According to a new study, patients taking medicines to treat hypothyroidism can be treated with excessive medication leading to increased risk of atrial fibrillation, a common cardiac arrhythmias associated with stroke.
The results were presented by researchers from the Intermountain Medical Center Heart Institute in Salt Lake City at the American Heart Association Scientific Session Conference in Chicago.
"We know that patients with hypothyroidism have a higher risk of atrial fibrillation, but we did not consider increased risk within what is considered the normal area of thyroid hormones. These results indicate that we may want to rethink what we usually call." Says lead researcher Jeffrey L. Anderson.
For the study, researchers examined the electronic records for 174,914 patients treated at Intermountain Healthcare facilities whose free thyroxine levels (fT4) were registered and were not on anti-thyroid drugs. Researchers then took what was considered a normal range of fT4 levels, divided into four quarters and then looked at the patients' records for a current or future diagnosis of atrial fibrillation.
They found a 40 percent increase in existing atrial fibrillation for patients in the highest quartile of fT4 levels compared with patients at the lowest and a 16 percent increase in new developing atrial fibrillation during 3 years of follow-up.
These results indicate that the optimal healthy range of fT4 should be reassessed and redefined, according to Dr Anderson.
"Thyroid hormones are associated with losing weight and having more energy, which can lead to people being treated in the high part of the normal range. Do we harm people by giving them a higher risk of atrial fibrillation and thus stroke?" Sa Dr Anderson.
The study also showed that fT4 should be measured, along with thyroid stimulating hormone (TSH), which is usually tested in patients with irregular thyroid hormone levels but was not helpful in the normal range of refining risk.
"The next step for researchers is to conduct a randomized study to see whether targeting a lower to a higher upper range of fT4 in patients treating thyroid hormone replacement therapy leads to a lower risk of atrial fibrillation and stroke along with other possible heart related problems such as atherosclerosis, "said Dr. Anderson.
Published: November 11, 2018, 14:01