Association between preoperative E/e' and early left ventricular systolic recovery after coronary artery bypass grafting

In patients with reduced or mildly reduced ejection fraction, the degree of systolic recovery after coronary artery bypass grafting (CABG) is heterogeneous. We assessed whether routine preoperative transthoracic echocardiography (TTE) indices-particularly E/e'-are associated with early postoperative improvement in left ventricular function.

We retrospectively analyzed patients undergoing isolated CABG at a single tertiary center (April 2019 to July 2025). Eligibility required a preoperative left ventricular ejection fraction (LVEF) of <50%. Emergency/salvage operations, 30-day deaths, and patients without an evaluable early postoperative TTE were excluded. The primary outcome was an absolute increase in the LVEF of ≥10 percentage points. Because of the limited number of outcome events, the primary association analysis used a single-predictor logistic regression model with preoperative E/e'. Sensitivity analyses excluded patients with preoperative atrial fibrillation (AF) and modeled postoperative LVEF as a continuous outcome adjusted for baseline LVEF.

Of 75 otherwise clinically eligible patients, three lacked an evaluable early postoperative TTE, leaving 72 patients for outcome analysis; 17 (23.6%) achieved an LVEF increase of ≥10 percentage points. A higher preoperative E/e' was associated with early LVEF improvement (OR 1.155 per 1-unit increase; 95% CI 1.04-1.28; p = 0.005; N = 66; 16 events). The apparent AUC was 0.700; after 1,000-resample bootstrap internal validation, the estimated optimism was 0.004 and the optimism-corrected AUC was 0.696 (95% bootstrap CI 0.526-0.885). The association persisted after excluding patients with AF (OR 1.14; 95% CI 1.02-1.27; p = 0.025). In a sensitivity analysis using postoperative LVEF as a continuous outcome, E/e' remained associated with postoperative LVEF after adjustment for baseline LVEF (β = 0.31 percentage points per 1-unit increase; 95% CI 0.01-0.61; p = 0.042).

A higher preoperative E/e' was associated with early improvement in LV systolic function after CABG among patients with a preoperative LVEF of <50% who survived to undergo early postoperative echocardiographic assessment. Given the small number of events and the single-center retrospective design, these findings are hypothesis-generating and require external validation.