Prospectively quantifying the propensity for atrial fibrillation: a mechanistic formulation

Area of Science:

• Computational biology
• Cardiac electrophysiology
• Medical physics

Background:

• Atrial fibrillation (AF) is a complex arrhythmia.
• Understanding the electrophysiologic basis of AF is crucial for developing effective treatments.
• Current therapeutic strategies for AF often lack precision.

Purpose of the Study:

• To establish quantitative relationships between key electrophysiologic parameters and the likelihood of cardiac tissue developing atrial fibrillation.
• To characterize the dynamics of electrical wave propagation during simulated AF episodes.
• To develop a predictive index for AF duration and type.

Main Methods:

• Utilized a computational model to simulate atrial fibrillation episodes.
• Employed Monte Carlo sampling to analyze episode durations and wave population dynamics.
• Investigated the influence of tissue area to boundary length ratio (A/BL), action potential duration (APD), resistance (R), and capacitance (C) on fibrillation.
• Determined the relationship between electrophysiologic parameters and the type of fibrillatory activity (multi-wavelet reentry vs. rotors).

Main Results:

• Simulated AF episode durations followed an exponential decay distribution.
• Wave population sizes during fibrillation followed a normal distribution.
• Fibrillation episode half-lives increased with A/BL and decreased with APD, R, or C.
• Multi-wavelet reentry (MWR) was reliably predicted by a specific ratio of R and C to APD (<0.18).
• A derived "fibrillogenicity index" (Fb = A/(BL*APD*R*C)) accurately predicted MWR episode duration (r² = 0.93).

Conclusions:

• Electrophysiologic parameters, including tissue geometry and cellular properties, quantitatively influence AF propensity and duration.
• The fibrillogenicity index provides a robust predictor of AF episode duration.
• These findings offer a theoretical foundation for developing personalized, titrated therapies for atrial fibrillation, potentially through pharmacologic or interventional approaches.