# Subclinical Hypothyroidism as a Risk for Coronary Artery Bypass Grafting

## TL;DR

This study finds that subclinical hypothyroidism increases the risk of heart surgery complications and adverse cardiovascular events after coronary artery bypass grafting.

## Contribution

The study provides new evidence linking subclinical hypothyroidism to worse outcomes following CABG surgery.

## Key findings

- SH patients had higher rates of MACE and postoperative complications like atrial fibrillation and pleural effusion.
- SH was associated with increased stroke risk but not with all-cause death or myocardial infarction.
- No significant difference in mediastinitis incidence was observed between SH and euthyroid patients.

## Abstract

The relationship between hypothyroidism and cardiovascular disease is well established. However, data on subclinical hypothyroidism (SH) and its impact on major adverse cardiovascular events (MACEs) and postoperative complications following coronary artery bypass grafting (CABG) remain limited. This study was aimed at evaluating whether SH is associated with an increased risk of these outcomes.

From 2010 to 2019, 863 patients who underwent CABG for cardiovascular diseases at a reference center were included. The primary outcomes included MACE (composite and individual events: all‐cause death, cardiovascular death, stroke, acute myocardial infarction [AMI], and new revascularization) and postoperative complications, including atrial fibrillation (AF), pleural effusion (PLE), pericardial effusion (PCE), infections at any site (IASs), and mediastinitis.

SH patients had higher rates of MACE (20.3% vs. 8.2%, p = 0.001), MACE 4p (22.0% vs. 12.9%, p = 0.002), and stroke (10.2% vs. 3.0%, p = 0.013) than those of euthyroid patients. No significant differences were observed in all‐cause death, cardiovascular death, AMI, or new revascularization. Postoperative complications were also more frequent in the SH group: AF (18.6% vs. 9.7%, p = 0.043), PLE (52.6% vs. 19.2%, p < 0.0001), PCE (20.3% vs. 7.8%, p = 0.03), and IAS (28.8% vs. 16.9%, p = 0.032). However, no significant difference was noted in the incidence of mediastinitis.

SH patients who underwent CABG had a higher frequency of MACE and postoperative complications than those of euthyroid patients.