This is a prospective cohort study of patients undergoing coronary artery bypass graft surgery. Prior to surgery, participants will undergo submaximal cardiopulmonary exercise testing on a treadmill. Participants will be followed for one month after surgery to assess mortality and non fatal complications.

Coronary artery bypass surgery (CABG) is a complex and expensive procedure with great potential for morbidity and mortality. Preoperative evaluation is of paramount importance to optimize results. There is much evidence about the benefits of the cardiopulmonary exercise testing (CPET) in the evaluation of preoperative risk in non-cardiac surgeries. Thus, it is important to evaluate the relationship between parameters obtained in the CPET and the outcomes after cardiac surgery, especially CABG.

This is a prospective cohort study in which participants undergo submaximal CEPT on a treadmill prior to CABG. Participants will be followed up for one month after surgery to assess mortality and non fatal complications. It is expected that poor cardiopulmonary fitness is related to worse outcomes in CABG, as already observed in other cardiac pathologies and in non-cardiac surgery.

Inclusion Criteria:

• Patients undergoing coronary artery bypass grafting surgery at the National Institute of Cardiology, Ministry of Health, Rio de Jnaeiro, Brazil.

Exclusion Criteria:

• Angina CCS IV, heart failure NYHA IV, inability to walk on a treadmill, severe left main coronary artery lesion.