Background: Subclinical hypothyroidism can be associated with the onset and progression of chronic heart failure.
Methods: We undertook a careful search of the literature aiming to review the possible pathogenetic mechanisms explaining the influence of subclinical hypothyroidism on the onset and progression of chronic heart failure.
Results: Thyroid hormones can influence the expression of genes involved in calcium handling and contractile properties of myocardiocytes. Subclinical hypothyroidism, therefore, can alter both cardiovascular morphology and function leading to changes in myocardiocytes shape and structure, and to alterations of both contractile and relaxing properties, impairing systolic as well as diastolic functions. Furthermore, it can favour dyslipidemia, endothelial dysfunction and diastolic hypertension, favouring atherogenesis and coronary heart disease, possibly evolving into chronic heart failure. Beside an influence on the onset of chronic heart failure, subclinical hypothyroidism can represent a risk factor for its progression, in particular hospitalization and mortality but the mechanisms involved need to be fully elucidated.
Conclusions: Subclinical hypothyroidism can be associated with the onset of chronic heart failure, because it can favour two frequent conditions that can evolve in heart failure: coronary heart disease and hypertension; it can also alter both cardiovascular morphology and function leading to heart failure progression in patients already affected through mechanisms still not completely understood.
Keywords: Amiodarone, cardiac remodeling, Chronic Heart Failure, levothyroxine replacement therapy, low T3 syndrome, Subclinical Hypothyroidism.