Background: Recent investigations have demonstrated that cerebral oxyhemoglobin (O(2)Hb) decreases during exercise in patients with left ventricular dysfunction, reflecting a cerebral hypoxia. We sought to establish a prognostic value of decreased cerebral O(2)Hb during exercise in cardiac patients, and to compare it with those of indexes obtained from cardiopulmonary exercise testing (CPX).
Methods and results: A total of 344 consecutive patients with coronary artery disease were enrolled in the study. All the patients performed CPX, during which cerebral O(2)Hb was continuously monitored using near-infrared spectroscopy. There were 13 cardiac deaths and 78 cardiovascular events during the prospective follow-up period of 1,231+/-538 days. The change of O(2)Hb measured at the forehead from rest to peak exercise (DeltaO(2)Hb) was significantly lower in non-survivors than in survivors (-1.5+/-3.3 vs 1.7+/-3.2 micromol/L, p=0.0004). By multivariate Cox proportional hazards analysis, DeltaO(2)Hb and left ventricular ejection fraction (LVEF) were found to be independent prognostic markers for cardiac deaths. The DeltaO(2)Hb, LVEF and peak oxygen uptake were found to be significant prognostic markers for cardiovascular events, mainly for heart failure worsening and sudden cardiac death.
Conclusion: The present findings suggest that a decrease in cerebral O(2)Hb during exercise predicts future cardiovascular events in patients with coronary artery disease.