Background: An atrioventricular defibrillator system with a floating atrial dipole (VDD ICD) can provide atrial sensing by a single lead. Our aim was to compare the arrhythmia detection efficacy of VDD ICDs with conventional single- (VVI) and dual-chamber (DDD) defibrillators. Methods: Data from consecutive patients undergoing ICD implantation were retrospectively analyzed. The primary endpoint was the incidence of device-detected, new-onset atrial arrhythmias, while secondary endpoints were sensing parameters, complication rates, incidence of appropriate/inappropriate ICD therapy, arrhythmic/heart failure-related hospitalizations, and all-cause mortality. Results: A total of 256 patients (mean age 64 ± 12 years, male 75%, primary prophylaxis 28%, mean follow-up 3.7 ± 2.4 years) were included (VVI: 93, VDD: 94, DDD: 69). Atrial arrhythmia episodes were detected more frequently by VDD systems compared to VVI ICDs (aHR 7.087; 95% CI 2.371–21.183; p < 0.001), and at a rate similar to that of DDD ICDs (aHR 1.781; 95% CI 0.737–4.301; p = 0.200). The rate of inappropriate shocks was not different among the three ICD systems. Conclusion: VDD devices revealed an advantage in atrial arrhythmia detection compared to VVI ICDs and were non-inferior to DDD systems. Their main indication may be closer monitoring in high-risk patients with atrial arrhythmias to help therapy optimization and not the improvement of tachycardia discrimination.

Limited data are available on long-term changes in the conduction system following transcatheter aortic valve implantation (TAVI). To assess AV conduction changes after TAVI and examine the relationship between pacemaker-derived parameters and surface ECG findings. We retrospectively analyzed patients who underwent PM implantation after TAVI between July 2014 and June 2023. Demographic, imaging, procedural, and ECG data were collected. A dedicated follow-up (FU) visit, including device interrogation and a 12-lead ECG recorded during temporary VVI pacing at 30 bpm, was performed on average 1.7 ± 1.3 years post-implant. Based on FU ECGs, patients were classified as having persistent (persAVB) or regressive AV block (regrAVB). Among 377 TAVI procedures, 33 PM implantations (8.7%) occurred a mean of 5.7 days post-procedure. Indications included third-degree AV block in 27 (81%), second-degree AV block in 3 (9%), and bradycardia in 3 (9%). FU ECGs were available for 14 patients; 7 (50%) showed conduction recovery. Baseline QRS duration was significantly wider in persAVB than in regrAVB (107.1 ± 27.3 ms vs. 80.7 ± 1.6 ms; p = 0.038). Median right ventricular pacing (RVp) burden was substantially higher in persAVB (100% [IQR 98.8-100%]) compared with regrAVB (0% [IQR 0-2.5%]; p < 0.001). Pacemaker dependency was present in 28% of persAVB patients and in none of the regrAVB group. A substantial proportion of patients showed recovery of atrioventricular conduction over time, particularly those without pre-existing conduction disturbances. The degree of RVp closely reflected conduction recovery status during follow-up.