Young Lan Kwak

Background/Objectives: Postoperative body temperature abnormalities are common yet underrecognized, and their association with acute kidney injury (AKI) remains unclear. In this study, we aimed to identify early postoperative temperature trajectories and evaluate their associations with AKI. Methods: This retrospective cohort study included 3274 adults undergoing valvular heart surgery with cardiopulmonary bypass. The patients’ temperatures were continuously measured using a pulmonary artery catheter for 12 postoperative hours, and temperature trajectories were identified using data-driven latrend class modeling. The primary outcome was severe AKI (KDIGO stage ≥ 2), and the secondary outcome was non-recovery AKI (≥72 h). Multivariable logistic regression and E-value sensitivity analysis were performed. Results: Four distinct temperature trajectories were identified: Class 1 (32.8%), initial normothermia progressing to mild hyperthermia (37.5–38.0 °C); Class 2 (27.4%), mild hypothermia (36.0–36.5 °C) with rapid normalization; Class 3 (24.4%), stable normothermia; and Class 4 (15.4%), lower-range mild hypothermia (35.5–36.0 °C) with delayed recovery. Severe AKI and non-recovery AKI occurred most frequently in Class 4 patients (15.1% vs. 2.9%, 3.9%, and 4.8% in Classes 1–3, p < 0.001; 15.1% vs. 1.7%, 4.0%, and 4.4%, p < 0.001, respectively). After adjusting for key clinical variables, Class 4 remained independently associated with severe AKI (OR 2.44, 95% CI: 1.69–3.57; E-value 4.33) and non-recovery AKI (OR 2.78, 95% CI: 1.89–4.00; E-value 4.97). Conclusions: Early postoperative temperature trajectories were significantly associated with severe AKI, with the highest risks in patients exhibiting lower-range mild hypothermia with delayed recovery. These findings suggest that early postoperative temperature patterns may be useful for risk stratification for severe AKI after cardiac surgery.

Background: Non-anemic iron deficiency (ID) may be harmful during cardiac surgery with cardiopulmonary bypass. However, its impact on off-pump coronary artery bypass (OPCAB) remains unclear. This study examined the association between non-anemic ID and outcomes following OPCAB. Methods: This single-center retrospective study included non-anemic patients who underwent OPCAB between November 2016 and May 2023. Patients were classified by preoperative ID status, defined as serum ferritin < 100 μg/L or 100–300 μg/L with C-reactive protein > 5 mg/L or transferrin saturation < 20%. The risk of primary outcome, defined as the composite of acute kidney injury, permanent stroke, deep sternal wound infection, hemostatic reoperation, prolonged mechanical ventilation, delirium, myocardial infarction, and 30-day mortality, was compared using multivariable logistic regression. Mediation analysis was performed to determine the indirect effects of non-anemic ID via perioperative red blood cell (RBC) transfusion.Results: Of the 433 non-anemic patients, 229 (52.9%) had ID. The incidence of composite outcome was similar between patients with and without ID (30.1% vs. 22.5%, P = 0.075). ID was not significantly associated with the composite outcome, whereas perioperative transfusion (odds ratio: 2.10, 95% CI [1.17–3.78], P = 0.013) showed significant associations. Perioperative RBC transfusion was more common in patients with ID (25.8% vs. 10.8%, P < 0.001). Mediation analysis suggested that RBC transfusion partially mediated the effect of ID on the composite outcome.Conclusions: Preoperative ID was not associated with adverse outcomes in non-anemic patients who had undergone OPCAB. However, its indirect impact via RBC transfusion warrants further investigation.

Summary: Introduction: Peri‐operative anaemia is a common problem in patients undergoing cardiac surgery. Postoperative anaemia is not well understood relative to pre‐operative anaemia; limited data exist on haemoglobin recovery and mortality after discharge, especially in the era of restrictive transfusion practice. We aimed to investigate the associations of pre‐operative and persistent postoperative anaemia with 1‐year mortality in patients undergoing valvular heart surgery. Methods: We identified patients who had undergone valvular heart surgery and allocated them to one of four groups based on their pre‐operative (haemoglobin ≥ 130 g.l ^‐1 and < 130 g.l ^‐1 in men and ≥ 120 g.l ^‐1 and < 120 g.l ^‐1 in women) and postoperative (measured 2 months after surgery; haemoglobin ≥ 100 g.l ^‐1 and < 100 g.l ^‐1 in both men and women) anaemia status. The four groups were: pre‐ and postoperative non‐anaemia (non‐anaemia–non‐anaemia); pre‐operative anaemia–postoperative non‐anaemia (anaemia–non‐anaemia); pre‐ and postoperative anaemia (anaemia–anaemia); and pre‐operative non‐anaemia–postoperative anaemia (non‐anaemia–anaemia). The primary outcome was 1‐year mortality. Results: Data from 2486 patients were included. Pre‐operative anaemia was diagnosed in 1107 patients (44.5%) and 279 (11.9%) met the diagnostic criteria for persistent anaemia 2 months postoperatively. The overall 1‐year mortality rate was 3.3%. The highest rate was observed in the anaemia–anaemia group (17.8%), followed by the non‐anaemia–anaemia (13.1%), anaemia–non‐anaemia (2.9%) and non‐anaemia–non‐anaemia (0.5%) groups. Multivariable Cox regression analysis showed that the non‐anaemia–anaemia group had the highest risk of 1‐year mortality (adjusted hazard ratio 14.44, 95%CI 4.88–42.69), followed by the anaemia–anaemia group (adjusted hazard ratio 10.94, 95%CI 4.41–27.16). Discussion: Our study highlights the high prevalence of persistent anaemia following valvular heart surgery. Persistent anaemia 2 months postoperatively is associated with an increased risk of 1‐year mortality.

Increased thrombogenicity prohibits favorable ischemic outcomes in coronary artery disease. This study investigated the association between increased maximal amplitude (MA) on thromboelastography (TEG), which reflects high platelet-fibrin clot strength, and 1-year major adverse cardiovascular events (MACE) in patients who underwent isolated multi-vessel off-pump coronary artery bypass surgery (OPCAB). Data from 657 patients were retrospectively analyzed. TEG was performed post-anesthesia induction. MACE was defined as cardiovascular death, repeat revascularization, myocardial infarction, stroke, or rehospitalization due to heart failure. Patients were analyzed by tertiles of MA (mm). Logistic regression analyzed the association between 1-year MACE and MA. The incidence of MACE increased with MA tertiles (1^st: [nd [65.0–70.3]: 9.3%; 3^rd [≥70.3]: 13%; p = 0.013). Logistic regression adjusted for known risk factors for MACE revealed an increased risk of MACE with higher MA tertiles (odds ratio [OR]: 1.99 [95% confidence interval {CI}: 0.92–4.55], p = 0.089 for the 2^nd tertile; OR 2.78 [95% CI: 1.32–6.28], p = 0.010 for the 3^rd tertile). A restricted cubic spline model revealed a linear relationship between MA and 1-year MACE. A 10-mm increase in MA was associated with a two-fold increase in the risk of 1-year MACE. The optimal MA cutoff for predicting MACE was 69.6 (normal range: 50.6–69.4). Increased thrombogenicity, reflected by elevated MA values, was linearly associated with the occurrence of 1-year MACE, highlighting the need for TEG screening and more aggressive, individualized perioperative anticoagulation management in selected patients with increased MA requiring OPCAB.

Background: The prognostic nutritional index (PNI) has been widely used as a nutritional metric in patients undergoing cardiac surgery because of its ability to incorporate both nutritional and inflammatory statuses. However, while preoperative PNI is well-known for its predictability of outcomes after coronary artery bypass grafting (CABG), the prognostic value of postoperative PNI has rarely been evaluated. This study investigated the changes in postoperative PNI values following off-pump coronary artery bypass (OPCAB) surgery using a trajectory analysis method and analyzed its influence on mortality outcomes.Methods: We retrospectively analyzed the data of 983 patients who underwent OPCAB surgery. PNI values from postoperative days 1, 2, 3, and 1 month was analyzed using the trajectory method, and patients were grouped based on the patterns of change in PNI values. The 1-year and overall mortality rates were compared between PNI trajectory groups. Additionally, multivariable logistic regression analysis was performed to identify independent risk factors for 1-year all-cause mortality, and multivariable Cox regression analysis was conducted for overall mortality.Results: The trajectory analysis categorized patients into two groups: the “PNI-improved group,” characterized by a sharp increase in PNI values after surgery, and the “PNI-fixed group,” which exhibited minimal changes in PNI values. The PNI-improved group had significantly lower 1-year mortality (1.1% vs. 9.5%, p < 0.001) and overall mortality (16.9% vs. 42.4%, p < 0.001) compared to the PNI-fixed group. Furthermore, the multivariable regression analysis indicated that the PNI trajectory pattern was an independent predictor of 1-year mortality (odds ratio: 7.931, 95% confidence interval [CI]: 3.117–20.180, p < 0.001) and overall mortality (hazard ratio: 2.120, 95% CI: 1.579–2.845, p < 0.001).Conclusions: Patients who exhibited a significant increase in PNI values during the month following OPCAB surgery experienced significantly lower 1-year and overall mortality rates than those with minimal changes in postoperative PNI values. The PNI recovery pattern was identified as an independent predictor of both 1-year and overall mortality after adjusting confounding factors. Recognizing the recovery patterns of postoperative PNI values after OPCAB surgery may be valuable for screening patients at high risk for mortality.