Cardiac Autonomic Neuropathy Measured by Heart Rate Variability and Markers of Subclinical Atherosclerosis in Early Type 2 Diabetes

Abstract

Cardiac autonomic neuropathy (CAN) is a critical complication of type 2 diabetes mellitus (T2DM). Heart rate variability (HRV) is a noninvasive tool to assess cardiac autonomic function. We aimed to evaluate whether CAN is associated with increased risk of atherosclerosis in T2DM. A total of 57 diabetic and 54 nondiabetic subjects, free of coronary heart disease, were recruited. Carotid intima media thickness (CIMT), coronary calcium score (CAC), and brachial Flow Mediated Dilation (FMD) were measured. Heart rate variability and vagal components of autonomic function were determined. Significant reduction of normalized HF power (P < 0.05) and total power (P < 0.01) was observed in T2DM. CIMT and CAC scores were significantly higher while FMD was significantly lower in diabetics (P < 0.01 for all). Median HbA1c levels were significantly higher in diabetics. CIMT was inversely and independently associated with total power both in diabetics and controls (P < 0.01 for both groups). There was also an inverse association between total power and median HbA1c. Autonomic dysfunction, especially parasympathetic neuropathy, was present since early-stage T2DM. This was related to subclinical atherosclerosis. Early detection of cardiac autonomic neuropathy can help us detect the development of atherosclerosis earlier in T2DM to prevent unfavorable outcomes.

Association of cardiovascular risk using non-linear heart rate variability measures with the framingham risk score in a rural population

“…(Tsuji et al, 1996) Studies by our laboratory and others have investigated the correlation between HRV and hypertension, cholesterol, gender, age, hyperglycemia and diabetes, smoking, body mass index, oxidative stress and heart disease. (Da Silva et al, 2004; Lampert et al, 2008; McLachlan et al, 2010; Tacoy et al, 2010; Thayer et al, 2010; Johnson et al, 2011; Khandoker et al, 2011; Kotecha et al, 2011; Fakhrzadeh et al, 2012; Matthews et al, 2012; Thiyagarajan et al, 2013) However, these studies did not stratify the cohorts according to the FRS but rather evaluated the magnitude of the HRV associated with presence or absence of the pathology being investigated. Hillebrand et al (2013) recently reported that HRV is a useful marker for incidence of CVD in a population without any signs of CVD based on lowered time domain HRV values (Hillebrand et al, 2013).…”

Cardiovascular variability is similarly altered in coronary patients with normal left ventricular function and in heart failure patients

“…This may have clinical relevance because alterations of cardiovascular variability have been linked to prognosis in coronary patients [41] and have been found to correlate with the degree of coronary stenosis [6,41,42]. Measuring cardiovascular variability could, therefore, help to better identify patients' risk and could favor proper adjustments of their management.…”

Cardiovascular Parasympathetic Changes in Type-II Diabetic Mellitus

“…Fisher B.M et.al.in a study seven subjects out 115 asymptomatic diabetic patients showed an abnormal response to 30:15 ratio and in among 9 symptomatic diabetic patients 8 patients have shown abnormal response [18] . Reduction HR response to standing in diabetics and cardiovascular autonomic function was decreased in type-II diabetics because of that severe damage to large myelinated nerve fibers in addition to the widespread neurological degeneration which usually affects the small nerve fibers of the autonomic nervous system was responsible for profound parasympathetic neuropathy in patients with type-2 DM [19].…”