Thyroid problems linked to sudden cardiac death

New research may help experts identify at-risk patients

Thyroid - Female Organs - Human Anatomy

A new predictor may help save lives from sudden cardiac death, according to a study released from the American Heart Association’s journal, Circulation.

Researchers say people with thyroid hormone levels at the higher end of normal range were at a significantly greater risk of dying from sudden cardiac death compared to those with levels at the lower end. During nine year of follow up of over 10,000 patients as part of the Rotterdam Study, Dutch researchers found:

  • People with thyroid hormone levels at the high end of the normal range were 2.5 times more likely to die of sudden cardiac death, compared to patients with levels at the lower end.
  • The 10-year risk of sudden cardiac death was four times greater in patients with higher thyroid levels compared to those with lower levels.
  • The increased risk was present even without the effects of other risk factors including high cholesterol and blood pressure.

Study raises questions about thyroid drugs

“The findings could have broad implications since thyroid hormone drugs are so commonly prescribed,” explained Dr. Vu Nguyen, a cardiologist with the Seton Heart Institute. “Additionally, people with thyroid levels that are still felt to be in the ‘normal’ range had a higher risk for sudden cardiac death. So this begs the question: Are we placing our patients in harm’s way by over-treating with thyroid replacement?”

Almost five percent of Americans have some form of hypothyroidism, or overactive thyroid, according to the National Institutes of Health. Women are more likely than men to have the condition. Thyroid hormones come from the thyroid gland and help regulate nearly all of the body’s organs, including the heart.

Adding to previous research on the thyroid-heart link

Studies have shown the link between abnormal levels of thyroid hormone and cardiovascular disease, but they haven’t established the hormone’s link to sudden cardiac death.

During sudden cardiac death, a person’s normal electrical rhythm malfunctions and causes the heart to stop beating. Past research shows more than half of all cardiovascular deaths stem from sudden cardiac death.

In this newest study, researchers linked the association of thyroid-stimulating hormone and free thyroxine thyroid hormone levels in blood samples with sudden cardiac deaths listed on medical records and death certificates.

So, is it time to stop taking your thyroid meds? No way, says Dr. Nguyen. The study raises some good questions, but needs more research. He says until then, it is too early for patients to discontinue taking their thyroid supplementation, which may be providing significant health benefits. Talk to your doctor if you are concerned about your risks of sudden cardiac arrest.

For more information about heart disease, click here.

Seton is part of Ascension, the nation’s largest Catholic and nonprofit health care system.