Is a Low Thyreotropin Level Predictive of Recurrent Arrhythmia After Catheter Ablative Surgery?

Completed

• Conditions: Atrial Fibrillation; Subclinical Hyperthyroidism

• Registration Number: NCT01789541
• Lead Sponsor: Karolinska Institutet

Brief Summary

Overt hyperthyroidism (so-called "goiter" in lay language) is a hormonal disturbance that is known to increase the risk of atrial fibrillation (a common heart arrhythmia with potentially severe consequences) in some patients. Previous research has indicated that even slight elevations in thyroid hormone levels - so called subclinical hyperthyroidism - may increase this risk. When atrial fibrillation and overt hyperthyroidism are found simultaneously in a patient, the hormonal imbalance must be treated first in order to later resolve the arrhythmia. It is unclear whether this strategy holds true for subclinical hyperthyroidism. Our two hypotheses are: 1) Subclinical hyperthyroidism is more prevalent in patients admitted for atrial fibrillation ablation than in the population as a whole, and 2) Patients with subclinical hyperthyroidism and atrial fibrillation benefit less from ablation than others.

As a control group, we have chosen patients admitted for ablation of AV-nodal Reentry Tachycardia at the same clinics as the cases. No correlation has ever been shown between AV-nodal Reentry Tachycardia and hyperthyroidism.

Detailed Description

Not available

Study Timeline

• Study Start: 2013-02
• Study First Submitted: 2013-02-05
• Study First Submitted QC: 2013-02-11
• Study First Posted: 2013-02-12
• Primary Completion: 2015-10
• Study Completion: 2015-11
• Status Verified: 2016-01
• Last Update Submitted: 2016-01-19
• Last Update Posted: 2016-01-20

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 327

Inclusion Criteria

• Atrial fibrillation or AV-nodal reentry tachycardia
• Fulfills criteria for ablation (severe arrhythmia symptoms; for atrial fibrillation patients, having tried at least one antiarrhythmic agent with poor effect)
• Admitted for ablation for the first time
• Has left blood samples for thyroid status (TSH, free T4, free T3)

Exclusion Criteria

• Atrial flutter
• Overt hyperthyroidism

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Prevalence of subclinical hyperthyroidism in patients undergoing atrial fibrillation ablation	1 day (Measured upon inclusion)

Secondary Outcome Measures

Name	Time	Method
Recurrent atrial fibrillation after ablation	6 months

Trial Locations

Locations (2)

Stockholm Arrhythmia Center; 🇸🇪 Stockholm, Sweden

Hjärtkliniken, Karolinska Universitetssjukhuset Huddinge; 🇸🇪 Stockholm, Sweden