The need for a subsequent transvenous system in patients implanted with subcutaneous implantable cardioverter-defibrillator

The absence of pacing capabilities may reduce the appeal of S-ICD devices for patients at risk of conduction disorders or with anti-tachycardia pacing/cardiac resynchronization (CRT) requirements. Reports of rates of S-ICD to TV-ICD system switch in real-world scenarios are limited.To investigate the need for a subsequent transvenous (TV) device in patients implanted with subcutaneous implantable cardioverter defibrillator (S-ICD) and its predictors.All patients implanted with an S-ICD were enrolled from the multicentered, real-world iSUSI registry. The need for a TV device and its clinical reason, alongside to appropriate and inappropriate device therapies were assessed. A logistic regression with Firth penalization was used to assess the association between baseline and procedural characteristics and the overall need for a subsequent TV device.A total of 1509 patients were enrolled (50.8±15.8 years; 76.9% male; 32.0% ischemic; LVEF 38 [30-60]%). Over 26.5 [13.4-42.9] months, 155 (10.3%) and 144 (9.3%) patients experienced appropriate and inappropriate device therapies. Forty-one (2.7%) patients required a TV device (n=13 bradycardia; n=10 need for CRT; n=10 inappropriate shocks). BMI >30 kg/m2 and CKD were associated with need for a TV device (OR 2.57 [1.37-4.81], p=0.003 and OR 2.67 [1.29-5.54], p=0.008).A low rate (2.7%) of conversion from S-ICD to a TV device was observed at follow-up, with need for anti-bradycardia pacing, ATP or CRT being the main reasons. BMI >30 kg/m2 and CKD predicted all-cause need for a TV device.