Hyperthyroidism was associated with significantly altered heart rate variability, indicating higher sympathetic and lower parasympathetic tone compared to euthyroid controls (P<0.001).
Case-Control (n=60)
No
Does hyperthyroidism alter heart rate variability parameters compared to euthyroid controls?
Hyperthyroidism is associated with increased sympathetic and decreased parasympathetic tone as measured by heart rate variability, suggesting higher cardiovascular risk.
p-value: p=<0.001
Background: Thyroid hormones exert effects on the heart and peripheral circulation. Heart rate variability (HRV) is a good marker for identifying the cardiovascular risk in patients with hyperthyroidism. Aims and Objective: To evaluate the impact of hyperthyroidism on autonomic tone and to compare the HRV parameters in patients with hyperthyroidism and healthy volunteers. Materials and Methods: This study was conducted at PSG Institute of Medical Sciences and Research, Coimbatore, Tamil Nadu, on 30 hyperthyroid patients (cases) with average age 39.23 ± 6.91 years and 30 healthy volunteers (controls) with average age 42.13 ± 6.78 years. After obtaining the written consent from the subjects, ECG was recorded for 10 min in a computerized physiograph in lead II. Results: Statistical analysis carried out by independent Students t-test showed a significant difference (P < 0.001) in HRV parameters of patients with hyperthyroid and healthy volunteers. Among the frequency domain measures, a decrease in high frequency (HF) in normalized units and increase in low frequency (LF) in normalized units, and in the ratio of LF to HF (LF/HF) in hyperthyroid patients was observed. Among the time domain measures, decrease in RR intervals, SDNN, RMSSD, and NN50 was observed in patients with hyperthyroid compared to those with euthyroidism. Conclusion: This study showed that individuals with hyperthyroidism had a higher sympathetic tone and a lower parasympathetic tone as compared to those with euthyroidism. Using HRV analysis, we can identify patients who are at risk for cardiac complications and early intervention can reduce mortality rates. Natl J Physiol Pharm Pharmacol 2015; 5(2.000): 93-97
Ramanathan et al. (Thu,) conducted a case-control in Hyperthyroidism (n=60). Hyperthyroidism vs. Euthyroidism (healthy volunteers) was evaluated on Heart rate variability (HRV) parameters (p=<0.001). Hyperthyroidism was associated with significantly altered heart rate variability, indicating higher sympathetic and lower parasympathetic tone compared to euthyroid controls (P<0.001).