was the only independent predictor of TRACT (OR, 0.018; 95% CI, 0.001-0.734; P = 0.034). Atrial degenerative change characterized by lower ANP/BNP ratio was associated with the occurrence of TRACT in patients with heart failure. TRVCT could also occur, but it required a longer recovery time than TRACT.

The wearable cardioverter defibrillator as a bridge to reimplantation in patients with ICD or CRT-D-related infections

BackgroundThe approach to treat device infection in patients with implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D) is a challenging procedure. Optimal treatment is complete extraction of the infected device. To protect these patients from sudden cardiac arrest while waiting for reimplantation and to avoid recurrent infection, a wearable cardioverter defibrillator (WCD) seems to be a valuable solution.Therefore, we investigated the management and outcome of patients with ICD or CRT-D infections using the WCD as a bridge to re-implantation after lead extraction procedures.MethodsWe conducted a retrospective study on consecutive patients who underwent ICD or CRT-D removal due to device-related local or systemic infections. All patients were prescribed a WCD at our center between 01/2012 and 10/2015. All patients returned to our outpatient clinic for regular ICD or CRT-D monitoring initially 1 and 3 months after reimplantation followed by 6-months intervals.ResultsTwenty-one patients (mean age 65.0 ± 8.0 years, male 76.2%) were included in the study. Complete lead extraction was achieved in all patients. While waiting for reimplantation one patient experienced a symptomatic episode of sustained ventricular tachycardia. This episode was converted successfully into sinus rhythm by a single 150 J shock.Mean follow-up time 392 ± 206 days, showing survival rate of 100% and freedom from reinfection in all patients.ConclusionThe WCD seems to be a valuable bridging option for patients with ICD or CRT-D infections, showing no recurrent device infection.

Living With Prophylactic ICD Therapy and the Risk of Sudden Cardiac Death: How Patients Negotiate Solutions and Problems.

Prophylactic implantable cardioverter defibrillator (ICD) therapy treats potentially lethal cardiac arrhythmias in patients who have not previously experienced such but are at considerable risk due to underlying heart disease. Most patients are unaware of their risk of sudden cardiac death (SCD) until the ICD is introduced to them. Thus, the problem of risk of death and the solution of ICD therapy are presented simultaneously. Based on ethnographic fieldwork in Danish hospitals, this article illustrates how clinicians narrate prophylactic ICD therapy as a benign therapy preventing risk of death and providing the good life. However, risk of SCD is not the most pressing problem for the patients. The article argues that the solution of ICD therapy ignores patients' experience of living with severe heart disease and introduces the risk of shock therapy. For patients, a good life does not equal absence of risk of death but a life without heart disease.

650Implanted cardioverter defibrillator (ICD) therapy in patients with suspected myocarditis: time of implantation and occurrence of ventricular arrhythmias

650Implanted cardioverter defibrillator (ICD) therapy in patients with suspected myocarditis: time of implantation and occurrence of ventricular arrhythmias

CMR in Phenotyping the Arrhythmic Substrate

The purpose of this review is to explore the role of cardiac magnetic resonance imaging (CMR) in the evaluation of myocardial disorders that can present with significant cardiac arrhythmias. In addition, we explore recent developments in the field of CMR in the evaluation of such conditions, such as T1 and T2 mapping techniques. The importance of CMR as a diagnostic tool in the evaluation of such conditions lies in the fact that in routine clinical practice these conditions are encountered relatively frequently, and often important clinical decisions are made based on the findings of cardiac investigations such as CMR, e.g., decisions surrounding revascularization or implantable cardioverter defibrillator (ICD) therapy. In fact, CMR is now included in many practice guidelines (American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines et al. in J Thorac Cardiovasc Surg, 142(6):e153–203, 2011; Authors/Task Force members et al. in Eur Heart J, 35(39):2733–79, 2014; Epstein et al. in Heart Rhythm, 5(6):934–55, 2008; Maron et al. in J Am Coll Cardiol, 42(9):1687–713, 2003) and is routinely used in the evaluation of cardiomyopathic and ischemic myocardial conditions in many institutions. Although late gadolinium enhancement (LGE)-CMR allows a very sensitive and reproducible qualitative assessment of myocardial replacement fibrosis, it is limited in regards to absolute quantification of myocardial fibrosis, and also, the assessment of diffuse fibrosis by CMR can be technically challenging. As a result, in recent years, T1 and T2 mapping techniques have been welcomed by the CMR community, as potential methods of quantitating myocardial fibrosis accurately. Areas of diffuse myocardial fibrosis have greater T1 values (by about 10–20%) than normal tissue, before intravenous Gd is given. Post-Gd administration, T1 values are lower than normal in diffuse myocardial fibrosis. Thus, using this technique maps can be generated that explore the myocardium in detail and can detect early myocardial fibrosis, often before the presence of LGE. T2-weighted CMR identifies myocardial edema before the onset of irreversible ischemic injury and has shown to have value in risk-stratifying patients with chest pain (Eitel and Friedrich in J Cardiovasc Magn Reson, 13:13, 2011). Clinical acceptance of T2-weighted CMR has, however, been limited by well-known technical problems associated with existing techniques. T2 quantification using T2 mapping in the future should overcome these problems. Both T1 and T2 mapping techniques are discussed in further detail below. The assessment of infarct heterogeneity, as measured by peri-infarct zone (PIZ) mass and percentage PIZ (%PIZ), as compared to normal myocardium, is a valuable CMR tool for the assessment of tissue characteristics in the peri-infarct region (Morgan and Kwong in Curr Treat Options Cardiovasc Med, 17(11):53, 2015). It has recently been shown to have useful prognostic information (Watanabe et al. in Circ Cardiovasc Imaging, 7(6):887–94, 2014) in patients with coronary artery disease (CAD) and left ventricular (LV) dysfunction referred for CMR. This is discussed in further detail below. A recent paper by Neilan et al. (JACC Cardiovasc Imaging, 8(4):414–23, (2015)) studied 137 patients who underwent CMR post-resuscitated cardiac arrest and found that in cases where the cause of sudden cardiac death (SCD) was not initially clear, the use of CMR provided a diagnosis in 104 patients (76%). In a multivariable analysis, the strongest predictors of recurrent events were the presence and the extent of LGE (p < 0.001). In summary, this paper, through recent evidence and clinical examples, explores those myocardial conditions which pose a significant clinical issue in the form of potentially dangerous cardiac dysrhythmias. Early detection of predictive myocardial characteristics beyond the traditional risk factors has been welcomed by cardiology and cardiac imaging communities. Much work is in progress to make new methods such as T1 and T2 mapping more clinically available and applicable and to ensure that imaging time is not lengthened beyond that which is comfortable for the patient.

Off-line analysis of electro-anatomical mapping in ventricular arrhythmias.

Sudden cardiac death due to ventricular tachycardia (VT) is a major health issue in patients with structural heart disease and depressed ejection fraction. If from one side, implantable cardioverter defibrillator (ICD) therapy has significantly improved survival of these patients, on the other hand, it has led to frequent ICD shocks as an emerging problem, being associated with poor quality of life, frequent hospitalizations and increased mortality. Scar-related re-entry due to the coexistence of surviving myocardial fibers within fibrotic tissue is the most common mechanism subtending VT both in ischemic and non-ischemic cardiomyopathies. In the last two decades, continuous efforts to determine VT mechanisms and effectively prevent and treat VT with a substrate-based approach has benefit from off-line analysis of data coming from invasive electroanatomical mapping as well as from noninvasive imaging modalities such as cardiac magnetic resonance able to identify the arrhythmic substrate. In this review, we walk over again established methods for VT substrate characterization and we present possible applications of new emerging technologies.

Ventricular Arrhythmia-Free Survival Following Therapeutic Hypothermia in Patients with Sudden Cardiac Death Due to Ventricular Tachycardia or Fibrillation

Background: The potential benefits of implantable cardioverter-defibrillator (ICD) therapy in patients with sudden cardiac death (SCD) treated with therapeutic hypothermia (TH) have not been well studied. Methods: Incidence of recurrent non-sustained ventricular arrhythmia, ICD therapy, and death were ascertained in 64 consecutive survivors of SCD due to ventricular fibrillation or tachycardia, who were treated with TH. Follow-up was 31.5 +/- 3.3 months in 41 ICD recipients and 36.3 +/- 3.9 months in 23 patients who did not receive an ICD due to the presence of a reversible cause of cardiac arrest, an acute myocardial infarction in 87%. Results: Combined incidence of ventricular arrhythmia, ICD therapy, or death in patients who underwent ICD placement (21.9%) were similar to overall mortality in the patients who did not receive an ICD (21.7%, p = 0.752). ICD placement was associated with a significant mortality benefit; 95.1% survival in ICD recipients vs. 78.3% in the no-ICD group (p = 0.038). Electrocardiographic findings of ST segment elevation on admission were associated with increased event rate in ICD recipients (p = 0.039) and increased mortality in SCD patients who did not receive an ICD (p < 0.001). Other studied variables had no significant effect on the investigated outcomes. Conclusions: SCD survivors treated with TH are at increased risk for recurrent arrhythmic events and derive significant mortality benefit from ICD implantation. Increased mortality in revascularized SCD patients with acute coronary syndrome, thought to have a reversible cause of cardiac arrest, calls for prospective trials investigating utility of ICD in this vulnerable patient population.

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.

Replacement of implantable cardioverter defibrillators and cardiac resynchronization therapy devices: results of the European Heart Rhythm Association survey.

The aim of this EP Wire was to assess the management, indications, and techniques for implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy (CRT) device replacement in Europe. A total of 24 centres in 14 European countries completed the questionnaire. All centres were members of the European Heart Rhythm Association Electrophysiology Research Network. Replacement procedures were performed by electrophysiologists in 52% of the centres, by cardiologists in 33%, and both in the remaining centres. In the majority of centres, the procedures were performed during a short hospitalization (<2 days; 61.2%), or on an outpatient basis (28%). The overwhelming majority of centres reported that they replaced ICDs at the end of battery life. Only in a small subset (<10%) of patients with ICD for primary prevention and without ventricular tachycardia (VT) since implantation, ICD was not replaced. In inherited primary arrhythmia syndromes, 80% of the centres always replaced the ICD at the end of battery life. After VT ablation, only few centres (9%) explanted or downgraded the device that was previously implanted for secondary prevention, but only in those patients without new VT episodes. Patient's life expectancy <1 year was the most commonly reported reason (61%) to downgrade from a CRT-D to a CRT-P device. While warfarin therapy was continued in 47% of the centres, non-vitamin K oral anticoagulants were discontinued without bridging 24 h prior to replacement procedures in 60%. Finally, in 65% of the centres, VT induction and shock testing during ICD and CRT-D replacement were performed only in the case of leads with a warning or with borderline measurements. This survey provides a snapshot of the perioperative management, indications, and techniques of ICD and CRT device replacement in Europe. It demonstrates some variations between participating centres, probably related to local policies and to the heterogeneity of the ICD population.

Terapia de resincronización cardíaca con o sin cardiodesfibrilador versus terapia con desfibrilador automático, Pereira (Colombia): un estudio de cohorte

Objective: To evaluate survival in patients with cardiac resynchronization with or without cardioverterdefibrillator versus patients with implantable cardioverter- defibrillator alone. Materials and methods: Retrospective cohort, the primary end point was death from cardiac causes, the exposure was electrophysiological therapies, and the information sources were medical files and other records. Results: 70 elderly patients with functional devices; 82 % of them received optimized medical therapy. No significant association was found between survival of patients with cardiac resynchronization therapy with or without defibrillator and cardioverter-defibrillator therapy alone (log rank test, p = 0.54), but the former had a longer survival time (ANOVA p = 0.0012). The hazard ratio was 0.017 for day 371 and 0.15 for day 2169. Fourteen deaths occurred during the observation period, three of them from non-cardiac causes. Conclusion: Cardiac resynchronization therapy was associated with significantly longer survival time.

Abstract 12976: Malignant Type of Electrical Storm in Patients With an Implantable Cardiac Shock Device: Results From the Nippon Storm Study

Introduction: Electrical storm (ES) referred to as multiple device therapies is an important clinical problem in patients (pts) with an implantable cardiac shock device (ICSD), such as implantable cardioverter-defibrillator or cardiac resynchronization therapy device with defibrillator. Detailed clinical aspects of ES, however, remain unclear in the Asian large population. Methods: We analyzed the data of the Nippon Storm Study which was a prospective observational study and consisted of 1570 pts enrolled from 48 Japanese ICSD centers designed to clarify the clinical aspects of ES. The study population included 493 (31%) pts with ischemic heart disease (IHD) and 357 (23%) pts with dilated cardiomyopathy (DCM). They had a mean LVEF of 43±19 %. Results: ES occurred in 96 (6.4%) pts during a median follow-up of 28 (23-33) months. Compared to pts without ES, pts with ES showed a significantly lower left ventricular ejection fraction (43% vs 38 %, respectively, p=0.005). No significant difference regarding ES incidence was observed between pts with IHD and pts with DCM (log-rank p=0.77). A sub-analysis of the ES characteristics revealed that the mortality in patients with shock therapy during the first ES episode and those with the incidence of multiple episodes of ES during the follow-up was significantly higher than those without (12/18 vs 30/78; p=0.03, 12/18 vs 26/78, p&lt;0.01, respectively, Table). Conclusions: Shock therapy during the first ES episode and multiple episodes of ES were related to significantly higher mortality in pts with ICSD. There can be a malignant entity of ES.

31 The New National Institute for Health and Care Excellence (NICE) TA314 Guidelines may have a Significant Impact on Implantable Cardioverter Defibrillator (ICD) and Cardiac Resynchronisation Therapy (CRT) Implant Rates in District General Hospitals

Implantable cardiac electronic devices have revolutionised the management of heart failure in patients with a reduced ejection fraction, already on optimal medical therapy. In June 2014 the National Institute for Health and Care Excellence (NICE) released new guidelines (TA314) regarding implantable cardioverter defibrillator (ICD) and cardiac resynchronisation therapy (CRT) devices, updating and amalgamating previous guidelines (TA95 and TA120) that were released in January 2006 and May 2007 respectively. These new guidelines have broadened the indications for device implantation. We undertook an audit to investigate the impact of the new NICE guidelines on the potential implant rates of ICDs and CRT devices in patients diagnosed with heart failure. The clinical records of 396 consecutive patients admitted to hospital by the nurse-led heart failure service between 01/01/2013 and 15/08/2014 were reviewed. 48 patients died during their admission, 60 had no recorded ejection fraction, and 22 had an existing device and were excluded from further analysis. 291 patients were included in the analysis (Table 1). Applying the NICE TA95 and TA120 guidelines, a total of 46 devices were indicated: 10 ICDs, 25 CRT-P devices and 11 CRT-D devices. Applying the NICE TA314 guidelines, a total of 122 devices were indicated: 53 ICDs, 24 CRT-P devices and 45 CRT-D devices (Table 2). The 53 ICDs indicated by the new guidelines included patients with a left ventricular ejection fraction ≤35%, QRS duration The additional 76 devices recommended by the 2014 guidelines corresponded mainly to an increase in the number of ICD and CRT-D devices, which represent the more expensive and technically challenging systems to instal. The estimated cost of the 46 devices recommended by the NICE TA95 and TA120 guidelines was £317,418. The estimated cost of the 122 devices recommended by the NICE TA314 guidelines was £1,148,725. This represented a potential £831,307 increase in spend on implantable cardiac devices over the study period. In conclusion, the new NICE guidelines for device therapy look set to significantly increase the number of patients for whom an implantable cardiac device is indicated. This has significant financial implications at both a local and national level, as well as consequences for workforce planning and training.

A case study of a 59-year-old male with a cardiac variant of Anderson–Fabry disease

Anderson–Fabry disease is a rare X-linked lysosomal storage disorder caused by deficiency of the enzyme alpha-galactosidase A, affecting around 1 in 100,000 births. Waste products build up within cells throughout the body, affecting the heart, nervous system, skin, eyes and kidneys. In the cardiac variant, Anderson–Fabry disease the effects are limited to the heart, causing left-ventricular hypertrophy (LVH), valve defects and conduction abnormalities. Involvement of the heart contributes to morbidity and premature death because of increased prevalence of heart failure, arrhythmia and strokes. Utilising a case study of a 59-year-old male with the cardiac variant of Anderson–Fabry disease, this article discusses the treatment options available, including dual chamber pacing and implantable cardioverter defibrillator (ICD) therapy, in line with American Heart Association/American College of Cardiology (AHA/ACC) guideline criteria. Additionally research into enzyme replacement therapy (ERT) suggests treatment can reverse damage and prevent further damage occurring, therefore the use of ERT and its effectiveness in this case is also discussed.

Immediate electrical storm of Torsades de Pointes after CRT-D implantation in an ischemic cardiomyopathy patient

Cardiac resynchronization therapy with an implantable cardioverter-defibrillator (CRT-D) is the preferred treatment for patients with severe heart failure, dyssynchrony, and an increased risk of sudden cardiac death or for primary ventricular arrhythmia survivors. Rarely, left ventricular epicardial pacing can induce ventricular tachyarrhythmia rather than a beneficial effect. We describe an ischemic cardiomyopathy patient who underwent CRT-D therapy and developed sustained torsades de pointes (TdP) immediately after switching to biventricular pacing (BVP) mode. Here, TdP possibly developed owing to the change in the dispersion of repolarization of the left ventricle myocardium. The diagnosis and management of BVP-induced ventricular arrhythmia is discussed.

Abstract 12981: Does Volume Overload Predict Failed Antitachycardia Pacing Therapy for Ventricular Tachycardia in Patients With an Implantable Cardioverter-Defibrillator?

Introduction: Decompensated heart failure (HF) increases the risk of Implantable Cardioverter-Defibrillator (ICD) therapy. Patients with failed antitachycardia pacing (ATP) for ventricular tachycardia (VT) termination, requiring ICD shock, have been reported to have worse outcomes compared to patients with effective ATP. Thoracic impedance (TI) is a diagnostic parameter found in many ICDs. In Medtronic devices, TI is transformed into a OptiVol index, which when elevated, may represent volume overload and can predict increased HF events. Hypothesis: Whether an elevated OptiVol index is associated with failed ATP for VT termination in ICD patients. Method: Retrospective review of a prospectively collected database of patients followed in a dedicated ICD clinic, enrolled in remote ICD monitoring and who received therapy for VT termination by an OptiVol-capable ICD. The level of OptiVol was measured near the time of VT events. VT events were divided into two groups: OptiVol index &lt;100 and OptiVol≥100, and distributions of successful and unsuccessful ATP were compared. Results: We analyzed 121 VT episodes that occurred in 39 ICD patients who received ATP or shock to terminate VT. Mean age of patients was 68.4 +/- 10 years and 32 patients (78%) were male. Ischemic cardiomyopathy was present in 20 patients (48.8%). Successful ATP was more likely when the VT event was associated with an OptiVol index &lt;100 (74.5% successful vs 25.5% unsuccessful, P&lt;0.001); whereas a VT event associated with an OptiVol≥100 was more likely to be unresponsive to ATP compared with ATP success (66.7% unsuccessful vs 33.3% successful, p&lt;0.001). Conclusions: Failed ATP, requiring shock therapy for VT, is associated with a measure of volume overload (OptiVol) and could explain the worse outcomes observed in patients who require ICD shocks.

24Acute and long-term outcomes for patients undergoing radiofrequency catheter ablation of scar-related ventricular tachycardia by robotic catheter navigation

Introduction: Robotically-guided ablation offers theoretical advantages with greater catheter stability that can improve lesion depth. We performed a non-randomised comparison of patients undergoing ventricular tachycardia (VT) ablation either manually or using the Hansen robotic system. Methods: Consecutive patients with infarct-related scar underwent VT ablation using the Hansen system to assess feasibility, and were compared with patients undergoing manual VT ablation during the study period. All cases underwent a transeptal endocardial approach, using CARTO™ and irrigated catheter ablation guided by activation and entrainment manoeuvres if VT was sustained and tolerated, or substrate modification. The 6 month pre-ablation Implantable Cardioverter Defibrillator (ICD) therapy (Anti-tachycardia pacing (ATP) + shocks) was compared with the post ablation burden represented as a 6 monthly rate of each patient's total therapy burden during follow up ((6/follow-up duration (mths)) x total therapies post ablation)). Results: 25pts had VT ablations for infarct related scar during the study period. 13 pts had robotically guided ablation and 12 pts had manual ablation. Patients in both the robotic and manual groups had significantly impaired left ventricular function (EF 27±14% vs. 32 + /-11% respectively; p=0.32). The previous coronary revascularisationapproach, use of cardiac resynchronisation and amiodarone were similar in both groups. However 31% (4/13) of patients undergoing robotic ablation had been referred due to a failed manual approach and persisting high therapy burden as compared to 8% (1/12) redo procedures in the manual group (p=0.37). This was reflected by a trend towards higher pre-ablation therapy burden in the robotic as compared to the manual group (mean 312±566 vs. 11±9, p=0.08; median 11 vs. 9.5, p=0.50). In each group, 1 patient presented with slow incessant VT below the device therapy zone, and 1 patient had their device implanted post ablation. Post-procedure, the clinical VT was non-inducible in 85% (11/13) of the robotic group and in 92% (11/12) of the manual group. There were no peri-procedural complications. Mean follow-up was 23.5 months. Long-term mortality rates were similar (31%, 4/13 vs. 25%, 3/12; p=1.0). Post ablation, the 6 monthly therapy burden fell in both the robotic (mean reduction=290±560, median 3, p=0.047 Wilcoxon signed rank test) and manual (mean reduction=5.3±19, median 6.5, p=0.03) group. The overall reduction in therapy across all patients was 93% in the robotic and by 48% in the manual group. Conclusions: In this feasibility study, robotic VT ablation had a similar safety profile to manual ablation and a trend towards greater therapy reduction in a sicker cohort of patients. Table comparing acute procedural outcomes, 6 month pre/post ablation ICD therapies, and mortality rates between the robotic and manual groups. †Students t-test. §Fisher's exact test. ‖ Wilcoxon signed rank test. ![Graphic][1] [1]: /embed/inline-graphic-1.gif

CHANGING PROFILE OF YOUNG PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY RECEIVING IMPLANTABLE CARDIOVERTER DEFIBRILLATORS

BACKGROUND: Implantable cardioverter defibrillator (ICD) therapy is increasingly -utilized for prevention of sudden cardiac death (SCD) in young patients with hypertrophic cardiomyopathy. The indications and ICD technology have changed significantly over the past 20 years, with downsized generators and leads more suitable for smaller patients. OBJECTIVE: Describe changes in pattern of implant indications and appropriate therapies during the last two decades in young HCM patients. METHODS: Multicenter and retrospective review of young HCM patients who underwent ICD implant for HCM. RESULTS: 120 HCM patients 21 years of age (14.2 years [0.9-21.8]) who underwent ICD implant between 1990 and 2010 were included. During a median follow up of 2.4 years (0.1-13.4), 7 patients died and 7 underwent heart transplant. Appropriate and inappropriate therapies were delivered in 33/120 patients (28%) and 37/120 (31%), respectively. Freedom from appropriate shocks at 2, 4 and 6 years was 37%, 19% and 19% for secondary prevention patients (n1⁄424) compared to 84%, 72% and 63% for primary prevention patients (n1⁄496). Patients were divided according to decade of ICD implant date ([1990-2000] and [20012010]). Secondary prevention indications decreased between the two decades (34% vs 12%, p<0.01). For primary prevention patients, time from diagnosis to implant was longer (4.2 vs 1.8 yrs, p1⁄40.02) and age at implant was older (14.3 vs 12.6 yrs, p1⁄40.04) in the recent era compared to the older era. This occurred despite similar SCD risk profiles using classic risk factors (p1⁄40.7). Time to first appropriate shock for primary prevention patients was shorter in the earlier era (p1⁄40.04). CONCLUSION: Over the last 20 years, ICD implant in young HCM patients for primary prevention has increased. Risk scores are comparable between both decades, suggesting an increase in number of patients referred for primary prevention ICD implant rather than broadening of indications.

APPROPRIATE AND INAPPROPRIATE IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR THERAPY IN PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY: INCIDENCE AND PREDICTORS

Previously described risk factors (RF) serve as reference for recommending implantable cardioverter-defibrillator (ICD) therapy in hypertrophic cardiomyopathy (HCM) patients for sudden cardiac death (SCD) prevention. In consecutive HCM patients with ICD placement, we sought to study the incidence &