Lower Risk for Cardiovascular Disease in Hyperthyroidism with Surgery

Which common treatment method for hyperthyroidism will lower a patient's risk for cardiovascular disease? Authors of a new study sought to find out.

Reference: Essi R, Saara M, Heini H, et al. Cardiovascular morbidity and mortality after treatment of hyperthyroidism with either radioactive iodine or thyroidectomy. Thyroid. 2018;28:1111-1120. 

Ryödi Essi, MD, and fellow researchers in Finland have found that thyroidectomy for hyperthyroidism conveys a lower risk for cardiovascular disease (CVD) than radioactive iodine (RAI) treatment with a state of hypothyroidism predicting the lowest risk of subsequent CVD. Click through the slides for details on their study and take home points for clinical practice.

Hyperthyroidism and CVD. While it is known that hyperthyroidism is associated with an increased risk of CV morbidity and mortality, it is unclear how CV morbidity before and after treatment with RAI or a thryoidectomy is affected by each treatment. Authors of this study sought to determine the impact of both treatment modalities (RAI and thyroidectomy) and treatment outcome on CV morbidity and mortality after treatment. 

The Study. This retrospective, register-based study looked at 6148 hyperthyroid patients treated with either RAI or thyroidectomy and 18 432 matched control subjects that were compared to research subjects. Discharge diagnoses were classified into 10 major subgroups based on CV diagnostic codes and follow-up ended on the date of the first hospitalization due to CVD, date of death, emigration, or common closing date. 

The Results:

  • 16% of patients and 15% of controls died during follow-up
  • By the time treatment began, the risk of CVD hospitalization increased in most CVD subgroups vs controls 
  • Hypertension was the CVD subgroup that was most frequently associated with hospitalization before treatment
  • The second most frequent subgroup had arrhythmias conferring a 5-fold increase in hospitalization pre-treatment
  • Risk of hospital admission due to CVD was higher among RAI-treated patients vs thyroidectomy-treated patients​

Results (continued):

  • Hospitalization risk due to arrhythmias and new-onset AF was higher in RAI-treated patients vs surgically treated patients 
  • No difference seen in overall CVD mortality among all hyperthyroid patients
  • RAI-treated patients had higher CVD mortality rate vs respective controls (p=0.004)
  • CVD mortality among thyroidectomy-treated patients and RAI patients treated to clinical hypothyroidism was comparable to control groups
  • After adjustment, CV mortality was significantly higher in RAI-treated patients vs thyroidectomy-treated patients
  • In Graves disease, risk of death due to any CVD was significantly lower with RAI (resulting in levothyroxine-treated hypothyroidism) than in Graves’ disease patients treated surgically unless they were treated with total thyroidectomy

Take Home Points:

  • Consider patient specific indications and risk posed by potential CV events when considering treatment for hypothyroidism
  • Treatment resulting in hypothyroidism requiring thyroid replacement therapy decreases CVD risk regardless of treatment modality
  • Be vigilant for CVD after hyperthyroid treatment, especially following RAI treatment
  • Goal of therapy is a comprehensive approach to hyperthyroidism including rapid and efficient management and rigorous follow-up for thyroid replacement therapy and CV risk assessment
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