<p>Heart failure is often accompanied by myocardial dysfunction and cardiac structural remodeling. However, the lack of a comprehensive numerical framework that integrates both electrical and mechanical processes limits our understanding of how structural and material changes drive heart failure progression. Therefore, we developed and validated advanced numerical methods capable of accurately simulating the electromechanical behavior of the heart. We explored and discussed several pathophysiological models of heart failure through comprehensive whole-heart numerical simulations. A full four-chamber heart model, incorporating modified equations for electrical signal diffusion and electromechanical coupling, was employed to achieve more complete and reliable calculations of cardiac active contraction. The computational methods utilized in this study are thoroughly discussed and validated against experimental and clinical data to ensure reliability. Subsequently, different left ventricular dilation models with varying degrees of hypertrophy, along with two pathological myocardial remodeling models representing material property alterations, were developed, and their numerical results were compared and analyzed. The findings confirm that left ventricular dilation impairs diastolic function and, at the numerical level, emphasize that myocardial material properties are critical factors influencing the heart’s pumping function. Mechanically, the study elucidates how structural and material changes contribute to heart failure and demonstrates the applicability and value of the proposed models and computational methods in studying structural heart diseases. These findings offer a fresh perspective on the pathological mechanisms of heart failure, shedding light on the complex interplay between structural and material changes within the heart muscle.</p>