Thyroid and Heart: A Fatal Pathophysiological Attraction in a Controversial Clinical Liaison

The thyroid–heart relationship has a long and articulated history of its own, a history that encompasses physiological and pathophysiological knowledge. In recent years, molecular biology studies, in an experimental context, have highlighted the extraordinary dialogue that exists among the two systems in the field of cardioprotection, which is an extremely important area for the treatment of cardiac diseases in both acute and chronic phases. In addition, in the last few years, several studies have been carried out on the prognostic impact of alterations in thyroid function, including subclinical ones, in heart disease, in particular in heart failure and acute myocardial infarction, with evidence of a negative prognostic impact of these and, therefore, with the suggestion to treat these alterations in order to prevent cardiac events, such as death. This review provides a comprehensive summary of the heart–thyroid relationship.