Comparison of novel intrinsic versus conventional antitachycardia pacing for ventricular tachycardia among implantable cardioverter-defibrillator recipients

INTRODUCTION

Intrinsic antitachycardia pacing (iATP) is a novel automated antitachycardia pacing (ATP) that provides individual treatment to terminate ventricular tachycardia (VT). However, the clinical efficacy of iATP in comparison with conventional ATP is unknown. We aim to compare the termination rate of VT between iATP and conventional ATP in patients with implantable cardioverter-defibrillators using a unique setting of different sequential orders of both ATP algorisms.

METHODS

Patients with the iATP algorithm were assigned to iATP-first and conventional ATP-first groups sequentially. In the iATP-first group, a maximum of seven iATP sequences were delivered, followed by conventional burst and ramp pacing. In contrast, in the conventional ATP-first group, two bursts and ramp pacing were initially programmed, followed by iATP sequences. We compared the success rates of VT termination in the first and secondary programmed ATP zones between the two groups.

RESULTS

Fifty-eight and 56 patients were enrolled in the iATP-first and conventional ATP-first groups, and 67 and 44 VTs were analyzed in each group, respectively. At the first single ATP therapy, success rates were 64% and 70% in the iATP and conventional groups, respectively. At the end of the first iATP treatment zone, the success rate increased from 64% to 85%. Moreover, secondary iATP therapy following the failure of conventional ATPs increased the success rate from 80% to 93%. There was a significant benefit of alternative iATP for VT termination compared to secondary conventional ATP (100% vs. 33%, p = .028).

CONCLUSIONS

iATP may be beneficial as a secondary therapy after failure of conventional ATP to terminate VT.

A Prospective, Multicentre Randomised Controlled Trial Comparing Catheter Ablation Versus Antiarrhythmic Drugs in Patients With Structural Heart Disease Related Ventricular Tachycardia: The CAAD-VT Trial Protocol

IMPORTANCE

Randomised trials have shown that catheter ablation (CA) is superior to medical therapy for ventricular tachycardia (VT) largely in patients with ischaemic heart disease. Whether this translates to patients with all forms and stages of structural heart disease (SHD-e.g., non-ischaemic heart disease) is unclear. This trial will help clarify whether catheter ablation offers superior outcomes compared to medical therapy for VT in all patients with SHD.

OBJECTIVE

To determine in patients with SHD and spontaneous or inducible VT, if catheter ablation is more efficacious than medical therapy in control of VT during follow-up.

DESIGN

Randomised controlled trial including 162 patients, with an allocation ratio of 1:1, stratified by left ventricular ejection fraction (LVEF) and geographical region of site, with a median follow-up of 18-months and a minimum follow-up of 1 year.

SETTING

Multicentre study performed in centres across Australia.

PARTICIPANTS

Structural heart disease patients with sustained VT or inducible VT (n=162).

INTERVENTION

Early treatment, within 30 days of randomisation, with catheter ablation (intervention) or initial treatment with antiarrhythmic drugs only (control).

MAIN OUTCOMES, MEASURES, AND RESULTS

Primary endpoint will be a composite of recurrent VT, VT storm (≥3 VT episodes in 24 hrs or incessant VT), or death. Secondary outcomes will include each of the individual primary endpoints, VT burden (number of VT episodes in the 6 months preceding intervention compared to the 6 months after intervention), cardiovascular hospitalisation, mortality (including all-cause mortality, cardiac death, and non-cardiac death) and LVEF (assessed by transthoracic echocardiography from baseline to 6-, 12-, 24- and 36-months post intervention).

CONCLUSIONS AND RELEVANCE

The Catheter Ablation versus Anti-arrhythmic Drugs for Ventricular Tachycardia (CAAD-VT) trial will help determine whether catheter ablation is superior to antiarrhythmic drug therapy alone, in patients with SHD-related VT.

TRIAL REGISTRY

Australian New Zealand Clinical Trials Registry (ANZCTR) TRIAL REGISTRATION ID: ACTRN12620000045910 TRIAL REGISTRATION URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=377617&isReview=true.

Laser Doppler flow for the hemodynamic differentiation of tachycardia

BACKGROUND

Implantable cardioverter defibrillators (ICDs) offer effective therapy for the prevention of sudden cardiac death (SCD) due to ventricular arrhythmias. However, inappropriate shocks have detrimental effects on survival and quality of life. The addition of hemodynamic monitoring may be useful in discriminating clinically important ventricular arrhythmias.

OBJECTIVE

In this study, we assess the ability of laser Doppler flowmetry to assess the hemodynamic effect of paced atrial and ventricular arrhythmias using mean arterial blood pressure as the reference.

METHODS

In this acute human study in patients undergoing an elective electrophysiological study, laser Doppler flowmetry, arterial blood pressure, and surface ECG were acquired during high-rate atrial and ventricular pacing to simulate supraventricular and ventricular tachycardias.

RESULTS

Arterial blood pressure and laser Doppler flow signals correlated well during atrial and ventricular pacing (rho = 0.694, p < .001). The hemodynamic impairment detected by both methods was greater during ventricular pacing than atrial pacing (-1.0% vs. 19.0%, p < .001). Laser Doppler flowmetry performed better than rate alone to identify hemodynamic impairments.

CONCLUSION

In this acute study, laser Doppler flowmetry tissue perfusion served as a good surrogate measure for arterial pressure, which could be incorporated into future ICDs.

Subcutaneous Versus Transvenous Implantable Defibrillator Therapy: A Systematic Review and Meta-Analysis of Randomized Trials and Propensity Score-Matched Studies

Background

Subcutaneous implantable cardioverter‐defibrillators (S‐ICDs) have been of great interest as an alternative to transvenous implantable cardioverter‐defibrillators (TV‐ICDs). No meta‐analyses synthesizing data from high‐quality studies have yet been published.

Methods and Results

An electronic literature search was conducted to retrieve randomized controlled trials or propensity score–matched studies comparing S‐ICD against TV‐ICD in patients with an implantable cardioverter‐defibrillator indication. The primary outcomes were device‐related complications and lead‐related complications. Secondary outcomes were inappropriate shocks, appropriate shock, all‐cause mortality, and infection. All outcomes were pooled under random‐effects meta‐analyses and reported as risk ratios (RRs) and 95% CIs. Kaplan–Meier curves of device‐related complications were digitized to retrieve individual patient data and pooled under a 1‐stage meta‐analysis using Cox models to determine hazard ratios (HRs) of patients undergoing S‐ICD versus TV‐ICD. A total of 5 studies (2387 patients) were retrieved. S‐ICD had a similar rate of device‐related complications compared with TV‐ICD (RR, 0.59 [95% CI, 0.33–1.04]; P=0.070), but a significantly lower lead‐related complication rate (RR, 0.14 [95% CI, 0.07–0.29]; P<0.0001). The individual patient data–based 1‐stage stratified Cox model for device‐related complications across 4 studies yielded no significant difference (shared‐frailty HR, 0.82 [95% CI, 0.61–1.09]; P=0.167), but visual inspection of pooled Kaplan–Meier curves suggested a divergence favoring S‐ICD. Secondary outcomes did not differ significantly between both modalities.

Conclusions

S‐ICD is clinically superior to TV‐ICD in terms of lead‐related complications while demonstrating comparable efficacy and safety. For device‐related complications, S‐ICD may be beneficial over TV‐ICD in the long term. These indicate that S‐ICD is likely a suitable substitute for TV‐ICD in patients requiring implantable cardioverter‐defibrillator implantation without a pacing indication.

Evaluation of the Novel Automated Anti-Tachycardia Pacing Algorithm Successfully Terminating Sustained Monomorphic Ventricular Tachycardia in an Electrophysiology Study

We report the usefulness of novel automated anti-tachycardia pacing (ATP) for ventricular tachycardia (VT) termination evaluated in an electrophysiology study. This intrinsic, automated ATP with an implanted cardiac resynchronization therapy-defibrillator successfully terminated the sustained VT, which had not been suppressed by repetitive burst pacing from the electrode catheter. The reproduction of programed pacing of the automated ATP by a right ventricular electrode catheter was effective in terminating VT, and this termination was absolute and reproducible. Further detailed assessment in an electrophysiology study could highlight the algorithm of the automated ATP and its possible benefit in terminating the reentrant VT.

Efficacy of antitachycardia pacing alert by remote monitoring of implantable cardioverter-defibrillators for out-of-hospital electrical storm

BACKGROUND

Remote monitoring (RM) has been shown to reduce all-cause mortality in patients with implantable cardioverter-defibrillators or cardiac resynchronization therapy defibrillators (ICD/CRT-D). Not all devices transmit an alert for antitachycardia pacing (ATP) therapy, and it is unknown whether differences of RM alert affect the outcomes of electrical storm (ES).

METHODS

We enrolled 42 patients with ICD/CRT-D whose out-of-hospital ES were detected by RM between 2013 and 2020. We divided their 54 episodes into two groups (ATP-alert-on; 22, ATP-alert-off; 32), and clinical outcomes were compared between the two groups.

RESULTS

In 35 of 54 episodes of ES, ventricular tachycardia (VT) could be terminated within 24 h of ES onset just by ATP (ATP-alert-on: 14, ATP-alert-off: 21); however, many patients subsequently received shock delivery for VT. Among the 35 episodes, only in ATP-alert-on group, seven patients were prompted to visit our hospital without ICD shock through confirmation of ES by ATP-alert. Episodes that led to shock delivery 24 h or longer after the ES onset were significantly less common in the ATP-alert-on group (ATP-alert-on: 1/14, ATP-alert-off: 9/21, p = .03). Although there were no significant differences in the number of shock deliveries between episodes in the two groups, the number of ATP deliveries were significantly fewer in the ATP-alert-on group (12[7-26] vs. 29[16-53] in ATP-alert-off group, p = .03). Multivariate logistic regression analyses showed that the only ATP-alert significantly reduced ATP deliveries (HR = 0.14, 95%CI = 0.04-0.57, p = .003).

CONCLUSION

Remote monitoring with an ATP-alert function during electrical storm may reduce appropriate ICD therapy through prompting early review.

Nontransvenous Cardiovascular Implantable Electronic Device Technology-A Review for the Anesthesiologist

There has been a recent shift in bradycardia pacing and defibrillation therapy to leadless pacemakers and extrathoracic cardioverter-defibrillator technology due to complications associated with transvenous devices. These innovations have implications for anesthesia care, as these novel devices have design and functionality features different from transvenous devices. Current perioperative guidelines do not address management of leadless pacemakers and the subcutaneous implantable cardioverter-defibrillator, although implantation rates are increasing globally. This article addresses the features and capabilities of nontransvenous cardiac implantable electronic devices, such as the Micra and the subcutaneous implantable cardioverter-defibrillator, and provides guidance for perioperative management.

Efficacy of antitachycardia pacing for electrical storms in patients with implantable defibrillators

INTRODUCTION

Although antitachycardia pacing (ATP) is effective in terminating ventricular tachyarrhythmias in patients with implantable cardioverter defibrillators (ICDs), the efficacy of ATP during an electrical storm (ES) and the positive impact on all-cause mortality have not been fully elucidated.

METHODS AND RESULTS

From 2010 to 2012, 1570 patients who underwent ICD implantation in 48 ICD centers in Japan were enrolled in the study and prospectively followed up. Patients with long QT syndrome, Brugada syndrome, and idiopathic ventricular fibrillation were excluded. The prevalence of shocks during ESs and impact on the all-cause mortality were evaluated. During a median follow-up of 28 months, there were 127 ESs in 84 patients. Of those 127 ESs, 80 ESs (63%) in 37 patients were treated by only ATP and the remaining 47 ESs in 47 patients required at least one shock. The lower ventricular rate of the initial arrhythmia during ES (odds ratio [OR]: 1.02 per unit; 95% confidence interval [CI]: 1.00-1.04; p = .02) and narrower QRS complex (OR: 1.03 per unit; 95% CI: 1.01-1.06; p < .01) were the independent predictors of ATP success during the ES. The patients treated with ATP alone tended to have lower all-cause mortality compared to those that required shocks during the ES (log-rank p = .10).

CONCLUSIONS

ATP was effective in patients suffering from ESs as it avoided painful shocks in more than half of the cases. Patients who received only ATP during ES tended to have lower mortality compared to those who received the shock.

The Year in Electrophysiology: Selected Highlights From 2020

This article is the third in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia. The authors thank the Editor-in-Chief Dr. Kaplan, the Associate Editor-in-Chief Dr. Augoustides, and the editorial board for the opportunity to continue this series; namely, the highlights of the year that pertain to electrophysiology in relation to cardiothoracic and vascular anesthesia. This third article focuses on the convergent procedure, His-bundle pacing, a comparison of subcutaneous and transvenous defibrillator therapies, the 2020 practice advisory update for the perioperative management of patients with cardiac implantable electronic devices, and a technology update regarding the Micra AV (Medtronic, Moundsview, MN), the EMPOWER leadless pacemaker (Boston Scientific, Marlborough, MA), WiSE-CRT (EBR Systems, Sunnyvale, CA), the Extravascular Implantable Cardioverter Defibrillator (Medtronic, Moundsview, MN), and the BAROSTIM NEO (CVRx Inc, Minneapolis, MN).

Updates in Ventricular Tachycardia Ablation

Sudden cardiac death (SCD) due to recurrent ventricular tachycardia is an important clinical sequela in patients with structural heart disease. As a result, ventricular tachycardia (VT) has emerged as a major clinical and public health problem. The mechanism of VT is predominantly mediated by re-entry in the presence of arrhythmogenic substrate (scar), though focal mechanisms are also important. Catheter ablation for VT, when compared to standard medical therapy, has been shown to improve VT-free survival and burden of device therapies. Approaches to VT ablation are dependent on the underlying disease process, broadly classified into idiopathic (no structural heart disease) or structural heart disease (ischemic or non-ischemic heart disease). This update aims to review recent advances made for the treatment of VT ablation, with respect to current clinical trials, peri-procedure risk assessments, pre-procedural cardiac imaging, electro-anatomic mapping and advances in catheter and non-catheter based ablation techniques.

Acute pathophysiological myocardial changes following intra-cardiac electrical shocks using a proteomic approach in a sheep model

Implantable cardioverter-defibrillators (ICD) are meant to fight life-threatening ventricular arrhythmias and reduce overall mortality. Ironically, life-saving shocks themselves have been shown to be independently associated with an increased mortality. We sought to identify myocardial changes at the protein level immediately after ICD electrical shocks using a proteomic approach. ICD were surgically implanted in 10 individuals of a healthy male sheep model: a control group (N = 5) without any shock delivery and a shock group (N = 5) with the delivery of 5 consecutive shocks at 41 J. Myocardial tissue samples were collected at the right-ventricle apex near to the lead coil and at the right ventricle basal free wall region. Global quantitative proteomics experiments on myocardial tissue samples were performed using mass spectrometry techniques. Proteome was significantly modified after electrical shock and several mechanisms were associated: protein, DNA and membrane damages due to extreme physical conditions induced by ICD-shock but also due to regulated cell death; metabolic remodeling; oxidative stress; calcium dysregulation; inflammation and fibrosis. These proteome modifications were seen in myocardium both “near” and “far” from electrical shock region. N-term acetylated troponin C was an interesting tissular biomarker, significantly decreased after electrical shock in the “far” region (AUC: 0.93). Our data support an acute shock-induced myocardial tissue injury which might be involved in acute paradoxical deleterious effects such as heart failure and ventricular arrhythmias.

Subcutaneous versus transvenous implantable defibrillator: An updated meta-analysis

BACKGROUND

Implantable cardioverter-defibrillator (ICD) placement is a well-established therapy for prevention of sudden cardiac death. The subcutaneous implantable cardioverter-defibrillator (S-ICD) was specifically designed to overcome some of the complications related to the transvenous implantable cardioverter-defibrillator (TV-ICD), such as lead complications and systemic infections. Evidence on the comparison of S-ICD vs TV-ICD are limited.

OBJECTIVE

The purpose of this study was to conduct an updated meta-analysis comparing S-ICD vs TV-ICD.

METHODS

Electronic databases were searched for studies directly comparing clinical outcomes and complications between S-ICD and TV-ICD. The primary outcome was the composite of clinically relevant complications (lead, pocket, major procedural complications; device-related infections) and inappropriate shocks. Secondary outcomes included death and the individual components of the primary outcome.

RESULTS

Thirteen studies comprising 9073 patients were included in the analysis. Mean left ventricular ejection fraction was 40% ± 10%; 30% of patients were female; and 73% had an ICD implanted for primary prevention. There was no statistically significant difference in the risk of the primary outcome between S-ICD and TV-ICD (odds ratio [OR] 0.80; 95% confidence interval [CI] 0.53-1.19). Patients with S-ICD had lower risk of lead complications (OR 0.14; 95% CI 0.06-0.29; P <.00001) and major procedural complications (OR 0.18; 95% CI 0.06-0.57; P = .003) but higher risk of pocket complications (OR 2.18; 95% CI 1.30-3.66; P = .003) compared to those with TV-ICD. No significant differences were found for the other outcomes.

CONCLUSION

In patients with an indication for ICD without the need for pacing, TV-ICD and S-ICD are overall comparable in terms of the composite of clinically relevant device-related complications and inappropriate shock.

Patient-by-patient basis anti-tachycardia pacing for fast ventricular tachycardia with structural heart diseases

BACKGROUND

Anti-tachycardia pacing (ATP) delivered from an implantable device is an important tool to terminate ventricular tachycardia (VT). But its real-world efficacy for fast VT has not been fully studied.

METHODS

Using the database of Nippon-storm study, effect of patient-by-patient basis ATP programming for fast VT (≥188 bpm) was assessed for the patients with structural heart diseases. Fast VTs were divided into three groups depending on heart rate (HR); Group A was 188-209 bpm, and Group-B and Group-C were 210-239 bpm and ≥240 bpm, respectively.

RESULTS

During a median follow-up of 28 months, 202 fast VT episodes (209 ± 19 bpm) were demonstrated in the 85 patients. ATP terminated 151 of the 202 episodes (74.8%) in total. The success rate of the ATP was not different among the three groups: 73.3% in Group A, 80.6% in Group B, and 66.7% in Group C. ATP success rate of >50% and >70% was 77.6% and 64.7% of the patients, respectively. Left ventricular ejection fraction (LVEF) was significantly higher in the patients with rather than without successful ATP therapy, and receiver operating characteristic (ROC) analysis revealed that LVEF of 23% was the optimal cut-off value. ATP was less effective in patients taking amiodarone, but etiology of the structural heart diseases, indication of the device implantation, and all Electrocardiogram (ECG) parameters were not useful predictors for successful ATP therapy.

CONCLUSIONS

ATP highly terminated fast VT with wide HR ranges in patients with structural heart diseases, and should be considered as the first-line therapy for fast VT except for patients with very low LVEF.

Myocardial Minimal Damage After Rapid Ventricular Pacing - the prospective randomized multicentre MyDate-Trial

Therapy of choice for the primary and secondary prevention of sudden cardiac death is the implantation of an implantable cardioverter defibrillator (ICD). Whereas appropriate and inappropriate ICD shocks lead to myocardial microdamage, this is not known for antitachycardia pacing (ATP). In total, 150 ICD recipients (66 ± 12 years, 81.3% male, 93.3% primary prevention, 30.0% resynchronization therapy) were randomly assigned to an ICD implantation with or without intraoperative ATP. In the group with ATP, the pacing maneuver was performed twice, each time applying 8 impulses à 6 Volt x 1.0 milliseconds to the myocardium. High sensitive Troponin T (hsTnT) levels were determined prior to the implantation and thereafter. There was no significant difference in the release of hsTnT between the two randomization groups (delta TnT without ATP in median 0.010 ng/ml [min. −0.016 ng/ml–max. 0.075 ng/ml] vs. with ATP in median 0.013 ng/ml [min. −0.005–0.287 ng/ml], p = 0.323). Setting a hsTnT cutoff of 0.059 ng/dl as a regularly augmented postoperative hsTnT level, no relevant difference between the two groups regarding the postoperative hsTnT levels above this cutoff could be identified (without ATP n = 10 [14.7%] vs. with ATP n = 16 [21.9%], p = 0.287). There was no significant difference in the release of high sensitive Troponin between patients without intraoperative ATP compared to those with intraoperative ATP. Hence, antitachycardia pacing does not seem to cause significant myocardial microdamage. This may further support its use as a painless and efficient method to terminate ventricular tachycardia in high-risk patients.

Clinical predictors of antitachycardia pacing response in implantable cardioverter defibrillator patients

BACKGROUND

Antitachycardia pacing (ATP) provides safe and painless termination of reentrant ventricular arrhythmias in patients with implantable cardioverter defibrillator (ICDs), improving their quality of life. Established predictors of ATP responsiveness are not well known; only longer ventricular tachycardia (VT) cycle length and higher ejection fraction have been found to predict ATP success.

OBJECTIVE

To investigate clinical and ECG predictors of ATP response in ICD patients with monomorphic VT.

METHODS

The ICD clinic database was searched for monomorphic VT events requiring ICD therapy in patients with ischemic or non-ischemic cardiomyopathy. Each patient's first ICD encounter for VT was assessed. Patient demographics, clinical characteristics, VT rate, and ATP responsiveness (always, sometimes, and never successful) were recorded. An ECG was analyzed for QRS morphology and duration. Data was assessed for predictors of ATP responsiveness.

RESULTS

In 527 patients, characteristics associated with always successful ATP included ACE-I/ARB therapy and slower VT rate (never successful ATP 197 ± 28 bpm, sometimes successful ATP 190 ± 27 bpm, always successful ATP 183 ± 22 bpm, P < .0001). Secondary prevention indication, amiodarone therapy, and longer QRS duration were associated with ATP failure. After multivariate analysis, only faster VT rate and amiodarone therapy were predictive of ATP failure.

CONCLUSIONS

Neither QRS morphology nor duration was predictive of ATP success. Slower VT rate was predictive of repeated ATP responsiveness. Amiodarone therapy, which is known to increase VT cycle length, interestingly was associated with ATP failure for unclear reasons. More individualized and possibly more aggressive ATP programming may be warranted in patients on amiodarone.

Effect of High Influenza Activity on Risk of Ventricular Arrhythmias Requiring Therapy in Patients With Implantable Cardiac Defibrillators and Cardiac Resynchronization Therapy Defibrillators

Influenza is associated with an increased risk of cardiovascular events. Influenza's association with ventricular arrhythmias (VAs) has not been adequately studied. We investigated the relation of seasonal influenza activity with the incidence of VAs requiring therapy in patients with an implantable cardiac defibrillator or cardiac resynchronization therapy defibrillator. We retrospectively studied 163,831 patients with an implantable cardiac defibrillator or cardiac resynchronization therapy defibrillator who were enrolled in the Abbott Medical Merlin.net remote-monitoring network between January 2009 and December 2015. We used cross-correlation to assess the temporal relationship between influenza activity and the incidence of VAs requiring shock or antitachycardia pacing (ATP). We used a generalized linear model to test the possible effect of seasonal influenza activity on the occurrence of VAs requiring shock or ATP treatment, after adjustment for within-patient effects, age, gender, device type, and calendar year. We found a significant correlation between influenza activity and the incidence of VAs requiring shock or ATP treatment. The multivariate generalized linear model showed that during high influenza activity, patients were more likely to have a VA treated with shock (odds ratio = 1.06, p < 0.001) or ATP (odds ratio = 1.06, p < 0.0001). The impact of high influenza activity was most prominent during the years 2014 and 2015. We conclude that high influenza activity is associated with increased risk of VAs requiring therapy.

Arrhythmic episodes in patients implanted with a cardioverter-defibrillator - results from the Prospective Study on Predictive Quality with Preferencing PainFree ATP therapies (4P)

Background

Little is known about the ICD performance using enhanced detection algorithms in unselected, non-trial patients. Performance of recent generation ICD equipped with SmartShock™ technology (SST) for detection and conversion of ventricular tachyarrhythmias (VTA) was investigated.

Methods

4P was a prospective, multicenter, observational study conducted in 10 Swiss implanting centers. Patients with a Class I indication according to international guidelines were included and received an ICD with SST. ICD discrimination capability was assessed by evaluating SST performance; therapy efficacy was assessed by rate of VTA conversions by ATP and by rescue shocks.

Results

Overall, 196 patients were included in the analysis with a mean duration of follow-up of 27.7 months (452 patient-years of observation). Patient-specific rather than recommended programming was preferred. Device-detected episodes were frequent (5147 episodes in 146 patients, 74.5%). In 44 patients (22.4%), 1274 episodes were categorized as VTA; only 215 episodes were symptomatic. ATP was the first-line therapy and highly effective (99.9% success rate at the episode level, 100.0% at the patient level). Rescue shocks were rare (66 episodes in 28 patients); 7 shocks in 5 patients (2.6%) were inappropriate. Death and hospitalization rates were low.

Conclusions

In a cohort of non-trial, unselected ICD patients, VTA episodes were frequent. The 4P results confirm the robustness of VTA detection by SST and the effectiveness of ATP treatment, hence limiting overall ICD shock burden.

Clinical outcomes of cardiac resynchronization therapy with and without a defibrillator in elderly patients with heart failure

BACKGROUND

Evidence regarding the incremental benefit of cardiac resynchronization therapy (CRT) with a defibrillator (CRT-D) versus without (CRT-P) in elderly patients with heart failure is limited. We compared mortality and cardiac hospitalisation between CRT-D and CRT-P in the elderly.

METHODS

A retrospective chart review identified all consecutive patients with age ≥75 with CRT implantation over the last 10 years at a Canadian tertiary care cardiac centre. Kaplan-Meier survival analyses and cumulative incidence curves were used to compare mortality and time to first cardiac hospitalisation, respectively, with CRT-D versus CRT-P over a 3 year period. Analyses were also repeated with propensity score matching based on age, sex, primary versus secondary prevention, date of implant, and Charlson Comorbidity Index.

RESULTS

One hundred and seventy CRT patients were identified. A total of 128 received CRT-D while 42 received CRT-P. Median age was 79 (IQR 77-81), and the majority were male (83%). CRT-P patients had a higher burden of comorbidities (Charlson score 7, IQR 6-8) than CRT-D patients (Charlson score 5, IQR 5-7; P < 0.001). There was no significant difference in survival between the two groups in an unmatched comparison (P = 0.69) and with a propensity score-matched cohort (P = 0.91). Secondary prevention CRT-D patients had a higher risk of hospitalisation compared to primary prevention CRT-D patients; however, there was no significant difference in hospitalisation between the CRT-D and CRT-P groups.

CONCLUSION

This study suggests there is no significant difference in mortality or cardiac hospitalisation between CRT-D and CRT-P in elderly patients with heart failure.

Organizational model and reactions to alerts in remote monitoring of cardiac implantable electronic devices: A survey from the Home Monitoring Expert Alliance project

BACKGROUND

This survey aimed to describe the organizational workflow of cardiac implantable electronic devices (CIEDs) remote monitoring (RM) service in ordinary practice.

METHODS

A questionnaire was designed for our purpose and completed by 49 sites participating to the Italian Home Monitoring Expert Alliance.

RESULTS

A dedicated organizational model for RM was set up for 86% of centers. The median RM team consisted of 2 (Interquartile range [IQR]: 1-3) physicians and 1 (IQR: 0-2) nurse. RM service was available in working hours and the median percentage of patients included was 100% (IQR: 10%-100%) for implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy (CRT) recipients and 5% (IQR:0%-30%) for pacemakers. In-office follow-up was performed every 12 and 6 months for pacemaker and ICD/CRT recipients, respectively. More than 90% of sites used to activate all technical alerts, with a prompt reaction in case of an out-of-range parameter. The threshold for atrial fibrillation (AF) daily burden notification in most cases ranged from 2.4 to 7.2 hours. All ventricular arrhythmias alerts were usually switched on: an inappropriate therapy or more than one appropriate episode triggered an urgent in-hospital visit. Concerning heart failure, low CRT percentage pacing alert was always used, while the other available notifications were less frequently switched on.

CONCLUSIONS

This survey showed that RM service was usually set up with a primary nursing model including on average two responsible physicians and one nurse and mainly offered to ICD/CRT patients. Technical, AF and ventricular arrhythmia alerts triggered prompt reactions, while heart failure related indexes were generally less applied.

Competitive athletes with implantable cardioverter-defibrillators-How to program? Data from the Implantable Cardioverter-Defibrillator Sports Registry

BACKGROUND

Athletes with an implantable cardioverter-defibrillator (ICD) may require unique optimal device-based tachycardia programming.

OBJECTIVE

The purpose of this study was to assess the association of tachycardia programming characteristics of ICDs with occurrence of shocks, transient loss-of-consciousness, and death among athletes.

METHODS

A subanalysis of a prospective, observational, international registry of 440 athletes with ICDs followed for a median of 44 months was performed. Programming characteristics were divided into groups for rate cutoff (very high, high, or low) and detection (long-detection interval [>nominal] or nominal). Endpoints included total, appropriate, and inappropriate shocks, transient loss-of-consciousness, and mortality.

RESULTS

In this cohort, 62% were programmed with high-rate cutoff and 30% with long detection. No athlete died of an arrhythmia (related or unrelated) to ICD shocks. Three patients had sustained ventricular tachycardia below programmed detection rate, presenting as palpations and/or dizziness. ICD shocks were received by 98 athletes (64 appropriate, 32 inappropriate); 2 patients received both. Programming a high-rate cutoff was associated with decreased risk of total (P = .01) and inappropriate (P = .04) shocks overall and during competition or practice. Programming long-detection intervals was associated with fewer total shocks. Single- vs dual-chamber devices and the number of zones were unrelated to risk of shock. Transient loss-of-consciousness, associated with 27 appropriate shocks, was not related to programming characteristics.

CONCLUSION

High-rate cutoff and long-detection duration programming of ICDs in athletes at risk for sudden death can reduce total and inappropriate ICD shocks without affecting survival or the incidence of transient loss-of-consciousness.

Mechanical Circulatory Support During Catheter Ablation of Ventricular Tachycardia: Indications and Options

Mapping of scar-related ventricular tachycardia (VT) in structural heart disease is fundamentally driven by identifying the critical isthmus of conduction that supports re-entry in and around myocardial scar. Mapping can be performed using activation and entrainment techniques during VT, or by substrate mapping performed in stable sinus or paced rhythm. Activation and entrainment mapping requires the patient to be in continuous VT, which may not be haemodynamically tolerated, or, if tolerated, may lead to adverse sequelae related to impaired end organ perfusion. Mechanical circulatory support (MCS) devices may facilitate haemodynamic stability and preserve end organ perfusion during sustained VT to permit mapping for long periods. Available options for haemodynamic support include an intra-aortic balloon pump (IABP), TandemHeart left atrial to femoral artery bypass system (CardiacAssist Inc., Pittsburgh, PA, USA), Impella left ventricle (LV) to aorta flow-assist system (Abiomed, Danvers, MA, USA), and extracorporeal membrane oxygenation (ECMO); the bypass and assist devices provide far better augmentation of cardiac output than IABP. MCS has potential key advantages including maintenance of vital organ perfusion, reduction of intra-cardiac filling pressures, reduction of LV volumes, wall stress, and myocardial consumption of oxygen, and improvement of coronary perfusion during prolonged periods of VT induction and/or mapping. Observational studies show MCS allows for longer duration of mapping, and increased likelihood of VT termination, without an increased risk of peri-procedural mortality or VT recurrence in follow-up, despite being used in a significantly sicker cohort of patients. However, MCS has increased risk of complications related to vascular access, bleeding, thromboembolic risk, mapping system interference, increase procedural complexity and increased cost. Acute haemodynamic decompensation occurs in ∼11% of patients undergoing VT ablation, and is associated with increased mortality. Prospectively identifying patients at risk of acute haemodynamic decompensation in the peri-procedural period may allow prophylactic MCS. Although observational studies of MCS in patients at high risk of haemodynamic decompensation are encouraging, its benefit needs to be proven in randomised trials. This review will summarise the indication for MCS, forms of MCS, procedural outcomes, complications and utility of MCS during VT ablation.