Effect of cardiorespiratory fitness on short-term morbidity and mortality after coronary artery bypass grafting.

Although preoperative risk assessment for coronary artery bypass grafting (CABG) has been evaluated with multiple predictive models, none have incorporated a low level of cardiorespiratory fitness, which represents one of the strongest predictors of all-cause and cardiovascular mortality in subjects with and without heart disease. The aim of the present study was to evaluate preoperative cardiorespiratory fitness, expressed as METs (1 MET = 3.5 ml O2/kg/min), and short-term morbidity and mortality after CABG. The Society of Thoracic Surgeons database was queried for patients who underwent CABG from January 2002 to December 2010 at Beaumont Health Systems. Electronic medical records were reviewed for peak or symptom-limited exercise testing <90 days before CABG. Peak METs were estimated from the achieved treadmill speed, grade, and duration or the cycle ergometer workload, corrected for body weight. Patients who met eligibility criteria (n = 596) were categorized into 2 groups: those with reduced aerobic capacity (<5 METs [n = 78]) and those achieving ≥5 METs (n = 518). Fisher's exact tests were used to compare preoperative aerobic capacity and short-term postoperative morbidity and mortality between the 2 groups. After adjusting for potential confounding variables, an inverse relation was found between cardiorespiratory fitness and complications after CABG. Specifically, low preoperative cardiorespiratory fitness (<5 METs) was associated with higher operative and 30-day mortality after CABG (p <0.05). In conclusion, these data suggest that preoperative cardiorespiratory fitness provides an independent and additive marker for mortality after CABG.