A Study of Cardiac Autonomic Neuropathy and Its Correlation with QTc Dispersion in Type-2 Diabetes Mellitus

Aims: To evaluate the presence of cardiac autonomic neuropathy in Type-2 Diabetes and to correlate autonomic dysfunction with QTc dispersion.

Study Design: This was a hospital based cross-sectional study carried out in the department of Medicine JSS Hospital Mysore, India between March 2012 and March 2013.

Methodology: We included 50 Diabetes patients (Cases) and 50 Non Diabetes healthy adults (Controls) of both genders. Five standard cardiovascular response tests were carried out (Valsalva ratio, expiration-inspiration ratio, immediate heart rate response to standing, fall of systolic blood pressure on standing and sustained hand grip test) to determine the severity of cardiac autonomic neuropathy. QTc dispersion was determined by subtracting heart rate-corrected minimum QTc interval (QTc min) from maximum QT interval (QTc max) from standard electrocardiogram.

Results: 17 patients (34%) had evidence of cardiac autonomic neuropathy. Of this 8 (16%) had borderline and 9(18%) had abnormal CAN. In the control group only 1(2%) had CAN. (P value of 0.000) Mean QTc in cases was 41.60+/-18.11) and in controls was 20.80(+/-4.88) QTc dispersion was 32.7(+/-13.0) in those without CAN and 48.75(+/-9.71) in borderline CAN and 67.77(+/-9.71_in abnormal CAN group. (P =0.000).

Conclusion: Prolonged QTc a feature of autonomic dysfunction due to diabetes. QTc dispersion correlates significantly with presence of cardiac autonomic neuropathy and may be a simple and useful measure for detection of cardiac autonomic neuropathy.