Heart failure phenotype and postoperative outcomes following coronary artery bypass grafting

Background

Heart failure (HF) increases postoperative morbidity and mortality after coronary artery bypass grafting (CABG). Heart failure with mildly reduced ejection fraction (HFmrEF) is a "gray zone" phenotype frequently underrepresented in clinical trials.

Purpose

To address the uncertainties in perioperative management in this patient population. We hypothesized that HFmrEF is not associated with a lower postoperative risk compared with HFrEF.

Methods

This retrospective observational cohort study included consecutive patients who underwent isolated CABG at our clinic from July to December 2024. Patients were classified as HFrEF or HFmrEF per 2021 ESC HF Guidelines. Exclusion criteria included patients with previous cardiac surgery, concomitant procedures, end-stage renal disease, hemodynamic instability and acute coronary syndrome. The primary endpoint was 1-year 4-point MACE (4P-MACE: cardiovascular death, HF hospitalization, nonfatal myocardial infarction, or nonfatal stroke). Secondary outcomes were ICU and hospital length of stay, mechanical ventilation duration, and prolonged inotropic support (≥24 h). One-year follow-up was obtained via structured telephone interview. Group comparisons were performed using the Mann-Whitney U test, or χ² test, and multivariable logistic regression was used to identify independent predictors. The study protocol was approved by the Institutional Ethics Committee.

Results

A total of 235 patients were included, of whom 157 (66.8%) had HFrEF and 78 (33.2%) had HFmrEF. HFrEF patients had higher EuroSCORE II values and more frequent preoperative loop-diuretic use (p = 0.003 and p <0.001). Fewer than 40% of patients were treated with all four GDMT pillars, preoperatively, increasing to ≈95% at discharge.

4P-MACE occurred in 31 patients (13.2%) and did not differ between HFrEF and HFmrEF (14.0% vs 11.5%, p = 0.598). HF phenotype was not independently associated with 4P-MACE after adjustment for age, sex, renal function, diabetes, and atrial fibrillation (OR 0.78, 95% CI 0.33-1.84, p = 0.57). Findings were similar after adding EuroSCORE II.

ICU stay was ≤1 day in >50% of patients, but prolonged ICU stays were more frequent in HFmrEF (p = 0.033). Hospital length of stay (p = 0.98) and mechanical ventilation duration were similar. Prolonged inotropic support occurred in 41% of HFrEF and 34% of HFmrEF (OR 0.75, 95% CI 0.43-1.31, p = 0.316). Postoperative atrial fibrillation occurred in 57 patients (p = 0.11). Increasing age was the only independent predictor (OR 1.07 per year, 95% CI 1.02-1.12, p = 0.004). Acute kidney injury occurred in 32 patients and was comparable between groups (p = 0.27).

Conclusion

HF phenotype was not associated with differences in postoperative outcomes after CABG. HFmrEF patients have demonstrated a perioperative and postoperative risk comparable to HFrEF group. Based on the data obtained, HFmrEF should not be regarded as a benign HF phenotype in the surgical setting.For image description, please refer to the figure legend and surrounding text.For image description, please refer to the figure legend and surrounding text.