Pitfalls of the S-ICD therapy: experiences from a large tertiary centre

Abstract

Aim: The subcutaneous ICD (S-ICD) has evolved to a potential first option for many patients who have to be protected from sudden cardiac death. Many trials have underlined a similar performance regarding its effectiveness in relation to transvenous ICDs and have shown the expected benefits concerning infective endocarditis and lead failure. However, there have also been problems due to the peculiarities of the device, such as oversensing and myopotentials. In this study, we present patients from a large tertiary centre suffering from complications with an S-ICD and propose possible solutions.

Methods and results: All S-ICD patients who experienced complications related to the device (n = 40) of our large-scale single-centre S-ICD registry (n = 351 patients) were included in this study. Baseline characteristics, complications occurring and solutions to these problems were documented over a mean follow-up of 50 months. In most cases (n = 23), patients suffered from oversensing (18 cases with T wave or P wave oversensing, 5 due to myopotentials). Re-programming successfully prevented further oversensing episode in 13/23 patients. In 9 patients, generator or lead-related complications, mostly due to infectious reasons (5/9), occurred. Further problems consisted of ineffective shocks in one patient and need for antibradycardia stimulation in 2 patients and indication for CRT in 2 other patients. In total, the S-ICD had to be extracted in 10 patients. 7 of them received a tv-ICD subsequently, 3 patients refused re-implantation of any ICD. One other patient kept the ICD but had antitachycardic therapy deactivated due to inappropriate shocks for myopotential oversensing.

Conclusion: The S-ICD is a valuable option for many patients for the prevention of sudden cardiac death. Nonetheless, certain problems are immanent to the S-ICD (limited re-programming options, size of the generator) and should be addressed in future generations of the S-ICD.

Keywords: ICD; Lead dysfunction; Pitfalls; S-ICD; Subcutaneous ICD; Troubleshooting; Ventricular arrhythmia.

Fig. 1

A patient with ischemic cardiomyopathy and sudden onset of T and also P wave oversensing resulting in an inappropriate shock. Because of the development of a left bundle branch block in course of the disease an indication for CRT emerged so that he received a CRT-ICD after these episodes

Fig. 2

A young women who survived SCD due to VF was presenting in our emergency department after having experienced an S-ICD shock during yoga exercises. S-ICD interrogation revealed massive myopotential oversensing leading to tachycardia detection and a consecutive shock delivery. After muscular relaxation due to changing of the body position after IAS there was proper sensing of S-ECG signals again

Fig. 3

A patient with a recently implanted S-ICD which took about 90° dorsal rotation. The left picture showing X ray immediately postoperatively. The rotation, which led to discomfort and swelling of the pocket, is present in the right picture