Impaired Chronotropic Response to Exercise in Acute Myocardial Infarction Patients with Type 2 Diabetes Mellitus.

Abstract

SUMMARYThis study was undertaken in acute myocardial infarction (AMI) patients with noninsulin-dependent diabetes mellitus (type 2 DM) to investigate their impaired chronotropic response to exercise. Seventy-one AMI subjects entered the study, 30 with type 2 DM and 41 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 under a ramp protocol. Anaerobic threshold (AT) and peak oxygen uptake (peak VO 2 ) were determined as indicators of exercise capacity. Plasma norepinephrine (NE) concentration was measured in blood samples obtained at 2 time points: during pre-exercise rest and immediately after peak exercise. The change in NE concentration during exercise, as an index of sympathetic nervous activity, was calculated as a percentage: ∆NE = [(NE during exercise)-(resting value)]/(resting value) × 100. The change in heart rate (HR) during exercise was calculated as a simple difference: ∆HR = [(peak HR) -(rest HR)]. Index of chronotropic response to exercise was then quantified as the ∆HR/∆NE during exercise. No significant intergroup differences in ejection fraction at rest or HR at peak exercise were observed. However, VO 2 at AT, peak VO 2 , ∆HR, and ∆HR/∆NE were significantly lower in the type 2 DM group than in the non-DM group. ∆HR correlated with VO 2 at AT (r = 0.49, P < 0.001) and with peak VO 2 (r = 0.53, P < 0.001) in all subjects. Also, ∆HR/∆NE correlated with VO 2 at AT (r = 0.42, P < 0.001) and with peak VO 2 (r = 0.44, P < 0.001) in all subjects. AMI patients with type 2 DM had impaired cardiopulmonary responses to maximal and submaximal exercise testing and impaired chronotropic response to exercise, even though their cardiac function at rest was similar to that of non-DM AMI patients. The data suggest that one mechanism of impaired cardiopulmo-

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

“…2 Because exercise capacity is reduced after AMI in patients with DM in comparison with similar patients without DM, comprehensive cardiac rehabilitation (CR) should be instituted in these patients after the onset of AMI. 3,4 It is important to clarify the mechanisms underlying the decline of exercise capacity after AMI in patients with DM, in order to offer the appropriate exercise training program to them.Heart rate (HR) response to exercise is regulated by the balance between sympathetic and parasympathetic nerve (SN and PN) activities in the human body. 5 An insufficient HR response to exercise caused by autonomic nervous dysfunction seems to be an important mechanisms in patients with DM who show decreased exercise capacity.…”

“…2 Because exercise capacity is reduced after AMI in patients with DM in comparison with similar patients without DM, comprehensive cardiac rehabilitation (CR) should be instituted in these patients after the onset of AMI. 3,4 It is important to clarify the mechanisms underlying the decline of exercise capacity after AMI in patients with DM, in order to offer the appropriate exercise training program to them.…”

“…5 An insufficient HR response to exercise caused by autonomic nervous dysfunction seems to be an important mechanisms in patients with DM who show decreased exercise capacity. 3,6 It is well known that norepinephrine (NE) secretion from the terminals of the SNs decreases during exercise in patients with DM, as compared with normal subjects. 7 A previous study concerning the relationship between HR response and SN activity during exercise showed that the HR response corresponding to NE secretion is reduced in AMI patients with DM, resulting in a decline in exercise capacity.…”

“…7 A previous study concerning the relationship between HR response and SN activity during exercise showed that the HR response corresponding to NE secretion is reduced in AMI patients with DM, resulting in a decline in exercise capacity. 3 In addition, it has been reported that patients with DM have not only SN dysfunction but also PN dysfunction, which is shown by a decrease in the high-frequency power (HF) in HR variability (HRV). 8 However, there are few reports evaluating the influence of PN activity separately from SN activity on the HR response to exercise and exercise capacity of patients with AMI, and moreover, the impact of DM in causing insufficient HR response to exercise.…”

Exercise and lifestyle intervention and high intensity interval training in patients with chronic kidney disease

“…This may indicate that autonomic dysfunction is influencing cardiorespiratory fitness through mechanisms other than chronotropic incompetence. Previous studies have identified chronotropic incompetence due to cardiac autonomic neuropathy in diabetic patients, (360,361) although the exact mechanisms for this change remain unclear. The decreased cardiorespiratory fitness observed in CKD patients is likely multifactorial and identifying the mechanisms through which autonomic dysfunction leads to reduce cardiorespiratory fitness warrants further investigation.…”