SUBMAXIMAL OXYGEN PULSE DIVIDED BY BODY WEIGHT DURING INCREMENTAL EXERCISE TEST¹

Abstract

The purpose of this study was to examine whether submaximal oxygen pulse divided by body weight (O₂ pulse/BW) during an incremental exercise test discriminated between trained and untrained men, correlated to left ventricular ejection fraction (LVEF) at rest in post-myocardial infarction patients, and was sensitive and specific in detecting ventricular dysfunction and mild ventricular dysfunction with myocardial ischemia during exercise. Forty-three trained men, 44 untrained men, and 21 post-myocardial infarction patients pedaled a cycle ergometer, with O₂ consumption, heart rate, and myocardial ischemia monitored during the exercise test. Work rate started at 10 W and increased 10 W/min stepwise; the O₂ pulse and O₂ pulse/BW at 10 through 120 W were calculated. The LVEF of the patients was measured at rest using radionuclide ventriculography three weeks after myocardial infarction. The results revealed that O₂ pulse/BW was significantly different between trained and untrained men at 80, 90, 100, 110, and 120 W, whereas O₂ pulse was significantly different only at 110 and 120 W. Oxygen pulse/BW at 10 W, as well as 30 through 120 W, significantly correlated to LVEF in the patients. The three patients with ventricular dysfunction (LVEF, <40%) plus the two patients with mild ventricular dysfunction (LVEF between 40 and 50%) and ST segment depression during exercise all had submaximal O₂ pulse/BW significantly lower than untrained men (sensitivity, 100%). Among the 11 patients with normal ventricular function (LVEF, >50%) plus the 5 patients with mild ventricular dysfunction but no ST segment depression, 13 patients did not have submaximal O₂ pulse/BW significantly lower than untrained men (specificity, 81%).