Abstract
Background: Hypothyroidism is a common endocrine disease and is also a factor that increases the risk of cardiovascular diseases. One of the main problems of thyroid disease in general and hypothyroidism in particular is causing cardiac arrhythmias, usually supraventricular arrhythmias, and the mechanism may be due to imbalance in the autonomic nervous system.
Objective: Describe the electrocardiogram characteristics and heart rate variability in patients with primary hypothyroidism and explore the relationship between electrocardiogram changes and some clinical and subclinical symptoms of hypothyroidism patients.
Methods: Cross-sectional description of 40 patients. Selection criteria are patients with a confirmed diagnosis of primary hypothyroidism. Characteristics of heart rate variability were assessed on 12-lead electrocardiogram and 24-hour Holter electrocardiogram.
Results: The study had the majority of women (70%), average age was 54 ± 13 years old, the age group with the highest rate was 40-60 years old, the rate of overweight and obesity was 52.5%. The most common clinical symptoms are muscle and joint pain (67.5%), dry skin, hair loss (60%), fatigue, and drowsiness (50%). On electrocardiogram images, 100% were in sinus rhythm, 27.5% had sinus bradycardia. There was one case of premature ventricular complexes, one case of 1st degree avioventricular block and three cases of right bundle branch block. On Holter ECG: 5% had sinus bradycardia, 80% had atrial premature beats, 20% had ventricular premature beats, 2,5% had 1st degree avioventricular block. There were no differences in heart rate variability among age groups, BMI and TSH index. There were no differences in mean, highest, and lowest heart rates between age, sex, BMI, and TSH groups.
Conclusions: Both overt and subclinical thyroid disorders were associated with significant changes in important ECG parameters.