[Heart and thyroid interactions]

Area of Science:

• Endocrinology
• Cardiology
• Internal Medicine

Background:

• Thyroid hormones are essential for cardiovascular (CV) health, influencing cardiac function, hemodynamics, and metabolic homeostasis.
• Thyroid dysfunction is prevalent and often misunderstood, yet it significantly impacts CV risk.
• Hormonal imbalances affect glucose, lipid, and coagulation pathways, crucial factors in CV risk assessment.

Purpose of the Study:

• To systematically review and summarize evidence on the association between thyroid dysfunction and cardiovascular morbidity and mortality.
• To elucidate the direct and indirect mechanisms through which thyroid dysfunction affects cardiovascular health.
• To evaluate the role of subclinical thyroid conditions in cardiovascular risk stratification and the benefits of their treatment.

Main Methods:

• Systematic literature review of existing evidence.
• Analysis of direct and indirect mechanisms of thyroid hormone action on the cardiovascular system.
• Evaluation of clinical outcomes related to overt and subclinical thyroid dysfunction.

Main Results:

• Overt hypothyroidism and hyperthyroidism are strongly linked to increased CV risk via direct and indirect pathways.
• Mechanisms include direct effects on myocardial cells and coronary flow, and indirect effects on vascular system, metabolism, and coagulation.
• The contribution of subclinical thyroid dysfunction to CV risk is less clear, but treatment shows benefits in specific populations.

Conclusions:

• Overt thyroid dysfunction poses a significant cardiovascular risk.
• Treatment of subclinical hypothyroidism is most beneficial for younger individuals with low CV risk.
• Treatment of subclinical hyperthyroidism offers greater advantages in older patients with comorbidities.