Computational models can help understand the hemodynamics of the coronary circulation, which is of the upmost importance to help clinicians before, during and after a coronary artery bypass graft surgery. In this paper, we propose a multiobjective optimization method for parameter estimation of a computational model representing the coronary circulation on patients with a triple vessel disease. This estimation was not based on any assumption regarding the development of the collateral circulation, like in previous works. Indeed, the collateral development of a given patient is estimated through the model parameters. Parameter estimation was performed using clinical data from three patients, obtained before and during an off-pump coronary artery bypass graft surgery (CABG). Results showed a better performance when comparing the simulation with clinical data, since the total error estimation for three patients was reduced by 40 ± 22%. Moreover, the proposed method provides new insight regarding the heterogeneous configuration of the alternative collateral vessels.