The Effect of Shock Burden on Heart Failure and Mortality

Implantable Cardiac Devices in Patients with Brady- and Tachy-Arrhythmias: An Update of the Literature

Implantable cardiac devices are a vital treatment option in the management of tachy/brady-arrhythmias and heart failure with conduction disease. In the recent years, these devices have become increasingly sophisticated, with high implantation success rates and longevity. However, these devices are not without risks and complications, which need to be carefully considered before implantation. In an era of rapidly evolving cardiac device therapies, this review article will provide an update on the literature and outline some of the emerging technologies that aim to maximise the efficiency of implantable devices and reduce complications. We discuss novel pacing techniques, including alternative pacing sites in anti-bradycardia and biventricular pacing, as well as the latest evidence surrounding leadless device technologies and patient selection for implantable device therapies.

Effect of sodium glucose cotransporter 2 inhibitors on atrial tachy-arrhythmia burden in patients with cardiac implantable electronic devices

INTRODUCTION

Use of sodium glucose cotransporter 2 inhibitors (SGLT2i) was associated with a reduction in atrial fibrillation hospitalizations. Therefore, we aim to evaluate the effects of SGLT2i on atrial tachy-arrhythmias (ATA) in patients with cardiac implantable electronic devices (CIEDs).

METHODS

All 13 888 consecutive patients implanted with a CIED in two tertiary medical centers were enrolled. Treatment with SGLT2i was assessed as a time dependent variable. The primary endpoint was the total number of ATA. Secondary endpoints included total number of ventricular tachy-arrhythmias (VTA), ATA and VTA, and death. All events were independently adjudicated blinded to the treatment. Multivariable propensity score modeling was performed.

RESULTS

During a total follow-up of 24 442 patient years there were 62 725 ATA and 10 324 VTA events. Use of SGLT2i (N = 696) was independently associated with a significant 22% reduction in the risk of ATA (hazard ratio [HR] = 0.78 [95% confidence interval {CI} = 0.70-0.87]; p < .001); 22% reduction in the risk of ATA/VTA (HR = 0.78 [95% CI = 0.71-0.85]; p < .001); and with a 35% reduction in the risk of all-cause mortality (HR = 0.65 [95% CI = 0.45-0.92]; p = .015), but was not significantly associated with VTA risk (HR = 0.92 [95% CI = 0.80-1.06]; p = .26). SGLT2i were associated with a lower ATA burden in heart failure (HF) patients but not among diabetes patients (HF: HR = 0.68, 95% CI = 0.58-0.80, p < .001 vs. Diabetes: HR = 0.95, 95% CI = 0.86-1.05, p = .29; p < .001 for interaction between SGLT2i indication and ATA burden).

CONCLUSION

Our real world findings suggest that in CIED HF patients, those with SGLT2i had a pronounced reduction in ATA burden and all-cause mortality when compared with those not on SGLT2i.

Prevention of Early Sudden Cardiac Death after Myocardial Infarction Using the Wearable Cardioverter Defibrillator-Results from a Real-World Cohort

BACKGROUND

After acute myocardial infarction (AMI), patients are at risk of sudden cardiac death. The VEST trial failed to show a reduction in arrhythmic mortality in AMI patients with an LVEF ≤ 35% prescribed with a WCD, having a lower-than-expected WCD wearing compliance.

OBJECTIVES

The aim was to investigate on outcomes of patients in a real-world Austrian cohort with good compliance.

METHODS

A retrospective analysis of all eligible Austrian WCD patients according to the VEST trial inclusion and exclusion criteria between 2010 and 2020 was performed.

RESULTS

In total, 105 Austrian patients (64 ± 11 years, 12% female; LVEF 28 ± 6%) received a WCD for a median of 69 (1; 277) days after AMI (wearing duration 23.5 (0; 24) hours/day). Within the first 90 days, 4/105 (3.8%) patients received 9 appropriate shocks (2 (1; 5) shocks). No inappropriate shocks were delivered, and 3/105 (2.9%) patients died during follow-up. Arrhythmic mortality (1.9% Austria vs. 1.6% VEST, p = 0.52), as well as all-cause mortality (2.9% vs. 3.1%, p = 0.42) was comparable in both cohorts.

CONCLUSIONS

The WCD is a safe treatment option in a highly selected cohort of patients with LVEF ≤ 35% after AMI. However, despite excellent WCD wearing duration in our cohort, the arrhythmic mortality rate was not significantly different.

Subcutaneous Implantable Cardioverter Defibrillator: A Contemporary Overview

The difference between subcutaneous implantable cardioverter defibrillators (S-ICDs) and transvenous ICDs (TV-ICDs) concerns a whole extra thoracic implantation, including a defibrillator coil and pulse generator, without endovascular components. The improved safety profile has allowed the S-ICD to be rapidly taken up, especially among younger patients. Reports of its role in different cardiac diseases at high risk of SCD such as hypertrophic and arrhythmic cardiomyopathies, as well as channelopathies, is increasing. S-ICDs show comparable efficacy, reliability, and safety outcomes compared to TV-ICD. However, some technical issues (i.e., the inability to perform anti-bradycardia pacing) strongly limit the employment of S-ICDs. Therefore, it still remains only an alternative to the traditional ICD thus far. This review aims to provide a contemporary overview of the role of S-ICDs compared to TV-ICDs in clinical practice, including technical aspects regarding device manufacture and implantation techniques. Newer outlooks and future perspectives of S-ICDs are also brought up to date.

Ventricular Tachycardia and ICD Therapy Burden With Catheter Ablation Versus Escalated Antiarrhythmic Drug Therapy

BACKGROUND

Catheter ablation improves ventricular tachycardia (VT) event-free (time to event) survival in patients with antiarrhythmic drug (AAD)-refractory VT and previous myocardial infarction (MI). The effects of ablation on recurrent VT and implantable cardioverter-defibrillator (ICD) therapy (burden) have yet to be investigated.

OBJECTIVES

This study sought to compare the VT and ICD therapy burden following treatment with either ablation or escalated AAD therapy among patients with VT and previous MI in the VANISH (Ventricular tachycardia AblatioN versus escalated antiarrhythmic drug therapy in ISchemic Heart disease) trial.

METHODS

The VANISH trial randomized patients with previous MI and VT despite initial AAD therapy to either escalated AAD treatment or catheter ablation. VT burden was defined as the total number of VT events treated with ≥1 appropriate ICD therapy. Appropriate ICD therapy burden was defined as the total number of appropriate shocks or antitachycardia pacing therapies (ATPs) delivered. The Anderson-Gill recurrent event model was used to compare burden between the treatment arms.

RESULTS

Of the 259 enrolled patients (median age, 69.8 years; 7.0% women), 132 patients were randomized to ablation and 129 patients were randomized to escalated AAD therapy. Over 23.4 months of follow-up, ablation-treated patients had a 40% lower shock-treated VT event burden and a 39% lower appropriate shock burden compared with patients who received escalated AAD therapy (P <0.05 for all). A reduction in VT burden, ATP-treated VT event burden, and appropriate ATP burden among ablation patients was only demonstrated in the stratum of patients with amiodarone-refractory VT (P <0.05 for all).

CONCLUSIONS

Among patients with AAD-refractory VT and a previous MI, catheter ablation reduced shock-treated VT event burden and appropriate shock burden compared with escalated AAD therapy. There was also lower VT burden, ATP-treated VT event burden, and appropriate ATP burden among ablation-treated patients; however, the effect was limited to patients with amiodarone-refractory VT.

Hybrid surgical epicardial cryoablation for ventricular tachycardia in the electrophysiology laboratory: a case report

Background

Scar-related ventricular tachycardia (VT) is a challenging medical condition, with catheter ablation providing a valuable treatment option. Whilst most VTs can be ablated endocardially, epicardial ablation is often required in patients with non-ischaemic cardiomyopathy. The percutaneous subxiphoid technique has become instrumental for epicardial access. However, it is not feasible in up to 28% of cases for multiple reasons.

Case summary

A 47-year-old patient was managed at our centre for VT storm and recurrent implantable cardioverter defibrillator shocks for monomorphic VT despite maximum drug therapy. No scar was noted during endocardial mapping, with confirmation of the localized epicardial scar on cardiac magnetic resonance imaging (CMR). Following failed percutaneous epicardial access, a successful hybrid surgical epicardial VT cryoablation via median sternotomy was performed in the electrophysiology (EP) laboratory utilizing data from CMR, prior endocardial ablation, and conventional EP mapping. The patient has remained arrhythmia-free for 30 months post-ablation without antiarrhythmic therapy.

Discussion

This case describes a practical multidisciplinary approach to managing a challenging clinical problem. Whilst the described technique is not entirely novel, this is the first case report that describes the practicalities and demonstrates the safety and feasibility of hybrid epicardial cryoablation via median sternotomy performed in the cardiac EP laboratory for the sole treatment of VT.

Antitachycardia pacing success in implantable cardioverter-defibrillators by patient, device, and programming characteristics

BACKGROUND

Antitachycardia pacing (ATP) is an established implantable cardioverter-defibrillator (ICD) therapy that terminates ventricular tachycardias (VTs) without painful ICD shocks. However, factors influencing ATP success are not well understood.

OBJECTIVE

The purpose of this study was to examine ATP success rates by patient, device, and programming characteristics.

METHODS

This retrospective analysis of the PainFree SmartShock Technology study included spontaneous ATP-treated monomorphic VT episodes. ATP success rates were calculated for various factors. Also, the relationship of ATP programming on shock burden and syncope were investigated.

RESULTS

Of the 2770 enrolled patients (2200 [79%] male; mean age 65 years), 1699 (61%) received an ICD and 1071 (39%) a cardiac resynchronization therapy - defibrillator. ATP had >80% rate of success for terminating VTs overall, with similar rates observed between ICD and cardiac resynchronization therapy - defibrillator devices (82.2% vs 80.3%, respectively; P = .81) as well as between primary and secondary prevention patients with ICDs (77.2% vs 83.9% respectively; P = .25). Arrhythmias with a median cycle length of ≥320 ms had a significantly higher ATP success rate (88.0%; 95% confidence interval 84.8%-90.6%). The cumulative percentage of ATP success increased from 71% at 1 ATP sequence delivered to 87% at ≥8 sequences delivered. Programming more ATP sequences was associated with lower shock burden (P = .0005). There was no evidence that more sequences were associated with higher rates of syncope (P = .16).

CONCLUSION

Delivering more ATP sequences resulted in a higher overall success of terminating VTs, while programming more ATP was associated with decreased shock burden and no evidence of increased syncope or acceleration. This suggests that more ATP sequences should be programmed when possible, but confirmation in prospective studies will be necessary.

Automatic daily remote monitoring in heart failure patients implanted with a cardiac resynchronisation therapy-defibrillator: a single-centre observational pilot study

INTRODUCTION

The impact of remote monitoring (RM) on clinical outcomes in heart failure (HF) patients with cardiac resynchronisation therapy-defibrillator (CRT-D) implantation is controversial. This study sought to evaluate the performance of an RM follow-up protocol using modified criteria of the PARTNERS HF trial in comparison with a conventional follow-up scheme.

MATERIAL AND METHODS

We compared cardiovascular (CV) mortality (primary endpoint) and hospitalisation events for decompensated HF, and the number of ambulatory in-office visits (secondary endpoint) in CRT-D implanted patients with automatic RM utilising daily transmissions (RM group, n = 45) and conventional follow-up (CFU group, n = 43) in a single-centre observational study.

RESULTS

After a median follow-up of 25 months, a significant advantage was seen in the RM group in terms of CV mortality (1 vs. 6 death event, p = 0.04), although RM follow-up was not an independent predictor for CV mortality (HR = 0.882; 95% CI: 0.25-3.09; p = 0.845). Patient CV mortality was independently influenced by hospitalisation events for decompensated HF (HR = 3.24; 95% CI: 8-84; p = 0.022) during follow-up. We observed significantly fewer hospitalisation events for decompensated HF (8 vs. 29 events, p = 0.046) in the RM group. Furthermore, a decreased number of total (161 vs. 263, p < 0.01) and unnecessary ambulatory in-office visits (6 vs. 19, p = 0.012) were seen in the RM group as compared to the CFU group.

CONCLUSIONS

Follow-up of CRT-D patients using automatic RM with daily transmissions based on modified PARTNERS HF criteria enabled more effective ambulatory interventions leading indirectly to improved CV survival. Moreover, RM directly decreased the number of HF hospitalizations and ambulatory follow-up burden compared to CRT-D patients with conventional follow-up.

Role of Implantable Cardioverter Defibrillator in Heart Failure With Contemporary Medical Therapy

Implantable cardioverter defibrillator therapy is indicated in a subset of patients with heart failure with reduced ejection as primary prevention for sudden cardiac death. The advent of novel medical therapies including mineralocorticoid receptor antagonists, angiotensin receptor blocker/neprilysin inhibitors, and sodium-glucose transporter 2 inhibitor in the past 2 decades has revolutionized heart failure with reduced ejection management. Current guideline-directed medical therapy has reduced all-cause mortality and sudden cardiac death and confers a considerable improvement in left ventricular ejection fraction over a short period of time. However, there is limited evidence at present to suggest whether implantable cardioverter defibrillator therapy continues to have the same benefit in sudden cardiac death prevention at current left ventricular ejection fraction cutoff indications for patients on contemporary guideline-directed medical therapy for heart failure with reduced ejection. In this review, the authors propose in lieu of current evidence that it is reasonable to reevaluate indications for implantable cardioverter defibrillator therapy in patients on contemporary guideline-directed medical therapy for heart failure with reduced ejection.

Sex Differences in the Risk of First and Recurrent Ventricular Tachyarrhythmias Among Patients Receiving an Implantable Cardioverter-Defibrillator for Primary Prevention

Importance

Current guidelines for primary implantable cardioverter-defibrillator (ICD) therapy do not account for sex differences in arrhythmic risk in ICD candidates.

Objective

To evaluate the association between sex and risk of ventricular tachyarrhythmia (VTA) and mortality.

Design, Setting, and Participants

This cohort study compared differences in the risk of VTA and mortality between 4506 men and women enrolled in the 4 Multicenter Automatic Defibrillator Implantation Trials (MADIT) between July 1, 1997, and December 31, 2011. Data from prospective randomized controlled multicenter studies were analyzed retrospectively. Men and women with an ICD or cardiac resynchronization therapy defibrillator who were enrolled in all MADIT studies were included. Data were analyzed between January 10 and June 10, 2021.

Exposures

ICD implant.

Main Outcomes and Measures

The primary end point was sustained VTA, defined as ICD-recorded, treated or monitored VTA at least 170/min or ventricular fibrillation. Secondary VTA end points included VTA at least 200/min, appropriate ICD shocks, and appropriate antitachycardia pacing. All end points were included in a first and recurrent event analysis.

Results

Of the 4506 study participants, 3431 were men (76%). Mean (SD) age of the cohort was 64 (12) years. For women vs men, the mean (SD) age (64 [12] years vs 64 [11] years) and left ventricular ejection fraction (24% vs 25%) were similar, but women exhibited a higher frequency of nonischemic cardiomyopathy (454 of 1075 women [42%] vs 2535 of 3431 men [74%]). Women had significantly lower 3-year cumulative probability of sustained VTA (16% vs 26%), fast VTA (9% vs 17%), and appropriate ICD shocks (7% vs 15%) compared with men (P < .001 for all). Multivariable analysis showed that female sex was independently associated with at least 40% lower risk of all first and recurrent VTA end points (P < .001 for all), including the primary end point (first event, HR = 60 [95% CI, 50-73], P < .001; recurrent event, HR = 49 [95% CI, 43-55], P < .001), after accounting for the competing risk of all-cause mortality and nonarrhythmic mortality. The lower VTA risk associated with female sex was consistent in risk subsets but was significantly more pronounced in patients with nonischemic cardiomyopathy (female vs male in the ischemic group: hazard ratio, 0.73 [95% CI, 0.56-0.95], P = .02; nonischemic group: hazard ratio, 0.50 [95% CI, 0.38-0.66], P < .001; P = .03 for interaction between female sex and cardiomyopathy).

Conclusions and Relevance

Findings suggest that women display a significantly lower risk of first and recurrent life-threatening VTA events than men, and that it is more pronounced in patients with nonischemic cardiomyopathy, suggesting a need for sex-specific risk assessment for primary prevention ICD therapy.

Reduction in Ventricular Tachyarrhythmia Burden in Patients Enrolled in the RAID Trial

BACKGROUND

The RAID (Ranolazine Implantable Cardioverter-Defibrillator) randomized placebo-controlled trial showed that ranolazine treatment was associated with reduction in recurrent ventricular tachycardia (VT) requiring appropriate implantable cardioverter-defibrillator (ICD) therapy.

OBJECTIVES

This study aimed to identify groups of patients in whom ranolazine treatment would result in the highest reduction of ventricular tachyarrhythmia (VTA) burden.

METHODS

Andersen-Gill analyses were performed to identify variables associated with risk for VTA burden among 1,012 patients enrolled in RAID. The primary endpoint was VTA burden defined as VTA episodes requiring appropriate treatment.

RESULTS

Multivariate analysis identified 7 factors associated with increased VTA burden: history of VTA, age ≥65 years, New York Heart Association functional class ≥III, QRS complex (≥130 ms), low ejection fraction (<30%), atrial fibrillation (AF), and concomitant antiarrhythmic drug (AAD) therapy. The effect of ranolazine on VTA burden was seen among patients without concomitant AAD therapy (HR [HR]: 0.68; 95% CI: 0.55-0.84; P < 0.001), whereas no effect was seen among those who are concomitantly treated with other AADs (HR: 1.33; 95% CI: 0.90-1.96; P = 0.16); P = 0.003 for interaction. In patients with cardiac resynchronization therapy (CRT) ICDs, ranolazine treatment was associated with a 36% risk reduction for VTA recurrence (HR: 0.64; 95% CI: 0.47-0.86; P < 0.001), whereas among patients with ICDs without CRT no significant effect was noted (HR: 0.94; 95% CI: 0.74-1.18; P = 0.57); P = 0.047 for interaction.

CONCLUSIONS

In patients with high risk for VTA, ranolazine is effective in reducing VTA burden, with significantly greater effect in CRT-treated patients, those without AF, and those not treated with concomitant AADs. In patients already on AADs or those with AF, the addition of ranolazine did not affect VTA burden. (Ranolazine Implantable Cardioverter-Defibrillator Trial [RAID]; NCT01215253).

Cardiac resynchronization therapy and ventricular tachyarrhythmia burden

BACKGROUND

Cardiac resynchronization therapy-defibrillator (CRT-D) may reduce the incidence of first ventricular tachyarrhythmia (VTA) in patients with heart failure (HF) and left bundle branch block (LBBB).

OBJECTIVE

The purpose of this study was to assess the effect of CRT-D on VTA burden in LBBB patients.

METHODS

We included 1281 patients with LBBB from MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy). VTA was defined as any treated or monitored sustained ventricular tachycardia (VT ≥180 bpm) or ventricular fibrillation (VF). Life-threatening VTA was defined as VT ≥200 bpm or VF. VTA recurrence was assessed using the Andersen-Gill model.

RESULTS

During a mean follow-up of 2.5 years, 964 VTA episodes occurred in 264 patients (21%). The VTA rate per 100 person-years was significantly lower in the CRT-D group compared with the implantable cardioverter-defibrillator (ICD) group (20 vs 34; P <.01). Multivariate analysis demonstrated that CRT-D treatment was associated with a 32% risk reduction for VTA recurrence (hazard ratio 0.68; 95% confidence interval 0.57-0.82; P <.001), 57% risk reduction for recurrent life-threatening VTA, 54% risk reduction for recurrent appropriate ICD shocks, and 25% risk reduction for the combined endpoint of VTA and death. The effect of CRT-D on VTA burden was consistent among all tested subgroups but was more pronounced among patients in New York Heart Association functional class I. Landmark analysis showed that at 2 years, the cumulative probability of death subsequent to year one was highest (16%) among patients who had ≥2 VTA events during their first year.

CONCLUSION

In patients with LBBB and HF, early intervention with CRT-D reduces mortality, VTA burden, and frequency of multiple appropriate ICD shocks. VTA burden is a powerful predictor of subsequent mortality.

Renal Denervation for the Management of Refractory Ventricular Arrhythmias: A Systematic Review

OBJECTIVES

The authors performed a systematic review and meta-analysis to determine the efficacy of renal denervation (RDN) in patients with refractory ventricular arrhythmias (VA) or electrical storm (ES).

BACKGROUND

Although catheter ablation is efficacious for the treatment of structural heart disease ventricular tachycardia (VT), there are proportion of patients who have refractory VT despite multiple procedures. In this setting, novel adjunctive therapies such as renal denervation have been performed.

METHODS

A systematic review of published data was performed. Studies that evaluated patients undergoing RDN for VA or ES were included. Outcome measures of VA, sudden cardiac death, ES, or device therapy were required. Case reports, editorials, and conference presentations were excluded. Random effects meta-analysis was conducted to explore change or final mean values in the study outcomes.

RESULTS

A total of 328 articles were identified by the literature search. Seven studies met the eligibility criteria and were included in the systematic review, with a total of 121 pooled patients. The weighted mean age was 63.8 ± 13.1 years, ejection fraction 30.5 ± 10.3%, 76% were men, 99% were on a beta blocker, 79% were on amiodarone, 46% had previously undergone catheter ablation, and 8.3% had previously undergone cardiac sympathetic denervation. Meta-analysis demonstrated a significant effect of RDN in reducing implantable cardiac defibrillator therapies, with a standardized mean difference (SMD) of -3.11 (p < 0.001). RDN also reduced the number of VA episodes (SMD -2.13; p < 0.001), antitachycardia pacing episodes (SMD -2.82; p = 0.002), and shocks (SMD -2.82; p = 0.002).

CONCLUSIONS

RDN is an effective treatment for refractory VAs and ES, although randomized data are lacking.

Predictors of Subcutaneous Implantable Cardioverter-Defibrillator Shocks and Prognostic Impact in Patients With Structural Heart Disease

BACKGROUND

In this study we aimed to assess long-term outcomes in subcutaneous implantable cardioverter-defibrillator (S-ICD) recipients with structural heart disease by focussing especially on shock incidence, predictors, and associated prognoses.

METHODS

In this multicenter registry‒based study, we retrospectively included all patients who underwent S-ICD implantation at 3 tertiary centers. The prognostic impact of S-ICD shock was assessed with a composite outcome that included all-cause death and hospitalisation for heart failure.

RESULTS

A total of 351 patients with underlying cardiomyopathy were included in the investigation. Using multivariable Fine and Gray regression models, secondary prevention, left ventricular ejection fraction (LVEF), conditional shock threshold, and QRS duration appeared to be independent predictors of appropriate S-ICD shock occurrence. In the multivariate Cox regression model adjusted for age, baseline LVEF, underlying cardiomyopathy subtype, New York Heart Association class, and appropriate shocks were significantly associated with increased composite prognostic outcome risk (hazard ratio [HR], 2.61; 95% confidence interval [CI], 1.21-5.65; P = 0.014), whereas inappropriate shocks were not (HR, 1.35; 95% CI, 0.75-4.48; P = 0.18). The analysis of each component of the composite prognostic outcome highlighted that the occurrence of appropriate shocks was associated with an increased risk of hospitalisation for heart failure (HR, 3.10; 95% CI, 1.26-7.58; P = 0.013) and a trend for mortality (HR, 2.19; 95% CI, 0.78-6.16; P = 0.14).

CONCLUSIONS

Appropriate S-ICD shocks were associated with a 3-fold increase in acute heart failure admission, whereas inappropriate shocks were not. Conditional shock threshold programming is an independent predictor of S-ICD shock, and its prognostic impact should be investigated further in patients with structural heart disease.