Simultaneous Endo‐Epicardial Mapping of the Human Right Atrium: Unraveling Atrial Excitation

Abstract

Background The significance of endo‐epicardial asynchrony (EEA) and atrial conduction block (CB), which play an important role in the pathophysiology of atrial fibrillation (AF) during sinus rhythm is poorly understood. The aim of our study was therefore to examine 3‐dimensional activation of the human right atrium (RA). Methods and Results Eighty patients (79% men, 39% history of AF) underwent simultaneous endo‐epicardial sinus rhythm mapping of the inferior, middle and superior RA. Areas of CB were defined as conduction delays of ≥12 ms, EEA as activation time differences of opposite electrodes of ≥15 ms and transmural CB as CB at similar endo‐epicardial sites. CB was more pronounced at the endocardium (all locations P <0.025). Amount, extensiveness and severity of CB was higher at the superior RA. Transmural CB at the inferior RA was associated with a higher incidence of post‐operative AF ( P =0.03). EEA occurred up to 84 ms and was more pronounced at the superior RA (superior: 27 ms [interquartile range, 18.3–39.3], versus mid‐RA: 20.3 ms [interquartile range, 0–29.9], and inferior RA: 0 ms [interquartile range, 0–21], P <0.001). Hypertension ( P =0.009), diabetes mellitus ( P =0.018), and hypercholesterolemia ( P =0.015) were associated with a higher degree of EEA. CB ( P =0.007) and EEA ( P =0.037) were more pronounced in patients with a history of persistent AF compared with patients without AF history. Conclusions This study provides important insights into complex atrial endo‐epicardial excitation. Significant differences in conduction disorders between the endo‐ and epicardium and a significant degree of EEA are already present during sinus rhythm and are more pronounced in patients with cardiovascular risk factors or a history of persistent AF.

Signal Fingerprinting as a Novel Diagnostic Tool to Identify Conduction Inhomogeneity

“…This explains recordings of LDP and FP during SR in all patients. In a series of prior mapping studies of the atria during SR, it was demonstrated that lines of CB most frequently occur at the superior part of the RA (sino-atrial node area) and BB, which is consistent with the high proportion of LDP and FP observed in the present study ( Teuwen et al, 2016 ; Kharbanda et al, 2020 ).…”

“…Simultaneous endo-epicardial high-resolution mapping studies demonstrated that fractionation of unipolar EGMs during SR is not only the result of slowing of conduction or pivoting of the wavefront around a line of CB, but that it can also be attributed to asynchronous activation of the endo- and epicardial wall. Even during SR, asynchronous activation up to 84 ms has been described ( Kharbanda et al, 2020 ).…”

Novel insights in pathophysiology of postoperative atrial fibrillation

“…Consistent with previous studies, EEA was defined as transmural difference in electrical activation of !15 milliseconds between every endo-epicardial electrode pair. 10,11 Classification of Programmed AES Prematurity index of programmed AES was expressed as the ratio between the coupling interval of the programmed AES and the preceding SR cycle length. In general, we aimed to achieve a mean prematurity index of approximately 50%.…”

Splitting the P-Wave: Improved Evaluation of Left Atrial Substrate Modification after Pulmonary Vein Isolation of Paroxysmal Atrial Fibrillation

“…Nevertheless, persistent AF patients, showing longer AF episodes that may significantly affect the atrial structure and function, may not respond positively to the PVI procedure in the long term, requiring repeated PVI sessions in some cases [ 1 , 4 , 5 ]. Apart from PVs, various right (RA) and left atrial (LA) sites additionally contribute to the AF perpetuation due to fibrosis, forming the so-called atrial substrate [ 6 , 7 , 8 , 9 , 10 , 11 ]. Frequent non-PV triggers are crista terminalis, interatrial septum, LA posterior wall, LA appendage, coronary sinus and ligament of Marshall.…”

“…Although remodeling can be present in both atria [ 10 ], it is LA which is principally affected from substrate modification after PVI. Notwithstanding, studies so far analyze the P-wave duration from the onset to the offset of the P-waves, thus including both atria indivisibly.…”