Electrogram morphology recurrence patterns during atrial fibrillation

Abstract

Background: Traditional mapping of atrial fibrillation (AF) is limited by changing electrogram morphologies and variable cycle lengths.

Objective: We tested the hypothesis that morphology recurrence plot analysis would identify sites of stable and repeatable electrogram morphology patterns.

Methods: AF electrograms recorded from left atrial (LA) and right atrial (RA) sites in 19 patients (10 men; mean age 59 ± 10 years) before AF ablation were analyzed. Morphology recurrence plots for each electrogram recording were created by cross-correlation of each automatically detected activation with every other activation in the recording. A recurrence percentage, the percentage of the most common morphology, and the mean cycle length of activations with the most recurrent morphology were computed.

Results: The morphology recurrence plots commonly showed checkerboard patterns of alternating high and low cross-correlation values, indicating periodic recurrences in morphologies. The mean recurrence percentage for all sites and all patients was 38 ± 25%. The highest recurrence percentage per patient averaged 83 ± 17%. The highest recurrence percentage was located in the RA in 5 patients and in the LA in 14 patients. Patients with sites of shortest mean cycle length of activations with the most recurrent morphology in the LA and RA had ablation failure rates of 25% and 100%, respectively (hazard ratio 4.95; P = .05).

Conclusion: A new technique to characterize electrogram morphology recurrence demonstrated that there is a distribution of sites with high and low repeatability of electrogram morphologies. Sites with rapid activation of highly repetitive morphology patterns may be critical to sustaining AF. Further testing of this approach to map and ablate AF sources is warranted.

Keywords: Atrial fibrillation; Electrograms; Mapping; Signal processing.

Figure 1

A) Illustration of a cross-correlation matrix for the first six activations of an AF electrogram. B) Illustration of a color coded cross-correlation matrix of all activations. Areas of red indicate high cross-correlation values thus morphology recurrence. Non-red areas indicate pairs of activations with less similar morphologies.

Figure 2

Examples of morphology recurrence plots from electrograms collected from two patients from different areas of the right and left atria. For Patient A, the SVC and the LIPV had the highest recurrence percentage values (Rec%) at 79%. The RSPV also had a high Rec% value at 77%. The shortest recurrence cycle length (CL_R) was found in the LIPV (201 ms). For Patient B, the right atrial septum had both the highest Rec% (71%) and the shortest CL_R (231 ms).

Figure 3

Examples of morphology recurrence plots the corresponding electrograms used to create the plot. A and B show plots of electrograms with similar cycle lengths (CLs), but different recurrence percentages (Rec%) and as a result different recurrence cycle lengths (CL_R). C shows electrograms with similar Rec% to those in example B but with much longer CL and CL_R.

Figure 4

Impulse diagrams showing the timings of detected activations from different sites in the right and left atria in one patient. The impulse diagrams on the left column depict the timings of all detected activations from each site and their corresponding cycle length (CL). The impulse diagrams on the right depict only the timings of activations with the most common morphology for each recording. The recurrence percentage (Rec%) and recurrence cycle length (CL_R) for each site are also shown on the right. The LIPV in this patient can be seen to clearly have the highest Rec% and the shortest CL_R.