Partial Fracture of a Subcutaneous ICD Lead from Mechanical Trauma

Introduction

Transvenous implantable cardioverter-defibrillators (TV-ICD) have electrode failure rates as high as 20% over 10-year follow-up, with 12% as a result of lead fractures.¹ The development of the subcutaneous ICD (S-ICD) offers the benefit of significantly reduced post-implant complication rates.² We present the first reported case of an S-ICD electrode failure secondary to partial fracture as a result of mechanical trauma. This case demonstrates the importance of a two-view chest x-ray in a patient with an S-ICD after mechanical fall or thoracic trauma, as well as the benefits of home monitoring.

Background

Implantable cardioverter-defibrillators (ICDs) are lifesaving devices that monitor and treat fatal ventricular arrhythmias. Indications for an ICD broadly include secondary prevention for those who have survived prior cardiac arrest, sustained VT/VF, or syncope caused by ventricular arrhythmia, and primary prevention for those at an increased risk of fatal ventricular arrhythmias.³ The evolution of ICD technology resulted in the development of the subcutaneous ICD, which allows for implantation of an ICD without the need for a transvenous ICD lead. S-ICDs can bypass TV-ICD complications such as lead dislodgement, lead fracture, externalization, embolization, insulation break, and tricuspid valve damage.⁴ S-ICDs are considered safe and effective, and are recommended for patients who meet criteria for a TV-ICD but do not have vascular access or are at high risk of infection.^2,3 S-ICDs have very low post-implant complication rates that are limited to localized infection or hematoma.⁵ 

Case Description

A 54-year-old male, with a past medical history of ischemic cardiomyopathy and heart failure with reduced ejection fraction (HFrEF) of 15%, was implanted with an S-ICD for primary prevention in April 2018 after his initial TV-ICD was explanted due to a lead infection. The patient arrived at the emergency department in August 2019, status post a mechanical fall, and was discharged on the same day. Several weeks later, the patient’s home monitoring system notified us that the impedance of his defibrillation electrode was greater than 400 ohms, suggesting a lead fracture. A two-view chest x-ray confirmed the S-ICD lead fracture proximal to the defibrillation coil (Figures 1 and 2). This fracture was most evident on the lateral view chest x-ray (Figure 1).

The sensing component of the lead remained intact (Figures 3A and 3B). Comparing the electrogram before and after the chest trauma showed no change. 

The patient was not able to make it for his S-ICD lead revision until November 2019. During the lead explant, the S-ICD lead was severed completely and removed in 2 pieces with manual traction at the most proximal end of the lead. A new S-ICD lead was then successfully re-implanted.

The patient is doing well to date, with his S-ICD showing intact sensing of his sensing and defibrillation electrode. We continue  to monitor his S-ICD through the home monitoring program.

Discussion

This is the first known case of a partially fractured S-ICD lead secondary to mechanical trauma confirmed with a 2-view chest x-ray and elevated impedance (>400 ohms) readings on the patient’s home monitoring system. Transvenous ICD and pacemaker lead fractures are a known complication secondary to chronic tension and stress from repetitive cardiac and thoracic movement, subclavian crush, Twiddler’s syndrome, thoracic trauma, thoracic outlet syndrome, and multiple other etiologies.^6-8 However, post-operative S-ICD implant complication rates are low and generally limited to localized infection and hematoma. To date, there has only been a single case reported of an S-ICD lead externalization demonstrating potential lead complications; there have not been any reported cases of an S-ICD lead fracture.⁹

This case demonstrates that S-ICD leads are susceptible to fracture. Direct mechanical trauma to the chest was the most likely cause of lead fracture, and associated stretching of the lead from the fall likely contributed to the fracture as it occurred just beyond the retaining suture. As the sensing function was still intact, there was a selective fracture of the defibrillator coil. This case also illustrates the benefits of home monitoring. The patient was unaware of damage sustained to the S-ICD lead, which could have led to failure of appropriate defibrillation therapy in the future. It is also important to obtain a 2-view chest x-ray on all patients who have chest trauma with an S-ICD, as a single anterior posterior chest x-ray does not clearly reveal a lead fracture. However, it is much more evident on the lateral chest x-ray. 

Disclosures: The authors have no conflicts of interest to report regarding the content herein.

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