Key result
Subclinical hypothyroidism in female patients was associated with lower parasympathetic activity and a predominance of sympathetic activity compared to normal controls.
Why the study?
Does subclinical hypothyroidism alter beat-to-beat QT variability and vascular stiffness in female patients compared to normal controls?
Case-Control
Does subclinical hypothyroidism alter beat-to-beat QT variability and vascular stiffness in female patients compared to normal controls?
Subclinical hypothyroidism in females is associated with autonomic dysfunction characterized by lower parasympathetic and higher sympathetic activity, suggesting QT variability may help assess cardiovascular risk.
Answers are grounded in this paper and cite their sources.
May signal heightened CV risk via autonomic imbalance; leaves open whether QT variability aids risk stratification in subclinical hypothyroidism.
BACKGROUND: Patients with subclinical hypothyroidism (SH) may have higher incidence of coronary heart disease and autonomic dysfunction. DESIGN OF THE STUDY: Prospective case control study. AIM AND OBJECTIVES: To evaluate beat-to-beat QT variability and vascular stiffness in patients with SH compared to normal controls. MATERIALS AND METHODS: We compared linear and nonlinear measures of cardiac repolarization liability using beat-to-beat QT intervals derived from the surface electrocardiogram during supine posture and vascular indices including pulse wave velocity and ankle-brachial index (ABI) during supine posture between female patients with SH and age- and sex-matched normal controls. Spectral analysis was done at very low frequency (LF) (0.003-0.04 Hz), Low frequency (LF) (0.04-0.15 Hz), and high frequency (HF) (0.15-0.4 Hz). The HF represents vagal regulation (parasympathetic) and LF represents both parasympathetic and sympathetic regulation. CONCLUSIONS: The cases had lower parasympathetic activity as compared to controls, and there was a predominance of sympathetic activity in cases. QTvi may be an important noninvasive tool in this group of patients to study the risk of cardiovascular mortality.
No takes yet. Share an insight, caveat, or question.
Kalra et al. (2016) conducted a case-control in Subclinical hypothyroidism. Subclinical hypothyroidism vs. Normal controls was evaluated on Beat-to-beat QT variability and vascular stiffness (parasympathetic and sympathetic activity) (p== 0.03). Subclinical hypothyroidism in female patients was associated with lower parasympathetic activity and a predominance of sympathetic activity compared to normal controls.
Synapse has enriched 10 related papers. Consider them for comparative context: