Identification of local atrial conduction heterogeneities using high-density conduction velocity estimation

Abstract

Aims Accurate determination of intra-atrial conduction velocity (CV) is essential to identify arrhythmogenic areas. The most optimal, commonly used, estimation methodology to measure conduction heterogeneity, including finite differences (FiD), polynomial surface fitting (PSF), and a novel technique using discrete velocity vectors (DVV), has not been determined. We aim (i) to identify the most suitable methodology to unravel local areas of conduction heterogeneities using high-density CV estimation techniques, (ii) to quantify intra-atrial differences in CV, and (iii) to localize areas of CV slowing associated with paroxysmal atrial fibrillation (PAF). Methods and results Intra-operative epicardial mapping (>5000 sites, interelectrode distances 2 mm) of the right and left atrium and Bachmann’s bundle (BB) was performed during sinus rhythm (SR) in 412 patients with or without PAF. The median atrial CV estimated using the DVV, PSF, and FiD techniques was 90.0 (62.4–116.8), 92.0 (70.6–123.2), and 89.4 (62.5–126.5) cm/s, respectively. The largest difference in CV estimates was found between PSF and DVV which was caused by smaller CV magnitudes detected only by the DVV technique. Using DVV, a lower CV at BB was found in PAF patients compared with those without atrial fibrillation (AF) [79.1 (72.2–91.2) vs. 88.3 (79.3–97.2) cm/s; P < 0.001]. Conclusions Areas of local conduction heterogeneities were most accurately identified using the DVV technique, whereas PSF and FiD techniques smoothen wavefront propagation thereby masking local areas of conduction slowing. Comparing patients with and without AF, slower wavefront propagation during SR was found at BB in PAF patients, indicating structural remodelling.

Reduction of Conduction Velocity in Patients with Atrial Fibrillation

“…In our AF group, CV was reduced and TAT was prolonged only at BB compared to patients without AF. Previously, we determined the most accurate methodology to measure local conduction heterogeneity and, as a sub-analysis, we determined the median CV at all locations in patients with paroxysmal AF and no AF [14]. Subsequently, we also found a reduced CV at BB in patients without AF [14].…”

“…Local CV was computed as an average of velocity estimations between neighbouring electrodes (longitudinal, transversal and diagonal) using discrete velocity vectors as previously described by van Schie et al [14]. Relative frequency distribution histograms of CVs were constructed to calculate median CV and variance of CV (∆ P 5 -P 95 ).…”

“…Previously, we determined the most accurate methodology to measure local conduction heterogeneity and, as a sub-analysis, we determined the median CV at all locations in patients with paroxysmal AF and no AF [14]. Subsequently, we also found a reduced CV at BB in patients without AF [14]. However, in that study we did not include patients with persistent or longstanding persistent AF who have varying degrees of atrial remodeling.…”

“…In addition, confounders of intra-atrial conduction, such as age, body mass index and left atrial enlargement, were not considered [7][8][9]. Patients were significantly older in the paroxysmal AF group (71 ± 9 years vs. 66 ± 10 years, p < 0.001) and more patients had left atrial enlargement (41% vs. 19%, <0.001) [14]. Another study, performed by Zheng et al, compared the average CV at the RA and LA between patients with paroxysmal AF and control patients with respectively atrioventricular nodal re-entry tachycardia and Wolff-Parkinson White syndrome using three-dimensional endocardial mapping [6].…”

“…Remarkably, CV was much lower than our findings in the AF group (LA: 50 cm/s vs. 94 cm/s; RA: 60 cm/s vs. 92 cm/s). To estimate CV, they only compared a triplet of sites, when we computed, for each atrial potential, an average of velocity estimations between all eight adjacent electrodes [6,14]. Furthermore, those triplet numbers of locations were not measured simultaneously during the same beat, as we did in our study with the 128-or 192 electrode array [6].…”