How Common is New Onset Atrial Fibrillation in Single Chamber ICD Patients? Sub-analysis From the PainFree SST Study

Introduction: Nearly 75% of ICD recipients have no history of atrial fibrillation (AF) at the time of initial implantation. Yet, many of these patients will develop new onset AF after implant which can lead to serious consequences if not detected and treated. To date, detection algorithms in single-chamber ICDs are not able to detect AF. We investigate how common is new onset AF in single chamber (SC) ICD recipients compared to CRT-D and dual chamber (DC) ICD recipients. Methods: A total of 924 patients with no history of AF from the PainFree SST study (CRT-D: N=321, DC ICD: N=303, SC ICD: N=300) were investigated. We used data from dual-chamber ICDs to estimate the incidence of new-onset AT/AF in SC ICD patients. A propensity score weighted analysis was performed using DC ICD data to match the baseline data of SC ICD patients. Patients with pacing indication were excluded from this evaluation because they would not be indicated for SC ICD. AT/AF-related complications include AT/AF-related serious adverse events, thromboembolic events, progress to AF lasting 7 days or more as well as inappropriate shocks due to AT/AF. Simulated SC ICD results were compared to actual DC and CRT-D results. Results: For AF episodes lasting 6 minutes or more, the incidence rates in CRT-D, DC ICD, and the estimated SC ICD were 28.0%, 23.4%, and 20.5% at 24 months, respectively (Table). The estimated incidence rates of AT/AF episodes in patients with SC ICD were comparable to those of DC ICD in each episode duration. Once the patients experienced first AT/AF episode, the complications were common (Table). Conclusions: AT/AF was frequently detected following implant in patients with no AF history receiving ICD or CRT-D and is associated subsequent AT/AF-related complications even in SC ICD recipients. Therefore, AT/AF monitoring in all ICDs patients may identify those at risk for these complications.