This article is more than 5 years old. Information may no longer be current.
Abnormal thyroid function independently predicted mortality in HF
Click Here to Manage Email Alerts
The relative risk for death increased by 60% for patients in the SCD-HeFT study who had moderately symptomatic HF and abnormal thyroid function.
The increased mortality risk was present in both hypothyroid and hyperthyroid states and persisted even after controlling for known mortality predictors, according to substudy data.
Researchers for SCD-HeFT randomly assigned patients with ischemic/nonischemic HF to amiodarone, implantable cardioverter defibrillator therapy or placebo. Levels of thyroid-stimulating hormone were measured at baseline and every 6 months during the 5-year study.
Of 2,225 patients included in the substudy, 87% had normal thyroid-stimulating hormone (TSH) levels of 0.3 mcU/mL to 5 mcU/mL at baseline, 12% had levels consistent with hypothyroidism and 1% had levels consistent with hyperthyroidism, according to the study abstract in JACC Heart Failure. Patients with hypothyroidism at baseline were more likely to be older, female and white, compared with euthyroid patients.
During follow-up, 89 baseline euthyroid patients developed abnormally low TSH levels and 341 developed abnormally high levels.
Amiodarone (mean dose, 300 mg) was associated with greater risk for developing abnormal TSH levels when compared with ICD therapy or placebo (P<.0001).
“Importantly, the benefits experienced by patients with ICDs were not affected by thyroid dysfunction,” the researchers wrote.
Mortality was higher for patients with baseline or new-onset abnormal thyroid function, compared with patients with normal thyroid function (hypothyroid: HR=1.58; 95% CI, 1.29-1.94 and hyperthyroid: HR=1.85; 95% CI, 1.21-2.83).
Judith E. Mitchell, MD, of SUNY Downstate Medical Center, and colleagues concluded: “Abnormal thyroid function in patients with symptomatic HF and ejection fractions ≥35% is associated with significantly increased risk for death, even after controlling for known mortality predictors.”
“The present findings of increased risk for mortality and a high prevalence of thyroid abnormalities with the use of amiodarone can be combined with other findings of increased adverse outcomes associated with thyroid abnormalities to influence and diagnosis and treatment of thyroid disease. …Clinicians should continue to measure TSH and [free thyroxine] in patients with symptoms compatible with thyroid disease … symptoms often found in those with HF. They should also be measured in patients at increased risk for thyroid abnormalities, including those using amiodarone, and in those with illnesses that may not tolerate thyroid abnormalities, including those with HF,” Steven Goldman, MD, of Tucson VA Hospital, Steven Thomson, MD, of Southern Arizona VA Medical Center, and Madeline McCarren, PhD, MPH, of Pharmacy Benefits Management Services, Department of Veterans Affairs, Hines, Ill., wrote in an accompanying editorial.
For more information:
Goldman S. JACC Heart Fail. 2013;1:56-57.
Mitchell JE. JACC Heart Fail. 2013;1:48-55.
Disclosure: See the study for a full list of relevant financial disclosures. Goldman, McCarren and Thomson report no relevant financial disclosures.