Linking atrial electromechanical remodeling to global cardiac performance in atrial fibrillation through a cardiac digital twin

Abstract

Atrial fibrillation (AF) and heart failure (HF) frequently coexist and are associated with adverse clinical outcomes. Beyond shared risk factors, increasing evidence suggests that AF can contribute to HF pathophysiology by disrupting atrial electromechanical function and atrioventricular coupling, thereby impairing ventricular filling even in the presence of preserved ventricular contractility. These observations motivate a deeper mechanistic understanding of AF itself, particularly at the atrial electromechanical level, where electrical remodeling leads to loss of coordinated atrial contraction and altered ventricular filling dynamics. In this context, computational modeling and cardiac digital twin approaches provide a powerful framework to isolate atrial driven mechanisms and to quantitatively assess how AF related electromechanical dysfunction impacts global cardiac performance. Despite extensive computational work focused on AF electrophysiology, multiscale and multiphysics models integrating detailed atrial electromechanics with closed-loop hemodynamics remain limited, restricting direct investigation of atrial dysfunction and its hemodynamic consequences.

The purpose of this study was to quantify how AF induced atrial electromechanical dysfunction affects ventricular filling and global cardiac performance using a multiphysics and multiscale cardiac digital twin. By comparing physiological and AF conditions with identical ventricular properties, we isolated atrial driven alterations in preload, stroke volume, and cardiac output.

We developed a multiphysics, multiscale biatrial electromechanical model coupled to a closed loop representation of the circulation. The framework integrates atrial electrophysiology, calcium driven contraction, orthotropic myocardial mechanics, and physiologically consistent hemodynamic loading. Sinus rhythm and persistent AF were simulated, and model parameters were calibrated to reproduce physiological atrial pressure volume behavior and ejection fractions.

During atrial fibrillation, loss of coordinated atrial contraction resulted in an approximately 20% reduction in cardiac output compared with physiological conditions, consistent with reductions reported in the literature for AF. This decrease was driven by impaired ventricular filling and reduced stroke volume, while ventricular ejection fraction remained preserved, with values close to 70% and no relevant differences between conditions. AF-related electromechanical remodeling included a reduction in active atrial tension of up to 45%.

This digital twin study demonstrates that atrial electromechanical dysfunction in AF can substantially impair global cardiac performance through atrial driven hemodynamic inefficiency. Disruption of atrial contraction and atrioventricular coupling was sufficient to reduce cardiac output, highlighting the central role of atrial mechanics in maintaining effective ventricular filling.Atrial electrical spread: Healthy vs AFFor image description, please refer to the figure legend and surrounding text.Cardiac PV loops: Healthy vs AFFor image description, please refer to the figure legend and surrounding text.