Clinical and echocardiographic predictors of atrioventricular synchrony provided by leadless pacemakers: results from the OptiVALL study
Authors: Briongos Figuero S , Estevez Paniagua A , Sanchez Hernandez A , Gomez Mariscal E , Jimenez Loeches S , Vaqueriza Cubillo D , Munoz-Aguilera R 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.
Background: Several clinical parameters and echocardiographic markers of atrial function were associated with A4 signal amplitude and high atrioventricular synchrony (AVS) in the MARVEL 2 study.

Purpose
To study the correlation between the amplitude of the A4 signal determined by the MICRA AV and, the active filling diastolic waves (A and A´ waves velocity) obtained by a transthoracic echocardiogram (TTE). We also aimed to assess echocardiographic and clinical predictors for optimal AVS.

Methods
The OptiVALL study is a single-centre and prospective study of consecutive patients implanted with MICRA AV. Baseline and procedure characteristics were obtained at implant and a TTE was performed within 48 h after the implant. Follow-up was routinely performed at 24 hours and at 1, 3, 6 and 12 months. Reprogramming of the atrial sensing parameters was guided by device counters, rate histograms and manual atrial mechanical tests. The pacing mode was programmed to VDD in all patients and AV conduction mode switch (VVI +) was deactivated. AVS was studied by an ambulatory 24-h Holter monitoring placed at 3-months follow-up. ECG recorded tracings were automatically and blindly analyzed with an ECG delineation system. 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.
Optimal AVS was defined as AVS≥ 85% of total cardiac cycles during the 24-h Holter-ECG monitor.

Results
Twenty-six patients who remained in VDD mode at all follow-up visits were included for analysis. Baseline, echocardiographic and procedure-related data is displayed in table 1. Total ECG recorded time was 550.8 hours and 2,291,953 cardiac cycles were analyzed. Average ambulatory AVS during the 24 h Holter monitoring was 87.3±6.3% and 20 out of 26 patients exhibited optimal AVS (≥85% of cardiac cycles).
There was no correlation between the active filling diastolic waves and the A4 signal amplitude (r Pearson=-0.251, p=0.237 for A4 signal Vs A´wave and r Pearson=0.018, p=0.932 for A4 signal vs A wave).
We did not find any relationship between several diastolic filling parameters (E, A, E/A ratio, E´, A´) and optimal AVS (table 2). There was also a trend towards better optimal AVS with higher E´/A´ ratios.
Optimal AVS was related to patients with smaller right atrium size and with lower body mass index. A trend towards optimal AVS was also found in devices deployed in mid interventricular septum locations. On the other hand, patients with diabetes showed lower rates of optimal AVS.

Conclusions
The correlation between the echocardiographic diastolic filling parameters and diastolic signals detected by the accelerometer of the MICRA AV is poor, so it seems to be as poor guidance to select proper candidates for MICRA AV.