Abstract

Background: Thyroid hormone has very deep effects on the heart and can cause sympathovagal imbalance. Sympathovagal imbalance can lead to cardiac autonomic neuropathy (CAN) in hypothyroid patients.

Aims and objectives: The study aimed to assess the CAN in hypothyroidism and compare CAN in hypothyroid patients and euthyroid subjects.

Materials and Methods: Fifty hypothyroid patients and 50 euthyroid subjects were selected for the study after satisfying the inclusion and exclusion criteria. Autonomic function tests were performed as per Ewing’s and Clarke criterion including three parasympathetic (deep breathing test, 30:15 ratio, and Valsalva ratio [VR]) and two (sustained handgrip and postural hypotension test) sympathetic tests.

Results: On comparing the mean of the test between euthyroid and hypothyroid patient, VR in parasympathetic and both sympathetic tests were statistically significant.

Conclusion: There is an increased prevalence of CAN in hypothyroidism in comparison to the controls.

Key words: Cardiac Autonomic Neuropathy; Deep Breathing Test; Valsalva Ratio; Sustained Handgrip; Postural Hypotension Test