Inappropriate Therapy and Shock Rates Between the Subcutaneous and Transvenous Implantable Cardiac Defibrillator: A Secondary Analysis of the PRAETORIAN Trial.

Background: Inappropriate therapy (IAT) is an undesirable side effect of implantable cardiac defibrillator (ICD) therapy. Early studies with the subcutaneous ICD (S-ICD) showed relatively high inappropriate shock (IAS) rates. The PRAETORIAN (Prospective Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) trial demonstrated that the S-ICD is noninferior to the transvenous ICD (TV-ICD) with regard to the combined end point of IAS and complications. This secondary analyses evaluates all IAT in the PRAETORIAN trial.
Methods: This international, multicenter trial randomized 849 patients with an indication for ICD therapy between S-ICD (n=426) and TV-ICD therapy (n=423). ICD programming was mandated by protocol. All analysis were performed in the modified intention-to-treat population.
Results: In both groups 42 patients experienced IAT (48-month Kaplan-Meier estimated cumulative incidence, 9.9% and 10.1%, respectively; hazard ratio (HR), 0.99 [95% CI, 0.65-1.52]; P =0.97). There was no significant difference in patients experiencing IAS between both groups ( P =0.14). In the S-ICD group, 81 IAT episodes with 124 IAS and 1 inappropriate antitachycardia pacing occurred versus 89 IAT episodes with 130 IAS and 124 inappropriate antitachycardia pacing in the TV-ICD group. IAT episodes were most frequently caused by supraventricular tachycardias in the TV-ICD group (n=83/89) versus cardiac oversensing in the S-ICD group (n=40/81). In the TV-ICD group, a baseline heart rate >80 bpm (HR, 1.99 [95% CI, 1.05-3.76]; P =0.03), a history of atrial fibrillation (HR, 2.66 [95% CI, 1.41-5.02]; P =0.003), and smoking (HR, 2.46 [95% CI, 1.31-4.09]; P =0.005) were independent predictors for IAT. A QRS duration >120 ms was an independent predictor for IAT caused by cardiac oversensing in the S-ICD group (HR, 3.13 [95% CI, 1.34-7.31]; P =0.008). Post-IAS interventions significantly reduced IAS recurrence in both groups ( P =0.046).
Conclusions: There was no significant difference in IAT and IAS rates between the S-ICD and TV-ICD in a conventional ICD population, but causes and predictors for IAT differed between the devices. After the first IAS, an intervention significantly reduced the recurrence rate of IAS.
Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022.
Competing Interests: Dr Knops reports consultancy fees and research grants from Abbott, Boston Scientific, Medtronic, and Cardiac, and has stock options from AtaCor Medical, Inc. Dr El Chami reports consultancy fees from Boston Scientific and Medtronic. Dr Mittal reports consultancy fees from Boston Scientific and Medtronic.Dr Neuzil reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. K.M. Kooiman reports consultancy fees from Boston Scientific. Dr Lambiase reports educational and research grants from and is in the research board of Boston Scientific, and reports research grants from Abbott. Dr Vernooy reports consultancy fees from Medtronic and Abbott. M.C. Burke is a consultant, receives honoraria, as well as research grants from Boston Scientific and has equity in and is chief medical officer for AtaCor Medical, Inc. Dr Wright has consultancy arrangements with Boston Scientific and Medtronic and a research grant from Boston Scientific. Dr Nordbeck reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. Dr Miller reports consultancy fees from Boston Scientific. Dr Whinnett is an advisor for Boston Scientific, on the advisory board for Medtronic and Abbot, and reports speaker fees from Medtronic. The other authors report no conflicts.