Impact of Ischemic and Valvular Heart Disease on Atrial Excitation:A High-Resolution Epicardial Mapping Study

Abstract

Background: The influence of underlying heart disease or presence of atrial fibrillation (AF) on atrial excitation during sinus rhythm (SR) is unknown. We investigated atrial activation patterns and total activation times of the entire atrial epicardial surface during SR in patients with ischemic and/or valvular heart disease with or without AF.

Methods and results: Intraoperative epicardial mapping (N=128/192 electrodes, interelectrode distances: 2 mm) of the right atrium, Bachmann's bundle (BB), left atrioventricular groove, and pulmonary vein area was performed during SR in 253 patients (186 male [74%], age 66±11 years) with ischemic heart disease (N=132, 52%) or ischemic valvular heart disease (N=121, 48%). As expected, SR origin was located at the superior intercaval region of the right atrium in 232 patients (92%). BB activation occurred via 1 wavefront from right-to-left (N=163, 64%), from the central part (N=18, 7%), or via multiple wavefronts (N=72, 28%). Left atrioventricular groove activation occurred via (1) BB: N=108, 43%; (2) pulmonary vein area: N=9, 3%; or (3) BB and pulmonary vein area: N=136, 54%; depending on which route had the shortest interatrial conduction time (P<0.001). Ischemic valvular heart disease patients more often had central BB activation and left atrioventricular groove activation via pulmonary vein area compared with ischemic heart disease patients (N=16 [13%] versus N=2 [2%]; P=0.009 and N=86 [71%] versus N=59 [45%]; P<0.001, respectively). Total activation times were longer in patients with AF (AF: 136±20 [92-186] ms; no AF: 114±17 [74-156] ms; P<0.001), because of prolongation of right atrium (P=0.018) and BB conduction times (P<0.001).

Conclusions: Atrial excitation during SR is affected by underlying heart disease and AF, resulting in alternative routes for BB and left atrioventricular groove activation and prolongation of total activation times. Knowledge of atrial excitation patterns during SR and its electropathological variations, as demonstrated in this study, is essential to further unravel the pathogenesis of AF.

Keywords: atrial fibrillation; coronary artery disease; sinus rhythm; valvular regurgitation.

Figure 1

Activation mapping of the right and left atrium. Left panel: Posterior view of the atria with epicardial mapping scheme (192 electrodes) (upper), classification of the anatomical regions (middle), and landmarks for calculation of duration of wavefront propagation from the origin of sinus rhythm (A) to the LAVG via BB (B) and via PVA (C). Upper right panel: Color‐coded activation maps per mapping site; electrodes activated within the first 5 ms are colored red. Lower right panel: Total activation map constructed relative to local activation times of the reference electrode, which was defined as 0 ms. Arrows indicate main trajectories of SR waves at the different atrial regions. BB indicates Bachmann's bundle; IIC, inferior intercaval; IL, inferolateral; IVC, inferior vena cava; LA, left atrium; LAVG, left atrioventricular groove; PVA, pulmonary vein area; PVL, pulmonary veins left; PVR, pulmonary veins right; RA, right atrium; SIC, superior intercaval; SL, superolateral; SR, sinus rhythm; SVC, superior vena cava.

Figure 2

Atrial patterns of activation. Left panel: Examples of excitation of the atrial epicardial surface during SR. Arrows indicate main trajectories of SR waves at the different atrial regions; see text for detailed explanation. Right panel: Relative incidences of different locations of the origin of activation, entry sites at BB and the LAVG. BB indicates Bachmann's bundle; C, central; IIC, inferior intercaval; L, left; LAVG, left atrioventricular groove; PVA, pulmonary vein area; R, right; SIC, superior intercaval; SL, superolateral; SR, sinus rhythm.

Figure 3

Activation of Bachmann's bundle and the left atrioventricular groove. Differences in incidences of entry sites of wavefronts at BB and LAVG between patients with IHD and (i)VHD. (i)VHD indicates (ischemic and) valvular heart disease; BB, Bachmann's bundle; C, central; IHD, ischemic heart disease; L, left; LAVG, left atrioventricular groove; PVA, pulmonary vein area; R, right.

Figure 4

Conduction times towards the left atrioventricular groove. Time differences (left panel) and total conduction times (right panel) between BB and PVA conduction routes towards LAVG in patients with LAVG activation via BB only, PVA only, or BB and PVA. BB indicates Bachmann's bundle; LAVG, left atrioventricular groove; PVA, pulmonary vein area.

Figure 5

Differences in total activation times. Upper panel: Differences in total activation time of the entire atrial surface between patients without and with AF, various underlying heart diseases and without or with LA dilation. Lower panel: Differences in total activation time of RA, BB and LA separately between patients without and with AF. (i)VHD indicates (ischemic and) valvular heart disease; AF, atrial fibrillation; BB, Bachmann's bundle; IHD, ischemic heart disease; LA, left atrium; MVD, mitral valve disease; RA, right atrium.