Prognostic impact of thyroid dysfunction in patients with incident heart failure: a nationwide study

Abstract

Abstract Background Thyroid hormones directly affect the cardiovascular system. Thyroid dysfunction can cause a variety of haemodynamic alterations and has been associated with an increased risk of atrial fibrillation (AF), heart failure (HF), and all-cause mortality. However, a paucity remains regarding knowledge on the prognostic impact of thyroid dysfunction in patients with HF. Purpose To examine the impact of the whole spectrum of thyroid dysfunction in patients with HF on the associated risk of AF, HF admissions, and all-cause mortality. Methods This Danish cohort study included patients with a first-time HF diagnosis from 2000–2021. According to blood samples within 6 months prior to the HF diagnosis, the study population was categorized based on thyroid function in 1) overt hypothyroidism, 2) subclinical hypothyroidism, 3) euthyroidism, 4) subclinical hyperthyroidism, and 5) overt hyperthyroidism. With up to one year of follow-up from the date of HF diagnosis, we used Aalen-Johansen estimator to examine the cumulative incidence frequency (CIF) of AF and HF admissions and Kaplan-Meier estimates to assess all-cause mortality. Multivariable Cox proportional hazard analysis was performed to investigate differences in outcomes among groups. Results Of the 7,380 individuals included in this study (56.6% female, median age 76.5 years [p25-p75: 67.9-84.1]), 102 (1.4%) had overt hypothyroidism, 1,706 (23.1%) had subclinical hypothyroidism, 4,374 (59.3%) were euthyroid, 691 (9.4%) had subclinical hyperthyroidism, and 507 (6.9%) had overt hyperthyroidism. Compared with euthyroid patients, the adjusted one-year hazard ratio (HR) for AF was 0.77 (95% CI, 0.49-1.20) for overt hypothyroidism, 1.01 (95% CI, 0.90-1.13) for subclinical hypothyroidism, 1.18 (95% CI, 1.01-1.38) for subclinical hyperthyroidism, and 1.19 (95% CI, 1.01-1.39) for overt hyperthyroidism (Figure). The adjusted one-year HR for HF hospitalizations was 1.51 (95% CI, 1.06-2.14) in patients with overt hypothyroidism, 1.07 (95% CI, 0.96-1.20) in patients with subclinical hypothyroidism, 0.99 (95% CI, 0.84-1.16) in patients with subclinical hyperthyroidism, and 1.26 (95% CI, 1.06-1.50) in patients with overt hyperthyroidism. The adjusted one-year HR for mortality was 1.81 (95% CI, 1.25-2.63) in patients with overt hypothyroidism, 1.25 (95% CI, 1.10-1.42) in patients with subclinical hypothyroidism, 1.15 (95% CI, 0.96-1.37) in patients with subclinical hyperthyroidism, and 1.46 (95% CI, 1.20-1.78) in patients with overt hyperthyroidism. Conclusion In patients with HF, overt and subclinical hyperthyroidism was associated with an increased rate of AF. Both hypo and hyperthyroid states were associated with increased risk of HF admission and mortality. Increased awareness regarding thyroid status in patients with HF is warranted.