Extrathoracic placement of a subcutaneous implantable cardioverter–defibrillator (ICD) was found to be noninferior to transvenous ICD in terms of device-related complications and the incidence of inappropriate shocks in patients with an indication for an ICD but no indication for pacing, according to a study published in the New England Journal of Medicine.
Subcutaneous ICD was introduced as a replacement for transvenous ICD to circumvent the potential complications (eg, pneumothorax, cardiac perforation) associated with the standard ICD design.
In the PRospective, rAndomizEd Comparison of subcuTaneOous and tRansvenous ImplANtable Cardioverter Defibrillator Therapy noniferiority trial (ClinicalTrials.gov Identifier: NCT01296022), 849 patients with an indication for ICD, but not for pacing, were implanted a subcutaneous (n=426) or transvenous (n=423) ICD. The study’s primary endpoint was a composite of complications associated with the device and occurrence of inappropriate shocks. Secondary endpoints included appropriate shocks and death.
Complications included infection related to the device that made extraction of the lead or generator necessary; pocket hematoma, blood transfusion, hospitalization prolongation; device-related thrombotic events; pneumothorax or hemothorax that resulted in intervention or hospitalization prolongation; cardiac perforation or tamponade; lead repositioning or replacement; and other lead- or generator-related complications that resulted in the need for medical or surgical intervention. Inappropriate ICD shocks included any shocks that were delivered for any rhythm other than ventricular tachycardia or ventricular fibrillation.
At a median follow-up period of 49.1 months, the composite of device-related complications and inappropriate shocks was reported in 68 patients who had received a subcutaneous ICD and 68 patients who had received a transvenous ICD (48-month Kaplan–Meier estimated cumulative incidence, 15.1% vs 15.7%, respectively; hazard ratio [HR], 0.99; 95% CI, 0.71-1.39; P =.01 for noninferiority; P =.95 for superiority).
Device-related complications occurred in 31 and 44 patients with a subcutaneous and transvenous ICD, respectively (HR, 0.69; 95% CI, 0.44-1.09). Inappropriate shocks occurred in 41 and 29 patients who had received a subcutaneous and transvenous ICD, respectively (HR, 1.43; 95% CI, 0.89-2.30). A greater number of patients who had been implanted subcutaneous vs transvenous ICD died (n=83 vs n=68, respectively; HR, 1.23; 95% CI, 0.89-1.70). Appropriate shocks were reported in 83 and 57 patients with a subcutaneous and transvenous ICD, respectively (HR, 1.52; 95% CI, 1.08-2.12).
Study limitations include lower experience with implantation of subcutaneous vs transvenous ICD, which may have influenced the clinical outcomes and the limited (48 months) follow-up period for the adequate assessment of long-term outcomes.
“The results of our trial showed that among patients with an indication for ICD therapy but not for pacing therapy, the subcutaneous ICD was noninferior to the transvenous ICD with respect to the cumulative incidence of the primary end point of device-related complications or inappropriate shocks,” concluded the study authors. Disclosure: This clinical trial was supported by Boston Scientific. Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Knops RE, Olde Nordkamp LRA, Delnoy PHM, et al. Subcutaneous or transvenous defibrillator therapy. N Engl J Med. 2020;383(6):526-536. doi:10.1056/NEJMoa1915932