There are two components to the study. In the first component, the investigators are testing the hypothesis that the presence of a supportive spouse attenuates ischemic responses to psychological stress in the laboratory. Using a counterbalanced crossover, repeated measures design, patients are asked to complete a public speaking task in the laboratory in two conditions: with a spouse present; and alone. Hemodynamic, radionuclide angiographic, and catecholamine responses to the task are assessed in both conditions.