A systematic review and meta-analysis of the association between implantable cardioverter-defibrillator shocks and long-term mortality

Amiodarone and β-blocker combination therapy versus β-blocker monotherapy for ICD shock prevention: A meta-analysis

While implantable cardioverter-defibrillator (ICD) shocks are a lifesaving therapy, they can negatively affect the patient's quality of life. Amiodarone is commonly combined with β-blockers (BB) in ICD recipients. However, this combination therapy's efficacy in preventing shocks compared to standard BB monotherapy is not well studied. The aim of this systematic review and meta-analysis is to determine if combined amiodarone and BB therapy improves prevention of ICD shock delivery compared to BB monotherapy. We performed a comprehensive literature search using PubMed, Cochrane, and Web of Science databases, for studies that assess the impact of amiodarone and BB versus BB monotherapy in patients with an ICD. The primary outcome was a total number of ICD shocks delivered by the end of the study period. Four studies: three retrospective studies and one randomized controlled trial (RCT), with a total of 5818 patients with ICDs, were included in the analysis. Follow-up periods ranged from 1 to 5 years. The combined amiodarone and BB group was not associated with a significantly lower number of ICD shocks compared to the BB monotherapy group (OR, 0.76; 95% CI, 0.44-1.31; P = .32). A combination therapy of amiodarone and BB was not associated with any further reduction in ICD shocks, hospitalizations, or mortality. Additional RCTs are recommended to further validate our findings.

Catheter ablation versus antiarrhythmic drug therapy for sustained ventricular tachycardia in patients with hypertrophic cardiomyopathy

BACKGROUND

Ventricular tachycardia (VT) is the primary cause of sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). However, the strategy for VT treatment in HCM patients remains unclear. This study is aimed to compare the effectiveness of catheter ablation versus antiarrhythmic drug (AAD) therapy for sustained VT in patients with HCM.

METHODS

A total of 28 HCM patients with sustained VT at 4 different centers between December 2012 and December 2021 were enrolled. Twelve underwent catheter ablation (ablation group) and sixteen received AAD therapy (AAD group). The primary outcome was VT recurrence during follow-up.

RESULTS

Baseline characteristics were comparable between two groups. After a mean follow-up of 31.4 ± 17.5 months, the primary outcome occurred in 35.7% of the ablation group and 90.6% of the AAD group (hazard ratio [HR], 0.29 [95%CI, 0.10-0.89]; P = 0.021). No differences in hospital admission due to cardiovascular cause (25.0% vs. 71.0%; P = 0.138) and cardiovascular cause-related mortality/heart transplantation (9.1% vs. 50.6%; P = 0.551) were observed. However, there was a significant reduction in the composite endpoint of VT recurrence, hospital admission due to cardiovascular cause, cardiovascular cause-related mortality, or heart transplantation in ablation group as compared to that of AAD group (42.9% vs. 93.7%; HR, 0.34 [95% CI, 0.12-0.95]; P = 0.029).

CONCLUSIONS

In HCM patients with sustained VT, catheter ablation reduced the VT recurrence, and the composite endpoint of VT recurrence, hospital admission due to cardiovascular cause, cardiovascular cause-related mortality, or heart transplantation as compared to AAD.

Ultra-Low-Temperature Cryoablation for Ventricular Tachycardia: An Early Single-Centre Report of Acute Results

Background

Endocardial catheter ablation for ventricular tachycardia (VT) may fail because of the inability to deliver transmural lesions. Ultra-low-temperature cryoablation (ULTC) uses near-critical nitrogen and can generate temperatures as low as -196 °C. We report a series of 18 patients who underwent ULTC at the McGill University Health Centre (MUHC), representing the largest single-centre experience to date.

Methods

Eighteen patients with monomorphic drug-refractory VT underwent VT ablation with ULTC at our institution as part of the first-in-human CryoCure-VT trial (NCT04893317). After voltage map, the mapping catheter was replaced with the ULTC catheter, and lesions were applied over a fixed duration of time (60-180 seconds), followed by a 60-second thaw and another application at the original duration (freeze-thaw-freeze). Duration of ablation time was selected depending on the wall thickness of the left ventricle monitored with intracardiac echo to achieve tissue depths of 4.5 to 7.5 mm.

Results

Baseline left ventricular ejection fraction was 32%, mean age 71 years, 94% were male. A total of 32 sustained VTs were induced in 16 of 18 patients. A total of 177 cryoablation lesions were delivered (9.8 lesions per patient). Of the 16 patients with inducible VT, 15 (94%) were rendered noninducible postablation, and 1 was inducible only for a nonclinical VT. Complications included 1 pericardial effusion that required drainage. From 18 patients, 16 (89%) were discharged within the first 24 hours postablation.

Conclusions

ULTC is feasible and permits acute control of monomorphic VT during VT ablation procedures in drug-refractory patients.

Machine learning-derived cycle length variability metrics predict spontaneously terminating ventricular tachycardia in implantable cardioverter defibrillator recipients

Aims

Implantable cardioverter defibrillator (ICD) therapies have been associated with increased mortality and should be minimized when safe to do so. We hypothesized that machine learning-derived ventricular tachycardia (VT) cycle length (CL) variability metrics could be used to discriminate between sustained and spontaneously terminating VT.

Methods and results

In this single-centre retrospective study, we analysed data from 69 VT episodes stored on ICDs from 27 patients (36 spontaneously terminating VT, 33 sustained VT). Several VT CL parameters including heart rate variability metrics were calculated. Additionally, a first order auto-regression model was fitted using the first 10 CLs. Using features derived from the first 10 CLs, a random forest classifier was used to predict VT termination. Sustained VT episodes had more stable CLs. Using data from the first 10 CLs only, there was greater CL variability in the spontaneously terminating episodes (mean of standard deviation of first 10 CLs: 20.1 ± 8.9 vs. 11.5 ± 7.8 ms, P < 0.0001). The auto-regression coefficient was significantly greater in spontaneously terminating episodes (mean auto-regression coefficient 0.39 ± 0.32 vs. 0.14 ± 0.39, P < 0.005). A random forest classifier with six features yielded an accuracy of 0.77 (95% confidence interval 0.67 to 0.87) for prediction of VT termination.

Conclusion

Ventricular tachycardia CL variability and instability are associated with spontaneously terminating VT and can be used to predict spontaneous VT termination. Given the harmful effects of unnecessary ICD shocks, this machine learning model could be incorporated into ICD algorithms to defer therapies for episodes of VT that are likely to self-terminate.

Oral mexiletine for ventricular tachyarrhythmias treatment in implantable cardioverter-defibrillator patients: a systematic review of the literature

INTRODUCTION

To evaluate the clinical outcomes of oral mexiletine (oMXT) to treat ventricular tachyarrhythmias (VTAs) in the era of implantable cardioverter-defibrillator (ICD) technology.

EVIDENCE ACQUISITION

A systematic search was conducted using PubMed, Embase and Cochrane databases following the PRISMA guidelines to collect literature data reporting oMXT efficacy and safety outcomes in treating VTAs in ICD recipients.

EVIDENCE SYNTHESIS

Final analysis included four studies accounting for a total of 91 patients with recurrent VTAs treated with oMXT. Amiodarone therapy was initially attempted in most patients (91.2%), while catheter ablation was performed in one-third of patients. VTA recurrences were observed in 55/91 patients (60.4%) during oMXT treatment compared to 91/91 (100%) before treatment (P<0.001). Appropriate therapies occurred in 55/88 ICD patients (62.5%) during oMXT treatment compared to 80/88 (90.9%) before treatment (P<0.001). After oMXT introduction, there was a significant reduction of the individual burden of VTA episodes and appropriate ICD therapies per patient, showing Hedges'g values of -1.103 (P=0.002) and -1.474 (P=0.008), respectively. Safety analysis showed a sample-weighted overall side-effect rate of 30%, while 21% of patients required drug reduction or discontinuation. Aggregated meta-regression analysis of the included studies and remote literature revealed a linear correlation between oMXT dosage and the overall side effects rate (r2 = 0.48; P=0.014).

CONCLUSIONS

Oral mexiletine provides an adjunctive treatment to manage VTAs and reduces appropriate therapies in ICD patients with moderate efficacy and acceptable safety profiles. These observations await confirmation through randomised clinical trials.

Rationale and study protocol for the BRITISH randomized trial (Using cardiovascular magnetic resonance identified scar as the benchmark risk indication tool for implantable cardioverter defibrillators in patients with nonischemic cardiomyopathy and severe systolic heart failure)

BACKGROUND

For patients with nonischemic cardiomyopathy (NICM), current guidelines recommend implantable cardioverter defibrillators (ICD) when left ventricular ejection fraction (LVEF) is ≤35%, but the DANISH trial failed to confirm that ICDs reduced all-cause mortality for such patients. Circumstantial evidence suggests that scar on CMR is predictive of sudden and arrhythmic death in this population. The presence of myocardial scar identified by cardiac magnetic resonance imaging (CMR) in patients with NICM and an LVEF ≤35% might identify patients at higher risk of sudden arrhythmic death, for whom an ICD is more likely to reduce all-cause mortality.

METHODS/DESIGN

The BRITISH trial is a prospective, multicenter, randomized controlled trial aiming to enrol 1,252 patients with NICM and an LVEF ≤35%. Patients with a nonischemic scar on CMR will be randomized to either: (1) ICD, with or without cardiac resynchronization (CRT-D), or (2) implantable loop recorder (ILR) or cardiac resynchronization (CRT-P). Patients who are screened for the trial but are found not to be eligible, predominantly due to an absence of scar or those who decline to be randomized will be enrolled in an observational registry. The primary endpoint is all-cause mortality, which we plan to assess at 3 years after the last participant is randomized. Secondary endpoints include clinical outcomes, appropriate and inappropriate device therapies, symptom severity and well-being, device-related complications, and analysis of the primary endpoint by subgroups with other risk markers.

CONCLUSION

The BRITISH trial will assess whether the use of CMR-defined scar to direct ICD implantation in patients with NICM and an LVEF ≤35% is associated with a reduction in mortality.

Efficiency of MVP ECG Risk Score for Prediction of Long-Term Atrial Fibrillation in Patients With ICD for Heart Failure With Reduced Ejection Fraction

BACKGROUND AND OBJECTIVES

The morphology-voltage-P-wave duration (MVP) electrocardiography (ECG) risk score is a newly defined scoring system that has recently been used for atrial fibrillation (AF) prediction. The aim of this study was to evaluate the ability of the MVP ECG risk score to predict AF in patients with an implantable cardioverter defibrillator (ICD) and heart failure with reduced ejection fraction in long-term follow-up.

METHODS

The study used a single-center, and retrospective design. The study included 328 patients who underwent ICD implantation in our hospital between January 2010 and April 2021, diagnosed with heart failure. The patients were divided into low, intermediate and high-risk categories according to the MVP ECG risk scores. The long-term development of atrial fibrillation was compared among these 3 groups.

RESULTS

The low-risk group included 191 patients, the intermediate-risk group 114 patients, and the high-risk group 23 patients. The long-term AF development rate was 12.0% in the low-risk group, 21.9% in the intermediate risk group, and 78.3% in the high-risk group. Patients in the high-risk group were found to have 5.2 times higher rates of long-term AF occurrence compared to low-risk group.

CONCLUSIONS

The MVP ECG risk score, which is an inexpensive, simple and easily accessible tool, was found to be a significant predictor of the development of AF in the long-term follow-up of patients with an ICD with heart failure with reduced ejection fraction. This risk score may be used to identify patients who require close follow-up for development and management of AF.

Catheter Ablation of Ventricular Arrhythmia in Patients With an Implantable Cardioverter-Defibrillator: A Systematic Review and Meta-analysis

BACKGROUND

Implantable cardioverter-defibrillator (ICD) shocks are associated with higher rates of mortality and reduced quality of life. In this study we aimed to investigate the effectiveness of catheter ablation (CA) of ventricular tachycardia in patients with an ICD.

METHODS

An electronic literature search was conducted to identify randomized controlled trials that compared CA vs control. The primary outcomes were recurrence of ventricular arrhythmia (ventricular tachycardia or ventricular fibrillation) and mortality. Kaplan-Meier curves for these outcomes were digitized to obtain individual patient data, which were pooled in a 1-stage meta-analysis to determine hazard ratios (HRs) and 95% confidence intervals (CIs). Secondary outcomes included cardiac hospitalization, electrical storm, syncope, appropriate ICD therapies, appropriate ICD shocks, and inappropriate shocks. For these, study-level HRs or risk ratios were obtained and pooled in random effects meta-analyses. Subgroup analysis was performed for trials that investigated prophylactic CA (before or during ICD implantation).

RESULTS

Data on 9 studies and 1103 patients were retrieved. CA significantly reduced ventricular tachycardia/ventricular fibrillation recurrence compared with control (shared frailty HR, 0.63; 95% CI, 0.49-0.81; P < 0.001) but not mortality (shared frailty HR, 0.84; 95% CI, 0.57-1.23; P = 0.361). CA was associated with significantly lower rates of cardiac hospitalization, electrical storm, appropriate ICD therapies and shocks, but not syncope or inappropriate shocks. Subgroup analysis showed similar results for prophylactic CA except that no significant difference was observed for cardiac hospitalizations.

CONCLUSIONS

CA is associated with reduced ventricular arrhythmia recurrence, appropriate ICD therapies/shocks, electrical storm, and cardiac hospitalization, and might be effective in preventing future morbidity. Future trials are needed to support the continued benefit of these promising results, and to investigate the optimal timing of ablation.

Case report: Stereotactic body radiation therapy with 12 Gy for silencing refractory ventricular tachycardia

BACKGROUND

Encouraging results have been reported for the treatment of ventricular tachycardia (VT) with stereotactic body radiation therapy (SBRT) with 25 Gy. SBRT with 12 Gy for refractory VT was designed to reduce long-term cardiac toxicity.

METHODS

Stereotactic body radiation therapy-VT simulation, planning, and treatment were performed using standard techniques. A patient was treated with a marginal dose of 12 Gy in a single fraction to the planning target volume (PTV). The goal was for at least ≥ 95% of the PTV to be covered by at least 95% of 12 Gy radiation.

RESULTS

From April 2021 through June 2022, a patient with refractory VT underwent treatment. The volume for PTV was 65.8 cm3. The mean radiation dose administered to the heart (the heart volume excluding the PTV) was 2.2 Gy. No acute or late toxicity was observed after SBRT. Six months after SBRT, the patient experienced new monomorphic right ventricular outflow tract (RVOT) VT. Interestingly, the substrate of the left ventricular basal to middle posteroseptal wall before SBRT was turned into scar zones with a local voltage < 0.5 mV. Catheter ablation to treat RVOT VT was performed, and the situation remains stable to date.

CONCLUSION

This study reports the first patient with refractory VT successfully treated with 12.0 Gy SBRT, suggesting that 12 Gy is a potential dose to treat refractory VT. Further investigations and enrollment of more patients are warranted to assess the long-term efficacy and side effects of this treatment.

Evaluation of Saline-Enhanced Radiofrequency Needle-Tip Ablation for Ventricular Tachycardia (SERF VT CANADA Trial)

BACKGROUND

Endocardial catheter ablation for ventricular tachycardia (VT) may fail owing to the inability to deliver transmural lesions. Saline-enhanced radiofrequency (SERF) ablation uses a needle-tip catheter that is placed at varying depths into the myocardial tissue and heated saline solution is injected along with radiofrequency power (RF), creating fully transmural lesions. We report the first in-human SERF ablation for VT in Canada.

METHODS

Twenty-five patients with ischemic and nonischemic cardiomyopathy, with recurrent monomorphic drug-refractory VT who had failed a prior catheter ablation underwent SERF ablation in 3 different centres in Canada. After a voltage map, the mapping catheter was replaced with the needle-tipped ablation catheter, which was located perpendicular to the myocardium and extended either 6 or 8 mm into the tissue. Sterile saline solution was infused at a flow rate of 10 mL/min and at 60 °C, and 20-50 W RF was used.

RESULTS

Baseline left ventricular ejection fraction was 33.3 ± 8.6%, mean age was 69.5 ± 6.4 years; 92% were male. From 43 clinical VTs induced, 42 were ablated and 266 SERF lesions were delivered (10.6 ± 4.9 per patient). Of the 42 treated clinical VTs, 41 VTs (98%) were noninducible and 24 patients (96%) had their VT eliminated. At 6 months' follow-up, 42% of patients were free from VT and there was a 73% reduction in shocks.

CONCLUSIONS

SERF ablation is feasible and permits control of symptomatic monomorphic VT in drug-refractory patients with a prior failed ablation.

Pharmacologic Management for Ventricular Arrhythmias: Overview of Anti-Arrhythmic Drugs

Ventricular arrhythmias (Vas) are a life-threatening condition and preventable cause of sudden cardiac death (SCD). With the increased utilization of implantable cardiac defibrillators (ICD), the focus of VA management has shifted toward reduction of morbidity from VAs and ICD therapies. Anti-arrhythmic drugs (AADs) can be an important adjunct therapy in the treatment of recurrent VAs. In the treatment of VAs secondary to structural heart disease, amiodarone remains the most well studied and current guideline-directed pharmacologic therapy. Beta blockers also serve as an important adjunct and are a largely underutilized medication with strong evidentiary support. In patients with defined syndromes in structurally normal hearts, AADs can offer tailored therapies in prevention of SCD and improvement in quality of life. Further clinical trials are warranted to investigate the role of newer therapeutic options and for the direct comparison of established AADs.

Contemporary Management of Complex Ventricular Arrhythmias

Percutaneous catheter ablation is an effective and safe therapy that can eliminate ventricular tachycardia, reducing the risks of both recurrent arrhythmia and shock therapies from a defibrillator. Successful ablation requires accurate identification of arrhythmic substrate and the effective delivery of energy to the targeted tissue. A thorough pre-procedural assessment is needed before considered 3D electroanatomical mapping can be performed. In contemporary practice, this must combine traditional electrophysiological techniques, such as activation and entrainment mapping, with more novel physiological mapping techniques for which there is an ever-increasing evidence base. Novel techniques to maximise energy delivery to the tissue must also be considered and balanced against their associated risks of complication. This review provides a comprehensive appraisal of contemporary practice and the evidence base that supports recent developments in mapping and ablation, while also considering potential future developments in the field.

Personalized subcutaneous implantable cardioverter-defibrillator sensing vectors generated by mathematical rotation increase device eligibility whilst preserving device performance

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.

S-ICD screening revisited: do passing vectors sometimes fail?

INTRODUCTION

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Sacubitril/valsartan versus angiotensin inhibitors and arrhythmia endpoints in heart failure with reduced ejection fraction

Background

Angiotensin receptor–neprilysin inhibitor (ARNI) therapy has been associated with improved survival for patients with symptomatic heart failure and reduced ejection fraction (HFrEF).

Objectives

We performed a meta-analysis of arrhythmia endpoints from studies comparing ARNI with angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) for patients with HFrEF to assess for incremental benefit.

Methods

We searched PubMed, Embase, and ClinicalTrials.gov. Baseline study characteristics were collected and outcomes were sustained ventricular arrhythmias, atrial arrhythmias, appropriate implantable cardioverter-defibrillator (ICD) therapy, sudden cardiac death (SCD), and biventricular (BiV) pacing rate.

Results

We included 9 studies, 4 randomized trials, and 5 observational studies (5589 patients on ARNI vs 5615 on ACEIs/ARBs). Follow-up ranged from 2 to 51 months. The mean age was 65.4 ± 9.8 years, with 77.3% male patients and a mean ejection fraction of 29.0% ± 7.6%. Ischemic cardiomyopathy was present in 62% of patients. In the ARNI group, there were less SCD (odds ratio [OR] 0.78, 95% confidence interval [CI] 0.63–0.96; P = .02), ventricular arrhythmias (OR 0.45, 95% CI 0.25–0.79; P = .005), and appropriate ICD therapy (OR 0.39, 95% CI 0.21–0.74; P = .004). Higher rates of BiV pacing were seen (mean difference 3.13, 95% CI 2.58–3.68; P < .00001) when compared with ACEIs/ARBs. No difference in atrial arrhythmias was seen.

Conclusion

ARNI therapy provides incremental benefit with respect to ventricular tachyarrhythmias/SCD, which may, in part, explain improved outcomes in patients with HFrEF compared to ACEIs/ARBs. There was increased BiV pacing and decreased ICD therapy in the ARNI group.

A new algorithm to reduce T-wave over-sensing based on phase space reconstruction in S-ICD system

BACKGROUND AND OBJECTIVE

The subcutaneous implantable cardioverter defibrillator (S-ICD) reduces mortality in individuals at high risk of sudden arrhythmic death, by rapid defibrillation of life-threatening arrhythmia. Unfortunately, S-ICD recipients are also at risk of inappropriate shock therapies, which themselves are associated with increased rates of mortality and morbidity. The commonest cause of inappropriate shock therapies is T wave oversensing (TWOS), where T waves are incorrectly counted as R waves leading to an overestimation of heart rate. It is important to develop a method to reduce TWOS and improve the accuracy of R-peak detection in S-ICD system.

METHODS

This paper introduces a novel algorithm to reduce TWOS based on phase space reconstruction (PSR); a common method used to analyse the chaotic characteristics of non-linear signals.

RESULTS

The algorithm was evaluated against 34 records from University Hospital Southampton (UHS) and all 48 records from the MIT-BIH arrhythmia database. In the UHS analysis we demonstrated a sensitivity of 99.88%, a positive predictive value of 99.99% and an accuracy of 99.88% with reductions in TWOS episodes (from 166 to 0). Whilst in the MIT-BIH analysis we demonstrated a sensitivity of 99.87%, a positive predictive value of 99.99% and an accuracy of 99.91% for R wave detection. The average processing time for 1 min ECG signals from all records is 2.9 s.

CONCLUSIONS

Our algorithm is sensitive for R-wave detection and can effectively reduce the TWOS with low computational complexity, and it would therefore have the potential to reduce inappropriate shock therapies in S-ICD recipients, which would significantly reduce shock related morbidity and mortality, and undoubtedly improving patient's quality of life.

Remote monitoring and telemedicine in heart failure: implementation and benefits

PURPOSE OF REVIEW

Remote monitoring (RM) of cardiac implantable electronic devices (CIEDs) is recommended as part of the individualized multidisciplinary follow-up of heart failure (HF) patients. Aim of this article is to critically review recent findings on RM, highlighting potential benefits and barriers to its implementation.

RECENT FINDINGS

Device-based RM is useful in the early detection of CIEDs technical issues and cardiac arrhythmias. Moreover, RM allows the continuous monitoring of several patients' clinical parameters associated with impending HF decompensation, but there is still uncertainty regarding its effectiveness in reducing mortality and hospitalizations. Implementation of RM strategies, together with a proactive physicians' attitude towards clinical actions in response to RM data reception, will make RM a more valuable tool, potentially leading to better outcomes.

Ambulatory advanced heart failure patients: timing of mechanical circulatory support - delaying the inevitable?

PURPOSE OF REVIEW

Current indications for continuous-flow left ventricular assist device (cfLVAD) implantation is for patients in cardiogenic shock or inotrope-dependent advanced heart failure. Risk stratification of noninotrope dependent ambulatory advanced heart failure patients is a subject of registries designed to help shared-decision making by clinicians and patients regarding the optimal timing of mechanical circulatory support (MCS).

RECENT FINDINGS

The Registry Evaluation of Vital Information for VADs in Ambulatory Life enrolled ambulatory noninotrope dependent advanced systolic heart failure patients who had 25% annualized risk of death, MCS, or heart transplantation (HT). Freedom from composite clinical outcome at 1-year follow-up was 23.5% for the entire cohort. Seattle Heart Failure Model Score and Natriuretic pepides were predictors with modest discriminatory power. Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile 4 patients had the highest risk (3.7-fold) of death, MCS or HT compared to INTERMACS profile 7.

SUMMARY

We propose individualized risk stratification for noninotrope dependent ambulatory advanced heart failure patients and include serial changes in end-organ function, nutritional parameters, frailty assessment, echocardiographic and hemodynamic data. The clinical journey of a patient with advanced heart failure should be tracked and discussed at each clinic visit for shared decision-making regarding timing of cfLVAD.

Frequency, predictors and prognostic impact of implantable cardioverter defibrillator shocks in a primary prevention population with heart failure and reduced ejection fraction

AIMS

The role of the implantable cardioverter defibrillator (ICD) in primary prevention real-world population is debated. We sought to evaluate the incidence, predictors and prognostic impact of ICD shocks in consecutive heart failure patients implanted for primary prevention at our tertiary institution.

METHODS AND RESULTS

We retrospectively selected a sample of 497 patients (mean age 64.8 years, 82.1% men, average left ventricular ejection fraction, LVEF, 27.1%). At long-term follow-up (median time 70.4 months), total mortality was 40.8%, and 16.5% of patients had received at least one appropriate shock (3.12%/year). Inappropriate shock [odds ratio (OR) 1.93, 95% confidence interval (95% CI) 1.08-3.47; P = 0.027] and length of follow-up (1 year, OR 1.01, 95% CI 1.00-1.01; P = 0.0031) were associated with the occurrence of appropriate shock, whereas atrial fibrillation (OR 2.65, 95% CI 1.55-4.51, P < 0.001), length of follow-up (1-year OR 1.01, 95% CI 1.00-1.01, P < 0.001) and appropriate shock (OR 1.93, 95% CI 1.08-3.47, P = 0.027) were associated with the occurrence of inappropriate shock. Neither appropriate nor inappropriate shock independently increased mortality risk, whereas older age (hazard ratio 1.05; 95% CI 1.04-1.07; P < 0.001), atrial fibrillation (hazard ratio 2.25; 95% CI 1.67-3.02; P < 0.001) and lower LVEF (hazard ratio 0.97; 95% CI 0.94-0.99; P = 0.004) did.

CONCLUSION

Incidence of shocks in real-world primary prevention ICD recipients might be lower than expected, and the association between ICD shocks and prolongation of survival is not as clear-cut as might be perceived. Further investigations from larger real-world samples are warranted.

Complication rates following ventricular tachycardia ablation in ischaemic and non-ischaemic cardiomyopathies: a systematic review

Background

Catheter ablation of ventricular tachycardia (VT) is associated with potential major complications, including mortality. The risk of acute complications in patients with ischaemic cardiomyopathy (ICM) and non-ischaemic cardiomyopathy (NICM) has not been systematically evaluated.

Methods

PubMed was searched for studies of catheter ablation of VT published between September 2009 and September 2019. Pre-specified primary outcomes were (1) rate of major acute complications, including death, and (2) mortality rate.

Results

A total of 7395 references were evaluated for relevance. From this, 50 studies with a total of 3833 patients undergoing 4319 VT ablation procedures fulfilled the inclusion criteria (mean age 59 years; male 82%; 2363 [62%] ICM; 1470 [38%] NICM). The overall major complication rate in ICM cohorts was 9.4% (95% CI, 8.1–10.7) and NICM cohorts was 7.1% (95% CI, 6.0–8.3). Reported complication rates were highly variable between studies (ICM I² = 90%; NICM I² = 89%). Vascular complications (ICM 2.5% [95% CI, 1.9–3.1]; NICM 1.2% [95% CI, 0.7–1.7]) and cerebrovascular events (ICM 0.5% [95% CI, 0.2–0.7]; NICM, 0.1% [95% CI, 0–0.2]) were significantly higher in ICM cohorts. Acute mortality rates in the ICM and NICM cohorts were low (ICM 0.9% [95% CI, 0.5–1.3]; NICM 0.6% [95% CI, 0.3–1.0]) with the majority of overall deaths (ICM 75%; NICM 80%) due to either recurrent VT or cardiogenic shock.

Conclusion

Overall acute complication rates of VT ablation are comparable between ICM and NICM patients. However, the pattern and predictors of complications vary depending on the underlying cardiomyopathy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10840-021-00948-6.

Beneficial effects of one-month sacubitril/valsartan treatment in a patient affected by end-stage dystrophinopathic cardiomyopathy

Dystrophinopathic cardiomyopathy (DCM) is an almost constant manifestation in Becker muscular dystrophy (BMD) patients significantly contributing to morbidity and mortality. The nearly complete replacement of the myocardium by fibrous and fatty connective tissue results in an irreversible cardiac failure, characterized by progressive reduction of the ejection fraction. According to PARADIGM-HF trial results, the European Society of Cardiology (ESC) guidelines recommend the use of sacubitril/valsartan in ambulatory patients with heart failure and reduced ejection fraction, who remain symptomatic despite an optimal medical therapy. To date, little is still known about the use of sacubitril/valsartan in DCM. We report the case of a patient with dystrophinopathic end stage dilated cardiomyopathy with reduced ejection fraction who successfully responded to sacubitril/valsartan treatment.

Permanent pacemaker implantation associated tricuspid regurgitation

OBJECTIVE

To determine the prevalence of tricuspid regurgitation in patients with dual-chamber permanent pacemaker implantation.

METHODS

This study included 153 patients undergoing permanent pacemaker implantation. All eligible candidates had baseline transthoracic echocardiography to rule out preexisting tricuspid regurgitation. Echocardiography across the tricuspid valve was repeated one month after permanent pacemaker implantation, and the frequency of significant tricuspid regurgitation was determined. The associations of potential effect modifiers (age, sex, height, body mass index categories, diabetes, and hypertension) with tricuspid regurgitation were assessed individually using simple and multivariable logistic regression models.

RESULTS

After dual-chamber permanent pacemaker implantation, significant tricuspid regurgitation was present in 22 (15.8%) patients. Tricuspid regurgitation was significantly associated with body mass index >30 kg·m^-2 (odds ratio = 32.84, 95% confidence interval: 1.26-853.82, p = 0.04).

CONCLUSION

Significant tricuspid regurgitation was present in substantial number of patients after dual-chamber pacemaker implantation and was independently associated with body mass index >30 kg·m^-2.

Role of medical reaction in management of inappropriate ventricular arrhythmia diagnosis: the inappropriate Therapy and HOme monitoRiNg (THORN) registry

AIMS

Implantable cardioverter-defibrillators (ICDs) reduce sudden cardiac death in selected patients but inappropriate ICD shocks have been associated with increased mortality. The THORN registry aims to describe the rate of inappropriate ventricular arrhythmia diagnoses and therapies in patients followed by remote monitoring, as well as the following delay to next patient contact (DNPC).

METHODS AND RESULTS

One thousand eight hundred and eighty-two patients issued from a large remote monitoring database first implanted with an ICD for primary or secondary prevention in 110 French hospitals from 2007 to 2014 constitute the THORN population. Among them, 504 patients were additionally followed prospectively for evaluation of the DNPC. Eight hundred and ninety-five out of 1551 (58%) patients had ischaemic heart disease and 358/771 (46%) were implanted for secondary prevention. During 13.7 ± 3.4 months of follow-up, the prevalence of first inappropriate diagnosis in a ventricular arrhythmia zone with enabled therapy was 162/1882 (9%). Among those patients, 122/162 (75%) suffered at least one inappropriate therapy and 58/162 (36%) at least one inappropriate shock. Eighty-three out of 162 (51%) of first inappropriate diagnosis occurred during the first 4 months following implantation. The median DNPC was 8 days (interquartile range 1-26). At least one other day with recording of an inappropriate diagnosis of the same cause occurred in 13/43 (30%) of available DNPC periods, with an inappropriate therapy in 7/13 (54%).

CONCLUSION

Inappropriate diagnoses occurred in 9% of patients implanted with an ICD during the first 14 months. The DNPC after inadequate ventricular arrhythmia diagnoses remains long in daily practice and should be optimized.

CLINICALTRIALS.GOV IDENTIFIER

NCT01594112.

The clinical impact of untreated slow ventricular tachycardia in patients carrying implantable cardiac defibrillators

INTRODUCTION

The clinical impact of slow ventricular tachycardia (VT), occurring in patients carrying implantable cardiac defibrillators (ICD), is still under debate.

METHODS AND RESULTS

From the UMBRELLA registry (multicenter, observational, and prospective study on patients with ICD), 659 episodes of slow VT were observed in 97 patients. Untreated slow VT (n = 93) had longer duration (23.7 min, CI95%: 10-39), compared with episodes treated effectively by anti-tachycardia pacing (ATP; n = 527; 0.32 min, IC95%: 0.22-0, 48) or shock (n = 39; 1 min, CI95%: 0.8-1.2). Despite of longer duration, the time to the first contact with the medical services was similar to those episodes treated by ATP (50 days [CI95%: 45-55] vs. 41 days [CI95%: 39-44]). However, both were significantly longer than the time observed in episodes treated with shock (10 days, CI95%: 6-15). This tendency was maintained with successive interrogations of the device (2nd and 3rd). There were no significant differences in mortality during follow-up (48 ± 16 months), neither other adverse outcomes, between patients who presented untreated slow TV and those who did not (log-rank p = 0.28). In a Cox regression analysis, the variable "presenting untreated episodes of slow VT" was not able to predict mortality. However, being in sinus rhythm (vs. atrial fibrillation, OR: 0.31, p = 0.009), narrower QRS (OR: 1.036, p = 0.037) and diabetes (OR 4.673, p = 0.049) appropriately predict survival.

CONCLUSIONS

Untreated slow VT does not significantly worsen patient prognosis. Our results support the limitation of therapies to ATP only, thus avoiding therapies that have been associated with increased risk of morbidity and mortality.

High mean entropy calculated from cardiac MRI texture analysis is associated with antitachycardia pacing failure

BACKGROUND

Antitachycardia pacing (ATP), which may avoid unnecessary implantable cardioverter-defibrillator (ICD) shocks, does not always terminate ventricular arrhythmias (VAs). Mean entropy calculated using cardiac magnetic resonance texture analysis (CMR-TA) has been shown to predict appropriate ICD therapy. We examined whether scar heterogeneity, quantified by mean entropy, is associated with ATP failure and explore potential mechanisms using computer modeling.

METHODS

A subanalysis of 114 patients undergoing CMR-TA where the primary endpoint was delivery of appropriate ICD therapy (ATP or shock therapy) was performed. Patients receiving appropriate ICD therapy (n = 33) were dichotomized into "successful ATP" versus "shock therapy" groups. In silico computer modeling was used to explore underlying mechanisms.

RESULTS

A total of 16 of 33 (48.5%) patients had successful ATP to terminate VA, and 17 of 33 (51.5%) patients required shock therapy. Mean entropy was significantly higher in the shock versus successful ATP group (6.1 ± 0.5 vs 5.5 ± 0.7, P = .037). Analysis of patients receiving ATP (n = 22) showed significantly higher mean entropy in the six of 22 patients that failed ATP (followed by rescue ICD shock) compared to 16 of 22 that had successful ATP (6.3 ± 0.7 vs 5.5 ± 0.7, P = .048). Computer modeling suggested inability of the paced wavefront in ATP to successfully propagate from the electrode site through patchy fibrosis as a possible mechanism of failed ATP.

CONCLUSIONS

Our findings suggest lower scar heterogeneity (mean entropy) is associated with successful ATP, whereas higher scar heterogeneity is associated with more aggressive VAs unresponsive to ATP requiring shock therapy that may be due to inability of the paced wavefront to propagate through scar and terminate the VA circuit.

Wide-area low-energy surface stimulation of large mammalian ventricular tissue

The epicardial and endocardial surfaces of the heart are attractive targets to administer antiarrhythmic electrotherapies. Electrically stimulating wide areas of the surfaces of small mammalian ventricles is straightforward given the relatively small scale of their myocardial dimensions compared to the tissue space constant and electrical field. However, it has yet to be proven for larger mammalian hearts with tissue properties and ventricular dimensions closer to humans. Our goal was to address the feasibility and impact of wide-area electrical stimulation on the ventricular surfaces of large mammalian hearts at different stimulus strengths. This was accomplished by placing long line electrodes on the ventricular surfaces of pig hearts that span wide areas, and activating them individually. Stimulus efficacy was assessed and compared between surfaces, and tissue viability was evaluated. Activation time was dependent on stimulation strength and location, achieving uniform linear stimulation at 9x threshold strength. Endocardial stimulation activated more tissue transmurally than epicardial stimulation, which could be considered a potential target for future cardiac electrotherapies. Overall, our results indicate that electrically stimulating wide areas of the ventricular surfaces of large mammals is achievable with line electrodes, minimal tissue damage, and energies under the human pain threshold (100 mJ).

Systematic Review and Meta-Analysis of Clinical Outcome After Implantable Cardioverter-Defibrillator Therapy in Patients With Chagas Heart Disease

OBJECTIVES

The goal of this analysis was to pool data from published studies on outcomes after implantable cardioverter-defibrillator (ICD) therapy in patients with Chagas heart disease (CHD).

BACKGROUND

CHD is characterized by a high burden of ventricular arrhythmias and an increased risk of sudden cardiac death. The indications for ICD are not well established.

METHODS

An extensive literature search without language restrictions was performed to identify all studies on ICD therapy in patients with CHD. A random effects model was used to calculate percentages and 95% confidence intervals (CIs).

RESULTS

Of 397 articles screened, 13 studies (all observational) were included. There were 1,041 patients (mean age at implantation 57 ± 11 years; 64% men), most of whom (92%) received an ICD for secondary prevention. Antiarrhythmic medication consisted of amiodarone (79%) and beta-blockers (44%). Overall, the annual all-cause mortality rate was 9.0% (95% CI: 6.9 to 11.7) in 2.8 ± 1.9 years of follow-up, and the annual sudden cardiac death rate was 2.0% (95% CI: 1.3 to 3.3) in 2.6 ± 1.9 years. In addition, 24.8% (95% CI: 15.7 to 37.0) of patients received 1 or more appropriate interventions (shocks or antitachycardia pacing), 4.7% (95% CI: 3.2 to 6.9) received inappropriate shocks, and 9.1% (95% CI: 5.5 to 14.7) had electric storms annually.

CONCLUSIONS

In patients with an ICD, annual all-cause mortality rate was 9%. Appropriate ICD interventions and electric storms were frequent, occurring at a rate of 25% and 9% per year, respectively. Inappropriate ICD shocks were not infrequent (5% per year). The benefits and risks of ICD therapy in patients with CHD should be carefully weighed until data from better studies become available.

Preventive Ventricular Tachycardia Ablation in Patients with Ischaemic Cardiomyopathy: Meta-analysis of Randomised Trials

Catheter ablation of ventricular tachycardia (VT) aims to treat the underlying arrhythmia substrate to prevent ICD therapies. The aim of this meta-analysis was to assess the safety and efficacy of VT ablation prior to or at the time of secondary prevention ICD implantation in patients with coronary artery disease, as compared with deferred VT ablation. Based on a systematic literature search, three randomised trials were considered eligible for inclusion in this analysis, and data on the number of patients with appropriate ICD shocks, appropriate ICD therapy, arrhythmic storm, death and major complications were extracted from each study. On pooled analysis, there was a significant reduction of appropriate ICD shocks (OR 2.58; 95% CI [1.54-4.34]; p<0.001) and appropriate ICD therapies (OR 2.04; 95% CI [1.15-3.61]; p=0.015) in patients undergoing VT ablation at the time of ICD implantation without significant differences with respect to complications (OR 1.39; 95% CI [0.43-4.51]; p=0.581). Mortality did not differ between both groups (OR 1.30; 95% CI [0.60-2.45]; p=0.422). Preventive catheter ablation of VT in patients with coronary heart disease at the time of secondary prevention ICD implantation results in a significant reduction of appropriate ICD shocks and any appropriate ICD therapy compared with patients without or with deferred VT ablation. No significant difference with respect to complications or mortality was observed between both treatment strategies.

Quantification of Electromechanical Coupling to Prevent Inappropriate Implantable Cardioverter-Defibrillator Shocks

OBJECTIVES

This study sought to test specialized processing of laser Doppler signals for discriminating ventricular fibrillation (VF) from common causes of inappropriate therapies.

BACKGROUND

Inappropriate implantable cardioverter-defibrillator (ICD) therapies remain a clinically important problem associated with morbidity and mortality. Tissue perfusion biomarkers, implemented to assist automated diagnosis of VF, sometimes mistake artifacts and random noise for perfusion, which could lead to shocks being inappropriately withheld.

METHODS

The study tested a novel processing algorithm that combines electrogram data and laser Doppler perfusion monitoring as a method for assessing circulatory status. Fifty patients undergoing VF induction during ICD implantation were recruited. Noninvasive laser Doppler and continuous electrograms were recorded during both sinus rhythm and VF. Two additional scenarios that might have led to inappropriate shocks were simulated for each patient: ventricular lead fracture and T-wave oversensing. The laser Doppler was analyzed using 3 methods for reducing noise: 1) running mean; 2) oscillatory height; and 3) a novel quantification of electromechanical coupling which gates laser Doppler relative to electrograms. In addition, the algorithm was tested during exercise-induced sinus tachycardia.

RESULTS

Only the electromechanical coupling algorithm found a clear perfusion cut off between sinus rhythm and VF (sensitivity and specificity of 100%). Sensitivity and specificity remained at 100% during simulated lead fracture and electrogram oversensing. (Area under the curve running mean: 0.91; oscillatory height: 0.86; electromechanical coupling: 1.00). Sinus tachycardia did not cause false positive results.

CONCLUSIONS

Quantifying the coupling between electrical and perfusion signals increases reliability of discrimination between VF and artifacts that ICDs may interpret as VF. Incorporating such methods into future ICDs may safely permit reductions of inappropriate shocks.

Effects of defibrillation shock in patients implanted with a subcutaneous defibrillator: a biomarker study

Aims

Implantable cardioverter defibrillator (ICD) shocks are associated with a subsequent increased risk of death, and an elevation of cardiac enzymes has been measured after defibrillation testing (DFT). In an experimental swine study, subcutaneous ICD (S-ICD) shocks caused less myocardial damage than traditional ICD shocks. The aim of our study was to investigate the association between S-ICD shock and acute cardiac damage in humans, as evaluated by means of sensitive and highly specific circulating biomarkers.

Methods and results

We calculated the variation in the serum levels of high-sensitivity cardiac troponin I (hs-CTnI) and creatine kinase-MB mass concentration (CK-MB mass), measured before and after an S-ICD shock delivered during intraoperative DFT. We also measured the degree of haemodynamic stress, as the variation in the serum levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and copeptin (CP), after the S-ICD shock. We analysed 30 consecutive patients who received an S-ICD and who underwent DFT by means of a single 65 J shock. The levels of biomarkers did not change from baseline to 1 h post-shock, i.e. hs-CTnI (from 0.029 ± 0.005 ng/mL to 0.030 ± 0.005 ng/mL, P = 0.079) and CK-MB mass (from 1.37 ± 0.17 ng/mL to 1.41 ± 0.18, P = 0.080) and remained stable 6 and 24 h after DFT. The plasma NT-proBNP did not change, whereas CP levels were significantly higher at 1 h post-shock evaluation. However, 6 h after DFT, the levels had returned to the baseline and remained stable at 24 h.

Conclusion

The S-ICD shock did not seem to cause myocardial injuries. Although CP levels temporarily rose after DFT, they returned to basal levels within 6 h, which suggests that DFT does not have long-term prognostic implications. ICD shocks are associated with a subsequent increased risk of death, and an elevation of cardiac enzymes has been measured after DFT. We showed that serum levels of biomarkers of myocardial damage did not increase after high-energy DFT in patients who had undergone S-ICD device implantation. This suggests that S-ICD shock does not have long-term prognostic implications.

Association between atrial fibrillation and patient-important outcomes in heart failure patients with implantable cardioverter-defibrillators: a systematic review and meta-analysis

AIMS

To assess the association between atrial fibrillation (AF) and all-cause mortality and implantable cardioverter-defibrillators (ICDs) therapies in heart failure (HF) patients with reduced ejection fraction and an ICD implanted.

METHODS AND RESULTS

A systematic MEDLINE search performed from inception through November 2016, supplemented by hand searching of reference lists, identified 62 eligible studies (227 998 patients) reporting on the association between AF and outcomes in HF patients; 36 studies included data on all-cause mortality, 30 on appropriate, and 17 on inappropriate ICD interventions. Hazard ratio, risk ratio, or odds ratio estimates were used based on data availability. Effect estimates were synthesized under a random-effects model. Implantable cardioverter-defibrillator-implanted HF patients with a history of AF had a 42% {combined effect estimate (cEE) 1.42 [95% confidence interval (CI) 1.28-1.57]} higher risk of all-cause mortality compared with patients with no AF history. Furthermore, AF patients had a higher risk of appropriate [cEE 1.44 (95% CI 1.27-1.64)] and inappropriate ICD interventions [cEE 2.05 (95% CI 1.75-2.44)].

CONCLUSION

Atrial fibrillation history is statistically significantly associated with adverse major clinical outcomes in ICD-implanted HF patients. Patients with AF have a higher risk of all-cause mortality, appropriate, and inappropriate ICD interventions compared with patients with no AF history. Whether AF may have an independent deleterious effect on HF prognosis or may simply be a marker of HF severity should be further investigated.

Anti-arrhythmic drug therapy in implantable cardioverter-defibrillator recipients

Implantable cardioverter-defibrillators (ICDs) have revolutionized the primary and secondary prevention of patients with ventricular arrhythmias. However, the adverse effects of appropriate or inappropriate shocks may require the adjunctive use of anti-arrhythmic drugs (AADs). Beta blockers are the cornerstone of pharmacological primary and secondary prevention of ventricular arrhythmias. In addition to their established efficacy at reducing the incidence of ventricular arrhythmias, beta-blockers are safe with few side effects. Amiodarone is superior to beta blockers and sotalol for the prevention of ventricular arrhythmia recurrence. However, long-term amiodarone use is associated with significant side effects that limit its utility. Sotalol and mexiletine are the main alternatives to amiodarone with a better side effect profile though they are less efficacious at preventing ventricular arrhythmia recurrence. Dofetilide, azimilide and ranolazine are emerging as therapeutic options for secondary prevention; more studies are needed to assess efficacy and safety in comparison to currently used agents. Beta blockers and amiodarone are the mainstay of therapy in patients experiencing electrical storm; their use reduces the frequency of ventricular arrhythmias and ICD intervention as well as affording time until catheter ablation can be considered.

Outcomes of cardiac resynchronisation therapy in patients with heart failure with atrial fibrillation: a systematic review and meta-analysis of observational studies

Background

Cardiac resynchronisation therapy (CRT) is beneficial in selected patients with heart failure (HF) in normal sinus rhythm (NSR). We sought to evaluate the impact of CRT with or without atrioventricular junction (AVJ) ablation in patients with HF with concomitant atrial fibrillation (AF).

Methods and results

Literature was searched (inception through 30 August 2017) for observational studies that reported outcomes in patients with HF with CRT and AF that reported all-cause and cardiovascular mortality. Thirty-one studies with 83, 571 patients were included. CRT did not decrease mortality compared with internal cardioverter defibrillator or medical therapy alone in patients with HF and AF with indications for CRT (OR: 0.851, 95% CI 0.616 to 1.176, p=0.328, I2=86.954). CRT-AF patients had significantly higher all-cause and cardiovascular mortality than CRT-NSR patients ([OR: 1.472, 95% CI 1.301 to 1.664, p=0.000] and [OR: 1.857, 95% CI 1.350 to 2.554, p=0.000] respectively). Change in left ventricular ejection fraction was not different between CRT patients with and without AF (p=0.705). AVJ ablation, however, improved all-cause mortality in CRT-AF patients when compared with CRT-AF patients without AVJ ablation (OR: 0.485, 95% CI 0.247 to 0.952, p=0.035). With AVJ ablation, there was no difference in all-cause mortality in CRT-AF patients compared with CRT-NSR patients (OR: 1.245, 95% CI 0.914 to 1.696, p=0.165).

Conclusion

The results of our meta-analysis suggest that AF was associated with decreased CRT benefits in patients with HF. CRT, however, benefits patients with AF with AVJ ablation.

LifeMap: towards the development of a new technology in sudden cardiac death risk stratification for clinical use

Sudden cardiac death (SCD) is a major cause of mortality presenting a significant unmet clinical need. Patients at risk of SCD are implanted with implantable cardioverter-defibrillators (ICDs) according to international guidelines based on clinical trial evidence. Implantable cardioverter-defibrillators are not inexpensive and not without problem in terms of inappropriate shocks and infection risk. Also, only a minority of patients implanted with the ICD ever use the device during its battery lifetime highlighting the fact that methods used for SCD risk stratification are inadequate. Better ways of predicting who is at risk of SCD are needed. In addition, there is no effective prevention due to the lack of understanding of the electrical mechanisms underlying SCD. Our group has been investigating the electrophysiological basis of ventricular fibrillation and have successfully applied our preclinical findings to translational studies in patients with ischaemic cardiomyopathy. We have developed two ECG markers which have been shown to be strong predictors of ventricular arrhythmias and SCD. Ongoing clinical studies are being carried out including a multicentre UK study to consolidate the evidence base. They are being incorporated into the technology, LifeMap, with the aim to develop a successful clinical tool for the assessment of SCD risk. We hereby present the scientific data leading to the technology and the development to date. The information provided here was presented at the European Heart Rhythm Association (EHRA) Europace/Cardiostim conference at which LifeMap won the EHRA Inventors Award 2016.

Stretch, Injury and Inflammation Markers Evaluation to Predict Clinical Outcomes After Implantable Cardioverter Defibrillator Therapy in Heart Failure Patients With Metabolic Syndrome

Background: Internal cardioverter defibrillator (ICD) therapy reduced all-cause mortality. Conversely, few studies reported that ICDs' shocks may reduce survival. Recently authors suggested that, multiple inflammatory and molecular pathways were related to worse prognosis in metabolic syndrome (MS) patients treated by ICDs. Therefore, it may be relevant to find new biomarkers to predict ICDs' shock and worse prognosis in treated patients. Methods: In 99 MS vs. 107 no MS patients treated by ICD for primary prevention, we evaluated all-cause mortality, cardiac deaths, hospitalization for heart failure, appropriate and inappropriate therapy, and survival after appropriate ICD therapy. Results: MS vs. no MS patients had higher levels of failing heart stress biomarkers. The highest values of ST2 were related to worse prognosis. Patients who had better survival after appropriate ICD therapy were those associated with lowest ST2 values. At multivariate Cox regression analysis, C reactive protein (CRP) (0.110 [0.027-0.446], p-value 0.002), troponine I (TnI) protein (0.010 [0.001-0.051], p-value 0.010), and B type natriuretic peptide (BNP) (1.151 [1.010-1.510], p-value 0.001), predicted all cause of deaths. BNP predicted cardiac deaths (1.010 [1.001-1.206], p-value 0.033). MS, and BNP predicted hospitalization for heart failure events (2.902 [1.345-4.795], p-value 0.001; 1.005 [1.000-1.016], p-value 0.007). ST2 predicted appropriate therapy (1.012 [1.007-1.260], p-value 0.001), as BNP (1.005 [1.001-1.160], p-value 0.028), LVEF (1.902 [1.857-1.950], p-value 0.001), and CRP (1.833 [1.878-1.993], p-value 0.028). ST2, and BNP predicted survival after ICD appropriate therapy (4.297 [1.985-9.302], p-value 0.001; 1.210 [1.072-1.685], p-value 0.024). Conclusions: ST2 values may differentiate MS patients with a higher risk of ICDs' therapy, and worse prognosis. Therefore, ST2 protein may be used as valid monitoring biomarker, and as a predictive biomarker in failing heart ICDs' patients affected by MS.

The Value of the Tei Index in Predicting Implantable Cardioverter Defibrillator Shocks

Objectives:

An implantable cardioverter defibrillator (ICD) decreases the risk of sudden death in the appropriate patients. However, a relationship between ICD shocks and increased mortality and morbidity has been suspected. This report is an investigation of an association between ICD shocks and the Tei index, an echocardiographic parameter now commonly used to predict cardiovascular events.

Methods:

The basic characteristics of 250 patients with chronic heart failure who had an ICD implanted and 2 years of follow-up device recordings were retrospectively analyzed. Patients who received shock therapy during follow-up were compared with those who did not, based on demographic and other characteristics and the Tei index.

Results:

The mean Tei index value of ICD shock recipients was significantly higher than the score of non-recipients of ICD shock (0.70±0.10 vs 0.56±0.10; p<0.001). The percentage of patients for whom it was primary prevention who received either appropriate or inappropriate ICD shocks was 28.9%, whereas in those who received an ICD for secondary prevention, the percentage was 71.1% (p<0.001). ICD shock recipient patients were older, and had a greater rate of hypertension and smoking pack-years compared with those to whom an ICD shock was not delivered (p<0.001).

Conclusion:

The results of this study demonstrated a relationship between the Tei index and ICD shocks, either appropriate or inappropriate. The Tei index is a simple method to predict ICD shocks.

Inappropriate shocks in single-chamber and subcutaneous implantable cardioverter-defibrillators: a systematic review and meta-analysis

AIMS

Single-chamber (VR-ICD) and subcutaneous (S-ICD) implantable cardioverter-defibrillators are effective to protect patients against sudden death but expose them to higher risk of inappropriate shock (IS). We sought to quantify the annual rate and influencing factors of ISs in VR- and S-ICDs from the literature.

METHODS AND RESULTS

PubMed, Embase, and Cochrane Library were searched for full text articles with IS rates. Poisson distribution estimated proportion of patients with ISs; rates were annualized based on follow-up duration. Random effects meta-analysis accounted for study-to-study variation. Out of 3264 articles, 16 qualified for the meta-analysis. Across studies, 6.4% [95% confidence interval (CI) 5.1-7.9%] of patients received an IS per year. Meta-regression analyses demonstrated that IS rates were lower in more recent studies [rate ratio (RR) per year: 0.93, 95% CI: 0.87-0.98; P = 0.01] and trended lower in studies with longer follow-up (RR per year: 0.78, 95% CI: 0.60-1.01; P = 0.06). Use of S-ICDs (RR: 1.81, 95% CI: 0.86-3.81; P = 0.12) and ventricular tachycardia zone programmed on (RR: 1.13, 95% CI: 0.65-1.97; P = 0.66) were not associated with a significantly increased change in risk. The IS rate observed in one of the more recent studies was significantly lower than predicted after accounting for covariates (RR: 0.29, 95% CI: 0.14-0.60; P < 0.001).

CONCLUSIONS

A comprehensive review of the literature shows that 6.4% of patients with ICDs experienced their first IS annually. One of the 16 studies was better than predicted with the lowest reported rate (1.9%) and could not be explained by timing of the study or other covariates.

Inappropriate ICD Shocks in Pediatric and Congenital Heart Disease Patients

Although implantable cardioverter-defibrillators (ICDs) have proven to be life-saving devices, there are frequent complications associated with their use, especially in the pediatric and congenital heart disease populations. Inappropriate shocks are a particularly frequent complication in these groups. This review discusses the causes and implications of inappropriate ICD shocks, and presents potential interventions that may assist in safely reducing the rates of inappropriate shocks in pediatric and congenital heart disease patients with ICDs.

Impact of statin therapy on all-cause mortality and ICD interventions in heart failure patients - a systematic review

OBJECTIVES

Implantable cardioverter defibrillators (ICDs) have a unique role for the primary and secondary prevention of sudden cardiac death (SCD). The aim of our systematic review is to present the existing data about the impact of statins on all-cause mortality and ICD interventions in heart failure (HF) patients who had an ICD implanted either for primary or for secondary prevention of SCD.

METHODS AND RESULTS

We searched PubMed database and the reference list of the relevant studies for retrieving studies evaluating the effect of statins on all-cause mortality and ICD interventions in HF patients. We finally included 17 relevant studies in our systematic review. Of them, nine studies included data about the impact of statins on all-cause mortality, eight studies about the impact of statins on appropriate ICD interventions and three studies about the impact of statins on inappropriate ICD interventions in HF patients. These data showed that statins seem to have a beneficial role in the reduction of all-cause mortality and ICD interventions in HF patients.

CONCLUSIONS

Statins seem to have a beneficial role in the reduction of all-cause mortality and ICD interventions in HF patients. However, further research about pleiotropic effects of statins is needed as well randomized control trials to elucidate the exact role of statin therapy in ICD outcomes.

Meta-analysis of Risk of Ventricular Arrhythmias After Improvement in Left Ventricular Ejection Fraction During Follow-Up in Patients With Primary Prevention Implantable Cardioverter Defibrillators

Implantable cardioverter defibrillators (ICDs) reduce the risk of sudden cardiac death in patients with impaired left ventricular ejection fraction (LVEF). However, there are limited data on the long-term benefit of ICD therapy in patients whose LVEF subsequently improves. We conducted a meta-analysis to evaluate the effect of LVEF improvement on ICD therapy during follow-up. Incidence rate ratios (IRRs) with 95% confidence intervals (CIs) were calculated using random-effects modeling. Sixteen studies with 3,959 patients were included in our analysis. Study arms were defined by LVEF improvement at follow-up (improved LVEF [>35%]: 1,622; low LVEF [≤35%] 2,337). Mean age (64.8 vs 64.9 years, p = 0.97) was similar, whereas men were overrepresented in the persistent low LVEF group (79% vs 72%, p <0.001). Appropriate ICD therapy rate was 9.7% (improved LVEF) versus 21.8% (low LVEF) over a median follow-up period of 2.9 years. In the meta-analysis, improved LVEF group had significantly lower (3.3% vs 7.2% per year IRR 0.52; CI 0.38 to 0.70; p <0.001) appropriate ICD therapies which was uniformly seen across all subgroups (ICD-only studies: IRR 0.59; p = 0.004) (cardiac resynchronization therapy-defibrillator-only studies: IRR 0.31; p = 0.002) (super-responder studies [mean LVEF > 45%]: IRR 0.53; p = 0.002). Inappropriate ICD therapy rates were, however, similar in both groups (3.01% vs 2.56% per year IRR 0.76; CI 0.43 to 1.36; p = 0.35). All-cause mortality rates in our meta-analysis favored (3.63% vs 8.23% per year IRR 0.49; CI 0.35 to 0.69; p <0.001) the improved LVEF group. In conclusion, our meta-analysis demonstrates that an improvement in LVEF is associated with a significantly reduced risk of ventricular arrhythmia and mortality. However, inappropriate ICD therapy rates remain similar.

[3-D mapping and ablation of recurrent ventricular tachycardia in patients with ischemic cardiomyopathy]

Catheter ablation of ventricular tachycardia (VT) is an established therapy for patients with ischemic cardiomyopathy to reduce implantable cardioverter-defibrillator (ICD) interventions and is a class I recommendation in international guidelines. Numerous publications confirm its value. Use of three-dimensional mapping systems with or without image integration is standard for ablation of complex arrhythmias. In patients with history of myocardial infarction they help to understand activation of reentrant circuits and are prerequisite for substrate mapping. While a combination of activation and substrate mapping is performed in many patients based on clinical presentation, substrate-based ablation appears to be superior to clinical VT ablation alone.

Identifying patients with less potential to benefit from implantable cardioverter-defibrillator therapy: comparison of the performance of four risk scoring systems

Purpose

Patients at high non-sudden cardiac death risk may gain no significant benefit from implantable cardioverter-defibrillator (ICD) therapy. A number of approaches have been proposed to identify these patients, including single clinical markers and more complex scoring systems. The aims of this study were to use the proposed scoring systems to (1) establish how many current ICD recipients may be too high risk to derive significant benefit from ICD therapy and (2) evaluate how well the scoring systems predict short-term mortality in an unselected ICD cohort.

Methods

We performed a single-centre retrospective observational study of all new ICD implants over 5 years (2009–2013). We used four published scoring systems (Bilchick, Goldenberg, Kramer and Parkash) and serum urea to identify new ICD recipients whose short-term predicted mortality risk was high. We evaluated how well the scoring systems predicted death.

Results

Over 5 years, there were 406 new implants (79% male, mean age 70 (60–76), 58% primary prevention). During a follow-up of 936 ± 560 days, 96 patients died. Using the scoring systems, the proportion of ICD recipients predicted to be at high short-term mortality risk were 5.9% (Bilchick), 34.7% (Goldenberg), 7.4% (Kramer), 21.4% (Parkash) and 25% (urea, cut-off of >9.28 mM). All four risk scores predicted mortality (P < 0.0001); however, none outperformed urea for the prediction of 1- or 3-year mortality.

Conclusions

Using published scoring systems, a significant proportion of current ICD recipients are at high short-term mortality risk. Although all four scoring systems predicted mortality during follow-up, none significantly outperformed serum urea.