# Surgical Volume and Outcomes of Intraoperative Transesophageal Echocardiography in Coronary Artery Bypass Graft

## TL;DR

The study finds that using intraoperative transesophageal echocardiography (TEE) during heart surgery improves survival for certain patients at low- and medium-volume hospitals, but not at high-volume hospitals.

## Contribution

The study identifies specific patient subgroups who benefit most from TEE during CABG surgery, depending on hospital surgical volume.

## Key findings

- Intraoperative TEE was associated with survival benefits at low and medium surgical volume hospitals.
- Patients with complex coronary disease or hemodynamic instability benefited most from TEE at low- and medium-volume hospitals.
- No survival benefit from TEE was observed at high-volume hospitals.

## Abstract

This cohort study examines the association of intraoperative transesophageal echocardiography use, 6 patient-level factors, and surgical volume of a hospital with survival outcomes of coronary artery bypass graft (CABG).

Among patients undergoing isolated coronary artery bypass graft (CABG), which subgroups derive the greatest survival benefit from intraoperative transesophageal echocardiography (TEE), and does this benefit vary by hospital surgical volume?

In this cohort study of 1.26 million patients who underwent isolated CABG, intraoperative TEE was associated with survival benefits at low and medium surgical volume hospitals, particularly among patients with greater than 50% left-main coronary stenosis, 3 or more diseased vessels, or preoperative inotrope use. No survival benefit was observed at high surgical volume hospitals.

These findings support a more individualized approach to TEE use during isolated CABG surgery and provide a rationale for future randomized evaluation.

The routine use of intraoperative transesophageal echocardiography (TEE) during coronary artery bypass graft (CABG) surgery remains controversial. Its benefit across different patient populations is unclear.

To identify patient subgroups with the greatest or least likelihood to benefit from intraoperative TEE during CABG, stratified by hospital surgical volume.

This 2-stage, matched retrospective cohort study applied target trial emulation methodologies to the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database (ACSD) to quantify the conditional treatment effect of intraoperative TEE among subpopulations undergoing isolated CABG at low, medium, and high surgical volume hospitals. The study cohort consisted of patients aged 18 years or older who underwent isolated CABG surgery between July 1, 2014, and June 30, 2022. Data analysis was conducted from August 8, 2023, to December 15, 2024.

Receipt of an intraoperative TEE during CABG surgery.

The primary outcome was mortality within 30 days of surgery. Statistical analyses included multivariable logistic regression and multiple TEE vs without TEE matched comparisons stratified by surgical volume and patient subpopulations.

Of 1 266 055 patients who underwent isolated CABG, 963 976 (76.1%) were male, and the mean (SD) age was 65.7 (10.0) years. Among these patients, 61.8% received TEE and 39.0% did not receive TEE. Intraoperative TEE use (vs without TEE) was associated with a significant survival benefit among patients treated at hospitals with low surgical volume (2.47% vs 2.94%; odds ratio [OR], 0.83 [95% CI, 0.78-0.89], P < .001) and medium surgical volume (2.09% vs 2.34%; OR, 0.89 [95% CI, 0.85-0.93], P < .001) but not high surgical volume (1.72% vs 1.77%; OR, 0.97 [95% CI, 0.91-1.03], P = .48). Among patients who underwent isolated CABG at low and medium surgical volume hospitals, TEE provided the greatest survival benefit to subpopulations with greater than 50% (vs ≤50%) left-main coronary stenosis, 3 or more (vs <3) diseased coronaries, and (3) a preoperative inotropic requirement.

In isolated CABG, intraoperative TEE was associated with survival benefit at low- and medium-volume hospitals, particularly in patients with complex coronary disease or hemodynamic instability, but not at high-volume hospitals. These results highlight persistent equipoise and the need for randomized evaluation.