Key result
Spontaneous PACs linked to ~13% greater conduction velocity heterogeneity vs sinus rhythm at Bachmann's bundle.
Why the study?
Loss of cell-to-cell communication causes local conduction disorders and directional heterogeneity in conduction velocity vectors, which may be unmasked by PACs.
Do premature atrial contractions increase local directional heterogeneities in conduction velocity vectors compared to sinus rhythm?
Observational (n=228)
Do premature atrial contractions increase local directional heterogeneities in conduction velocity vectors compared to sinus rhythm?
Premature atrial contractions increase local directional heterogeneity in conduction velocity, particularly at Bachmann's bundle and the pulmonary vein area, which is more pronounced in patients with atrial fibrillation.
Premature atrial contractions may promote atrial fibrillation substrate; hypothesis-generating and requires prospective validation before clinical implications.
AIMS: Loss of cell-to-cell communication results in local conduction disorders and directional heterogeneity (LDH) in conduction velocity (CV) vectors, which may be unmasked by premature atrial contractions (PACs). We quantified LDH and examined differences between sinus rhythm (SR) and spontaneous PACs in patients with and without atrial fibrillation (AF). METHODS AND RESULTS: Intra-operative epicardial mapping of the right and left atrium (RA, LA), Bachmann's bundle (BB) and pulmonary vein area (PVA) was performed in 228 patients (54 with AF). Conduction velocity vectors were computed at each electrode using discrete velocity vectors. Directions and magnitudes of individual vectors were compared with surrounding vectors to identify LDH. Five hundred and three PACs [2 (1-3) per patient; prematurity index of 45 ± 12%] were included. During SR, most LDH were found at BB and LA [11.9 (8.3-14.9) % and 11.3 (8.0-15.2) %] and CV was lowest at BB [83.5 (72.4-94.3) cm/s, all P < 0.05]. Compared with SR, the largest increase in LDH during PAC was found at BB and PVA [+13.0 (7.7, 18.3) % and +12.5 (10.8, 14.2) %, P < 0.001]; CV decreased particularly at BB, PVA and LA [-10.0 (-13.2, -6.9) cm/s, -9.3 (-12.5, -6.2) cm/s and -9.1 (-11.7, -6.6) cm/s, P < 0.001]. Comparing patients with and without AF, more LDH were found during SR in AF patients at PVA and BB, although the increase in LDH during PACs was similar for all sites. CONCLUSION: Local directional heterogeneity is a novel methodology to quantify local heterogeneity in CV as a possible indicator of electropathology. Intra-operative high-resolution mapping indeed revealed that LDH increased during PACs particularly at BB and PVA. Also, patients with AF already have more LDH during SR, which becomes more pronounced during PACs.
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Schie et al. (2023) conducted an observational in Atrial fibrillation (n=228). Premature atrial contractions (PACs) vs. Sinus rhythm (SR) was evaluated on Local directional heterogeneity (LDH) in conduction velocity vectors (p=<0.001). Spontaneous premature atrial contractions increased local directional heterogeneity in conduction velocity compared to sinus rhythm, particularly at Bachmann's bundle (+13.0%; P<0.001).
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