Simple l-TGA may not yield symptoms in infancy. However, since the morphologic right ventricle normally functions in a low pressure system, the right ventricle may eventually hypertrophy due to increased pressure of ejecting into the systemic circulation of the aorta, and produce symptoms such as dyspnea or fatigue may develop.

Complex l-TGA in contrast, may be associated with symptoms earlier in the natural history of the disase depending on the nature, degree and number of accompanying defect(s). If a right-to-left or bidirectional shunt is present, the list of signs and symptoms may include mild cyanosis. Infants and children can present with congestive heart failure CHF, due to a large VSD or severe tricuspid regurgitation.

Simple l-TGA may be “accidentally” diagnosed in adulthood, as an incidental finding as part of the evaluation or treatment of other conditions.