Early Six-Minute Walk Test May Predict Midterm Outcomes Following Coronary Artery Bypass Grafting

ABSTRACT Objective: This study aims to investigate the ability of the six-minute walk distance (6MWD) as a prognostic marker for midterm clinical outcomes three months after coronary artery bypass grafting (CABG), to identify possible predictors of fall in 6MWD in the early postoperative period, and to establish the percentage fall in early postoperative 6MWD, considering the preoperative baseline as 100%. Methods: A prospective cohort of patients undergoing elective CABG were included. The percentage fall in 6MWD was assessed by the difference between preoperative and postoperative day (POD) five. Clinical outcomes were evaluated three months after hospital discharge. Results: There was a significant decrease in 6MWD on POD5 compared with preoperative baseline values (percentage fall of 32.5±16.5%, P<0.0001). Linear regression analysis showed an independent association of the percentage fall of 6MWD with cardiopulmonary bypass (CPB) and preoperative inspiratory muscle strength. Receiver operating characteristic curve analysis revealed that the best cutoff value of percentage fall in 6MWD to predict poorer clinical outcomes at three months was 34.6% (area under the curve = 0.82, sensitivity = 78.95%, specificity = 76.19%, P=0.0001). Conclusion: This study indicates that a cutoff value of 34.6% in percentage fall of 6MWD on POD5 was able to predict poorer clinical outcomes at three months of follow-up after CABG. Use of CPB and preoperative inspiratory muscle strength were independent predictors of percentage fall of 6MWD in the postoperative period. These findings further support the clinical application of 6MWD and propose an inpatient preventive strategy to guide clinical management over time.