Thumb-ECG Ambulant Screening for Atrial Fibrillation in Patients Treated for Hyperthyroidism (TAMBOURINE)

Study Overview
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Brief Summary
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Background: Atrial fibrillation is a common heart rhythm disturbance affecting some 1-2% of the western population. It may cause symptoms such as irregular heartbeats, shortness of breath, and fatigue. It may also be asymptomatic (ie silent atrial fibrillation). In some cases, atrial fibrillation is permanent whereas in others it is sporadic. Regardless of symptoms, there is an increased risk of stroke in some patients with this condition. Novel technologies are being developed to increase detection of silent atrial fibrillation, in order to find patients who might benefit from treatment with oral anticoagulants (blood-thinning medications) in order to reduce the risk of stroke. One of these technologies is thumb-ECG, a simple way for a patient to have his or her heart rhythm reliably analyzed at home. Hyperthyroidism (sometimes referred to as toxic goiter) is defined as an excessive production of thyroid hormone. It is known that hyperthyroidism may cause atrial fibrillation in about 8% of cases. Objective: To provide thumb-ECG-monitors to hyperthyroid patients before and after treating their hormonal disturbance, in order to find episodes of silent atrial fibrillation. Design: Prospective observational study. Hypotheses: Primary hypothesis: Silent atrial fibrillation is at least as common as overt atrial fibrillation in hyperthyroid patients. Secondary hypothesis nr 1: Atrial fibrillation continues to be more prevalent compared to the normal population even after hyperthyroidism is treated. Secondary hypothesis nr 2: The majority of patients with hyperthyroidism and atrial fibrillation are at increased risk of stroke and should be considered for treatment with oral anticoagulants.

Official Title
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Thumb-ECG Ambulant Screening for Atrial Fibrillation in Patients Treated for Hyperthyroidism (TAMBOURINE)

Conditions
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Hyperthyroidism, Atrial Fibrillation

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patient is deemed suitable for treatment with radioiodine or antithyroid drugs Patient has a thyreotropin (TSH) value below 0,1 mIU/L, measured less than 2 weeks before inclusion Patient has a CHADS-VASc-score of 1 point or higher (excluding if 1 point is for female sex only) Patient gives written consent to participate in study Exclusion Criteria: Patient has a previously known diagnosis of atrial fibrillation
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Hyperthyroid patients<br>Patients with hyperthyroidism admitted for treatment with radioiodine or antithyroid drugs | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Prevalence of asymptomatic (silent) atrial fibrillation in hyperthyroid patients | Upon inclusion, each patient will receive a thumb-ECG-monitor to take home. He/she will register his/her heart rhythm twice daily, and can also register at will upon symptoms. This will continue for 2 weeks, after which the monitor is returned. | Upon inclusion and 2 weeks onwards | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Prevalence of asymptomatic (silent) atrial fibrillation in patients treated for hyperthyroidism. | When a patient comes back to the policlinic after hyperthyroidism treatment (typically 3 months later), the same procedure is performed as upon inclusion. Thumb-ECG-monitoring is performed during a 2-week period. | Between 12 and 14 weeks after inclusion | 
| Prevalence of risk factors for stroke in patients with atrial fibrillation | Risk factors for stroke in atrial fibrillation according to the CHADS-VASc-scoring system. | Momentary (day 1, upon inclusion) |