Purpose: The aim of this study was to identify impaired chronotropic response to exercise during cardiopulmonary exercise test after acute myocardial infarction(AMI) in patients with type 2 diabetes mellitus(DM).
Background: The abnormal cardiovascular responses to exercise that are caused by cardiac autonomic nervous system dysfunction in patients with type 2 DM and acute myocardial infarction during cardiopulmonary exercise test(CPET) are not elucidated.
Method: We retrospectively reviewed patients who underwent CPET after AMI and have type 2 DM in a single exercise laboratory. Variables of CPET, Demographic data, presence of concomitant diseases, characteristics of AMI, angiography findings were evaluated.
Results: 204 AMI subjects were enrolled in this study, 29 with type 2 DM and 175 age and body mass index-matched non-DM (control) patients. One month after the onset of AMI, these patients underwent cardiopulmonary exercise testing on a treadmill. Peak oxygen uptake (peak VO2) were determined as indicators of exercise capacity. The change in heart rate (HR) during exercise was calculated as a simple difference: ΔHR= [(peak HR) - (rest HR)]. Significant intergroup differences in left ventricular diastolic function (E/E’ 11.97±4.30 in DM vs 10.27±3.11 in non DM, p = 0.014), peak VO2 uptake (23.63±5.97 vs 26.14±6.42 mL/min, p = 0.045), maximal METs (6.71±1.69 vs 7.46±.84, p = 0.04) and ΔHR (56.97±20.24 vs 80.38±20.13 beats/min, p = 0.002). ΔHR correlated with peak VO2 (r = 0.553, P < 0.0001) in all subjects.
Conclusion: Patients with AMI and type 2 DM had impaired cardiopulmonary responses to maximal and impaired chronotropic response to exercise, even though their cardiac function at rest was similar to that of non-DM AMI patients.