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Aims: Cardiac resynchronization therapy (CRT) reduces the incidence of sudden cardiac death and the use of appropriate implantable cardioverter-defibrillator (ICD) therapies (AICDTs); however, this antiarrhythmic effect is only observed in certain groups of patients. To gain insight into the effects of CRT on ventricular arrhythmia (VA) burden, we compared the incidence of AICDT use in four groups of patients: patients with ischaemic cardiomyopathy vs. non-ischaemic dilated cardiomyopathy (NIDC) and patients implanted with an ICD vs. CRT-ICD.Methods and Results: We analysed 689 consecutive patients (mean follow-up 37 ± 16 months) included in the Umbrella registry, a multicentre prospective registry including patients implanted with ICD or CRT-ICD devices with remote monitoring capabilities in 48 Spanish Hospitals. The primary outcome was the time to first AICDT. Despite a worse clinical risk profile, NIDC patients receiving a CRT-ICD had a lower cumulative probability of first AICDT use at 2 years compared with patients implanted with an ICD [24.7 vs. 41.6%, hazard ratio (HR): 0.49, P = 0.003]; on the other hand, there were no significant differences in the incidence of first AICDT use at 2 years in ischaemic patients (22.6 vs. 21.9%, P = NS). Multivariate analysis confirmed the association of CRT with lower AICDT rates amongst NIDC patients (Adjusted HR: 0.55, CI 95% 0.35-0.87).Conclusions: These data suggest that CRT is associated with significantly lower rates of first AICDT use in NIDC patients, but not in ischaemic patients. This study suggests that ICD patients with NIDC and left bundle branch block experiencing VAs may benefit from an upgrade to CRT-ICD despite being in a good functional class. [ABSTRACT FROM AUTHOR]

Aims: The benefit of implantable cardioverter-defibrillators (ICDs) in patients at risk of sudden death has been established in randomized clinical trials (RCTs) using the ICD models available at the time. However, observational large-scale data on the incidence of arrhythmias in up-to-date ICDs implanted according to the current guidelines are scarce. The aim was to assess the incidence of arrhythmias in a large, current ICD population based on a blinded peer review of the detected episodes.Methods and Results: UMBRELLA is a multicentre, observational registry of ICD patients followed by remote monitoring. Stored episodes were classified by a blinded committee of experts. Subgroup analyses were based on clinical profiles established by previous pivotal RCTs of ICDs. Of 1514 enrolled patients, 605 (39.9%) patients had 5951 episodes after 26 ± 17 months follow-up, being 3353 of them (56.3%) sustained ventricular arrhythmias (SVA), and 13.2% of SVA were self-terminated. Appropriate and inappropriate shocks occurred in 11.6 and 5% of patients, respectively. The 3 years cumulative incidence of SVA was 25% (95% CI: 21-28%) in primary prevention patients and 41% (95% CI: 36-47%) in secondary prevention patients (P < 0.001). Male gender, secondary prevention, and atrial fibrillation as basal rhythm were significantly related to a higher incidence of SVA.Conclusion: This real-world analysis suggests that modern ICD patients have a low rate of appropriate and inappropriate shocks. The risk of SVA in secondary prevention patients is less than what has been reported in RCTs. [ABSTRACT FROM AUTHOR]

Objective: A safety threshold for baseline rhythm R-wave amplitudes during follow-up of implantable cardioverter defibrillators (ICD) has not been established. We aimed to analyse the amplitude distribution and undersensing rate during spontaneous episodes of ventricular fibrillation (VF), and define a safety amplitude threshold for baseline R-waves.Methods: Data were obtained from an observational multicentre registry conducted at 48 centres in Spain. Baseline R-wave amplitudes and VF events were prospectively registered by remote monitoring. Signal processing algorithms were used to compare amplitudes of baseline R-waves with VF R-waves. All undersensed R-waves after the blanking period (120 ms) were manually marked.Results: We studied 2507 patients from August 2011 to September 2014, which yielded 229 VF episodes (cycle length 189.6±29.1 ms) from 83 patients that were suitable for R-wave comparisons (follow-up 2.7±2.6 years). The majority (77.6%) of VF R-waves (n=13953) showed lower amplitudes than the reference baseline R-wave. The decrease in VF amplitude was progressively attenuated among subgroups of baseline R-wave amplitude (≥17; ≥12 to <17; ≥7 to <12; ≥2.2 to <7 mV) from the highest to the lowest: median deviations -51.2% to +22.4%, respectively (p=0.027). There were no significant differences in undersensing rates of VF R-waves among subgroups. Both the normalised histogram distribution and the undersensing risk function obtained from the ≥2.2 to <7 mV subgroup enabled the prediction that baseline R-wave amplitudes ≤2.5 mV (interquartile range: 2.3-2.8 mV) may lead to ≥25% of undersensed VF R-waves.Conclusions: Baseline R-wave amplitudes ≤2.5 mV during follow-up of patients with ICDs may lead to high risk of delayed detection of VF.Trial Registration Number: NCT01561144; results. [ABSTRACT FROM AUTHOR]

Small-Caliber Lead Failure After Generator Exchange Introduction and Objectives The Sprint Fidelis defibrillator lead (Medtronic) was recalled in 2007 due to an increased risk of failure. The generator exchange (GE) procedure has been associated with the development of Fidelis lead dysfunction. The aim of this study was to compare the rate of dysfunction between Sprint Fidelis and other defibrillator leads during the first year after GE. Methods A multicenter retrospective study involving patients from the UMBRELLA database who underwent GE with previous normal lead function and minimum follow-up of 1 year after the procedure was performed. The incidence of lead dysfunction was determined via remote monitoring and defined as pacing impedance > 1,500 ohm, high-voltage impedance > 100 ohm, R wave sensing under 2 mV, or the presence of VT/VF episodes classified as noise. Results A total of 531 patients were included (114 Fidelis). In the first year after GE, the total incidence of lead dysfunction was 3.6%. No significant differences were found between Fidelis and the others in survival analysis (3.5% vs. 3.6%, respectively, log-rank 0.002, P = 0.962). Conclusions According to our results, the preventive removal/replacement of the Sprint Fidelis leads with normal function until GE is not a recommended practice since the rate of dysfunction after the procedure in this subgroup is no different compared with other defibrillator leads. [ABSTRACT FROM AUTHOR]

Aims: Hypertrophic cardiomyopathy is one of the main causes of sudden death in young people. Recent clinical practice guidelines include a risk prediction model for sudden death (HCM Risk-SCD), which facilitates the decision of whether to implant a defibrillator. The aim of our study was to ascertain the percentage of events in our series of primary prevention implantable cardioverter-defibrillator recipients with hypertrophic cardiomyopathy and whether HCM Risk-SCD predicts the onset of arrhythmic events.Methods and Results: This was an observational, retrospective cohort study, which included 48 primary prevention defibrillator recipient patients with HCM. We compiled their demographic and clinical characteristics, estimated 5-year risk using HCM Risk-SCD, and collected the documentation on arrhythmias during follow-up. The majority was male (66.7%) and mean age at implantation was 44.44 ± 14.46 years. Non-sustained ventricular tachycardia was the most prevalent risk factor (66.67%), followed by a family history of sudden death (47.92%). Mean HCM Risk-SCD was 6.15 ± 5.01%. HCM Risk-SCD was the only factor independently associated with the onset of ventricular tachyarrhythmia, above any other classic risk factor or association [odds ratio = 1.46 (95% confidence interval 1.051-2.013); P = 0.02]. None of the 11 patients estimated as low risk using HCM Risk-SCD suffered any appropriate events (P < 0.05).Conclusions: During an average follow-up of 4 years, 16.67% presented appropriate events (4.16%/year). HCM Risk-SCD predicted the onset of events more suitably than classic risk factors. [ABSTRACT FROM AUTHOR]

Background We sought to assess the efficacy of high-energy shocks to restore rhythm and predictors of success in patients with sustained ventricular arrhythmias and implantable cardioverter defibrillator (ICD). Methods and results Data from 162 patients included in the UMBRELLA study that experienced one or more episodes of ventricular tachycardia (VT) for which ICD shocks of at least 30 Joules were delivered (appropriate high-energy shocks) were analyzed. In total, 456 ventricular arrhythmia episodes were registered. Forty four episodes (9.6%) from 39 patients (24%) had at least one ineffective high-energy shock delivered. Hypertrophic cardiomyopathy was more frequent among patients with unsuccessful shocks (10.3% vs 2.4%). Patients with ineffective shocks had higher proportion of sustained monomorphic ventricular arrhythmias (86.4%; the other 13.6% were sustained polymorphic and ventricular fibrillation [VF]) compared with patients with all their shocks effective (62.9%, P = 0.02). No statistical differences were found between groups in time from detection to the high-energy shock delivery, in tachycardia cycle length, or in antitachycardia pacing, but patients with ineffective high-energy shocks had higher proportion of previously ineffective low-energy shock (9.1% vs 0.5%, P = 0.01). Conclusion We found a substantial rate of ineffective high-energy shocks for the treatment of VT or VF in patients with ICD. High-energy shock efficacy seems to be reduced by hypertrophic cardiomyopathy and by the administration of previous low-energy shocks. [ABSTRACT FROM AUTHOR]

Multiple Bursts for Fast Ventricular Tachycardia Introduction An empirical sequence of burst antitachycardia pacing (ATP) is effective in terminating fast ventricular tachycardias (FVT) in patients with implantable cardioverter-defibrillators (ICDs). We aimed to determine whether multiple ATP bursts for termination of FVT results in shock reduction compared to a single ATP burst. Methods and Results We analyzed data from the Umbrella trial, a multicenter prospective observational study of ICD patients followed by the CareLink Monitoring System. We compared the safety and effectiveness of a single ATP burst (Group 1) with a strategy of successive ATP sequences (Group 2) for termination of FVT episodes (cycle lengths 250-320 milliseconds) before shock therapy. Over a mean follow-up of 35 months, a total of 650 FVT episodes were detected in 154 patients (mean cycle length: 299 ± 18 milliseconds). Effectiveness of the first burst ATP in Group 1 was 73% and shocks were required in 27% of episodes. Effectiveness of the first burst ATP in Group 2 was 77%, and this increased to 91% with the third or successive ATP bursts. Shocks were required in 9% of episodes in group 2, representing a 67% reduction in the need of high-energy shocks. Median duration of FVT episodes and mortality in both groups were similar. Multivariate analysis indicated that programming multiple ATP bursts (OR 3.4, 95%CI 1.7-6.8, P = 0.001) was an independent predictor of ATP effectiveness. Conclusion This study provides first evidence that a strategy of multiple burst ATP sequences for termination of FVT episodes leads to a clinically meaningful reduction in the need for shocks. [ABSTRACT FROM AUTHOR]

Copyright of Revista Española de Cardiología (18855857) is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Española de Cardiología (18855857) is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Española de Cardiología (18855857) is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Española de Cardiología (18855857) is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background Large-scale studies describing modern populations using an implantable cardioverter-defibrillator (ICD) are lacking. We aimed to analyze the incidence of arrhythmia, device interventions, and mortality in a broad spectrum of real-world ICD patients with different heart disorders. Methods and Results The UMBRELLA study is a prospective, multicenter, nationwide study of contemporary patients using an ICD followed up by remote monitoring, with a blinded review of arrhythmic episodes. From November 2005 to November 2017, 4296 patients were followed up. After 46.6±27.3 months, 16 067 episodes of sustained ventricular arrhythmia occurred in 1344 patients (31.3%). Appropriate ICD therapy occurred in 27.3% of study population. Patients with ischemic cardiomyopathy (hazard ratio [HR], 1.51; 95% CI, 1.29-1.78), dilated cardiomyopathy (HR, 1.28; 95% CI, 1.07-1.53), and valvular heart disease (HR, 1.94; 95% CI, 1.43-2.62) exhibited a higher risk of appropriate ICD therapies, whereas patients with hypertrophic cardiomyopathy (HR, 0.72; 95% CI, 0.54-0.96) and Brugada syndrome (HR, 0.25; 95% CI, 0.14-0.45) showed a lower risk. All-cause death was 13.4% at follow-up. Ischemic cardiomyopathy (HR, 3.09; 95% CI, 2.58-5.90), dilated cardiomyopathy (HR, 3.33; 95% CI, 2.18-5.10), and valvular heart disease (HR, 3.97; 95% CI, 2.25-6.99) had the worst prognoses. Delayed high-rate detection was enabled in 39.7% of patients, and single-zone programming occurred in 52.6% of primary prevention patients. Both parameters correlated with lower risk of first appropriate ICD therapy, with no excess risk of mortality. The rate of inappropriate shocks at follow-up was low (6%) and did not differ among type of ICD but was lower in SmartShock-capable devices. Conclusions Irrespective of the cause, contemporary ICD patients with heart failure-related disorders had a similar risk of ICD life-saving interventions and death. Current ICD programming recommendations still need to be implemented. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NTC01561144.

Aims: Concerns about the prognostic value of NYHA functional class (FC) in heart failure (HF) patients carrying a prophylactic implantable cardioverter defibrillator (ICD) are still present. We aimed to compare whether mortality and arrhythmic risk were different, in a cohort of HF patients undergoing ICD-only implant, according to their FC., Methods and Results: HF patients with left ventricle ejection fraction (LVEF) ≤35%, undergoing first prophylactic ICD-only implant were collected from a multicentre nationwide registry (2006-2015). Six hundred and twenty-one patients were identified (101 patients in NYHA I; 411 in NYHA II; 109 in NYHA III). After a mean follow-up of 4.4 years (±2.1), 126 patients died (20.3%). All-cause mortality risk was higher in symptomatic patients: 13.9% in NYHA I patients, 18.3% in NYHA II patients (HR: 1.8, 95% CI 1.1-3.2), and 32.9% in NYHA III patients (HR: 3.9, 95% CI 2.1-7.3). Seventy-eight out of all deaths were due to cardiovascular causes (12.6%). Cardiovascular mortality risk was also higher in symptomatic patients: 6.9% in NYHA I patients, 11% in NYHA II patients (HR: 2.2, 95% CI 1.1-4.9), and 23.9% in NYHA III (HR: 5.5, 95% CI 2.4-12.7). One hundred and seventeen patients received a first appropriate ICD therapy (19.4%). Arrhythmia free survival did not differ among study groups [20.8% in NYHA I patients, 18.7% in NYHA II (HR: 1.1, 95% CI 0.6-1.7) and 20.8% in NYHA III patients (HR: 1.3, 95% CI 0.7-2.5)]. NYHA class independently predicted cardiovascular mortality (NYHA III vs. NYHA I: HR, 4.7; 95% CI, 1.7-12.8, P = 0.002; NYHA II vs. NYHA I: HR, 2.1, 95% CI, 1.0-5.6, P = 0.05) but not all-cause death (NYHA III vs. NYHA I: HR: 1.8, 95% CI 0.8-3.9, P = 0.11; NYHA II vs. NYHA I: HR, 1.1, 95% CI 0.6-2.2, P = 0.71;). Atrial fibrillation, chronic kidney disease, and diabetes emerged as predictors of both all-cause death [(HR: 1.8, 95% CI 1.2-2.8, P = 0.005), (HR: 2.2, 95% CI 1.4-3.4, P < 0.001), (HR: 2.0, 95% CI 1.3-3.1, P = 0.001), respectively] and cardiovascular mortality [(HR: 1.8, 95% CI 1.1-3.1, P = 0.02), (HR: 3.1, 95% CI 1.8-5.4, P < 0.001), (HR: 1.7, 95% CI 1.1-3, P = 0.032), respectively]., Conclusions: Mortality in HF patients undergoing prophylactic ICD implantation was higher in symptomatic patients. NYHA functional class along with other comorbidities might be helpful to identify a subgroup of ICD carriers with poorer prognosis and higher risk of cardiovascular death., (© 2019 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.)

Background: Concerns about the efficacy of prophylactic ICD in non-ischemic cardiomyopathy (NICM) heart failure (HF) patients are still present. We aimed to assess whether survival and arrhythmic risk were different among ischemic cardiomyopathy (ICM) and NICM ICD-only patients, along with specific predictors for mortality., Methods: HF patients undergoing ICD-only implant were extracted from the nationwide multicenter UMBRELLA registry. Arrhythmic events were collected by remote monitoring and reviewed by a committee of experts., Results: 782 patients (556 ICM; 226 NICM) were recruited: mean ejection fraction of 26.6%; 83.4% in NYHA class II-III; mean QRS duration of 108.9 ms (only 14.9% with QRS > 130 ms). After 4.35 years of mean follow-up, all-cause mortality rate was 4.2%/year. In propensity-score (PS) analysis no survival differences between ICM and NICM subgroups appeared (mortality rates: 19.4% vs. 20%, p = 0.375). Age (hazard ratio [HR] = 1.02, p = 0.009), diabetes (HR = 2.61, p ≤ 0.001), chronic obstructive pulmonary disease (HR = 2.13, p = 0.002), and previous HF (HR = 2.28, p = 0.027) correlated with increased mortality for the entire population, however atrial fibrillation (AF) (HR = 2.68, p = 0.002) and chronic kidney disease (HR = 3.74, p ≤ 0.001) emerged as specific predictors in NICM patients. At follow-up, 134 patients (17.1%) were delivered a first appropriate ICD therapy (5.1%/year) without significant differences between ICM and NICM patients in the PS analysis (17.6% vs. 15.8%, p = 0.968). ICD shocks were associated with a higher mortality (HR = 2.88, p < 0.001) but longer detection windows (HR = 0.57, p = 0.042) correlated with fewer appropriate therapies., Conclusions: Mortality and arrhythmia free survival is similar among ICM and NICM HF patients undergoing ICD-only implant for primary prevention strategy., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Introduction and Objectives: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy characterized by progressive fibrofatty replacement of predominantly right ventricular myocardium. This cardiomyopathy is a frequent cause of sudden cardiac death in young people and athletes. The aim of our study was to determine the incidence of pathological or likely pathological desmosomal mutations in patients with high-risk definite ARVC., Methods: This was an observational, retrospective cohort study, which included 36 patients diagnosed with high-risk ARVC in our hospital between January 1998 and January 2015. Genetic analysis was performed using next-generation sequencing., Results: Most patients were male (28 patients, 78%) with a mean age at diagnosis of 45 ± 18 years. A pathogenic or probably pathogenic desmosomal mutation was detected in 26 of the 35 index cases (74%): 5 nonsense, 14 frameshift, 1 splice, and 6 missense. Novel mutations were found in 15 patients (71%). The presence or absence of desmosomal mutations causing the disease and the type of mutation were not associated with specific electrocardiographic, clinical, arrhythmic, anatomic, or prognostic characteristics., Conclusions: The incidence of pathological or likely pathological desmosomal mutations in ARVC is very high, with most mutations causing truncation. The presence of desmosomal mutations was not associated with prognosis., (Copyright © 2017 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.)

Background: Different types of ventricular arrhythmias (monomorphic ventricular tachycardia [VT], polymorphic VT, or ventricular fibrillation) can be detected by implantable cardiac defibrillators (ICDs) in fast VT zone. The efficacy of antitachycardia pacing (ATP) depends on the type of the treated arrhythmia. We hypothesized that an automatic algorithm based on morphological affinity of ICD far-field electrograms during tachycardia can predict ATP success and the need of shock., Methods: The algorithm was evaluated on ventricular arrhythmias recorded in CareLink ICD remote monitoring system (Medtronic Inc., Minneapolis, MN, USA). Patients were selected if first ATP programmed was a burst of eight pulses at 88% coupling interval and if a far-field electrogram was available. The algorithm calculated a stability coefficient (SC) for all their stored ATP-treated fast ventricular arrhythmia (VA) episodes (LC 200-300 ms), analyzing the morphology homogeneity of the last eight recorded far-field electrograms before ventricular arrhythmias detection., Results: Inclusion criteria were fulfilled by 717 patients from 29 centers. Three hundred and twenty fast VA were recorded in 103 patients. A higher SC was observed in episodes terminated with the first-ATP (0.78 [0.72-0.84] vs 0.74 [0.60-0.84]; P = 0.006). These differences were especially marked among the 62 episodes of very fast VA (CL ≤250 ms) (0.77 [0.74-0.85] vs 0.64 [0.51-0.8]; P = 0.006). In the multivariate analysis, a SC > 70% was independently associated with a higher likelihood of first-ATP success (odds ratio [OR] = 2.5; [95% confidence interval (CI) = 1.4-4.5], P = 0.001) and a lower need of shock (OR = 0.37; [95% CI = 0.2-0.7], P = 0.002)., Conclusion: This automatic algorithm (stability coefficient) shows that ATP therapy response can be predicted in fast ventricular arrhythmias through morphology evaluation., (© 2016 Wiley Periodicals, Inc.)

Introduction and Objectives: Implantable cardioverter-defibrillators reduce mortality in some patients with heart disease. Battery replacement is a frequent occurrence in clinical practice and is required in up to 30% of implants. The benefit/risk ratio of defibrillators varies over time and should be reevaluated at the time of replacement. The aim of this study was to determine the clinical characteristics and incidence of defibrillator therapies in patients who underwent generator replacement., Methods: This multicenter retrospective study involved patients from the UMBRELLA national registry who underwent replacement due to defibrillator battery depletion. The incidence of ventricular arrhythmias was determined via remote monitoring. Risk factors for sustained ventricular arrhythmia after replacement were analyzed., Results: A total of 354 patients were included (mean age [standard deviation], 61.8 [14.5] years; men, 80%; secondary prevention, 42%; ventricular arrhythmias in the explanted generator, 62%). After a 25-month follow-up, 70 patients (20%) received appropriate therapies and 8 (2.3%) received inappropriate discharges. Male sex, structural heart disease, heart failure, and the absence of resynchronization were independent predictors of ventricular arrhythmia occurrence., Conclusions: One-fifth of patients had appropriate defibrillator therapies in the first 2 years after generator replacement. Determination of the factors associated with arrhythmia occurrence after replacement may be useful to optimize implantable cardioverter-defibrillator treatment., (Copyright © 2014 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.)

Introduction and Objectives: To summarize the findings of the Spanish Implantable Cardioverter-Defibrillator (ICD) Registry for 2008 compiled by the Spanish Society of Cardiology Working Group on Implantable Cardioverter-Defibrillators., Methods: Prospective data recorded voluntarily on single-page questionnaires were sent to the Spanish Society of Cardiology by each implantation team., Results: Overall, 3486 device implantations were reported, which is 84.7% of the estimated total number of implantations. The reported implantation rate was 76 per million population and the estimated total implantation rate was 90 per million. The proportion of first implantations was 78.1%. There continued to be substantial regional variations within Spain. The majority of ICD implantations took place in men (mean age 62+/-12 years) who had severe or moderate-to-severe ventricular dysfunction and were in New York Heart Association functional class II. Ischemic heart disease was the most frequent underlying cardiac condition, followed by dilated cardiomyopathy. The number of indications for primary prevention increased relative to the previous year, especially in patients with ischemic cardiomyopathy, and now account for 57% of first implantations. The types of ICD implanted were unchanged from 2007. Overall, 73.6% of ICDs were implanted by cardiac electrophysiologists., Conclusions: The 2008 Spanish ICD Registry includes data on almost 85% of all ICD implantations performed in Spain. Although the number has continued to increase, it still remains far from the European average. There was a significant increase in indications for primary prevention. Substantial regional variations continue to exist within Spain.

Aims: Implantable cardioverter defibrillators (ICDs) are increasingly being used for treatment of ventricular tachycardia (VT)/fibrillation. Inappropriate therapy delivery remains the most frequent complication in patients with ICDs, resulting in psychological distress, proarrhythmia, and battery life reduction. We aim to determine if inappropriate therapies could be reduced by using a morphology discrimination criterion., Methods and Results: We evaluated the performance of the Wavelet morphology discrimination algorithm (Medtronic, Inc.) independently from other discrimination enhancements (rate onset and interval stability). A non-randomized, prospective, multicenter, and observational study was designed to determine the sensitivity and specificity of the new morphology criterion. Sensitivity and specificity in slow tachycardia with cycle length (CL) between 340 and 500 ms were analysed as a pre-specified secondary endpoint. A total of 771 spontaneous episodes in 106 patients were analysed. Five hundred and twenty-two episodes corresponded to true supraventricular tachycardia (SVT) with ventricular CL in the VT or FVT zone, of which 473 had therapy appropriately withheld. Of the 249 episodes of true VT/FVT, 21 were classified according to the Wavelet criteria as SVT (specificity: 90.6%; sensitivity: 91.6%). All of them were spontaneously terminated with no adverse clinical consequences. No syncopal episodes occurred. For VTs in the slowest analysed range (CL: 340-500 ms), a total of 235 episodes were studied, yielding a specificity of 95.9% and sensitivity of 83.2%., Conclusion: Wavelet discrimination criteria in single-chamber ICDs as the sole discriminator can significantly reduce inappropriate therapy for SVT, not only in the range of VTs in the slowest analysed range (340-500 ms for this study) but also for faster VTs. No significant clinical consequences were found when the algorithm was used, but final data should prompt the use of the algorithm in combination with a high rate time-out feature.

Introduction and Objectives: We report the results of the first Catheter Ablation Registry of the Arrhythmia Working Group of the Andalusian Society of Cardiology (AWGASC) for 2000., Methods: The register includes information about the ablation procedures performed in 2000, which was collected retrospectively and submitted voluntarily by four out of six cardiac electrophysiology laboratories of the AWGASC. A total of 424 patients (mean age 45 18 years; 50% men) were included. Twelve patients underwent two different ablation procedures, bringing the total number of procedures to 436. The overall success rate (based on current criteria), success rate by procedure, in-hospital mortality, and major complications are reported., Results: The type and distribution of the ablation procedures were atrioventricular nodal re-entry tachycardia ablation, 34%; accessory pathway ablation, 39%; ventricular tachycardia ablation, 8%; atrial tachycardia ablation, 3%; atrioventricular junctional ablation, 9%, and cavo-tricuspid isthmus ablation, 9%. The overall success rate was 94% (range 97.8% to 87.4% in different laboratories), rate of major complications 1.1% (range 0% to 3.7%), and overall mortality 0.23% (1 patient)., Conclusions: These findings summarize the indications and results of catheter ablation procedures performed in 2000 at four cardiac electrophysiology laboratories in Andalusia. This is the first multicenter registry in Spain.