Impact of atmospheric pollutant exposure on atrial fibrillation dynamics: Insights from 3D models

Air pollution is responsible for millions of global deaths annually. The most dangerous pollutants for health are particulate matter (PM), nitrogen oxides (NO_x), sulfur dioxide (SO₂), and carbon monoxide (CO). Recent studies have demonstrated an increased probability of cardiac arrhythmias, such as atrial fibrillation (AF). AF is the most common type of sustained cardiac arrhythmia, characterized by a process of atrial remodeling, where fibrosis is a hallmark of arrhythmogenic structural remodeling, which alters tissue composition and function. In addition to AF, both the genesis and aggravation of fibrosis have been reported as an effect of exposure to air pollutants. However, since most studies are epidemiological, the pathophysiological mechanisms by which pollutants aggravate AF in humans remain unclear. In this study, the effects of major atmospheric pollutants on the aggravation of AF were evaluated. Mathematical formulations describing pollutant-induced alterations in ionic currents were incorporated into a Courtemanche human atrial myocyte model previously remodeled for AF, which was then coupled to a three-dimensional atrial model. Structural remodeling was represented using the MacCannell fibroblast model. Electrogram recordings from virtual basket catheters were analyzed, and approximate entropy was computed. Results showed that pollutant exposure produced a marked loss of the action potential plateau and, at high concentrations, reduced action potential duration by approximately 35% in both atria. Likewise, pollutants favor the aggravation of AF, characterized by a greater number of reentries, in a concentration-dependent manner. The left atrial electrograms exhibited significantly increased approximate entropy; the effect was larger as the concentrations of the pollutants increased. These findings provide mechanistic insights into the effect of pollutants on the aggravation of atrial arrhythmias and may support public policies aimed at mitigating air pollution.