Endocrine Abstracts

Introduction: Thyroid hormones represent a biomarker of heart rhythm disorders and pathophysiological origins remain unknown. Some of these disorders like atrial fibrillation (AF) are major issues particularly in asymptomatic patients with in Hyperthyroidism and cause of thromboembolic complications.

Aim: Taking into account the uncertainty of prevalence of cardiac rhythm disorders, we aimed to investigate the prevalence of rhythmic cardiac complications and its risk factors in patients with hyperthyroidism.

Methods: We conducted a cross-sectional study on 30 patients with uncontrolled hyperthyroidism. Clinical, biological and therapeutic data were collected. A 24-h Rhythmic Holter monitoring has been performed to all patients.

Results: The patients were seven male and 23 female, mean age was 44.8 ± 14.4 years. Twenty three patients (77%) had palpitation. The mean heart rate was 95 ± 14 (66 – 124) and 16 patients (53%) had tachycardia. Electrocardiogram showed ventricular premature complexes in one patient (3%). Atrial fibrillation was present in two patients (7%). The 24-h Rhythmic Holter monitoring revealed tachycardia in 16 patients (53%), supra-ventricular premature contraction in 16 patients (53%). Thirteen patients (43%) had ventricular premature complexes. Atrial fibrillation was present in three patients (10%), it was permanent in one patient (3%) and paroxysmal in two (7%). The study of risk factors showed that age > 50 years, the presence of nodules (palpable and on ultrasound) and negativity of TSH receptor antibodies were associated to atrial fibrillationP=0.041, P=0.020, P=0.029, P=0.008. Toxic nodular goiter was associated to atrial fibrillationP=0.004.

Conclusion: Hyperthyroidism increases heart rate and may cause arrhythmia, mainly atrial fibrillation. This complication is more frequent in older patients with toxic nodular goiter.