Objective: The purpose is to provide an update on the current knowledge of the pathophysiology, the mecha-nisms, and the cardiovascular impact of the different stages of thyroid dysfunction in heart failure patients.
Methods: Recent finding the influence of thyroid hor-mones on the cardiovascular system involves the regu-lation of key processes related to maintenance of car-diac function; however, no long-term studies available show that intervening the thyroid dysfunction changes the incidence or the prognosis in heart failure indivi-duals. Future research shall focus on the effects of car-diovascular morbidity and mortality associated with different treatment modalities for hyper and hypothy-roidism.
Results: T hyroid hormones play a significant role in cardiovascular homeostasis. Molecular action mecha-nisms of thyroid hormones are genomics and non-ge-nomics, both result in balanced effects that explain at least partially the changes in cardiac output, cardiac contractility, blood pressure, vascular resistance, and rhythm disturbances that result from thyroid dysfunc-tion. Hyperthyroidism results in increased heart rate, blood volume, LV stroke volume, ejection fraction, and cardiac output, while hypothyroidism is associated with decreased cardiac contractility, increased systemic vascular resistance and decreased cardiac output. However despite the beneficial effects on some cardiac out-comes using thyroid hormones, long-term trials are not available, and the impact on major outcomes is unclear on this population.
Conclusions: Thyroid dysfunction has been associated with different clinical results in heart failure individu-als; treatment with thyroid hormones in patients with hypothyroidism improves cardiovascular risk factors, but the effect on cardiovascular events has not been assessed in randomized, controlled trials.