The S-ICD™ (subcutaneous implantable cardioverter-defibrillator, Boston Scientific) performed similarly in patients with and without structural heart disease, according to a recent article in Clinical Research in Cardiology.

Between June 2010 and April 2019, 294 S-ICD devices were implanted at a single institution. In this study, researchers included S-ICD patients from this initial group with structural heart disease (n=144) such as ischemic cardiomyopathy, dilated cardiomyopathy, or hypertrophic cardiomyopathy and S-ICD patients with electrical or idiopathic ventricular fibrillation (n=83) for a total of 227 patients with a mean follow-up period of 18 months.

In the structural heart disease group, 19 appropriate shocks were delivered in 17 patients. In the electrical group, 8 appropriate shocks were delivered in 7 patients. All 27 shocks terminated ventricular arrhythmia initially. Inappropriate shocks occurred in 9 patients (23 shocks) in the structural group and 4 patients (9 shocks) in the electric group. Inappropriate shocks in 13 patients could be addressed by reprogramming. Overall, there were not significantly more shocks in the structural group.

There were no significant differences between both groups for appropriate and inappropriate shocks, but there was a significant difference between the first- and second-generation S-ICDs. The second-generation S-ICDs had significantly reduced inappropriate shocks in the whole study population, which was driven by the reduction in inappropriate shocks in the structural group.

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The peri- and post-operative safety was high. Only 2% to 3% in both groups required operative revisions. Limitations of S-ICD therapy include a missing option for ATP, which is why transvenous ICD especially in patients with structural heart diseases. The success of S-ICD therapy requires careful patient selection.

The researchers conclude that “the S-ICD is a feasible option not only in patients without structural but also in a selected patient collective with structural heart disease […] Future evidence can be expected by the ongoing PRAETORIAN trial which may help to further identify the most suitable device for the individual patient.”

Reference

Willy K, Reinke F, Bögeholz N, et al. Outcome differences and device performance of the subcutaneous ICD in patients with and without structural heart disease [published online October 31, 2019]. Clin Res Cardiol. doi:10.1007/s00392-019-01564-1