A study of electrocardiographic changes in thyroid disorders

Introduction: Thyroid plays an important role in the orchestration of various metabolic functions in the body and thus thyroid dysfunction can produce dramatic cardiovascular effects, often mimicking primary cardiac disease. Aims: The aim was to study the spectrum of electrocardiographic (ECG) changes in hypothyroidism and hyperthyroidism. Materials and Methods: The present study included 26 cases of hypothyroidism and 24 cases of hyperthyroidism conducted in Department of Medicine, Chirayu Medical College and Hospital, Bhopal. 20 age- and sex-matched euthyroid controls were also included in the study for comparison. Serum free T3, T4, and thyroid-stimulating hormone were done using sensitive chemiluminescence technology. Twelve lead ECG was done in each patient. Results: The predominant abnormality found on ECG study of hypothyroid cases was sinus bradycardia that was found in16 (61.5%) cases (P < 0.05). ST-T changes in the form of T-wave inversion or ST segment depression and flattening was present in 7 cases (26.9%). Sinus tachycardia was the commonest abnormality in hyperthyroidism seen in 19 (79.2%) cases. Atrial fibrillation was seen in three (12.5%) cases and ST-T changes in 2 (8.3%) cases. Conclusion: Sinus bradycardia is the commonest ECG change in hypothyroidism and sinus tachycardia was the predominant ECG change in hyperthyroidism. Therefore, electrocardiography is a sensitive tool to detect cardiac manifestations in thyroid disorders.