Atrial fibrillation and hyperthyroidism: A literature review

Abstract

Atrial fibrillation is the most common arrhythmia worldwide with increasing frequency noted with age. Hyperthyroidism is a well-known cause of atrial fibrillation with a 16%–60% prevalence of atrial fibrillation in patients with known hyperthyroidism Ross et al. (2016). While hyperthyroidism as a causative factor of atrial fibrillation is well established, this literature review aims to answer several questions on this topic including:1. The relationship of atrial fibrillation to hyperthyroidism2. Atrial fibrillation as a predictor of hyperthyroidism3. The pathophysiology of thyrotoxic atrial fibrillation4. Subclinical hyperthyroidism and the relationship with atrial fibrillation5. Cardioversion and Catheter ablation of hyperthyroid patients with atrial fibrillation6. Thrombotic risk of hyperthyroid patients with atrial fibrillation7. Management of Thyrotoxic Atrial fibrillation8. Pharmacological rhythm control in patients with hyperthyroidism and atrial fibrillation9. Treatment of Hyperthyroidism to prevent atrial fibrillation10. Clinical Implications of Hyperthyroidism and Atrial Fibrillation

Cardiorespiratory Arrest Associated with Propranolol use in Thyrotoxic Heart Disease

“…A trial fibrillation occurs in 10-15% of patients with hyperthyroidism [7]. In contrast, it is uncommon to present with paroxysmal supraventricular tachycardia, or wide complex supraventricular tachycardia as demonstrated in this case [3,8].…”

“…Increased thyroid hormone activates the renin-angiotensin system and magnifies the sensitivity of beta-adrenergic receptors to catecholamine, which increases left ventricular contractility and heart rate. The activation of the reninangiotensin system also decreases systemic vascular resistance, and increases blood volume [5][6][7]. The chain of reaction subsequently increases myocardial oxygen consumption, cardiac output and cardiac workload [1].…”

“…In thyrotoxicosis, the reduced electrical threshold of a trial depolarization usually leads to rhythm disturbance [7]. A trial fibrillation occurs in 10-15% of patients with hyperthyroidism [7].…”

“…The use of beta blockers should be carefully considered, even avoided, in patients who may have thyrotoxic cardiomyopathy as evidenced by longstanding hyperthyroidism and cardiomegaly in chest radiography [8,12]. A lower dose of Propranolol, such as 0.5mg intravenously should be instituted instead of the full dose in the first instance [7,14].…”

“…When left heart failure or low cardiac output is detected, short-acting beta-blockers such as esmolol can be considered [7]. Having an equipotent effect to Propranolol, Esmolol has been used successfully in managing tachyarrhythmia and a trial fibrillation in hyperthyroid patients [2].…”