Changes in thyroid-stimulating hormone biorhythm in patients with atrial fibrillation, coronary heart disease and chronic heart failure
Purpose. We assessed the relationship between daytime changes in thyrotropin secretion and clinical features of atrial fibrillation in combination with coronary heart disease and chronic heart failure. Materials and methods. We had investigated the plasma levels of thyroid stimulating hormone (TSH) and free triiodothyronine (free T3) twice a day (at 7.00 a.m. and 6.00 p.m.) in 133 patients with coronary artery disease, chronic heart failure (HF) with and without atrial fibrillation (AF). Such indicators as presence or absence of AF, severity of angina pectoris and CHF, frequency of paroxysms of AF, were taken into account. Results. The values of TSH levels in the morning and in the evening were significantly different and in most patients (68.4%) rhythmically changed and reached high values in the morning and low values in the evening. Some subjects showed the opposite trend, and the higher values of TSH in the evening were recorded in this group. We called this phenomenon as the inversion of TSH range. A tendency to more severe clinical course of coronary artery disease and atrial fibrillation was revealed in patients with TSH inversion.