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

Abstract

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 (V̇O2peak), and plasma norepinephrine (NE) levels were measured during CPX. The high-frequency power (HF) was analyzed by HR variability. The ΔHR/logΔNE obtained from changes of HR and NE from rest to peak exercise and HR change from baseline to the minimum HF (ΔHRHF) were calculated as parameters of HR response derived from SN and PN activities, respectively. ΔHR, V̇O2peak, ΔHR/logΔNE, and ΔHRHF were significantly lower in the DM (+) group than in the DM (-) group, and both of them showed positive correlations with V̇O2peak. 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.