AV synchronous pacing in patients implanted with leadless pacemakers: a real-world cohort study

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Backgroung Leadless pacemakers (LPM) were developed to overcome complications related to endovenous devices. Devices carrying an accelerometer-based atrial sensing algorithm provided good AV synchrony in a 5-hours study. Methods Prospective study of patients implanted with LPM capable of AV synchronous pacing at our institution. We performed a close follow-up consisting of device check-ups 24 h after the implant and 1-3-6-12 months later. Changes in programming were guided by device counters and rate histograms. Once AV synchrony derived from counters (AM-VP + AM-VS) remained stable for at least two consecutive months, a 24 hours Holter monitoring was performed. ECG recordings were automatically and blindly analyzed with a delineation system based on the wavelet transform developed by Martinez et al.1 Cardiac cycles were defined as synchronous if a ventricular event followed the P-wave by ≤300 ms. AV synchrony was calculated by dividing the number of synchronous cycles by the total number of cardiac cycles. Our aim was to describe AV synchrony in a real-world setting and to determine which echocardiographic and programming parameters were related to optimal AV synchrony (≥85% of total cardiac cycles). Results A total of 18 patients (12 males, mean age 82.6 ±8.1) were included. Indications for pacing were complete AV block (n=10) and second-degree AV block (n=8). Device reprogramming was needed in all patients at follow-up. The 24 h Holter monitoring was performed 118.8±43.8 days after the implant. Implant data and, device settings and programming at Holter date is displayed in Table 1. One patient was excluded from the analysis due to the development of severe sinus node disease. Total ECG recorded time was 386.8 hours and 1,537,995 cardiac cycles were analyzed. Median AV synchrony, after Holter monitoring analysis, was 88.2% (interquartile range 79.9-95,1%) and 12 out of 17 patients showed an AV synchrony ≥85% of cardiac cycles. Optimal AV synchrony was related to smaller right atrium size (13.2±3.4 cm2 vs 15.6±1.2 cm2 for AV synchrony ≥85 and <85%, respectively) but no association appeared between diastolic parameters (E, A, E/A ratio, E´, A´) and AV synchrony. Rate smoothing algorithm was associated with higher rates of optimal AV synchrony (81.8% of patients with algorithm OFF vs 50% of patients activated). Besides, higher A3 threshold (7.1±3.5 m/s2 vs 4.2 ± 1.1 m/s2) and longer A3 window (620.8±25.7 ms vs 600 ms for AV synchrony ≥85% and <85%, respectively) were also linked to optimal AV synchrony. Multivariate analysis did not show any independent predictor of AV synchrony. Conclusions In our cohort of LPM patients we obtained high percentages of AV synchronous pacing in a real-life setting. Device reprogramming was often needed, and larger studies are desirable to confirm our data.