The role of advanced echocardiography in predicting atrioventricular synchrony in leadless pacemakers: A3 a still unknown parameter
F Troisi, V P Caccavo, M Dadamo, L Sgarra, P Guida, N Vitulano, G Katsouras, A Di Monaco, D Ciliberti, F Quadrini, V Perniciaro, M M Ciccone, M GrimaldiAbstract
Introduction
Leadless cardiac pacemakers represent an alternative to traditional transvenous pacemakers in providing atrioventricular synchrony (AVS). However, achieving high AVS remains a challenge, especially in patients with a high pacing rate. The accelerometer of the Micra-AV leadless device senses atrial mechanical activity and uses this information to provide AVS ventricular pacing. Specifically, the device senses: 1) A1: onset of ventricular systole, mitral and tricuspid valve closure; 2) A2: end of ventricular systole, aortic and pulmonic valve closure; 3) A3: ventricular diastole, passive ventricular filling corresponding to the E wave on Doppler echo; 4) A4: atrial systole corresponding to the A wave on Doppler echo (picture 1). Much effort has been made to identify predictors of good A4 signal amplitude, which determines the ability of the Micra-AV to pace maintaining AVS. The MARVEL2 study demonstrated that A4 wave amplitude is critical to ensure a high AVS rate. In recent years, in addition to traditional echocardiographic parameters, the left atrium has been studied with a new functional parameter, atrial strain (LAs).
Purpose
Our study evaluates the correlations between echocardiographic parameters with A3-A4 amplitude in patients implanted with Micra-AV pacemaker.
Methods
Eight patients (75±13 years; 5 females), implanted with Micra-AV, underwent complete echocardiography focused on the study of the left atrium. Morphological and functional parameters were evaluated, with 2D and 4D methods, using dedicated advanced echocardiography software. All patients, after implantation, underwent a complete electronic control of the leadless pacemaker to evaluate the amplitude of the A3 and A4 waves in all sensing vectors.
Results
Our study data showed that the A3 parameter may play a role, together with A4, in identifying patients with a good probability of obtaining adequate AVS, when implanted with a Micra-AV. We observed that A3 correlates inversely with the mean E/e’ ratio, with the LA volume indexed in 2D and with the LA volume in 4D (p<0.05). A direct correlation emerged (picture 2) between A3 amplitude and LAs reservoir, both calculated with 2D and 4D software and an inverse correlation between A3 amplitude and LAs contraction (in 2D and 4D). Finally, the inverse correlation between A4 amplitude and LAs contraction was further confirmed.
Conclusions
Patient selection is crucial to achieve good clinical outcomes. In this context, echocardiographic parameters appear promising in identifying subjects with better outcome.