Coronary Disease, Feasibility Studies, Female, Heart, Humans, Iodine Radioisotopes, Iodobenzenes, Male, Middle Aged, Myocardial Revascularization, Myocardium, Predictive Value of Tests, Radionuclide Ventriculography, Stroke Volume, Tomography, Emission-Computed, Single-Photon, Ventricular Function, Left