Cardiac magnetic resonance imaging assessment of Del Nido versus cold blood cardioplegia in patients with low ejection fraction undergoing combined coronary artery bypass graft and mitral valve replacement: Early outcomes

Background: This study aimed to compare the effects of Del Nido cardioplegia (DNC) and conventional cold blood cardioplegia (CBC) on early myocardial functional recovery, as assessed by cardiac magnetic resonance imaging, in patients with reduced ejection fraction undergoing concomitant coronary artery bypass grafting (CABG) and mitral valve replacement (MVR). Methods: This single-center prospective study was conducted between April 2024 and January 2025 and included 42 patients with a left ventricular ejection fraction (LVEF) <45% who underwent concomitant CABG and MVR. The mean age was 62.2±10.6 years, and 69.0% (n=29) of the patients were male. Patients were divided into two groups according to the myocardial protection strategy used: CBC (n=23) and DNC (n=19). Preoperative demographic, laboratory, and echocardiographic data were collected, and CMR was performed approximately 1 week before surgery to establish baseline values. Intraoperative parameters, postoperative clinical, laboratory, and echocardiographic findings as well as follow-up CMR findings obtained 1 month postoperatively were analyzed and compared between the groups. Results: The aortic cross-clamp time was significantly longer in the DNC group than in the CBC group (p=0.016), whereas the total volume of infused cardioplegia was comparable between the groups (p=0.323). Intraoperative blood transfusion requirements were significantly higher in the DNC group (p=0.013). Regarding myocardial recovery, the DNC group demonstrated superior biventricular improvement. Significant reductions in left ventricular end-diastolic volume (p<0.001) and end-systolic volume (p<0.001) indicated pronounced reverse remodeling and were accompanied by a modest increase in LVEF (p=0.046). Similarly, postoperative right ventricular (RV) function was significantly better in the DNC group (p=0.026), with a significant decrease in the RV end-systolic volume index (p=0.025), reflecting improved systolic emptying. Although in-hospital mortality was numerically higher in the DNC group (31.6% vs. 8.7%), the difference was not statistically significant (p=0.112). Importantly, all deaths were associated with refractory low cardiac output syndrome during the postoperative intensive care unit stay. Conclusion: CMR findings suggest that DNC may be a safe and effective myocardial protection strategy in patients with reduced LVEF undergoing CABG and MVR. Furthermore, DNC appeared superior to CBC in promoting early biventricular reverse remodeling in this study population. The higher mortality observed in the DNC group may be attributable to the small sample size, longer cross-clamp times, greater operative complexity, and potential selection bias.