What is the optimal treatment order for concurrent hyperthyroidism and atrial fibrillation (Afib)?

From the Guidelines

When treating concurrent hyperthyroidism and atrial fibrillation (AFib), the primary focus should be on controlling the hyperthyroidism first, as it is often the underlying cause of the AFib, and then managing the AFib according to the latest guidelines, such as the 2024 ESC guidelines 1. The optimal treatment order involves addressing the hyperthyroidism with anti-thyroid medications like methimazole or propylthiouracil, while simultaneously controlling the heart rate with beta-blockers such as metoprolol or propranolol, as recommended by the 2006 ACC/AHA/ESC guidelines 1. Key considerations in managing AFib in the context of hyperthyroidism include:

• Controlling the ventricular rate to prevent complications, with beta-blockers being the preferred initial therapy, unless contraindicated, in which case nondihydropyridine calcium channel antagonists are recommended 1.
• Assessing the risk of thromboembolism using tools like the CHA2DS2-VA score and considering anticoagulation based on this risk, with direct oral anticoagulants (DOACs) preferred over vitamin K antagonists (VKAs) in eligible patients, as per the 2024 ESC guidelines 1.
• Evaluating and managing comorbidities and risk factors that contribute to AFib, such as hypertension, heart failure, and diabetes mellitus, to improve overall outcomes.
• Considering rhythm control strategies, including cardioversion, antiarrhythmic drugs, and catheter or surgical ablation, for patients who remain symptomatic despite optimal rate control and have a suitable profile for these interventions, as outlined in the 2024 ESC guidelines 1. The approach to managing concurrent hyperthyroidism and AFib should be patient-centered, involving shared decision-making and a multidisciplinary team, with a focus on improving quality of life and reducing morbidity and mortality, as emphasized by the latest guidelines 1.

From the Research

Optimal Treatment Order for Concurrent Hyperthyroidism and Atrial Fibrillation (Afib)

The optimal treatment order for concurrent hyperthyroidism and atrial fibrillation (Afib) involves several key considerations:

• Restoring thyroid function to a euthyroid state is essential in managing hyperthyroidism-related Afib, as the majority of patients spontaneously revert to sinus rhythm in 4-6 months during or after restoration of euthyroidism 2.
• Rate control with beta-blockers is a first-line therapy for hyperthyroidism-related Afib, reserving rhythm control for cases of persistent Afib 2.
• The use of anticoagulation therapy should be guided by the clinical thromboembolic risk score CHA2DS2-VASc score, similar to patients with non-hyperthyroidism-related Afib 2, 3.
• Treatment with novel direct oral anticoagulants may be beneficial and safer than warfarin in patients with hyperthyroidism-related Afib 2.
• Attempted cardioversion should be deferred until approximately the fourth month of maintaining a euthyroid state, as more than 56% of Afib spontaneously reverts to sinus rhythm when thyroid hormone levels start to decline 4.

Specific Treatment Approaches

Some studies have investigated specific treatment approaches for hyperthyroidism-related Afib:

• The use of amiodarone and methimazole has been reported to be effective in restoring sinus rhythm and normalizing serum thyroid hormone levels in a patient with hyperthyroidism and Afib 5.
• Beta-blockers have been shown to reduce left ventricular hypertrophy and atrial and ventricular arrhythmias in patients with hyperthyroidism 6.
• Anticoagulation therapy, such as warfarin, has been found to effectively reduce the incidence of stroke in patients with hyperthyroidism-related Afib and a CHA2DS2-VASc score ≥1 3.