1Universitätsklinikum Münster Klinik für Kardiologie II - Rhythmologie Münster, Deutschland
Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) has become a valuable treatment option for patients with an ICD but no pacing indication. Occasionally, pacemaker (PM)-dependent patients develop an indication for ICD therapy, when transvenous lead implantation is not feasible or to be avoided e.g., in congenital heart disease, lack of vascular access or prior tricuspid valve replacement. In these specific scenarios, addition of an S-ICD to a previously implanted permanent PM may be considered, although experience with this combination therapy is scarce.
Methods: We reviewed our single centre S-ICD experience. Nine patients (age at S-ICD implantation 49±12 years, 5 male) underwent S-ICD implantation after previous implantation of a transvenous (n=3) or epicardial (n=6) PM from 2015 to 2020. All patients had a history of structural heart disease (n=1 ischaemic cardiomyopathy, n=1 dilated cardiomyopathy, n=3 valvular heart disease, n=4 congenital heart disease). Three patients had a history of endocarditis, one patient had a history of device-related endocarditis and one patient had a history of device pocket infection. ICD indication was primary preventive in two patients, seven patients had a secondary preventive ICD indication after an aborted sudden cardiac death due to ventricular fibrillation (VF) (n=5) or ventricular tachycardia (VT) (n=2). In two patients, a previously implanted secondary preventive ICD was explanted prior due to device-related tricuspid valve endocarditis (n=1) or right ventricular lead exit block requiring open-heart surgery (n=1). Indications for PM therapy were third degree atrioventricular block (n=6), symptomatic bradycardic atrial fibrillation (n=2), or sinus node dysfunction (n=1). All patients were carefully screened before S-ICD implantation in supine and upright position.
Results: S-ICD implantation was performed successfully without complications in 7 patients. One patient developed a haematoma requiring re-operation. In another patient, a haematoma was treated conservatively. Mean follow-up after S-ICD implantation was 52 ± 20 months. One patient was lost to follow-up. In total, five appropriate ICD shocks for VF were successfully delivered in one patient, in the other patients, no sustained arrhythmias were documented. One patient had an inappropriate ICD shock caused by T-wave oversensing of a supraventricular tachycardia. During follow-up no complications between the S-ICD and the implanted PM occurred and permanent inactivation or removal of the implanted ICD or PM were not required. There were no other complications such as skin erosion or device infections. None of the analysed patients was switched to a conventional ICD.
Conclusion: The present study reports experience with the combined use of the S-ICD and a permanent transvenous or epicardial PM in one of the largest patient populations analysed to date. The combination of an S-ICD with a permanent PM appears to be a successful approach in certain circumstances including patients with a history of endocarditis, complex congenital heart disease, or valvular heart disease in whom (additional) transvenous lead implantation is not feasible or particularly complex. Important issues regarding device type, programming, and device testing need to be addressed at the time of implantation.