Outcomes of Subcutaneous Implantable Cardioverter Defibrillators in Patients Being Considered for Heart Transplantation: A Retrospective Cohort Study
Rohan Joshua Krishnaswamy, Callum Alec Cherrett, Aaron Argyris Adonopulos, Peter Simon Macdonald, Christopher Simon Hayward, Kavitha Muthiah, Alasdair John Watson, Rajesh Natarajan SubbiahABSTRACT
Introduction
Subcutaneous implantable cardioverter defibrillators (S‐ICD) are an alternative to transvenous devices (TV‐ICD) in patients not requiring bradycardia pacing, resynchronization (CRT) or anti‐tachycardia pacing (ATP). At our center, S‐ICDs are often preferred in patients being considered for heart transplantation (HTx) without pacing/CRT/ATP needs, as their removal post‐HTx avoids retained transvenous leads which can preclude MRI surveillance for graft rejection. We assessed outcomes of S‐ICDs in this population.
Methods
We retrospectively reviewed 201 S‐ICD implants at our center; July 2016 ‐ March 2025.
Results
We identified 33 patients (22 male; age 46 ± 13 years) who, at time of S‐ICD implant, had been referred for HTx evaluation or were referred at any time thereafter. Etiologies were nonischemic cardiomyopathy ( n = 18), hypertrophic cardiomyopathy ( n = 5), ischemic cardiomyopathy ( n = 4), congenital heart disease ( n = 4), and myocarditis ( n = 2). Median follow‐up was 296 days [IQR = 72–798]. Two patients died, both non‐arrhythmic. Four patients received appropriate S‐ICD therapies and three had inappropriate shocks due to P‐ or T‐wave oversensing (TWOS) ( n = 2), or a rapidly conducted atrial arrhythmia ( n = 1). Three patients, all with hypertrophic cardiomyopathy, received transvenous device upgrades: one to CRT‐P for disease progression, one to TV‐ICD for ATP‐terminable ventricular tachycardia and one to TV‐ICD due to inappropriate shocks from TWOS. Thirteen patients underwent HTx at median 257 days [IQR = 130–453] post S‐ICD; three of whom were bridged with HeartMate 3 LVADs. One LVAD patient needed S‐ICD deactivation due to electromagnetic interference. There were no retained device components following HTx and S‐ICD extraction.
Conclusion
In selected pre‐HTx patients, S‐ICDs offer arrhythmic protection while avoiding retained leads post‐HTx.