Quantifying fractionation and rate in human atrial fibrillation using monophasic action potentials: implications for...

Area of Science:

• Electrophysiology
• Cardiac Arrhythmia Research
• Signal Processing in Cardiology

Background:

• Substrate mapping is crucial for atrial fibrillation (AF) ablation.
• Traditional bipolar electrograms have limitations in accurately representing waveform shape, leading to ambiguity in identifying true electrogram fragmentation versus noise.
• The accuracy of dominant frequencies (DFs) from bipolar signals in estimating AF rate is questionable.

Purpose of the Study:

• To evaluate the utility of monophasic action potentials (MAPs) for improved assessment of AF rate and fractionated electrograms during mapping.
• To compare the accuracy of MAPs versus bipolar electrograms in characterizing AF substrate and determining AF rate.

Main Methods:

• Comparison of fractionation and AF rate estimates using MAPs and bipolar electrograms in 28 patients with AF.
• Analysis of spectral and time-domain measures, including dominant frequencies (DFs) and autocorrelation, for cycle length (CL) estimation.
• Filtering of MAPs to derive bipolar electrograms for direct comparison.

Main Results:

• Fractionation was significantly overestimated in bipolar electrograms compared to MAPs (P = 0.005).
• MAPs accurately represented AF cycle length (CL) via DF (r = 0.73, P < 0.001), while bipolar signals showed poor correlation (r = 0.29, P = 0.07) due to double counting.
• A novel autocorrelation method demonstrated high accuracy for CL estimation in both MAPs (89% accuracy) and bipoles (77% accuracy).

Conclusions:

• MAPs offer a superior representation of atrial fibrillation organization and rate by accurately portraying fibrillatory waveform shape.
• MAPs provide a more reliable method for assessing electrogram variability, fragmentation, and rate in AF substrate mapping.
• This technique may lead to more precise AF ablation strategies.