Circadian rhythms of thyroid hormones in patients with ischemic heart disease, arterial hypertension, and atrial fibrillation

Abstract

To evaluate the interrelationship between diurnal changes in thyrotropic hormone (TTH), free triiodothyronine (FT3), and clinical features of IHD in combination with AH and atrial fibrillation (AF). Levels of TTH, FT3, and plasma cortisol were measured in 133 patients with IHD and AH with or without paroxysmal AF. The studied indexes included duration ofIHD, AH, and AF; presence or absence of AF and AH; incidence rate of AF episodes per week; severity of exertional angina; systolic and diastolic BP; and EchoCG data. Morning and evening TTH levels were significantly different and reached high values in the morning and low values in the evening in most patients (n=91; 68.4%). A part of patients (n=42; 31.6%) showed anopposite tendency with high TTH values in the evening, i.e., inversion of the TTH fluctuations. Such patients more often had a history of myocardial infarction, a high class of exertional angina, and recurrence of paroxysmal AF. Patients with the TTH inversion had ashorter AH duration but somewhat higher BP. A part of IHD patients had inversed TTH circadian changes associated with more severe clinical manifestations of cardiovascular pathology.