Patients with thyrotoxicosis had high hospitalization rates for cardiovascular disease (CVD), and excess CVD mortality persisted for many years after thyroid-ablative treatment in patients who received radioactive iodine who did not become hypothyroid, according to a research summary published in Clinical Thyroidology.
Of note, CVD was not increased in patients who received a thyroidectomy or radioactive iodine treatment who became hypothyroid after radioactive iodine therapy.
Thyrotoxicosis has been associated with an increase in CVD. Investigators in the current study conducted a retrospective register-based study of patients who had been treated for thyrotoxicosis from 1986 through 2007 to assess the long-term cardiovascular and CVD outcomes after radioactive iodine treatment and thyroidectomy treatment (near-total and total).1
The cohort included 4334 patients in the thyroidectomy subgroup and 1814 patients who received radioactive iodine treatment. At the time of treatment, the odds ratio for any CVD was 1.61 in thyrotoxic patients compared with control patients (P <.001).
At about 25 years posttreatment, the adjusted hazard ratio for CVD-related hospitalization was 1.15 (95% CI, 1.09-1.21) vs matched control patients. Mortality resulting from CVD was increased in patients treated with radioactive iodine vs thyroidectomy, after adjusting for confounders and prevalent CVD (hazard ratio, 2.05; 95% CI, 1.69-2.48). However, when radioactive iodine-treated patients who failed to become hypothyroid were eliminated, no significant difference was seen in CVD mortality between thyroidectomy-treated and radioactive iodine-treated patients.
The most important insight of this article, according to the study summary, “is that the risks of CVD morbidity and mortality persist for long after ablative treatment, and it is not so much the treatment modality chosen that determines the risk as it is the efficacy of the treatment in eliminating thyrotoxicosis.”2
1. Essi R, Saara M, Heini H, Matti V, Anssi A, Pia J. Cardiovascular morbidity and mortality after treatment of hyperthyroidism with either radioactive iodine or thyroidectomy. Thyroid. 2018;28(9):1111-1120.
2. Emerson, CH. Therapy-induced hypothyroidism reduces long-term post-treatment cardiovascular morbidity and mortality in Graves’ disease and toxic multinodular goiter. Clin Thyroidol. 2018;30(9):408-411.