The Subclinical Hypothyroid State might Predict 30 Day Readmission in Patients with an Acute Heart Failure Syndrome and Reduced Left Ventricular Ejection Fraction.

Abstract

Introduction Thyroid hormone has an essential role on the functional capability of cardiac muscle with its gene modulation and induction of vasodilatory effects. There is a considerable evidence to suggest the role of thyroid hormone in acute coronary syndrome (ACS) patients but less is known about its prognostic role in heart failure (HF) patients. We aim to evaluate the association between the subclinical hypothyroid state and event rates including 30-day all-cause and HF readmission in patients with an index hospitalization for an acute HF syndrome (AHFS). Methods A retrospective chart review analysis of 1,020 patients, who were admitted to Bronx-Care Hospital Center with the diagnosis of an AHFS was conducted. We reviewed cases from January 1, 2012 to December 31, 2017. The subclinical hypothyroid state was defined as thyroid stimulating hormone (TSH) level>4.50 mIU/L with a normal thyroxine (T4) level. Subjects with preexisting thyroid disease or receiving thyroid replacement therapy were excluded. HF with preserved ejection fraction (HFpEF) was defined as left ventricular ejection fraction (LVEF)>40% and HF with reduced ejection fraction (HFrEF) was defined as having LVEF≤40%. Percentage of 30-day all-cause readmission and mortality was calculated in both cohorts of AHFS (HFpEF and HFrEF) with and without subclinical hypothyroidism. Results The mean age of our 1,020 AHFS population was 66 ± 15.1 years. Of 1,020 patients admitted with AHFS, 635 (63%) patients were found to have HFrEF and 385 with HFpEF(37%). There were 64 (6.27%) patients with AHFS found to have subclinical hypothyroidism. There were more males than females (52% versus 48%). The percentage of hospital readmission within 30 days was higher for patients with subclinical hypothyroidism compared to those without subclinical hypothyroidism in the HFrEF group (42.9% versus 27.2%, P = 0.029). Hospital readmission within 30 days for patients with subclinical hypothyroidism compared to those without subclinical hypothyroidism in HFpEF group did not differ (30% versus 22%, P = 0.675). Additionally, all-cause mortality was higher among patients with subclinical hypothyroidism compared to patients without subclinical hypothyroidism in the HFrEF group (20% versus 6.0%, P Conclusion Subclinical hypothyroidism during an index hospital admission for an AHFS was an independent predictor of readmission in 30 days in patients with HFrEF but not in patients with HFpEF. It is also related to an adverse outcome such as all-cause mortality. Further studies regarding the concept of tissue thyroid and the potential for a therapeutic target are warranted.