The Heart and Your Thyroid: What You Need to Know

With Essie Ryodi, MD, and Ravi Dave, MD

If you have hyperthyroidism or Graves’ disease, you know that the excess thyroid hormone produced by an overactive thyroid can speed up your heart as well as affect every other organ in your body, translating to heart palpations and feelings of nervousness and anxiety.

Not only can the extra thyroid hormone make your heart beat faster, experts say, it puts a strain on the heart by pushing it to work harder, too. And raises concerns about your long-term cardiac health should the situation go unchecked. That means you want to be sure to discuss your risk of cardiovascular disease with your doctor, as one treatment: surgery may be linked with less risk than radioactive iodine ablation, or RAI,1 according to findings published in the journal, Thyroid.

With Graves' disease, the right medication is essential to improve heart health.

Cardiovascular Risk is Persists for 20 Years After Thyroid Treatment

"The most important finding is that patients with hyperthyroidism have an increased risk of cardiovascular disease that is sustained up to two decades after good [hyperthyroid] treatment," says lead author Essi Ryodi, MD, a cardiologist at Tempere Heart Hospital in Finland. Also important, she tells EndocrineWeb, is that overall, “those patients treated with surgery fared better than those treated with radioactive iodine ablation (RAI).”

However, she adds that ''the patients treated with RAI more efficiently [so that they become hypothyroid] had a similar risk of CVD compared to patients treated with thyroidectomy, so long as hypothyroidism is achieved,'' so that levothyroxine is needed.

The Finnish team concluded this after taking a two-decade look back at more than 6,000 patients with hyperthyroidism, comparing them with more than 18,000 patients with no thyroid issues. They also compared patients who had their hyperthyroidism corrected by radioactive iodine therapy and those who had their thyroid removed surgically. They looked to see who had the most cardiovascular disease (CVD) risk after treatment.1

"Hyperthyroidism increased cardiovascular morbidity [illnesses] compared to age- and sex-matched controls. The risk [of cardiac outcomes] can be decreased by effective treatment for hyperthyroidism. The results underline the importance of an immediate and efficient management of hyperthyroidism, and an active follow up for cardiovascular risk after the treatment for hyperthyroidism," according to the authors.

In effect, any treatment that renders the patients hypothyroid whether by surgery or fully effective radioactive iodine therapy offers the best chance of lowering cardiovascular risk.1

While several earlier studies have found that risk for cardiovascular problems persists in these patients, Dr. Ryodi says, "our study was the first to compare the risk of CVD between two different [treatments]." So anyone with hyperthyroidism, regardless of the treatment, will also need to keep close tabs on their heart health for quite a while.

Patients Evaluated for Hyperthyroid Disease or Graves’ Thyroiditis  

The researchers identified two groups of patients (15% male and 85% female) treated for their hyperthyroidism over about 20 years.1 The first group included 4,334 men and women treated with surgery (thyroidectomy) in Finland between 1986 and 2007. The second group included 1,814 men and women who had received RAI treatment during the same time period.

The researchers compared these two group to a third group of 18,432 patients who were matched by age and sex to the patients who had a diagnosed with an overproduction of thyroid hormone. The median age (half younger, half older) of the patients at the time they were treated was 49 years old.1

If patients were treated first with RAI and then had surgery, they were analyzed with the surgery group. Those who had surgery first then received RAI therapy were analyzed with the RAI group.

As for patients with Graves’ thyroiditis, only those who received treatment that with RAI that achieved full hypothyroidism requiring levothyroxine supplementation has a lower risk of cardiac death, but the same level of risk for cardiac outcomes overall.1

Regardless of the reason for the hyperthyroidism, the treatment that achieves a hypothyroid state in the patient offers the lowest risk for future CVD, according to Dr. Ryodi.

Finding Trends in Cardiovascular Disease with Hyperthyroidism

Before treatment, those with hyperthyroid symptoms were more likely than those with no thyroid disease to become hospitalized for heart issues—often, very high blood pressure or abnormal heart rhythms, such as atrial fibrillation.1

By the time the patients with hyperthyroidism or thyroiditis were treated, those with thyroid issues were five times more likely to have been admitted to the hospital for cardiac arrhythmias  than the non-hospitalized patients.1

When the researchers looked specifically at the RAI group and surgery group, assessing them separately against the healthy comparison group, both thyroid treatment groups were more likely to have been hospitalized for heart issues.1 Compared to the thyroid patients who showed no signs of cardiovascular disease, the risk of hospitalization for most other cardiac issues was also increased in the RAI patients but not in the surgery patients.

After treatment, the risk of going to the hospital lessened among those receiving thyroid replacement but was still present. People who were not receiving thyroid replacement hormone experienced a greater rate of abnormal heart rhythms and high blood pressure that sent them to the hospital—that was true for those receiving either surgery or RAI, but slightly more likely for those having had radioactive iodine treatment.1

Drilling Down on Risks within the Treated Groups

The researchers wanted to see who were more likely to need hospitalization after treatment—those who had had surgery or those who had received RAI therapy. They reported that those who had RAI were 14% more likely to develop cardiac problems down the road.1 However, this remained true only in those patients who still had an active thyroid.

Next, the researchers looked at death from cardiovascular disease. Overall, there was no difference between the thyroid patients who developed a cardiac condition and the patients in the comparison group.1 When the researchers looked at subgroups by age, they found that the individuals who had RAI had a higher rate of death attributed to CVD as compared to those without thyroid issues.

The difference disappeared, however, when the researchers compared those treated with surgery and those treated effectively with RAI—meaning RAI treatment that resulted in levothyroxine-treated hypothyroidism, the goal of the therapy.1

Tips to Lower Your Risk of Cardiovascular Disease

The finding of the risk persisting is valuable information, Ravi Dave, MD, director of interventional cardiology at UCLA Medical Center, Santa Monica, and professor of medicine at UCLA David Geffen School of Medicine told EndocrineWeb. As Dr. Dave was not involved in the research, he agreed to review the study to offer comment.

Therefore, regardless of whether you opt for surgery or RAI, the goal of treatment must make you fully hypothyroid. As such, "achieving an earlier hypothyroid status portends the best prognosis.," says Dr. Dave. Follow up care with your doctor who might suggest you see a cardiologist, is advised, he adds.

For those who are newly diagnosed with hyperthyroidism or Graves’ thyroiditis, he says there are three points you should keep in mind:

  •  "Know that your risk of heart disease is high and will continue to be so for the next 20 years.
  • After thyroid treatment, any cardiac symptoms will subside but your risk will be lowest if you are fully hypothyroid.
  • The earlier you get treated, the better you will feel."

Dr. Ryodi offers some additional advice to patients with hyperthyroidism or Graves’ thyroiditis:

  • Make certain to have your blood pressure checked regularly; if it rises above140/90 mm/Hg then be sure you follow the treatment.
  • Exercise regularly
  • Follow a heart-healthy diet that including watching your dietary sodium (keeping it low) and eating plenty of fiber-rich (eg, vegetables, fruit, and whole grains).
  • Be aware of your blood cholesterol levels and get high cholesterol under control.
  • If you smoke, quit. Talk to your doctor about what might help you be successful now.

Neither the Finnish researchers nor Dr. Dave have any financial conflicts of interest.

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