Investigation of the atrial conduction time measured by tissue Doppler imaging at the left atrial appendage and the actual electrical conduction time: consideration of left atrial remodeling in atrial fibrillation patients

Atrial conduction explains the occurrence of the P-wave dispersion phenomenon, but weakly

BACKGROUND

P-wave dispersion (PWD) is believed to be caused by inhomogeneous atrial conduction. This statement, however, is based on limited little solid evidence. The aim of this study was to determine the relationship between atrial conduction and PWD by means of invasive electrophysiological studies.

METHODS

Cross-sectional study in 153 patients with accessory pathways and atrioventricular node reentry tachycardia (AVNRT) undergoing an electrophysiological study. Different atrial conduction times were measured and correlated with PWD.

RESULTS

Only the interatrial (P-DCS) and left intra-atrial conduction times (ΔDCS-PCS) showed a significant correlation with PWD, but this correlation was weak. Multivariate linear regression analysis determined that both P-DCS (β = 0.242; P = .008) and ΔDCS-PCS (β = 0.295; P < .001) are independent predictors of PWD. Performing the multivariate analysis for arrhythmic substrates, it is observed that only ΔDCS-PCS continued to be an independent predictor of PWD. Analysis of the receiver operating characteristic curves showed that regardless of the types of arrhythmic substrates, PWD discriminates significantly, but moderately, to patients with P-DCS and ΔDCS-PCS ≥75 percentile.

CONCLUSIONS

Interatrial and intraleft atrial conduction times were directly and significantly correlated with PWD, but only weakly, and were independent predictors of PWD. In general, PWD correctly discriminates patients with high values in interatrial and intraleft atrial conduction times, but moderately. This is maintained in cases with accessory pathways; however, in patients with AVNRT it only does so for intraleft atrial conduction times. Interatrial and intraleft atrial conduction times weakly explains PWD.

Atrial reverse remodeling represented by the atrial conduction time in persistent atrial fibrillation patients after catheter ablation: its impact on predicting late atrial fibrillation recurrence

BACKGROUND

The aim of this study was to examine the reduction in the atrial conduction time during the follow-up phase of catheter ablation in persistent atrial fibrillation (PsAF) patients, which would suggest atrial reverse remodeling, and to investigate its impact on predicting AF recurrence.

METHODS

Fifty-seven PsAF patients underwent radiofrequency catheter ablation. The P-wave to left atrial appendage (LAA) conduction time was measured by transthoracic echocardiography using tissue Doppler imaging (P-LAA TDI), within 24 h and 6 months after ablation.

RESULTS

The accuracy of the P-LAA TDI was confirmed by measuring the actual electrophysiological data during the ablation (90 ± 13 ms, r = 0.754, p < 0.001). The P-LAA TDI was significantly reduced (170 ± 18 msec to 159 ± 19 msec, p < 0.001) at the 6-month follow-up. Sixteen patients (28%) had an AF recurrence by 12 months of follow-up. The no-AF recurrence group had a significantly reduced P-LAA TDI 6 months later (165 ± 15 msec to 155 ± 18 msec, p < 0.001), while there was no significance in the AF recurrence group (184 ± 21 msec to 174 ± 16 msec, p = 0.091). The P-LAA TDI was a predictive factor of AF recurrence after ablation with a cut-off value of >175 msec (sensitivity = 0.750, specificity = 0.780) when measured within 24 h after ablation and >166 msec (sensitivity = 0.750, specificity = 0.756) when calculated at 6 months of follow-up.

CONCLUSIONS

In PsAF patients, a significant reduction in the P-LAA TDI was observed at 6 months of follow-up, which may have represented the occurrence of left atrial reverse remodeling. These findings suggested that the P-LAA TDI time in the follow-up was appropriate for predicting late AF recurrences.

Alternans in atria: Mechanisms and clinical relevance

Atrial fibrillation is the most common sustained arrhythmia and its prevalence is rapidly rising with the aging of the population. Cardiac alternans, defined as cyclic beat-to-beat alternations in contraction force, action potential (AP) duration and intracellular Ca²⁺ release at constant stimulation rate, has been associated with the development of ventricular arrhythmias. Recent clinical data also provide strong evidence that alternans plays a central role in arrhythmogenesis in atria. The aim of this article is to review the mechanisms that are responsible for repolarization alternans and contribute to the transition from spatially concordant alternans to the more arrhythmogenic spatially discordant alternans in atria.

Association Between the Left Atrial and Left Atrial Appendages Systole Strain Rate in Patients with Atrial Fibrillation

BACKGROUND The aim of this research was to explore the association between the left atrial (LA) and left atrial appendages (LAA) systole strain rate (SSR) in patients with atrial fibrillation (AF), and to provide evidence to aid in the assessment of disease progression. MATERIAL AND METHODS A total of 180 patients with AF were selected for the study (130 patients with paroxysmal AF (Par AF) and 50 patients with persistence AF (PerAF).In addition, 60 healthy individuals were selected as a control group. The total and side wall SSRs were calculated. RESULTS The total SSR in the control group was higher than in the ParAF and PerAF groups (2.87±0.45 vs. 2.15±0.56 vs. 1.92±0.62 and 6.24±1.61 vs. 4.45±1.42 vs. 3.66±1.55). The total SSR of LAA was correlated with that of LA in the AF patient groups and the control group; the correlation coefficients were 0.720, 0.563, and 0.421. However, the ratio of total SSR of LAA to that of LA was not significant statistically different among the three groups (2.24±0.41 vs. 2.35±0.58 vs. 2.03±0.56). The posterior wall had the lowest SSRs in the control group and ParAF group. CONCLUSIONS The SSRs of AF patients were lower than that of healthy individuals, and the degree was associated with disease progression. The SSR was different in different side walls, and gradually shorten with disease progression.