Subcutaneous Implantable Cardioverter-Defibrillator Therapies

Subcutaneous implantable cardioverter-defibrillator (S-ICD) therapies represent a significant advance in the prevention of sudden cardiac death. By positioning both the generator and the lead entirely beneath the skin, these systems eliminate the need for intravascular leads and avoid many associated complications such as bloodstream infection, lead fracture, venous obstruction and endocarditis. Worldwide adoption has grown among patients who require defibrillation but not pacing support—particularly younger individuals, those with inherited arrhythmia syndromes or limited venous access. Modern devices feature improved sensing algorithms to reduce oversensing of muscle artefacts and T-wave signals, yielding low rates of inappropriate shocks. Surgical refinements, including intermuscular generator placement and refined lead positioning, have enhanced patient comfort and cosmetic outcomes. Emerging designs aim to integrate antitachycardia pacing via wireless linkages with leadless pacemakers and may broaden eligibility, offering a combined solution for both brady- and tachyarrhythmias without transvenous hardware. These innovations promise to reshape clinical practice by delivering reliable arrhythmia termination with an improved long-term safety profile.

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Subcutaneous Implantable Cardioverter-Defibrillator Therapies publication trend

The graph below shows the total number of articles in subcutaneous implantable cardioverter-defibrillator therapies across all publications each year (not limited to Nature Index journals).

Technical terms

Subcutaneous implantable cardioverter-defibrillator (S-ICD): A defibrillation device implanted entirely beneath the skin, using a subcutaneous lead to detect and terminate life-threatening ventricular arrhythmias without intravascular hardware.

Inappropriate shock: Delivery of a high-energy shock in the absence of ventricular tachyarrhythmia, often triggered by oversensing of benign signals such as T waves or myopotentials.

Antitachycardia pacing (ATP): Rapid pacing impulses delivered to interrupt and terminate ventricular tachycardia without resorting to high-energy shocks.

Intravascular lead: A conductor routed through a blood vessel in traditional transvenous systems to sense cardiac activity and deliver pacing or defibrillation therapies.

Defibrillation threshold (DFT): The minimum energy level required to reliably terminate induced ventricular fibrillation during intraoperative testing.

References

1. Modern subcutaneous implantable defibrillator therapy in patients with cardiomyopathies and channelopathies: data from a large multicentre registry. EP Europace (2023).
2. Subcutaneous implantable cardioverter-defibrillators: long-term results of the EFFORTLESS study. European Heart Journal (2022).
3. The modular cardiac rhythm management system: the EMPOWER leadless pacemaker and the EMBLEM subcutaneous ICD. Herzschrittmachertherapie + Elektrophysiologie (2018).