Early Experience with the Subcutaneous ICD

Abstract

The Subcutaneous Internal Cardiac Defibrillator (S-ICD) represents a major advance in the care of patients who have an indication for an internal cardiac defibrillator without pacing indications. Its main advantage is that it can deliver a shock to cardiovert ventricular arrhythmias utilising a tunnelled subcutaneous lead, negating the risks associated with conventional transvenous systems. Initial studies have shown comparable efficacy in cardioversion of induced and spontaneous ventricular tachycardia (VT) and ventricular fibrillation (VF) when compared to conventional transvenous systems. In addition, inappropriate shocks occurred in a similar percentage of patients to conventional ICD studies. Complication rates are low and relate largely to localised wound infections, treated successfully with antibiotics. The long term efficacy of the device is yet to be ascertained, however, a randomised trial & prospective registries are currently in progress to enable direct comparison with transvenous ICDs. This article summarises the early clinical experience and trials in the implantation of the S-ICD.

Multicentre early experience with totally subcutaneous cardioverter-defibrillators in Poland

“…Implantation of an S-ICD is technically a novel procedure for cardiologists, thus new surgical skills are needed to be mastered [6,23,25,27]. All procedures were successfully performed in our population, which is consistent with the high success rate of S-ICD implantation reported by other authors [15,28]. The procedures performed in Poland were usually done by electrophysiologists, but in some centres the first few implantations were supported by cardiac or general surgeons.…”

“…Interestingly, in further experience published by one of the Polish centres the subcutaneous generator placement used at the beginning was then abandoned in favour of an intermuscular ap-proach [31]. Overall implantation time (mean: 84 ±14 min) was within the limits reported by others (mean: 45-101 min) [22,25,28].…”

Sudden Cardiac Death

“…Ongoing challenges with the S-ICD include T-wave oversensing and discrimination of AF with rapid ventricular rates from VT/VF in the VF zone. 139 Nevertheless, studies have shown similar rates of inappropriate shocks comparing the S-ICD system and standard transvenous ICD systems. At present, the S-ICD is an attractive option for patients in whom transvenous lead or septic complications are particularly likely to occur.…”

“…A S-ICD (nontransvenous) has been recently developed that avoids some of the problems associated with transvenous lead systems. 139 The S-ICD is placed in the left lateral position via a lateral submammary incision and the lead is tunneled to be positioned parasternally. Implant complications are minor and are usually due to wound infections that can be treated with antibiotics.…”

“…At present, the S-ICD is an attractive option for patients in whom transvenous lead or septic complications are particularly likely to occur. 139 Some patients who are at risk for VT/VF may only need temporary protection from SCD because their risk is reversible or because they are still in the process of having their candidacy for an ICD assessed. This include early post-MI or CABG patients, those with as yet untreated CHF, those undergoing a workup for other potentially reversible causes of SCD, and those waiting for ICD system infection to be cleared.…”