Cardiopulmonary response abnormalities during exercise in patients with acute myocardial infarction complicated by non-insulin-dependent diabetes mellitus

The main purpose of this study was to investigate the cardiopulmonary response during exercise in patients with acute myocardial infarction (AMI) complicated by non-insulin-dependent diabetes mellitus (NIDDM). Among 179 AMI patients who entered the study, 60 had NIDDM. They were matched with 119 non-NIDDM patients for age, height, and creatine kinase-MB. One month after the onset of AMI, cardiopulmonary exercise testing was performed on a treadmill with a ramp protocol. The anaerobic threshold, peak oxygen uptake (peak VO 2 ), and peak exercise time were measured to assess temporal changes in exercise tolerance. At the respiratory compensation point, tidal volume was measured as an index of pulmonary capillary wedge pressure, end-tidal CO 2 was measured as an index of reserve cardiac output, and the ventilatory equivalent of CO 2 (VE/VCO 2 ) was determined as an index of ventilation efficiency. There were no significant differences between the two groups with respect to the ejection fraction at rest, exercise time, or heart rate at peak exercise. However, VO 2 and heart rate increases with regard to exercise time (defined as the VO 2 and heart rate slopes), tidal volume, and end-tidal CO 2 at the respiratory compensation point were significantly lower, and VE/VCO 2 at the respiratory compensation point was significantly higher, for the NIDDM group than for the nondiabetes group. Patients with NIDDM-complicated AMI had impaired maximal and submaximal cardiopulmonary responses to exercise, even though their cardiac function at rest was similar to that of the non-NIDDM group.