MAXIMAL BLOOD LACTATE LEVEL ACTS AS A MAJOR DISCRIMINANT VARIABLE IN EXERCISE TESTING FOR CORONARY-ARTERY DISEASE DETECTION IN MEN

Background The interpretation of exercise stress testing for coronary artery disease detection is affected by the many differences in chosen variables and mathematical methods. We conducted a prospective trial to evaluate a global muscle fatigue parameter-the blood lactate level achieved at maximal exercise-as a method of distinguishing between dis eased and nondiseased coronary status. Methods and Results We evaluate d 236 consecutive male patients without previous myocardial infarction who had been referred for the diagnosis of coronary artery disease. N one of the patients had cardiomyopathy, severe cardiac heart failure, or valvular heart disease. Blood lactate concentration at maximal exer cise was measured as well as other classic variables. Correlations bet ween variables and coronary status as assessed by coronary arteriograp hy were described using receiver operating characteristic (ROC) curves and logistic regression analysis. The first four most powerful variab les (lactate level, maximal power output, exercise duration, and perce ntage of maximal predicted heart rate), which are directly representat ive of the global functional capacity, showed values of 0.777, 0.775, 0.760, and 0.740, respectively, by ROC curve analysis. Mean+/-SD blood lactate level at peak exercise reached 7.68+/-2.70 mmol/L in the 153 diseased and 10.56+/-2.75 mmol/L in the 83 nondiseased patients (P<.00 01). After adjustment for other variables, blood lactate level remaine d a significant predictor of coronary artery disease by logistic regre ssion analysis (adjusted odds ratio, 1.2; confidence interval, 1.04 to 1.4). Conclusions Global muscle fatigue as assessed by lactate levels in the blood at maximal exercise appears to be a powerful distinguish er of diseased and nondiseased coronary status.