Of these, 8881 participants had serum TSH values in the reference range of 0.4 to 4.4 mIU/L. Medical records and death certificates were the source of information regarding the diagnosis of sudden cardiac death. Baseline evaluations included a physical examination, electrocardiogram, a panel of laboratory measurements, and a detailed history.
The 10,318 study participants were followed for a maximum of 21.2 years, with an average follow-up of 9.2 years. There were 261 cases of sudden cardiac death. In the entire group, higher levels of FT4 were associated with an 87% increase in the risk of sudden cardiac death. In euthyroid participants, higher levels of FT4 were associated with a >2-fold risk of sudden cardiac death. In euthyroid participants, the 10-year risk for sudden cardiac death increased from 1% to almost 4% with increasing FT4 values.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
In subjects 45 years of age or older at baseline who are euthyroid by conventional criteria, higher FT4 levels at baseline are associated with an increased occurrence of sudden cardiac death over the next decade. However, this study demonstrates only an association and not a cause and effect. Further, there is nothing in this study that would suggest any therapy would be indicated. Additional clinical trials are also needed to confirm these results.
— Alan P. Farwell, MD, FACE
ATA THYROID BROCHURE LINKS
Hyperthyroidism (Overactive): http://www.thyroid.org/ hyperthyroidism/
Graves’ Disease: http://www.thyroid.org/graves-disease/
Thyroid Function Tests: http://www.thyroid.org/ thyroid-function-tests/