His bundle pacing for newly acquired pacing needs in patients implanted with a subcutaneous implantable cardioverter defibrillator: A feasibility study based on the automated screening score and clinical cases

Comparison of automated subcutaneous defibrillator screening between different pacing sites in cardiac pacing device carriers

AIMS

The compatibility of cardiac pacing with the presence of a subcutaneous implantable cardioverter-defibrillator (S-ICD) has been investigated, but S-ICD screening test results have not been compared among different pacing sites. The objective was to compare S-ICD screening results among different cardiac pacing sites and to assess the electrocardiographic predictors of success.

METHODS AND RESULTS

This prospective single-centre study conducted automated S-ICD screening in 102 carriers of cardiac pacing devices in conduction system (CSP), biventricular (BVP), right ventricular outflow tract (RVOT), or right ventricular apex (RVA) pacing sites. The study included 102 patients: 40 with CSP (20 left bundle pacing and 20 His bundle pacing), 21 with BVP, and 20 and 21 with RVOT and RVA pacing, respectively. The percentage of positive screenings was significantly higher for CSP (97.5%) than for the other patient groups (BVP 71.4%, RVOT 70%, and RVA 19%). In multivariate analysis, positive screening was associated with a narrower QRS (OR 0.95 [0.92-0.98] P = 0.001) and higher R/T ratio in precordial leads (1.76 [1.18-2.61]).

CONCLUSION

A higher S-ICD eligibility rate of cardiac pacing device carriers was obtained in CSP than in conventional pacing (RVA or RVOT) or BVP. The presence of narrower paced QRS width and paced corrected QT interval and of higher R/T ratio in precordial and limb leads are electrocardiographic predictors of a positive response to screening.

S-ICDs: advantages and opportunities for improvement

INTRODUCTION

The subcutaneous implantable cardioverter defibrillator (S-ICD) is currently in its third generation and has been adopted in guidelines and in mainstream clinical practice. Considerable improvements have been made since the introduction of this device over a decade ago.

AREAS COVERED

A literature search was undertaken in Pubmed on articles relating to the S-ICD.

EXPERT OPINION

The therapy has been proven to be safe and effective and is a valuable option in selected patients. Nevertheless, there remain many shortcomings of the S-ICD which are discussed in this review, and which hopefully will be addressed by future generations of the device.

Arrhythmias in adults with congenital heart disease and heart failure

Arrhythmias and heart failure are among the most common complications encountered by adults with congenital heart disease (CHD). In this contemporary review, we explore the interactions between arrhythmias and heart failure and discuss management strategies. Major knowledge gaps are highlighted throughout. Interactions between arrhythmias and heart failure are complex and bidirectional, with one begetting the other. Arrhythmias can provoke heart failure through various mechanisms: conduction disturbances may contribute to inefficient ventricular filling and contraction patterns; bradyarrhythmias and tachyarrhythmias can result in a reduction in cardiac output; hypoxemia may be exacerbated by right-to-left shunting; and tachycardia-induced cardiomyopathy has potentially devastating consequences if the diagnosis is delayed. In turn, heart failure promotes arrhythmogenesis through various structural (eg, fibrosis, chamber dilation, hypertrophy) and electrical remodeling effects that include changes to ion currents and channels and connexin expression, along with shortening of atrial and ventricular refractory periods with increased heterogeneity. Several shared comorbidities can contribute to, and modulate the impact of, arrhythmias and heart failure. Preemptive arrhythmia management can potentially mitigate effects on heart failure exacerbations. Similarly, optimal heart failure control could curtail its impact on arrhythmogenesis. Treatment strategies to prevent or treat heart failure in adults with CHD encompass pharmacological agents, catheter ablation, and device therapies including defibrillators, cardiac resynchronization therapy, and His bundle pacing. High-priority research avenues with major knowledge gaps include tachycardia-induced cardiomyopathy, catheter ablation of atrial fibrillation, defibrillator indications in high-risk subsets, and the role of cardiac resynchronization therapy and His bundle pacing in diverse forms of CHD.

State-of-the-art consensus on non-transvenous implantable cardioverter-defibrillator therapy

Within the last decade, implantable cardioverter-defibrillator (ICD) systems with non-transvenous leads were developed in order to minimize complications related to the cardiovascular position of transvenous ICD leads. This national expert consensus gives an overview of potential indications for the implantation of non-transvenous ICD systems, and provides specific recommendations for implantation, follow-up, and complication management in patients with subcutaneous ICD. Regarding particular issues like the necessity for shock efficacy testing, or the clinical outcome as compared to transvenous ICD, randomized data are expected in the near future.