Javier Alzueta

Preventing ventricular dysfunction in pacemaker patients without advanced heart failure: results from a multicentre international randomized trial (PREVENT-HF)

Previous experimental and clinical studies have consistently suggested that right ventricular (RV) apical pacing has important adverse effects. Ventricular pacing (VP), however, is required, and cannot be reduced in many patients with atrioventricular (AV) block. The PREVENT‐HF study was an international randomized trial that explored differences in left ventricular (LV) remodelling during RV apical vs. biventricular (BIV) pacing in patients with AV block.

An Even More Physiological Pacing: Changing the Sequence of Ventricular Activation

Physiological pacing includes preservation of A -V sequential stimulation and adaptation of heart rate to body requirements. However the sequence of ventricular activation (VA) is also important. In four patients with aortic valvular disease, LBBB and HV ~ 70 msec a Medtronic Versatrax DDD pacemaker was implanted at the time of aortic valve surgery. The ventricular electrode was placed in the free wall of the LV. With ditTerents pulse generator A-V intervals (PG-A V), we obtained: A) LBBB morphology when PG-AV was > A-V conducted interval (C-AV); B) “RBBB” morphology when PG-A V < C-A V, and C) intermediate (“fusion”) morphology when PG-A V ⋍ CAV. A mean delay of 70 ± 5 msec between beginning of the spontaneous activation of RV and arrival of stimulation to ventricular electrode in LV favoured these fusion beats. The sequence of mechanical ventricular emptying was non-invasively assessed by radioisotopic (Tc-99 m Pyp labelled red blood cells) study of the “wave of emptying” and of phase histograms, using the Fourier’s analysis. The most “normal” pattern was found in C. LV ejection fraction (radioisotopic cineangiogram) was 0.59 ± 0.035 in C versus 0.51 ± 0.047 in B (p < 0.001) and 0.47 ± 0.045 in A (p < 0.001). We conclude than an appropriate placement of ventricular electrode besides a correct programation of A-V delay in DDD pacemakers allows for a more synergistic ventricular activation in patients with LBBB, improving their ventricular performance.

Persistence of secondary mitral regurgitation and response to cardiac resynchronization therapy

AIMS Cardiac resynchronization therapy (CRT) improves survival and quality of life in advanced heart failure (HF). Although mitral regurgitation (MR) reduction has been reported, its presence has been associated with non-response to CRT. This study was undertaken to assess the potential role of significant mitral regurgitation (SMR) persistence after CRT on clinical outcome, major arrhythmic events, and echocardiographic response in the mid-long term. METHODS AND RESULTS Seventy-six patients (28.9% women, 63 +/- 11 years) with dilated cardiomyopathy in advanced HF were included. SMR, defined as regurgitant orifice area > or =0.20 cm(2), was assessed at baseline and its evolution 6 months after CRT. Clinical outcome (cardiovascular death/HF readmission), major arrhythmic events, and echocardiographic response (reverse remodelling) were recorded on follow-up. Thirty-two patients (42.1%) presented baseline SMR, becoming non-significant in 11 of the 32 patients (34.3%) 6 months after CRT. Its persistence was associated with higher rates of clinical events (46.4 vs. 18.7%, P = 0.011), arrhythmic events (35.7 vs. 14.5%, P = 0.034), and less reverse remodelling (28.5 vs. 83.3%, P < 0.001). CONCLUSION CRT can reduce moderate or severe baseline MR to non-significant in one-third of patients. However, its persistence was associated with worse clinical evolution, greater incidence of arrhythmic events, and less reverse remodelling.

Morphology discrimination criterion wavelet improves rhythm discrimination in single-chamber implantable cardioverter-defibrillators: Spanish Register of morphology discrimination criterion wavelet (REMEDIO).

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.

Spanish Implantable Cardioverter-defibrillator Registry. Eleventh Official Report of the Spanish Society of Cardiology Electrophysiology and Arrhythmias Section (2014).

INTRODUCTION AND OBJECTIVES We present the results of the Spanish Implantable Cardioverter-defibrillator Registry for 2014, as compiled by the Electrophysiology and Arrhythmia Section of the Spanish Society of Cardiology. METHODS Data collection sheets were voluntarily completed by each implantation team and prospectively sent to the Spanish Society of Cardiology. RESULTS The number of reported implantations was 4911 (82% of the estimated total number of implantations). The implantation rate was 106 per million population while the estimated rate was 128. First implantations comprised 72.2%. Data were obtained from 162 hospitals (8 more than in 2013). Most implantations (82%) were performed in men. The mean patient age was 61.8±13.7 years. Most patients showed severe or moderate-to-severe ventricular dysfunction and were in New York Heart Association functional class II. The most frequent cardiac condition was ischemic heart disease, followed by dilated cardiomyopathy. Implantations for primary prevention indications comprised 58.5%. Electrophysiologists performed 85.6% of the implantations. CONCLUSIONS The 2014 Spanish Implantable Cardioverter-defibrillator Registry received information on 82% of the implantations performed in Spain. The number of implantations has increased from previous years and the percentage of implantations for primary prevention indications has increased from the previous year.

Clinical use of automatic pacemaker algorithms: results of the AUTOMATICITY registry.

AIMS Follow-up of the ever-increasing numbers of patients with implantable cardiac devices places a heavy burden on clinical departments. Device automaticity may alleviate the follow-up burden by minimizing the time for physician involvement. The aim of the prospective, multicentre AUTOMATICITY registry was to examine the performance of a subset of programmed automatic algorithms during patient follow-up and their acceptance by implanting physicians. METHODS AND RESULTS The clinical use of automatic algorithms from the Insignia pacemakers (PM; Boston Scientific, St Paul, MN, USA) was evaluated: atrial and ventricular AutoSense (sensitivity adjustment), ventricular Automatic Capture (threshold verification and output setting), AutoLifeStyle (sensor settings adjustment). The objective of the study was to assess the reprogramming rates within 12 months of implant, the reasons for reprogramming and relationship to adverse events. A total of 960 patients were enrolled in the study. The proportion of patients free from any algorithm reprogramming at 12 months was 86.1%. A total of 2736 algorithms were activated at enrolment, with 156 (5.7%) being reprogrammed in 115 patients at 12 months for any reason. Forty-nine reprogrammings (1.8%) were unintentional or related to changes in device settings such that the algorithm was no longer available, 33 (1.2%) were due to suspected sensing issues, and 22 (0.8%) were assumed related to the algorithm. The individual 12-month reprogramming-free rates were: ventricular AutoSense 94.3%, Atrial AutoSense 93.3%, AutoLifeStyle 93.9%, and Automatic Capture 95.9%. CONCLUSION The results of the AUTOMATICITY registry show that automatic measurement of key settings and automatic adjustment to optimal programming is feasible and safe. The simplicity of PM follow-up and avoidance of frequent reprogramming may contribute to a more effective use of hospital time and resources.

Comparison of the new risk prediction model (HCM Risk-SCD) and classic risk factors for sudden death in patients with hypertrophic cardiomyopathy and defibrillator

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.

Serum levels of interleukin-2 predict the recurrence of atrial fibrillation after pulmonary vein ablation.

AIMS Interleukin-2 has a significant antitumor activity in some types of cancer, and has been associated with the development of atrial fibrillation (AF). In addition, IL-2 serum levels in recent onset AF have been related with pharmaceutical cardioversion outcomes. We evaluated the hypothesis that a relationship exists between inflammation and the outcome of catheter ablation of AF. METHODS We studied 44 patients with paroxysmal AF who underwent catheter ablation. Patients with structural heart disease, coronary artery or valve disease, active inflammatory disease, known or suspected neoplasm, endocrinopathies, or exposure to anti-inflammatory drugs were excluded. All study participants underwent evaluation with a standardized protocol, including echocardiography, and cytokine levels of interleukin-2, interleukin-4, interleukin-6, interleukin-10, tumour necrosis factor-alpha, and gamma-interferon determination before procedure. Clinical and electrocardiographic follow-up were performed with Holter-ECG at 3, 6 and 12months in order to know if sinus rhythm was maintained. RESULTS After catheter ablation of the 44 patients included (53±10years, 27.3% female), all patients returned to sinus rhythm. During the first year of follow-up seven patients (15.9%) experienced recurrence of AF. The demographics, clinical and echocardiographic features, and pharmacological treatments of these patients were similar to those who maintained sinus rhythm. The only independent factor predictive of recurrence of AF was an elevated level of IL-2 (OR 1.18, 95% CI 1.12-1.38). CONCLUSIONS High serum levels of interleukin-2, a pro-inflammatory non-vascular cytokine, are associated with the recurrence of AF in patients undergoing catheter ablation.

Safety threshold of R-wave amplitudes in patients with implantable cardioverter defibrillator

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.

Clinical Profile and Incidence of Ventricular Arrhythmia in Patients Undergoing Defibrillator Generator Replacement in Spain

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.