1. In this randomized controlled trial, subcutaneous implantable cardioverter defibrillators (S-ICD) resulted in a lower risk of perioperative complications as compared to transvenous ICDs (TV-ICD).
2. There was no significant difference in inappropriate or failed ICD shocks between groups, though the trial was not statistically powered to detect meaningful differences.
Evidence Rating Level: 2 (Good)
Study Rundown: ICDs detect and correct arrhythmias to improve survival for patients at elevated risk of cardiac arrest. Traditional TV-ICD implantations are associated with perioperative complications, such as vascular injury and pleural or cardiac perforation. Lead replacement is also associated with an increased risk of severe infection and death. S-ICD is placed in the subcutaneous plane, which reduces complications of implantation. In this randomized control trial, the perioperative and long-term safety of S-ICDs were compared with TV-ICDs. While ICD efficacy, determined by the incidence of inappropriate and failed ICD shocks, was evaluated, the study was not statistically powered to detect meaningful differences between groups. Patients were followed at six-month intervals for an average of 2.5 years. The incidence of perioperative lead-related complications within six months of implantation was significantly lower in the S-ICD group compared to the TV-ICD group. S-ICD was associated with more ICD site pain than the TV-ICD group at day one and 30 post-implantation, but not at six months. There were no significant differences in surgical ICD revision, inappropriate shocks, or failed shocks between groups. As a limitation, the trial was not statistically powered to detect differences in rates of failed or inappropriate shocks. However, the trial is still underway to determine long-term outcomes.
In-Depth [randomized controlled trial]: In this randomized control study, the perioperative safety and efficacy of S-ICD (n=251) and TV-ICD (n=252) were compared in patients with an indication for an ICD who were under 60 years old, had a cardiogenetic phenotype, and risk factors for lead complications. Patients were followed at six-month intervals for a mean of 2.5 years (standard deviation, 1.1). The primary perioperative safety outcomes included cardiac perforation, cardiac tamponade, lead dislodgement, deep venous thrombosis, and pneumothorax. The efficacy outcomes were the rate of inappropriate and failed ICD shocks. Though, these could not be determined as the study was not statistically powered to identify meaningful differences between groups. For the primary safety outcome, perioperative lead-related complications within six months of implantation were significantly lower in the S-ICD group compared to the TV-ICD group (p=0.001). The incidence of myocardial infarction, device infection, stroke, transient ischemic attack, and death were not significantly different between groups. One perioperative death occurred in the S-ICD group, which may be due to lidocaine toxicity. Patients in the S-ICD groups experienced more ICD site pain compared to the TV-ICD group at post implications day one (on a ten-point numeric rating scale, 4.2 [4.0 to 4.4] vs. 2.9 [2.6 to 3.1]; p<0.001) and day 30 (1.3 [1.1 to 1.5] vs. 0.9 [0.7 to 1.2]; p=0.035). No differences in ICD site pain were found at six months. During long-term follow-up, there were no significant differences in surgical ICD revision, inappropriate shocks, or failed shocks. This is the first clinical trial to evaluate whether S-ICD reduces perioperative ICD-related complications. The present trial is still underway to evaluate the long-term efficacy and safety outcomes of S-ICD. Successful implementation of S-ICD may reduce lead- and implantation-related adverse outcomes for patients.
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