Inappropriate Therapy and Shock Rates Between the Subcutaneous and Transvenous Implantable Cardiac Defibrillator: A Secondary Analysis of the PRAETORIAN Trial.
Olde Nordkamp LRA., Pepplinkhuizen S., Ghani A., Boersma LVA., Kuschyk J., El-Chami MF., Behr ER., Brouwer TF., Kaab S., Mittal S., Quast A-FBE., van der Stuijt W., Smeding L., de Veld JA., Tijssen JGP., Bijsterveld NR., Richter S., Brouwer MA., de Groot JR., Kooiman KM., Lambiase PD., Neuzil P., Vernooy K., Alings M., Betts TR., Bracke FALE., Burke MC., de Jong JSSG., Wright DJ., Jansen WPJ., Whinnett ZI., Nordbeck P., Knaut M., Philbert BT., van Opstal JM., Chicos AB., Allaart CP., Borger van der Burg AE., Dizon JM., Miller MA., Nemirovsky D., Surber R., Upadhyay GA., Weiss R., de Weger A., Wilde AAM., Knops RE., PRAETORIAN Investigators None.
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 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.