Integration of electricity and heat is one of the most promising options to achieve a sustainable low-carbon energy system in presence of Renewable Energy Sources (RES). In this respect, there are ongoing studies worldwide with the aim of assessing the performance of fully-integrated energy systems. However, while they are encouraging in terms of results, the planning is generally made without considering electrical network constraints, missing to capture the real technical and economic performance of integrated systems. In this paper, a new model for integrated electricity and heat active network management based on a dual-horizon Dynamic AC OPF is presented. The model is capable to plan and optimise operations for different multi-energy technologies considering both electrical network and associated inter-temporal constraints and uncertainties, allowing assessing the potential benefits and available flexibility brought by energy integration.