Subclinical hypothyroidism associated with adverse cardiac outcomes
New research from the University of Pennsylvania shows that patients with severe heart failure have higher levels of thyroid hormones, which can be responsible for causing atrial fibrillation.
The study was presented April 2 at ENDO 2017, the annual meeting hosted by the Endocrine Society in Orlando. The research was led by Lakshmi Kannan, MD, a fellow at the university.
Her study examined more than 1,300 patients who were enrolled in prior research and had pre-existing moderate-to-advanced heart failure. They examined the associations between thyroid disorders and the risk of ventricular assist device placement, heart transplantation and death in the patients.
On average, the patients were 57 years old and 35 percent of them were women. More than 150 of them were taking amiodarone and 174 were taking levothyroxine. Data also showed that less than 1 percent of them were overtly hypothyroid, 6 percent were subclinically hypothyroid, 88 percent were euthyroid, 5 percent were subclinically hyperthyroid and 1 percent were overtly hyperthyroid.
"Our results indicate that having subclinical hypothyroidism, a mild decrease in thyroid function, is associated with increased likelihood of needing mechanical assistance to the heart with devices, heart transplantation or death," Kannan said in a statement. "We also found that blood tests commonly performed to assess thyroid function, including thyroid stimulating hormone (TSH) levels and two distinct thyroid hormones called thyroxine (T4) and triiodothyronine (T3), are associated with the severity of heart failure.”
Results from the study showed that in patients with pre-existing heart failure, higher TSH and T4, and lower T3 levels were linked with more severe cases of heart failure. In contrast, patients who only had higher levels of T4 were linked with a greater chance of developing atrial fibrillation.
"Heart failure is the leading cause of hospitalization in the United States, and when it is unable to be managed with medications, may require heart transplantation or lead to death," Kannan said. "Further studies are needed to evaluate risks and benefits of thyroid hormone replacement in heart failure patients with mild thyroid disorders."
Senior Writer
As a Senior Writer for TriMed Media Group, Katherine primarily focuses on producing news stories, Q&As and features for Cardiovascular Business. She reports on several facets of the cardiology industry, including emerging technology, new clinical trials and findings, and quality initiatives among providers. She is based out of TriMed's Chicago office and holds a bachelor's degree in journalism from Columbia College Chicago. Her work has appeared in Modern Healthcare, Crain's Chicago Business and The Detroit News. She joined TriMed in 2016.