Heart rate variability in hyperthyroidism on sub Saharan African patients: a case-control study

Area of Science:

• Cardiology
• Endocrinology
• Autonomic Neuroscience

Background:

• Hyperthyroidism, a condition of excess thyroid hormones, can impact cardiovascular function.
• Cardiac autonomic dysfunction is a known complication of thyroid disorders, but data in newly diagnosed, untreated patients, especially in Sub-Saharan Africa, is limited.

Purpose of the Study:

• To investigate heart rate variability (HRV) in patients with freshly diagnosed, untreated hyperthyroidism.
• To assess cardiac autonomic function using Ewing battery tests and compare results with matched controls.

Main Methods:

• Recruited 10 hyperthyroid patients and 10 age/sex-matched controls.
• Performed Ewing battery tests for cardiac autonomic dysfunction assessment.
• Assessed HRV using 24-hour ECG, analyzing time-domain (SDNN, RMSSD) and frequency-domain (LF, HF, HF/LH ratio) parameters.

Main Results:

• Hyperthyroid patients had significantly higher heart rates compared to controls (p=0.006).
• A trend towards reduced SDNN and RMSSD (time-domain) was observed in hyperthyroid patients.
• Frequency-domain analysis showed non-significant alterations in LF and HF power, with all patients exhibiting impaired parasympathetic activity.

Conclusions:

• Untreated, newly diagnosed hyperthyroidism is associated with altered heart rate variability and impaired parasympathetic activity.
• These findings underscore the importance of early diagnosis and treatment of hyperthyroidism to prevent cardiovascular complications.