Electrophysiological Properties of the Left Atrium Evaluated by Coronary Sinus Pacing in Patients with Atrial Fibrillation

Abstract

Repetitive atrial firing (RAF), marked fragmentation of atrial activity (FAA), and interatrial conduction delay (CD) have been shown to be electrophysiological features of the atrium in patients with atrial fibrillation (AF). Moreover, it has been observed that atrial extrastimuli are more likely to induce AF when delivered from the right atrial appendage (RAA) than from the distal coronary sinus (CSd). We examined the electrophysiological properties of the atrial muscle by CS and RAA stimulation in patients with paroxysmal AF. Patients were divided into two groups: group I, consisting of 18 patients with clinical paroxysmal AF; and group II, consisting of 22 patients with various cardiac arrhythmias in which the substrate does not exist in the atrium. In group I, the following values of electrophysiological parameters of the atrium indicated that AF was more likely to be induced during RAA pacing than CSd pacing: atrial effective refractory period (RAA vs CSd: 201 +/- 28 ms vs 240 +/- 35 ms, P < 0.001), RAF zone (16 +/- 25 ms vs 0 +/- 0 ms, P < 0.03), FAA zone (38 +/- 37 ms vs 5 +/- 19 ms, P < 0.01), maximum interatrial conduction time (144 +/- 19 ms vs 93 +/- 19 ms, P < 0.0001) and CD zone (53 +/- 21 ms vs 9 +/- 18 ms, P < 0.0001). The values of the electrophysiological parameters of the atrium evaluated by CSd pacing in group I patients were not significantly different from those in group II patients. In conclusion, when coronary sinus stimulation is performed, electrophysiological properties of the atrium in patients with AF show a significant decrease in atrial vulnerability compared to stimulation from RAA and also show similar values to those in patients without AF. It might be suggested that the left posterior or posterolateral atrium is electrophysiologically stable even in patients with paroxysmal AF.

Inducibility of atrial fibrillation during electrophysiologic evaluation is associated with increased dispersion of atrial refractoriness

“…Those patients with induction of AF showed a larger dispersion of refractoriness due to a marked difference between ERP at the right atrium and those obtained along the CS. These findings are in accordance with other authors, who reported shorter ERP in the high right atrium when compared with distal CS in patients with AF [7,21]. This may be explained by a non-uniform distribution of vagal nerve endings, which seems to cause greater changes in refractory period in the RAA than in left atrium [22].…”

“…Therefore, it is not possible to compare ERP to the right atrium and pulmonary veins in this population. Nevertheless, in previous studies, the distal CS ERP was accepted as reflecting the ERP of the local left atrial tissue [21,33]. Finally, although the number of subjects included in the study allowed for the identification of significant differences in the dispersion of atrial refractoriness, the resulting sample was relatively small, representing only a subpopulation of patients with PAF and absent or minimal structural heart disease.…”

Atrial Electrophysiological Properties Evaluated by Right and Left Atrial Pacing in Patients with or without Atrial Fibrillation.

“…Our results differed from those of Ishimatsu, et al 3) who showed that the MCT from the HRA to the DCS during HRA pacing was significantly longer than that from the DCS to the HRA during DCS pacing in patients with or without paroxysmal AF. This discrepancy is not apparent but could be due to a different patient population.…”

“…2,3) The incremental conduction delay at different atrial regions during HRA pacing has been shown to be significantly attenuated by "biatrial pacing" defined as pacing simultaneously from the HRA and the DCS. 2,4) The wavelength for circus movement in the heart has been defined as the distance traveled by the depolarization wave during the duration of the refractory period (wavelength=conduc-tion velocity X refractory period).…”

Single-Site Bachmann's Bundle Pacing Is Beneficial While Coronary Sinus Pacing Results in Echocardiographic Right Heart Pacemaker Syndrome in Brady-Tachycardia Patients

“…Data on the harmful effect of CSp on RA function are rare, as most studies have focused on LA function and its beneficial electrical properties. 28 Only a few studies have assessed the RA function during CSp. Kutarski et al investigated the influence of CSp on signal-avaraged P-wave time domain parameters and demonstrated that in patients with interatrial conduction disturbances, CSp reduced LA late potentials, but at the same time failed to restore homogeneity of activation within the RA.…”