The anemia conundrum in contemporary redo cardiac surgery

Abstract

Abstract Aims Preoperative anemia has been associated with increased morbidity and mortality after cardiac surgery, but little is known on its prognostic value in the setting of redo procedure. This study aimed to investigate whether preoperative anemia is an independent determinant of adverse events in this augmented risk patients subset. Methods A retrospective, observational, cohort study of prospectively collected data was undertaken on 409 consecutive patients referred for redo cardiac procedures between January 2011 and December 2020 (mean age of 62 ± 12.7 years, octogenarians 5.6%, female sex 52.8%, diabetes 19.5%, chronic kidney disease 30%, urgent/emergent status 34.8%, third-time sternotomy 9.8%). The EuroSCORE II calculated an average mortality risk of 25.7 ± 15.4%. The prevalence of preoperative anemia (according to World Health Organization definition) and its relationships with postoperative morbidity were obtained. Selection bias was assessed with propensity-adjustment method. Results The prevalence of preoperative anemia was 41%. In unmatched analysis, significant differences between the anemic and non-anemic group emerged in the risk of postoperative stroke (0.6% vs 4.4%, p = 0.023), postoperative renal dysfunction (29,7% vs 15.6%, p = 0.001), need for prolonged ventilation (18.1% vs 7.2%, p = 0.002), high dosage inotropes (53.1% vs 32.9%, p < 0.001) along with both length of ICU and hospital stay (8.2±15.9 vs 4.3±5.4 days, p=0.003 and 18.8±17.4 vs 14.9±11.1, p=0.012 ). After propensity matching (143 pairs), preoperative anemia was still significantly associated with postoperative renal dysfunction, stroke and need for high dosage inotropes cardiac morbidity. Anemia proved also a significant predictor of acute kidney injury at univariate analysis. Conclusions Preoperative anemia is significantly associated with acute kidney injury, stroke and need for high dosage inotropes in patients referred for redo procedures. Further studies are warranted to determine whether preoperative low hemoglobin concentration is a marker of severity of illness or a modifiable risk factor.