- A retrospective cohort study from Denmark suggests that levothyroxine (L-T4) therapy is associated with increased risk for all-cause mortality, cardiovascular death, and major adverse cardiovascular events (MACE) in hypothyroid patients with heart failure (HF).
- Risk for myocardial infarction (MI) was higher with ongoing treatment, lower with incident use.
Why this matters
- Relative benefits of L-T4 treatment in HF remains controversial.
- Ongoing L-T4 treatment at baseline was associated with increased risk for all-cause mortality (incidence rate ratio [IRR], 1.25; 95% CI, 1.21-1.29), cardiovascular death (IRR, 1.23; 95% CI, 1.18-1.27), and MACE (IRR, 1.26; 95% CI, 1.22-1.31).
- L-T4 initiated during follow-up was tied to increased risk for all-cause mortality (IRR, 1.13; 95% CI, 1.10-1.16), cardiovascular death (IRR, 1.11; 95% CI, 1.08-1.15), and MACE (IRR, 1.05; 95% CI, 1.02-1.09).
- Increased risk for MI (IRR 1.32; 95% CI, 1.23-1.41) was observed with ongoing treatment; reduced risk (IRR 0.87; 95% CI, 0.81-0.93) was observed with incident treatment.
- 224,670 patients with HF from Danish comprehensive healthcare usage registers; 6560 received L-T4 at baseline and 9007 initiated L-T4 during follow-up.
- Funding: The Music publishers Agnes and Knut Mørks Foundation; FUKAP.
- Retrospective study design.
- Lack of some clinical information in database.