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.

Background: Modern implantable cardioverter-defibrillators (ICDs) utilize single-chamber (SC) or dual-chamber (DC) discrimination algorithms to differentiate between tachyarrhythmias and minimize the risk of inappropriate therapies. While modern SC algorithms, especially those with morphology detection, are considered comparable to DC algorithms, the available data are limited. We aimed to compare the efficacy of SC and DC discrimination algorithms in malignant tachyarrhythmias. Methods: We retrospectively analyzed data from all patients with ICDs from a single manufacturer (Biotronik, Berlin, Germany) who were remotely monitored and followed up at two tertiary centers. Patients were divided into SC and DC groups, based on the programmed discrimination algorithm. The primary outcome was the risk of inappropriate therapies comparing SC vs. DC discriminators. A sensitivity analysis was also conducted, including only a subgroup of SC patients with active morphology discrimination. Results: A total of 557 patients were included. The distribution of the implanted ICDs was as follows: 76 VVI; 226 VDD; 76 DDD; and 179 CRT-D devices. A total of 124 ICDs were programmed utilizing SC and 433 were programmed into the DC discriminators group. Among the SC group, 47 (39%) ICDs used active morphology discrimination. The incidence of inappropriate ICD therapies did not differ among the SC and DC discrimination groups (Hazard Ratio [HR] 1.165; 95% Confidence Interval [CI] 0.393–3.448; p = 0.783). The predefined sensitivity analysis did not reveal any significant difference regarding this outcome (HR 1.809; 95% CI 0.241–13.577; p = 0.564). Conclusions: In this bicentric, remote monitoring-based study, the risk of inappropriate therapy in the SC group was similar to that of the DC group. Based on our results, SC discrimination is a suitable option, even for patients with dual-chamber devices.

Aims: Atrial fibrillation is the most common sustained cardiac arrhythmia, associated with considerable morbidity and mortality. Early detection is essential for optimal management. While wearable smart devices have shown promise, smartphone applications using photoplethysmography have also emerged as potential screening tools, but their diagnostic accuracy has not been adequately validated. This study aimed to compare the diagnostic performance of two commercially available photoplethysmography-based smartphone applications. Methods and results: In this prospective multicentre study, consecutive patients from three cardiology centres underwent simultaneous recordings with the FibriCheck® and Preventicus Heartbeats® applications and a 12-lead electrocardiogram during hospital admission or outpatient evaluation. Electrocardiograms were independently interpreted by blinded cardiologists. Diagnostic accuracy, rate of inconclusive recordings, technical performance, features, and pricing were compared between the two applications. A total of 206 patients (median age 69.5 years, 64.1% male) with 216 electrocardiograms were analysed; atrial fibrillation was present in 43.1%. Successful photoplethysmography recordings were obtained in 97.7% of FibriCheck (mean attempts 1.2 ± 0.7) and 87.5% of Preventicus Heartbeats (1.6 ± 1.3) measurements. Sensitivity and specificity were 89.0% and 100.0% for FibriCheck, and 86.4% and 99.0% for Preventicus Heartbeats. Inconclusive reading rates (where the algorithm indicated a suspicion of mild arrhythmia) were 8.5% and 11.1%, respectively. Conclusion: Both smartphone applications demonstrated high and comparable diagnostic accuracy for atrial fibrillation detection in a real-world population. These tools represent a viable, non-invasive option for early rhythm screening and follow-up, potentially improving patient outcomes, although further refinement is needed to reduce inconclusive recordings.

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.