Complex fractionated atrial electrograms, high dominant frequency regions, and left atrial voltages during sinus rhythm and atrial fibrillation

Abstract

Background: Ablation targeting complex fractionated atrial electrograms (CFAEs) or high dominant frequency (DF) sites is generally effective for persistent atrial fibrillation (AF). CFAEs and/or high DF sites may exist in low-voltage regions, which theoretically represent abnormal substrates. However, whether CFAEs or high DF sites reflect low voltage substrates during sinus rhythm (SR) is unknown.

Methods: Sixteen patients with AF (8 with paroxysmal AF; 8, persistent AF) underwent high-density mapping of the left atrium (LA) with a 3-dimensional electroanatomic mapping system before ablation. The LA was divided into 7 segments and the mean bipolar voltage recorded during AF and SR, CFAEs (cycle lengths of 50-120 ms), and DF sites were assessed in each segment with either a duo-decapolar ring catheter (n=10) or a 64-pole basket catheter (n=6). Low-voltage areas were defined as those of <0.5 mV during AF and <1.0 mV during SR.

Results: Regional mean voltage recorded from the basket catheter showed good correlation between AF and SR (r=0.60, p<0.01); however, the % low-voltage area in the LA recorded from the ring catheter showed weak correlation (r=0.34, p=0.05). Mean voltage was lower during AF than during SR (1.0 mV [IQR, 0.5-1.4] vs. 2.6 mV [IQR, 1.8-3.6], p<0.01). The regional and overall % low-voltage area of the LA was greater during AF than during SR (20% vs. 11%, p=0.05). CFAEs and high DF sites (>8 Hz) did not correlate with % low-voltage sites during SR; however, CFAEs sites were located in high-voltage regions during AF and high DF sites were located in low voltage regions during AF.

Conclusions: CFAEs and high DF areas during AF do not reflect damaged atrial myocardium as shown by the SR voltage. However, CFAEs and high DF sites may demonstrate different electrophysiologic properties because of different voltage amplitude during AF.

Keywords: Atrial fibrillation; Complex fractionated atrial electrogram; Dominant frequency; Sinus rhythm.

Fig. 1

A. X-ray position of the basket catheter in the left atrium. A-P=antero-posterior. B. Basket catheter position shown on the NavX system. C. Left atrial segmentation. The left atrium was divided into 7 segments and analyzed.

Fig. 2

Mapping images of areas of left atrial bipolar voltage during atrial fibrillation (AF, upper panel) and sinus rhythm (SR, lower panel). Low-voltage areas during AF were defined as those <0.5 mV and are shown in grey color. Low-voltage areas during SR were defined as those <1.0 mV and are shown in non-purple colors.

Fig. 3

Graphs of low-voltage points in each left atrial segment. Low-voltage points from 5 similar positions in each segment were higher during atrial fibrillation (AF) than during sinus rhythm (SR); however, low-voltage points during SR and AF were significantly correlated. The left panel shows all low voltage points, whereas the two right panels show points for paroxysmal AF (upper panel) and persistent AF (lower panel).

Fig. 4

Scatter plots of low-voltage points recorded at the same position. Low-voltage points recorded from the basket catheter were higher during atrial fibrillation (AF) than during sinus rhythm (SR); however, low-voltage points during SR and AF were significantly correlated. Upper panel shows all low-voltage points, whereas the two lower panels show points for paroxysmal AF (left panel) and persistent AF (right panel).

Fig. 5

A. Representative maps of complex fractionated atrial electrogram (CFAE) locations (upper panel) and left atrial voltage during sinus rhythm (SR, lower panel). The CFAE areas are shown in non-purple colors. Low-voltage areas during SR were defined as those <1.0 mV and are shown in non-purple colors. Note that there was no overlap between the CFAE areas and the low-voltage areas during SR. B. Representative maps comparing the high dominant frequency (DF) locations (upper panel) and left atrial voltage recorded during sinus rhythm (SR, lower panel). The high DF areas are shown in purple color. The low-voltage areas during SR were defined as those <1.0 mV and are shown in non-purple colors. Note that there was no overlap between the high DF areas and low voltage areas during SR.

Fig. 6

Graphs comparing left atrial bipolar voltage recorded during atrial fibrillation (AF, left panel) and during sinus rhythm (SR, right panel) at the complex fractionated atrial electrogram (CFAE-positive and CFAE-negative) sites. Note that the CFAE-positive sites showed higher voltage during AF than the CFAE-negative sites; however, there was no difference in the SR voltage between the high DF and non-high DF sites.

Fig. 7

Graphs of left atrial bipolar voltage recorded during atrial fibrillation (AF, left panel) and during sinus rhythm (SR, right panel) at the high dominant frequency (DF) and non-high DF sites. Note that the high DF sites showed lower voltage during AF than the complex fractionated atrial electrogram (–) sites; however, there was no difference in the SR voltage between the high DF and non-high DF sites.