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Cardiac electrophysiology and mechanics are intrinsically linked via excitation–contraction coupling (ECC) on the one hand and mechano-electric coupling (MEC) on the other (Quinn & Kohl, 2021). Yet, despite numerous studies, there remain many open fundamental questions, especially at the whole organ level, regarding the role of electro-mechanical cross-talk in cardiac autoregulation, in arrhythmogenesis and in therapeutic interventions. These questions have remained unanswered partly as a result of a lack of appropriate techniques to simultaneously monitor cardiac electrics and mechanics with high enough resolution in three spatial dimensions and time (4D). Studies typically measure electrophysiology and mechanics at different spatial and temporal scales in whole heart, making it hard to directly relate the two. This is particularly true for the assessment of ECC and MEC in vivo, which offers the most physiologically realistic conditions, but typically yields data with relatively low resolution. Electrophysiological measurements from closed-chested models rely on catheter-based electroanatomical mapping (from the endocardial surface) or electrocardiographic imaging (ECGI, where electrodes on the torso are used in combination with structural imaging and computational approaches to predict the electrical activity on the epi- and endocardial surfaces of the heart). However, direct comparisons from electroanatomical mapping with ECGI can show poor agreement, and both modalities are limited to 2D plus time information. Electrode socks or flexible membranes that can be wrapped around the heart in open-chested models provide higher spatial resolution, but this is still limited to near-surface activity and to the recording of extracellular potential dynamics. Measurements of mechanical activity in 4D are plausible through non-invasive structural imaging modalities including ultrasound, computed tomography and magnetic resonance imaging. However, these are constrained by the time needed for imaging and relatively low spatial resolution. In practice, 2D plus time ultrasound remains the most common method to study cardiac mechanics. Although this offers regionally-resolved transmural insight, aligning the resulting datasets with electrical information from the cardiac surfaces remains challenging. Isolated hearts lead to significantly better access for control and measurements, albeit in less physiological conditions. Here, panoramic optical mapping of transmembrane voltage has been combined with motion tracking techniques to provide simultaneous assessment of ECC and MEC at the epicardial surface. Initial attempts used externally applied surface markers for tracking, which limits spatial resolution obtainable. More advanced approaches have used the inherent contrast of the voltage reporting dye-loaded heart, which allows higher spatial resolutions. Single-view optical mapping of a moderately contracting heart can be performed; however, only points that remain well within the field of view throughout the heartbeat can be adequately tracked. Moving to panoramic optical mapping without surface markers generally required electromechanical uncoupling of the heart (such as using blebbistatin) at the end of recordings, in combination with a separate set of high-resolution camera data, to generate the 3D structural heart volumes needed for data projection and integration. The need for electromechanical uncoupling limits the duration of recordings and prevents systematic physiological studies. Furthermore, even with panoramic studies, the entire ventricular surface has not been recorded previously. The apex, in particular, is frequently not recorded, despite its importance as a common organizing area for arrhythmias. In this issue of The Journal of Physiology, Chowdhary et al. (2026) present a major methodological advance from previous studies, overcoming the fundamental limitations of needing to pharmacologically inhibit contraction or to use fiducial markers during voltage-imaging. By introducing an approach with 12 synchronized cameras, they have ensured sufficient surface coverage to generate full 3D deforming models of the heart from optical mapping videos. This approach enables the systematic study of near-epicardial electrophysiology and mechanics in whole beating hearts, including assessing electro-mechanical cross-talk at the submillimetre scale. In doing so, this work opens the door to investigations ranging from basic questions involving the interaction of electrophysiology and mechanics through to examining how pathological alterations may drive disease and finally, assessing responses to treatment. A further extension of this work would be to incorporate 3D ultrasound or depth-resolved optical mapping, extending analysis from the cardiac surface to the full thickness of the tissue, enabling true volumetric assessment of electro-mechanical coupling (Bernus & Walton, 2021; Christoph et al., 2018). This would ideally be linked to experimental approaches that represent cardiac physiology more closely. A recent study demonstrated that a balloon in the left ventricle, as is commonly used for mechanical loading in isolated hearts, cannot replicate mechanically-induced changes in electrophysiology that occur in vivo during changes in preload (Lewetag et al., 2024). Thus, optimizing techniques for mechanical loading of isolated hearts is needed, as is the improvement of oxygen and nutrient supply (given the lack of blood in most isolated heart experiments). Overall, the work by Chowdhary et al. (2026) provides a significant step towards being exploring the roles and interactions of cardiac ECC and MEC in health and disease, taking us closer to representing in vivo (patho)physiology. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. No competing interests declared. L.B. and C.Z.-J. were responsible for the conception or design of the work; drafting the work or revising it criticaly for important intelectual content; and giving final approval of the manuscript submitted for publication. Agreement to be accountable for all aspects of the work. All authors agreem to be accountable for all aspects of the work. Laura Bear acknowledges funding from the Agence Nationale de la Recherche(ANR-10-IAHU-04 LIRYC and JCJC TUNE ANR-22-CE17-0023), Institut National de la Santé et de la Recherche Médicale Tremplin International Grant(2025-262 CARDILOAD). Callum M Zgierski-Johnston acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 502822458. Open access funding enabled and organized by Projekt DEAL.