The Effect of Over-and-undertreatment of Hypothyroidism on Hospitalization Outcomes of Patients with Decompensated Heart Failure

Background:
Hypothyroidism has profound effects on cardiac function, however, the effect of over- and undertreatment of hypothyroidism on hospitalization outcomes of patients with acute exacerbation of heart failure (HF) has not been evaluated yet.

Methods:
We conducted retrospective cohort analyses of outcomes among 231 consecutive patients with treated hypothyroidism who were admitted to the internal medicine departments of Shamir Medical Center with HF from 2011 to 2019. Patients were divided into three groups according to their TSH levels. The main outcomes were functional deterioration, in-hospital mortality, and recurrent hospitalization within three months.

Results:
Among 231 patients, 106 were euthyroid, 14 were overtreated, and 111 were undertreated. Patients’ mean age was 79.8±9.4 years. In-hospital mortality occurred in 4.7% in euthyroid patients, 14.3% in the overtreated group, and 10.7% in the undertreated group (p= 0.183). Differences in 30- and 90-days mortality or functional deterioration were not significantly different. However, in patients with extreme values of TSH (<0.4mIU/L or >10mIU/L), there was a higher 90 days mortality rate (30.4% vs 15.1%, p=0.016), as compared to patients with normal or mildly increased TSH (0.4-10 mIU/L).

Conclusion:
Our results show that mild under- or overtreatment of hypothyroidism did not have a significant detrimental effect on mortality, functional deterioration, or rehospitalization of patients with acute decompensated HF. However, significant over- and undertreatment do cause adverse hospitalization outcomes. Larger cohorts are needed to establish the relationship between treatment targets and hospitalization outcomes of patients who are at risk for decompensation of HF.