Influence of autonomic nervous dysfunction characterizing effect of diabetes mellitus on heart rate response and exercise capacity in patients undergoing cardiac rehabilitation for acute myocardial infarction

Background The aim of this study was to clarify the influence of sympathetic and parasympathetic nerve (SN and PN) dysfunction on the heart rate (HR) response to exercise and the exercise capacity of patients with acute myocardial infarction (AMI) and diabetes mellitus (DM). Methods and Results Fifty-two male patients who underwent cardiopulmonary exercise testing (CPX) 1 month after onset of AMI were divided into 2 groups: (DM (+) group, n=20; DM (-) group, n=32). HR, peak oxygen uptake (VO2peak), and plasma norepinephrine (NE) levels were measured during CPX. The high-frequency power (HF) was analyzed by HR variability. The Delta HR/log Delta NE obtained from changes of HR and NE from rest to peak exercise and HR change from baseline to the minimum HF (Delta HRHF) were calculated as parameters of HR response derived from SN and PN activities, respectively. Delta HR, VO2peak, Delta HR/log Delta NE, and Delta HRHF were signifiantly lower in the DM (+) group than in the DM (-) group, and both of them showed positive correlations with VO2peak. Conclusion An inadequate HR response to exercise is a major factor causing a decline of exercise capacity, which is derived from both of SN and PN dysfunction, in AMI patients with DM.