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Abstract: Alternans occur prior to ventricular fibrillation and is a medical condition of heart that leads to sudden cardiac death (SCD). The presence of the electrical alternans induces, through the mechanism of the excitation-contraction coupling, an alternation in the heart muscle contractile activity. This work provides a study on the cardiac alternans annihilation by applied electrical and mechanical perturbation. In particular, we address annihilation of alternans in medically relevant size heart tissue by considering modulation of ionic cur- rents in Luo-Rudy-1 (LR1) cardiac cell model, in which the control algorithm involves a combined electrical boundary pacing control and a spatially distributed calcium based control which perturbs the calcium in the cells. A parabolic partial differential equation (PDE) which is adapted from the ionic model is investigated to get an insight in terms of the controllability and stabilizability of the tissue for the suggested control input. Compli- mentary to this, we also address a novel mechanism of alternans annihilation which uses a Nash-Panfilov model coupled with the stress equilibrium equations. The coupled model includes an additional variable to represent the active stress which defines the mechanical properties of the tissue and is utilized in the feedback algorithm as an independent input from the pacing based controller realization in alternans annihilation.