Clinical trial NCT01945229: Thumb-ECG Ambulant Screening for Atrial Fibrillation in Patients Treated for Hyperthyroidism (TAMBOURINE)
Official title: Thumb-ECG Ambulant Screening for Atrial Fibrillation in Patients Treated for Hyperthyroidism (TAMBOURINE)
Study type: OBSERVATIONAL
Overall status: TERMINATED
Conditions: Hyperthyroidism
Atrial Fibrillation
Lead sponsor: Karolinska Institutet
Sponsor class: OTHER
First posted: 2013-09-18
Enrollment: 110
Sex: ALL
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: We will screen all patients residing in the extended region around Stockholm, Sweden who have been referred and admitted to the Radiumhemmet clinic for investigation (and usually treatment) with radioiodine. As of February 2016, we will also include patients referred for treatment with antithyroid drugs at the endocrinology clinics of 1) Sahlgrenska University Hospital, Gothemburg Sweden, 2) Karolinska University Hospital, Stockholm, Sweden, 3) Danderyds Hospital, Stockholm, Sweden

Brief summary: 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.


Eligibility criteria: 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

Primary outcomes:
measure: Prevalence of asymptomatic (silent) atrial fibrillation in hyperthyroid patients
timeFrame: Upon inclusion and 2 weeks onwards
Secondary outcomes:
measure: Prevalence of asymptomatic (silent) atrial fibrillation in patients treated for hyperthyroidism.
timeFrame: Between 12 and 14 weeks after inclusion
measure: Prevalence of risk factors for stroke in patients with atrial fibrillation
timeFrame: Momentary (day 1, upon inclusion)
Other outcomes:
Locations:
city: Gothemburg
country: Sweden
facility: Medicine Clinic, Sahlgrenska University Hospital
city: Stockholm
country: Sweden
facility: Endocrinology Clinik, Karolinska University Hospital
city: Stockholm
country: Sweden
facility: Medicine Clinic, Danderyds Hospital
Study officials:
affiliation: Karolinska Institutet
name: Mårten Rosenqvist, Prof
role: STUDY_CHAIR
References:
citation: Frost L, Vestergaard P, Mosekilde L. Hyperthyroidism and risk of atrial fibrillation or flutter: a population-based study. Arch Intern Med. 2004 Aug 9-23;164(15):1675-8. doi: 10.1001/archinte.164.15.1675.
citation: Osman F, Franklyn JA, Holder RL, Sheppard MC, Gammage MD. Cardiovascular manifestations of hyperthyroidism before and after antithyroid therapy: a matched case-control study. J Am Coll Cardiol. 2007 Jan 2;49(1):71-81. doi: 10.1016/j.jacc.2006.08.042. Epub 2006 Dec 13.
citation: Metso S, Auvinen A, Salmi J, Huhtala H, Jaatinen P. Increased long-term cardiovascular morbidity among patients treated with radioactive iodine for hyperthyroidism. Clin Endocrinol (Oxf). 2008 Mar;68(3):450-7. doi: 10.1111/j.1365-2265.2007.03064.x. Epub 2007 Oct 17.
citation: Camm AJ, Lip GY, De Caterina R, Savelieva I, Atar D, Hohnloser SH, Hindricks G, Kirchhof P; ESC Committee for Practice Guidelines (CPG). 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation. Developed with the special contribution of the European Heart Rhythm Association. Eur Heart J. 2012 Nov;33(21):2719-47. doi: 10.1093/eurheartj/ehs253. Epub 2012 Aug 24. No abstract available.