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S-ICD eligibility is assessed at pre-implant screening where surface ECG traces are used as surrogates for S-ICD vectors. In heart failure (HF) patients undergoing diuresis, electrolytes and fluid shifts can cause changes in R and T waves. Subsequently, T:R ratio, a major predictor of S-ICD eligibility, can be dynamic.This is a prospective study of patients with structurally normal hearts and HF patients undergoing diuresis. All patients were fitted with Holters® to record their S-ICD vectors. Our deep learning model was used to analyze the T:R ratios across the recordings. Welch two sample t-test and Mann-Whitney U were used to compare the data between the two groups.Twenty-one patients (age 58.43 ± 18.92, 62% male, 14 HF, 7 normal hearts) were enrolled. There was a significant difference in the T:R ratios between both groups. Mean T: R was higher in the HF group (0.18 ± 0.08 vs 0.10 ± 0.05, p .001). Standard deviation of T: R was also higher in the HF group (0.09 ± 0.05 vs 0.07 ± 0.04, p = .024). There was no difference between leads within the same group.T:R ratio, a main determinant for S-ICD eligibility, is higher and has more tendency to fluctuate in HF patients undergoing diuresis. We hypothesize that our novel neural network model could be used to select HF patients eligible for S-ICD by better characterization of T:R ratio reducing the risk of T-wave over-sensing (TWO) and inappropriate shocks. Further work is required to consolidate our findings before applying to clinical practice.

Background Cardiac implanted electronic devices (CIEDs) can detect short durations of previously unrecognised atrial fibrillation (AF). The prognostic significance of device-detected subclinical AF, in the context of contemporary heart failure (HF) therapy, is unclear. Methods Amongst patients enrolled in the Remote Monitoring in HF with implanted devices (REM-HF) trial, three categories were defined based on total AF duration in the first year of follow-up: no AF, subclinical AF (≥6 min to ≤24 h), and AF >24 h. All-cause mortality, stroke, and cardiovascular hospitalisation were assessed. Results 1561 patients (94.6%) had rhythm data: 71 (4.6%) had subclinical AF (median of 4 episodes, total duration 3.1 h) and 279 (17.9%) had AF >24 h. During 2.8 ± 0.8 years' follow-up, 39 (2.5%) patients had a stroke. Stroke rate was highest amongst patients with subclinical AF (2.0 per 100-person years) versus no AF or AF >24 h (0.8 and 1.0 per 100-person years, respectively). In the overall cohort, AF >24 h was not an independent predictor of stroke. However, amongst patients with no history of AF (n = 932), new-onset subclinical AF conferred a three-fold higher stroke risk (adjusted HR 3.35, 95%CI 1.15–9.77, p = 0.027). AF >24 h was associated with more frequent emergency cardiovascular hospitalisation (adjusted HR 1.46, 95%CI 1.19–1.79, p Conclusions In patients with HF and a CIED, subclinical AF was infrequent but, as a new finding, was associated with an increased risk of stroke. Anticoagulation remains an important consideration in this population, particularly when the clinical profile indicates a high stroke risk.

Haemodialysis patients who require defibrillator therapy are expected to benefit from the entirely avascular subcutaneous defibrillator (S-ICD), but haemodialysis is associated with dynamic changes in R and T wave amplitude which can impact S-ICD eligibility. A continuous assessment of S-ICD eligibility during haemodialysis has not previously been performed.Continuous surface ECG recordings were obtained from a cohort of patients undergoing maintenance haemodialysis, but without an indication for an ICD. Automated vector screening was retrospectively performed at one-minute intervals throughout the dialysis session. Variations in S-ICD eligibility were calculated and in vectors with high degrees of variation, the underlying mechanism was identified.72 vector recordings (mean duration 254.1 ± 6.0 min) were obtained from 24 patients (mean age 64.3 ± 5.5 years, 68% male). At the start of haemodialysis 47 vectors were S-ICD eligible (65.2%). At the end of session, all of these vectors had remained eligible, and an additional 6 vectors had also become eligible (73.6%). High vector score variability was observed in 7 patients and the commonest cause was a progressive change in R:T ratio (71.5%).In a haemodialysis population, a single haemodialysis session can be associated with a potential change in S-ICD eligibility in 8.4% of vectors, with up to 12.5% of vectors showing high degrees of variability, most commonly due to variations in R:T ratio. In an S-ICD population with similar characteristics S-ICD screening prior to haemodialysis would be expected to more accurately identify vectors that retain eligibility.

Pre-implant ECG screening is performed to ensure that S-ICD recipients have at least one suitable sensing vector, yet cardiac over-sensing remains the commonest cause of inappropriate shock therapy in the S-ICD population. One explanation would be the presence of dynamic variations in ECG morphology that result in variations in vector eligibility.Adult ICD patients had a 24-h ambulatory ECG performed using a digital Holter positioned to record all three S-ICD vectors. Using an S-ICD simulator, automated screening was then performed at one-minute intervals. In vectors with a mean vector score 100 (the accepted value for a passing vector when screened on a single occasion), the percentage of all screening assessments that passed, eligible vector time (EVT), was calculated. EVT was compared statistically to QRS duration, corrected time to peak T (pTc) and mean vector score.Ambulatory monitoring was performed in 14 patients (mean age 63.7 ± 5.2 years, 71.4% male) with 42 vectors analysed. In 19 vectors the mean vector score was 100. Within this "passing" cohort EVT varied between 42.7% and 100%. In 7/19 (37%) the EVT was 75%. A negative correlation was found between QRS duration and EVT (Pearson correlation -.60, p = .007). No correlation was found between EVT and mean vector score or pTc.Vector eligibility is dynamic. When "passing" vectors are subjected to repeated screening, 37% are found to be ineligible, more than a quarter of the time. Further investigation is required to determine the clinical significance of these findings.

Aims Approximately 5.7% of potential subcutaneous implantable cardioverter-defibrillator (S-ICD) recipients are ineligible by virtue of their vector morphology, with higher rates of ineligibility observed in some at-risk groups. Mathematical vector rotation is a novel technique that can generate a personalized sensing vector, one with maximal R:T ratio, using electrocardiogram (ECG) signal recorded from the present S-ICD location. Methods and results A cohort of S-ICD ineligible patients were identified through ECG screening of ICD patients with no ventricular pacing requirement and their personalized vectors were generated using ECG signal from a Holter monitor. Subcutaneous ICD eligibility in this cohort was then recalculated. In a separate cohort, episodes of arrhythmia were recorded in patients undergoing arrhythmia induction, and arrhythmia detection in standard S-ICD vectors was compared to rotated vectors using an S-ICD simulator. Ninety-two participants (mean age 64.9 ± 2.7 years) underwent screening and 5.4% were found to be S-ICD ineligible. Personalized vector generation increased the R:T ratio in these vectors from 2.21 to 7.21 (4.54–9.88, P < 0.001) increasing the cohort eligibility from 94.6% to 100%. Rotated S-ICD vectors also showed high ventricular fibrillation (VF) detection sensitivity (97.8%), low time to VF detection (6.1 s), and excellent tachycardia discrimination (sensitivity 96%, specificity 88%), with no significant differences between rotated and standard vectors. Conclusion In S-ICD ineligible patients, mathematical vector rotation can generate a personalized vector that is associated with a significant increase in R:T ratio, resulting in universal device eligibility in our cohort. Ventricular fibrillation detection efficacy, time to VF detection, and tachycardia discrimination were not affected by vector rotation.

Among different cardiac arrhythmias, Ventricular Arrhythmias (VA) are fatal and life-threatening. Therefore, the detection and classification of VA is crucial task for cardiologists. However, in some cases, the ECG morphologies of two kinds of VA - Ventricular Tachycardia (VT) and Ventricular Fibrillation (VF) are similar and difficult to distinguish by human eyes. In this study, we present a low computational complexity arrhythmia classifier with high accuracy based on Phase Space Reconstruction (PSR). It is used to classify normal electrocardiogram (ECG), atrial fibrillation (AF), VT, VF and VT followed by VF. The Creighton University Ventricular Tachyarrhythmia Database (CUDB), Physikalisch-Technische Bundesanstalt Diagnostic Database (PTBDB), MIT-BIH Atrial Fibrillation Database (MIT-BIH AFDB) from PhysioNet databank and University Hospital Southampton database (UHSDB) are used for evaluation and comparison of the proposed algorithm. Two PSR diagrams were plotted based on a window length of 5 s ECG with two different time delays and the PSR-based features were extracted from them using the box-counting technique. This process was applied on 122 records with more than 5500 windows of ECG signals. The results show an average sensitivity of 98.73%, specificity of 99.71% and accuracy of 99.56%. The average computational time of our proposed method for one 5 s window processing is 1.9 s and therefore has the potential in real-time arrhythmia classification applications.

Introduction Techniques exist which allow surface ECGs to be reconstructed from reduced lead sets. We aimed to reconstruct an 8-lead ECG from two independent S-ICD sensing electrodes vectors as proof of this principle. Methods Participants with ICDs ( N =61) underwent 3minute ECGs using a TMSi Porti7 multi-channel signal recorder (TMS international, The Netherlands) with electrodes in the standard S-ICD and 12-lead positions. Participants were randomised to either a training ( N =31) or validation ( N =30) group. The transformation used was a linear combination of the 2 independent S-ICD vectors to each of the 8 independent leads of the 12-lead ECG, with coefficients selected that minimized the root mean square error (RMSE) between recorded and derived ECGs when applied to the training group. The transformation was then applied to the validation group and agreement between the recorded and derived lead pairs was measured by Pearson correlation coefficient ( r ) and normalised RMSE (NRMSE). Results In total, 27 patients with complete data sets were included in the validation set consisting of 57,888 data points from 216 full lead sets. The distribution of the r and NRMSE were skewed. Mean r =0.770 (SE 0.024), median r =0.925. NRMSE mean=0.233 (SE 0.015) median=0.171. Conclusions We have demonstrated that the reconstruction of an 8-lead ECG from two S-ICD vectors is possible. If perfected, the ability to generate accurate multi-lead surface ECG data from an S-ICD would potentially allow recording and review of clinical arrhythmias at follow-up.

The article contains data pertaining to the reconstruction of an 8-lead ECG from 2 subcutaneous implantable cardioverter defibrillator vectors. The location of electrodes on the precordium required for the data collection are detailed; the flow chart for patient selection and exclusion is shown; the summary data of the root mean square error (RMSE) (in microvolts) and Pearson r for the ECG transformation all cases and the pearson correlation for all the leads measured and reconstructed leads are also shown. Detailed background, methodology and discussion can be found in the linked research article.

Aims Studies of remote monitoring (RM) in heart failure (HF) speculate that patients with atrial fibrillation (AF) derive the greatest benefit. We compared the impact of RM vs. usual care on clinical outcomes for patients with and without AF enrolled in the Remote Management of Heart Failure Using Implanted Electronic Devices (REM-HF) trial. Methods and results Rhythm status was available for 1561 patients (94.6%). Three categories were defined based on total AF duration during the first year of follow-up: (i) no AF (n = 1211, 77.6%), (ii) paroxysmal AF (≥6 min to ≤7 days; n = 92, 5.9%), and (iii) persistent/permanent AF (>7 days; n = 258, 16.5%). Clinical activity, mortality, and hospitalisation rates were compared between treatment strategies for each group. RM resulted in a greater volume of clinical activity in patients with any AF, vs. no AF, with the highest per-patient intervention required for patients with persistent/permanent AF. During 2.8 ± 0.8 years of follow-up, RM was not associated with a reduction in all-cause or cardiovascular mortality for patients with AF. However, in patients with persistent/permanent AF, RM conferred an increased risk of recurrent cardiovascular [hazard ratio (HR) 1.40, 95% confidence interval (CI) 1.06-1.85, P = 0.018] and HF-related (HR 2.05, 95% CI 1.14-3.69, P = 0.016) hospitalisations. Conclusion In patients with HF and a cardiac implanted electronic device, RM generated greater clinical activity for patients with AF, with no associated reduction in mortality, and conversely, greater risk of cardiovascular hospitalisation amongst patients with persistent/permanent AF. RM strategies may vary in their capability to guide HF management; modified approaches may be needed to improve outcomes for HF patients with AF.

Background In the ICD Sports Safety Registry, death, arrhythmia- or shock-related physical injury did not occur in athletes who continue competitive sports after implantable cardioverter-defibrillator (ICD) implantation. However, data from non-competitive ICD recipients is lacking. This report describes arrhythmic events and lead performance in intensive recreational athletes with ICDs enrolled in the European recreational arm of the Registry, and compares their outcome with those of the competitive athletes in the Registry. Methods The Registry recruited 317 competitive athletes ≥ 18 years old, receiving an ICD for primary or secondary prevention (234 US; 83 non-US). In Europe, Israel and Australia only, an additional cohort of 80 ‘auto-competitive’ recreational athletes was also included, engaged in intense physical activity on a regular basis (≥2×/week and/or ≥ 2 h/week) with the explicit aim to improve their physical performance limits. Athletes were followed for a median of 44 and 49 months, respectively. ICD shock data and clinical outcomes were adjudicated by three electrophysiologists. Results Compared with competitive athletes, recreational athletes were older (median 44 vs. 37 years; p = 0.0004), more frequently men (79% vs. 68%; p = 0.06), with less idiopathic ventricular fibrillation or catecholaminergic polymorphic ventricular tachycardia (1.3% vs. 15.4%), less congenital heart disease (1.3% vs. 6.9%) and more arrhythmogenic right ventricular cardiomyopathy (23.8% vs. 13.6%) ( p Conclusions Participants in recreational sports had less frequent appropriate and inappropriate shocks during physical activity than participants in competitive sports. Shocks did not cause death or injury. Recreational athletes with ICDs can engage in sports without severe adverse outcomes unless other reasons preclude continuation.

Objectives This study was conceived to determine the safety and efficacy of the subcutaneous implantable cardioverter-defibrillator (S-ICD) in patients with congenital heart disease (CHD). Background The S-ICD is a treatment option for patients with CHD in which a transvenous device is contraindicated due to anatomic considerations. However, efficacy in this group has not been determined. Methods A pooled analysis of 865 patients in the EFFORTLESS (Evaluation of Factors Affecting the Clinical Outcome and Cost-Effectiveness) registry (an international observational database) and a U.S. Investigational Device Exemption study were reviewed. Results Nineteen CHD patients versus 846 non-CHD patients with a median follow-up of 567 days and 639 days, respectively, were included. There were no deaths and no appropriate shocks for ventricular tachycardia/ventricular fibrillation in the CHD cohort, versus 26 deaths (3.1%, p = 0.42) and 111 appropriate shocks in 59 patients (7.1%) in the non-CHD cohort (p = 0.23). There were similar complication rates for the CHD versus non-CHD groups (10.5 vs. 9.6% [p = 0.89]), with inappropriate shocks for T-wave oversensing as the only complication in the CHD group (n = 2). The rate of inappropriate shocks was similar for both groups (10.5% vs. 10.9% [p = 0.96]). Successful defibrillation testing at 80J was comparable for the CHD versus non-CHD groups (100% vs. 98.5%). Conclusions The overall analysis of the CHD cohort from the pooled data of the Investigational Device Exemption study and the EFFORTLESS registry shows that the S-ICD is a safe option in CHD patients deemed to be at high risk for sudden cardiac death who do not have pacing indications. Further research to accurately define sudden cardiac death risk in the diverse anatomic substrates of CHD patients is warranted.

Background - This study investigated the impact of a right parasternal sensing electrode position on the R- and T-wave amplitudes and the R:T ratio in three subcutaneous implantable cardioverter defibrillator (S-ICD) vectors in patients with adult congenital heart disease (ACHD) and normal controls. Methods - Conventional left parasternal sensing electrode position and right parasternal sensing electrode positions were used to collect 10-second electrograms, recorded through an 80-electrode body surface mapping technology (Prime ECG™ system, Heartscape Technologies Inc., now Verathon, Columbia, MD, USA). Recordings were made in the supine, prone, left lateral, right lateral, sitting, and standing positions in using both the standard electrode vector position and the right parasternal positions. Results - Forty patients were recruited and 37 patients were used for analysis. Twenty-seven (73%) had complex ACHD; 10 patients had normal hearts and acted as controls. A total of 3,708 data points were analyzed. There were no significant differences in the R:T ratio when measured in ACHD patients in the right compared to the left parasternal lead position. In contrast, there were important differences in the magnitude of the R:T ratio when measured in control patients in the right compared to the left parasternal lead position; in the primary vector, the R:T ratio was greater in right than left by 2.99 (P = 0.0002; 95% confidence interval [CI]: 1.48–4.50) and in the secondary vector, the R:T ratio was smaller in the right than in the left by 0.77 (P = 0.004; 95% CI: ?1.58–0.05). Conclusion - In selected patients, a right parasternal lead position may provide a useful alternative sensing configuration for the S-ICD.

BackgroundThe sensitivity and specificity of the subcutaneous implantable cardioverter defibrillator (S-ICD) pre-implant screening tool required clinical evaluation.MethodsBipolar vectors were derived from electrodes positioned at locations similar to those employed for S-ICD sensing and pre-implant screening electrodes, and recordings collected through 80-electrode PRIME®-ECGs, in six different postures, from 40 subjects (10 healthy controls, and 30 patients with complex congenital heart disease (CCHD); 10 with Tetralogy of Fallot (TOF), 10 with single ventricle physiology (SVP), and 10 with transposition of great arteries (TGA)). The resulting vectors were analysed using the S-ICD pre-implant screening tool (Boston Scientific) and processed through the sensing algorithm of S-ICD (Boston Scientific). The data were then evaluated using 2 × 2 contingency tables. Fisher exact and McNemar tests were used for a comparison of the different categories of CCHD, and p < 0.05 vs. controls considered to be statistically significant.Results57% of patients were male, mean age of 36.3 years. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the S-ICD screening tool were 95%, 79%, 59% and 98%, respectively, for controls, and 84%, 79%, 76% and 86%, respectively, in patients with CCHD (p = 0.0001).ConclusionThe S-ICD screening tool was comparatively more sensitive in normal controls but less specific in both CCHD patients and controls; a possible explanation for the reported high incidence of inappropriate S-ICD shocks. Thus, we propose a pre-implant screening device using the S-ICD sensing algorithm to minimise false exclusion and selection, and hence minimise potentially inappropriate shocks.

Introduction It has been suggested that sudden cardiac death (SCD) contributes around 50% of cardiovascular and 27% of all-cause mortality in hemodialysis patients. The true burden of arrhythmias and arrhythmic deaths in this population, however, remains poorly characterised. Cardio Renal Arrhythmia Study in Hemodialysis (CRASH-ILR) is a prospective, implantable loop recorder single centre study of 30 established hemodialysis patients and one of the first to provide long-term ambulatory ECG monitoring. Methods 30 patients (60% male) aged 68±12 years receiving hemodialysis for 45±40 months with varied etiology (diabetes 37%, hypertension 23%) and left ventricular ejection fraction (LVEF) 55±8% received a Reveal XT implantable loop recorder (Medtronic, USA) between August 2011 and October 2014. ECG data from loop recorders were transmitted at each hemodialysis session using a remote monitoring system. Primary outcome was SCD or implantation of a (tachy or bradyarrhythmia controlling) device and secondary outcome, the development of arrhythmia necessitating medical intervention. Results During 379,512 hours of continuous ECG monitoring (mean 12,648±9,024 hours/patient), there were 8 deaths—2 SCD and 6 due to generalised deterioration/sepsis. 5 (20%) patients had a primary outcome event (2 SCD, 3 pacemaker implantations for bradyarrhythmia). 10 (33%) patients reached an arrhythmic primary or secondary end point. Median event free survival for any arrhythmia was 2.6 years (95% confidence intervals 1.6–3.6 years). Conclusions The findings confirm the high mortality rate seen in hemodialysis populations and contrary to initial expectations, bradyarrhythmias emerged as a common and potentially significant arrhythmic event.

Objective Cardiac resynchronisation therapy (CRT) is limited by a substantial proportion of non-responders. Left ventricular endocardial pacing (LVEP) may offer enhanced possibility to deliver CRT in patients with a failed attempt at implantation and to improve clinical status of CRT non-responders. Methods The ALternate Site Cardiac ResYNChronisation (ALSYNC) study was a prospective, multi-centre cohort study that included 118 CRT patients with a successfully implanted endocardial left ventricular (LV) lead, including 90 failed coronary sinus (CS) implants and 28 prior non-responders who had worsened or unchanged heart failure status after at least 6 months of optimal conventional CRT therapy. Results Patients were followed for 19 ± 9 months. At baseline, prior non-responders were sicker as evidenced by a larger LV end-diastolic diameter (70 ± 12 vs 65 ± 9 mm, p = .03) and a trend towards larger LV end-systolic volume index (LVESVi, 95 ± 51 vs 74 ± 39 ml/m2, p = .07), and were more frequently anti-coagulated (96% vs 72%, p = .008) despite similar history of atrial fibrillation (54% vs 51%, p = .83). At 6 months, LVEP significantly improved LV ejection fraction (2.3 ± 7.5 and 8.6 ± 10.0%), New York Heart Association Class (0.4 ± 0.9 and 0.7 ± 0.8), LVESVi (9 ± 16 and 18 ± 43 ml/m2), and six-minute walk test (56 ± 73 and 54 ± 92 m) in prior non-responders and failed CS implants, relative to baseline (all p Conclusion These data suggest that a sizable proportion of CRT non-responders can improve by LVEP, though to a lesser extent than failed CS implants. Clinical trial registration—URL: http://www.clinicaltrials.gov . Unique identifier: NCT01277783

Aims: Remote management of heart failure using implantable electronic devices (REM-HF) aimed to assess the clinical and cost-effectiveness of remote monitoring (RM) of heart failure in patients with cardiac implanted electronic devices (CIEDs).Methods and results: Between 29 September 2011 and 31 March 2014, we randomly assigned 1650 patients with heart failure and a CIED to active RM or usual care (UC). The active RM pathway included formalized remote follow-up protocols, and UC was standard practice in nine recruiting centres in England. The primary endpoint in the time to event analysis was the 1st event of death from any cause or unplanned hospitalization for cardiovascular reasons. Secondary endpoints included death from any cause, death from cardiovascular reasons, death from cardiovascular reasons and unplanned cardiovascular hospitalization, unplanned cardiovascular hospitalization, and unplanned hospitalization. REM-HF is registered with ISRCTN (96536028). The mean age of the population was 70 years (range 23–98); 86% were male. Patients were followed for a median of 2.8 years (range 0–4.3 years) completing on 31 January 2016. Patient adherence was high with a drop out of 4.3% over the course of the study. The incidence of the primary endpoint did not differ significantly between active RM and UC groups, which occurred in 42.4 and 40.8% of patients, respectively [hazard ratio 1.01; 95% confidence interval (CI) 0.87–1.18; P = 0.87]. There were no significant differences between the two groups with respect to any of the secondary endpoints or the time to the primary endpoint components.Conclusion: Among patients with heart failure and a CIED, RM using weekly downloads and a formalized follow up approach does not improve outcomes.

Aims Risk stratification of sudden cardiac death (SCD) is challenging. Fragmented QRS (fQRS) is proposed as a non-invasive electrocardiogram marker associated with mortality and SCD. Results from individual studies including small numbers of patients are discrepant. We therefore performed a meta-analysis of studies evaluating fQRS as a risk stratification tool to predict all-cause mortality and SCD. Methods and results Electronic databases and bibliographies were systematically searched (1996–2014). Twelve studies (5009 patients) recruiting patients with coronary artery disease or non-ischaemic cardiomyopathy met our inclusion criteria. Fragmented QRS was associated with an all-cause mortality relative risk of 1.71 (CI 1.02–2.85) and a relative risk of SCD of 2.20 (CI 1.05–4.62). Subgroup analysis demonstrated greater mortality and SCD risk in those with left ventricular ejection fraction >35% and SCD risk in those with QRS duration

In this paper, we address the problem of detecting the presence of a myocardial scar from the standard electrocardiogram (ECG)/vectorcardiogram (VCG) recordings, giving effort to develop a screening system for the early detection of the scar in the point-of-care. Based on the pathophysiological implications of scarred myocardium, which results in disordered electrical conduction, we have implemented four distinct ECG signal processing methodologies in order to obtain a set of features that can capture the presence of the myocardial scar. Two of these methodologies are: 1) the use of a template ECG heartbeat, from records with scar absence coupled with wavelet coherence analysis and 2) the utilization of the VCG are novel approaches for detecting scar presence. Following, the pool of extracted features is utilized to formulate a support vector machine classification model through supervised learning. Feature selection is also employed to remove redundant features and maximize the classifier's performance. The classification experiments using 260 records from three different databases reveal that the proposed system achieves 89.22% accuracy when applying tenfold cross validation, and 82.07% success rate when testing it on databases with different inherent characteristics with similar levels of sensitivity (76%) and specificity (87.5%).

In this paper, we propose a novel statistical index for the early diagnosis of ventricular arrhythmia (VA) using the time delay phase-space reconstruction (PSR) technique, from the electrocardiogram (ECG) signal. Patients with two classes of fatal VA - with preceding ventricular premature beats (VPBs) and with no VPBs have been analysed using extensive simulations. Three subclasses of VA with VPBs viz. ventricular tachycardia (VT), ventricular fibrillation (VF) and VT followed by VF are analyzed using the proposed technique. Measures of descriptive statistics like mean ({\mu}), standard deviation ({\sigma}), coefficient of variation (CV = {\sigma}/{\mu}), skewness ({\gamma}) and kurtosis (\{beta}) in phase-space diagrams are studied for a sliding window of 10 beats of ECG signal using the box-counting technique. Subsequently, a hybrid prediction index which is composed of a weighted sum of CV and kurtosis has been proposed for predicting the impending arrhythmia before its actual occurrence. The early diagnosis involves crossing the upper bound of a hybrid index which is capable of predicting an impending arrhythmia 356 ECG beats, on average (with 192 beats standard deviation) before its onset when tested with 32 VA patients (both with and without VPBs). The early diagnosis result is also verified using a leave out cross-validation (LOOCV) scheme with 96.88% sensitivity, 100% specificity and 98.44% accuracy., Comment: 25 pages, 16 figures, 2 tables

Background T wave oversensing (TWOS) is the commonest cause of inappropriate shocks in subcutaneous implantable cardioverter defibrillators (S-ICDs). We hypothesise that predictors of TWOS can be derived from surface ECG parameters. Methods In a cohort of SICD recipients in two UK centres, all patients who had TWOS (study group) were compared to all those who had not (control group). The pre-implant screen was scanned and the R wave, T wave amplitudes, QRS interval, time to peak T wave, QT interval and R:T ratio was measured using digital callipers. Logistic regression was performed to identify ECG predictors of TWOS. Results One hundred one patients were studied. Six (5.9%) had TWOS. The mean age of the population was 58.6±18years and the median follow-up was 19.5months. By univariate analysis, the predictors of TWOS are QRS duration (140.7±28.7 vs. 105.9±24.6, P =0.007), time to peak T wave (corrected for heart rate, pTc) (403.9±22.6 vs. 347.8±41.4, P =0.006), QTc interval (500.4±41.2 vs. 446.8±49.7, P =0.021), and R:T ratio (3.5±1.1 vs. 9.5±13.2, P =0.034). By multivariate analysis, time to pTc is the most predictive of TWOS. A time to pTc of 390ms cut-off point provided a sensitivity 38.5%, a specificity of 98.9%, a positive predictive value for TWOS of 83.3%, and a negative predictive value of 91.6% (AUC=0.687). Conclusion In this study, time to pTc is the most powerful ECG predictor of TWOS.

International audience; AIMS: The ALternate Site Cardiac ResYNChronization (ALSYNC) study evaluated the feasibility and safety of left ventricular endocardial pacing (LVEP) using a market-released pacing lead implanted via a single pectoral access by a novel atrial transseptal lead delivery system. METHODS AND RESULTS: ALSYNC was a prospective clinical investigation with a minimum of 12-month follow-up in 18 centres of cardiac resynchronization therapy (CRT)-indicated patients, who had failed or were unsuitable for conventional CRT. The ALSYNC system comprises the investigational lead delivery system and LVEP lead. Patients required warfarin therapy post-implant. The primary study objective was safety at 6-month follow-up, which was defined as freedom from complications related to the lead delivery system, implant procedure, or the lead ≥70%. The ALSYNC study enrolled 138 patients. The LVEP lead implant success rate was 89.4%. Freedom from complications meeting the definition of primary endpoint was 82.2% at 6 months (95% CI 75.6-88.8%). In the study, 14 transient ischaemic attacks (9 patients, 6.8%), 5 non-disabling strokes (5 patients, 3.8%), and 23 deaths (17.4%) were observed. No death was from a primary endpoint complication. At 6 months, the New York Heart Association class improved in 59% of patients, and 55% had LV end-systolic volume reduction of 15% or greater. Those patients enrolled after CRT non-response showed similar improvement with LVEP. CONCLUSIONS: The ALSYNC study demonstrates clinical feasibility, and provides an early indication of possible benefit and risk of LVEP. CLINICAL TRIAL: NCT01277783

AIMS: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease predominantly caused by mutations in desmosomal protein genes. Lamin A/C gene (LMNA) mutations are associated with dilated cardiomyopathy, conduction abnormalities and high incidence of sudden cardiac death. In this study, we screened a large cohort of ARVC patients for LMNA mutations. METHODS AND RESULTS: One hundred and eight patients from unrelated families with borderline (n = 27) or definite (n = 81) diagnosis of ARVC were genetically tested for five desmosomal genes and LMNA. Sixty-one (56.5%) were positive for desmosomal gene mutations. Standard polymerase chain reaction (PCR) amplification of the 12 protein-coding LMNA exons was performed and mutational screening performed by direct sequencing. Four patients (4%) without desmosomal gene mutations carried LMNA variants. Three had severe right ventricular involvement, and during follow-up three died (two suddenly and one from congestive heart failure); all three had conduction abnormalities on resting 12-lead electrocardiogram (ECG). Myocardial tissue from two patients showed myocyte loss and fibro-fatty replacement. In one of these, immunohistochemical staining with antibody to plakoglobin showed reduced/absent staining of the intercalated discs in the myocardium. CONCLUSION: Lamin A/C gene mutations can be found in severe forms of ARVC. Lamin A/C gene should be added to desmosomal genes when genetically testing patients with suspected ARVC, particularly when they also have ECG evidence for conduction disease.

Background: Many implantable cardioverter defibrillator (ICD) recipients may develop indications for cardiac resynchronization therapy (CRT) during follow-up. However, the actual upgrade rate during follow-up in clinical practice is not known. Methods: We performed a single center retrospective observational study of all new ICD implants over 5 years (2003–2007). The rate of CRT upgrade of patients initially implanted with a single-/dual-chamber ICD during follow-up was assessed. The impact of using alternative criteria on the need for CRT in ICD recipients at initial implant was also evaluated. Results: During the study period, there were 549 new ICD implants. The initial implant was a single/dual-chamber ICD in 73% (n = 399) and a CRT-D in 27% (n = 150). During follow-up (48±20 months) of the 399 ICD recipients, 70 (17.5%) died and 15 (3.8%) were upgraded to CRT, including eight cases where left ventricular lead implant had been initially unsuccessful. Upgrade rates at 1, 3, and 5 years were 0.03%, 2.4%, and 5.1%, respectively. Using alternative CRT criteria (left ventricular ejection fraction [LVEF]≤30%, QRS ≥130 ms, New York Heart Association I-IV) 42.6% (n = 234) of ICD recipients met criteria for CRT at initial implant. Conclusion: In this retrospective single center study, rates of CRT upgrade in ICD recipients over the medium term were low, which may reflect underuse in otherwise appropriate candidates. The more liberal use of CRT at initial implant in patients with a reduced LVEF, a broad QRS, but only mild heart failure symptoms would require approximately 50% increase in CRT use in ICD recipients at initial implant, and may help address some of the suggested underutilization. (PACE 2012; 35:73–80)

Atrial fibrillation (AF) is the most common sustained arrhythmia and an important source for mortality and morbidity on a population level. Despite the clear association between AF and death, stroke, and other cardiovascular events, there is no evidence that rhythm control treatment improves outcome in AF patients. The poor outcome of rhythm control relates to the severity of the atrial substrate for AF not only due to the underlying atrial remodelling process but also due to the poor efficacy and adverse events of the currently available ion-channel antiarrhythmic drugs and ablation techniques. Data suggest, however, an association between sinus rhythm maintenance and improved survival. Hypothetically, sinus rhythm may also lead to a lower risk of stroke and heart failure. The presence of AF, thus, seems one of the modifiable factors associated with death and cardiovascular morbidity in AF patients. Patients with a short history of AF and the underlying heart disease have not been studied before. It is fair to assume that abolishment of AF in these patients is more successful and possibly also safer, which could translate into a prognostic benefit of early rhythm control therapy. Several trials are now investigating whether aggressive early rhythm control therapy can reduce cardiovascular morbidity and mortality and increase maintenance of sinus rhythm. In the present paper we describe the background of these studies and provide some information on their design.

Aims Implantable cardioverter defibrillator (ICD) therapy improves survival in patients at high sudden cardiac death (SCD) risk. However, some patient groups fulfilling indications for ICD therapy may not gain significant benefit: patients whose absolute risk of SCD is low and patients whose risk of death even with an ICD is high. The value of biomarkers in identifying patients’ potential for survival benefit from ICD therapy is unknown. We performed a pilot study to investigate this. Methods and results Five established cardiovascular biomarkers were measured in patients with ICDs on the background of left ventricular dysfunction: N-terminal pro-brain natriuretic peptide [NT-proBNP], soluble ST2 [sST2], growth differentiation factor-15, C-reactive protein, and interleukin-6. The endpoints were all-cause mortality and survival with appropriate ICD therapy. One hundred and fifty-six patients were enrolled (age 69 years [Q1–Q3 62–77], 85% male, 76% ischaemic aetiology). During a follow-up of 15 ± 3 months, 12 patients died and 43 survived with appropriate ICD therapy. In a Cox proportional hazards model, the strongest predictors of death were Log sST2 ( P < 0.001), serum creatinine ( P < 0.001), and Log NT-proBNP ( P = 0.002). The strongest predictor of survival with appropriate ICD therapy was Log NT-proBNP ( P = 0.01). Conclusion The biomarkers NT-proBNP and sST2 are promising biomarkers for identifying patients with little potential to gain significant survival benefit from ICD therapy. However, their incremental benefit, in addition to currently available clinical risk prediction models, remains unclear. These results demand a confirmatory prospective cohort study, designed and powered to derive and validate prediction algorithms incorporating these markers.

This paper presents an artificial neural network (ANN) for modeling multicategorical land use changes. Compared to conventional statistical models and cellular automata models, ANNs have both the architecture appropriate for addressing complex problems and the power for spatio-temporal prediction. The model consists of two layers with multiple input and output units. Bayesian regularization was used for network training in order to select an optimal model that avoids over-fitting problem. When trained and applied to predict changes in parcel use in a coastal county from 1990 to 2008, the ANN model performed well as measured by high prediction accuracy (82.0-98.5%) and high Kappa coefficient (81.4-97.5%) with only slight variation across five different land use categories. ANN also outperformed the benchmark multinomial logistic regression by average 17.5 percentage points in categorical accuracy and by 9.2 percentage points in overall accuracy. The authors used the ANN model to predict future parcel use change from 2007 to 2030.

Aim of the document Palpitations are among the most common symptoms that prompt patients to consult general practitioners, cardiologists, or emergency healthcare services.1–4 Very often, however, the diagnostic and therapeutic management of this symptom proves to be poorly efficacious and somewhat frustrating for both the patient and the physician. Indeed, in many cases a definitive, or at least probable, diagnosis of the cause of palpitations is not reached and no specific therapy is initiated.5,6 This means that many patients continue to suffer recurrences of their symptoms, which impair their quality of life and mental balance, lead to the potential risk of adverse clinical events, and induce continual recourse to healthcare facilities. These difficulties stem from the fact that palpitations are generally a transitory symptom. Indeed, at the moment of clinical evaluation, the patient is often asymptomatic and the diagnostic evaluation focuses on the search for pathological conditions that may be responsible for the symptom. This gives rise to some uncertainty in establishing a cause–effect relationship between any anomalies that may be detected and the palpitations themselves. Moreover, as palpitations may be caused by a wide range of different physiological and pathological conditions, clinicians tend to apply a number of instrumental investigations, laboratory tests, and specialist examinations, which are both time-consuming and costly. Comparable, for example, to syncope, such an approach is warranted in selected patients, whereas other patients with palpitations may not require such careful follow-up. The initial clinical assessment should, therefore, include an educated estimation of the likelihood of a relevant underlying arrhythmia in a patient with palpitations (‘gatekeeper' function). The current management of patients with palpitations is guided chiefly by the clinical experience of the physician. Indeed, the literature lacks specific policy documents or recommendations regarding the most appropriate diagnostic work-up to be adopted in individual …

Background— Characterization of sudden cardiac death (SCD) risk remains a challenge in the application of implantable cardioverter-defibrillator (ICD) therapy. Late gadolinium enhancement cardiac MRI (LGE-CMR) can accurately identify myocardial scar. We performed a retrospective, single-center observational study to evaluate the association between the extent and distribution of left ventricular scar, quantified using LGE-CMR, and the burden of ventricular arrhythmias in patients with coronary artery disease and ICDs. Methods and Results— All patients included (2006 to 2009) had undergone LGE-CMR before ICD implantation. Scar (defined as myocardium with a signal intensity ≥50% of the maximum in scar tissue) was characterized in terms of percent scar, scar surface area, and number of transmural left ventricular scar segments. The end point was appropriate ICD therapy. Sixty-four patients (mean age, 66±11 years; male sex, 51) were included. During 19±10 months follow-up, appropriate ICD therapy occurred in 19 (30%) patients. In Cox regression analyses, both percent scar (hazard ratio per 10%, 1.75; 95% CI, 1.09 to 2.81; P =0.02) and number of transmural scar segments (hazard ratio per segment, 1.40; 95% CI, 1.15 to 1.70; P =0.001) were significantly associated with the occurrence of appropriate ICD therapy. Conclusions— In this pilot study, the extent of myocardial scar characterized by LGE-CMR was significantly associated with the occurrence of spontaneous ventricular arrhythmias. We hypothesize that scar quantification by LGE-CMR may prove a valuable risk stratification tool for the occurrence of ventricular arrhythmias, which may have implications for patient selection for ICD therapy.