Advancements in Pacing and ICD Technologies: Potential Implications for Complex Congenital Heart Disease in Adults

Adults with congenital heart disease (ACHD) represent a rapidly growing population with a high burden of bradyarrhythmias and ventricular arrhythmias requiring cardiac implantable electronic devices. However, conventional transvenous pacing and defibrillator systems often present important challenges in this population due to complex anatomy, limited venous access, intracardiac shunts, and the cumulative risk of lead-related complications over a patient’s lifetime. Recent technological advances—including conduction system pacing, leadless pacemakers, subcutaneous and extravascular implantable cardioverter-defibrillators, and emerging modular pacing–defibrillator platforms—have expanded the range of device strategies available for ACHD patients. These innovations aim to reduce intravascular hardware, improve physiological ventricular activation, and enable device therapies tailored to complex congenital anatomy. However, the evidence supporting both conventional and emerging technologies in ACHD patients remains limited and is derived largely from small observational studies and registry data. In addition, the substantial heterogeneity of congenital heart diseases and their prior surgical repair complicates extrapolation of outcomes across patient subgroups. Careful patient selection, anatomical assessment, and consideration of long-term device management therefore remain central to clinical decision-making. In this narrative review, we summarise recent developments in pacing and defibrillator technologies and discuss their potential implications for adults with congenital heart disease. To support clinical decision-making, we also propose a pragmatic ACHD-specific device-selection algorithm integrating anatomical, electrophysiological, and long-term management considerations. • Adult congenital heart disease patients present unique anatomical and lifelong challenges that limit conventional transvenous pacing and ICD strategies and demand individualised device selection. • Traditional epicardial and transvenous systems are associated with substantial long-term complications in ACHD, including lead failure, infection, thromboembolism, and repeated surgical re-intervention. • Advances in ICD technology, including subcutaneous and extravascular ICDs, reduce intravascular risk while broadening defibrillation capabilities in selected ACHD patients. • Modular and hybrid systems, combining leadless pacing with extravascular or subcutaneous ICDs, enable flexible, anatomy-adapted therapy while minimising transvenous hardware and long-term lead burden. • A pragmatic four-step ACHD-specific device-selection algorithm is proposed to guide clinicians in matching evolving technologies to anatomy, substrate, and long-term patient needs.