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Excess triiodothyronine as a risk factor of coronary events
1Medical Clinic 1, Medical University of Lübeck, Ratzeburger Allee 160, D-23538 Lübeck, Germany.
Insights
Elevated triiodothyronine (T3) levels in patients admitted to the hospital are linked to a higher risk of coronary events like angina and myocardial infarction (MI). This thyroid hormone excess may contribute to the development and worsening of acute myocardial ischemia.
Area of Science:
- Cardiology
- Endocrinology
- Thyroid Research
Background:
- Thyrotoxicosis commonly presents with cardiac abnormalities such as arrhythmias and heart failure.
- The specific link between excess thyroid hormone and conditions like angina pectoris and myocardial infarction (MI) requires further investigation.
Purpose of the Study:
- To investigate the association between thyroid function, specifically triiodothyronine (T3) levels, and the occurrence of angina pectoris and myocardial infarction (MI).
- To determine if elevated T3 levels predict future coronary events in patients admitted to the hospital.
Main Methods:
- Thyroid function tests were performed on 1049 patients (aged 40+) upon emergency admission.
- Patients were assessed for angina and MI using current diagnostic criteria.
- A subset of 185 patients initially presenting with angina or acute MI were followed for 3 years to observe subsequent coronary events.
Main Results:
- Patients with elevated serum free and total triiodothyronine (T3) levels showed a significantly higher rate of angina and MI (odds ratio, 2.6; P=.007).
- An elevated free T3 level upon admission was identified as a risk factor for subsequent coronary events over the 3-year follow-up period (adjusted odds ratio, 4.8; P=.02).
Conclusions:
- Elevated serum free T3 levels at hospital admission are associated with a 2.6-fold increased likelihood of a concurrent coronary event.
- An initially elevated T3 level increases the risk of developing a subsequent coronary event by approximately 3-fold over three years.
- Excess T3 appears to be a contributing factor in the development and progression of acute myocardial ischemia.
Background:
Abnormalities in cardiac function, eg, arrhythmias and congestive heart failure, often accompany thyrotoxicosis. A relationship between thyroid hormone excess and the cardiac complications of angina pectoris and myocardial infarction (MI) remains largely speculative.
Methods:
The results of thyroid function studies on blood samples drawn from a total of 1049 patients (aged 40 years or older) immediately on emergency medical admission were related to frequencies of angina pectoris and myocardial infarction as determined according to current diagnostic algorithms. After 3 years, those patients who had initially presented with angina pectoris or acute MI were observed for subsequent coronary events; of these (n=185), 98% of the subjects (n=181) could be reevaluated.
Results:
On hospital admission, the relative rate of angina pectoris and MI was markedly high (odds ratio, 2.6; 95% confidence interval, 1.3-5.2; P=.007) in patients with elevated serum free and total triiodothyronine (T(3)) levels. An initially elevated free T(3) level was a risk factor for subsequent coronary events during the 3-year follow-up (adjusted odds ratio, 4.8; 95% confidence interval, 1.3-17.4; P=.02).
Conclusions:
An elevation of serum free T(3) levels at hospital admission is associated with a 2.6-fold greater likelihood of the presence of a coronary event. Moreover, an initially elevated T(3) level is associated with a 3-fold higher risk of developing a subsequent coronary event during the next 3 years. Excess T(3) seemed to be a factor associated with the development and progression of acute myocardial ischemia.