The thyroid-heart axis-hormone dynamics and outcomes in cardiogenic shock following myocardial infarction

Thyroid hormone alterations are common in critical illness and may reflect disease severity. Their prognostic significance in infarct-related cardiogenic shock remains incompletely defined.

In this prospective cohort study from a cardiogenic shock registry, 41 patients with acute myocardial infarction complicated by cardiogenic shock underwent serial measurements of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), and free thyroxine (fT4) at baseline and 24, 48, 72, and 96 h after percutaneous coronary intervention. Associations between hormone trajectories and in-hospital mortality were assessed using longitudinal and small-sample-robust methods.

Thyroid trajectories diverged by outcome. Survivors maintained higher TSH concentrations over time, whereas non-survivors showed progressive suppression. fT3 declined in both groups early after presentation, with a steeper overall decline in non-survivors and outcome separation becoming most apparent later in the observation period. Lower fT3 was associated with greater illness severity and higher mortality risk. fT4 decreased over time in both groups without consistent between-group differences.

In conclusion, dynamic alterations in thyroid hormone levels, particularly reductions in fT3, were associated with greater illness severity and adverse outcomes in cardiogenic shock. Serial thyroid function assessment may improve risk stratification in acute cardiovascular critical illness and warrants further evaluation in larger prospective studies.