Rationale and Design of the IMPROVE Trial: A Multicenter, Randomized, Controlled, Open-label, Blinded-endpoint Trial Assessing the Efficacy of Remote Ischemic Conditioning in Patients Undergoing Off-Pump Coronary Artery Bypass Grafting.

INTRODUCTION: Despite the appearance of off-pump coronary artery bypass grafting (CABG), ischemia-reperfusion injury (IRI) in the perioperative period still arouses concerns of clinicians. Remote ischemic conditioning (RIC) is the process of repeated ischemia and reperfusion in the peripheral vessels, which is proven to reduce IRI in vital organs. However, the effect of RIC in patients undergoing off-pump CABG is still unclear. METHODS: This IMPROVE trial is a national, multicenter, randomized, controlled, open-label, blinded-endpoint clinical trial designed to assess whether RIC intervention can improve short-term prognosis of patients undergoing off-pump CABG. It plans to enroll 648 patients who will be randomly assigned into a RIC group or control group. Patients in the RIC group will receive four cycles of 5 min of pressurization (about 200 mmHg) and 5 min of rest in the 3 days before and 7 days after the surgery. PLANNED OUTCOMES: The primary outcome is the occurrence of major adverse cardiovascular and cerebrovascular events (MACCE) within the 3-month follow-up. MACCE is defined as all-cause death, myocardial infarction, stroke, and coronary revascularization surgery. CLINICAL TRIAL REGISTRATION: NCT06141525 (ClinicalTrials.gov).

Aortic Root Reinforcement Combined with Vascular Grafts Eversion and Built-in Procedure (XJ-Procedure) for Acute Type A Aortic Dissection Surgery.

INTRODUCTION: Current root reinforcement methods for acute type A aortic dissection (ATAAD) risk the tearing of endothelial tissue by sutures. This study proposed a novel technique for aortic root reinforcement and evaluated its effectiveness. METHODS: Patients who diagnosed with ATAAD and had mild to moderate aortic root involvement, combined with aortic arch involvement undergoing Sun's procedure in the First Affiliated Hospital of Xi'an Jiaotong University from January 2020 to December 2021, were retrospectively enrolled. They were divided into two groups according to their surgical procedures of aortic root: continuous aortic root suture group (CARS group) and aortic root reinforcement combined with vascular grafts eversion and built-in procedure (XJ-procedure) group. The 30-day mortality rates and incidence of operation-related complications were evaluated. RESULTS: The study cohort comprised 183 patients, including 114 in the XJ-procedure group. The 30-day mortality rates were 7.2% in the CARS group and 6.9% in the XJ-procedure group (P = 1.000). The incidence of residual aortic root dissection in the XJ-procedure group was lower than that in the CARS group before discharge (1.8% vs. 10.1%, P = 0.028), at 3-month (0% vs. 8.7%, P = 0.002) and 6-month (0% vs. 7.2%, P = 0.007) follow-up. In the CARS group, the incidence of anastomotic pseudoaneurysm was 2.9%, 2.9%, and 2.9% compared with none in the XJ-procedure group before discharge, at 3 and 6 months. The XJ-procedure group also showed less chest tube drainage in the first 24-h after the surgery, with lower incidence of hemodialysis and sepsis during hospitalization. No differences were observed in the incidence of bleeding necessitating reoperation and severe aortic regurgitation between the two groups. CONCLUSIONS: The XJ-procedure did not increase 30-day mortality and effectively reduced the incidence of residual aortic root dissection during the 6-month follow-up. Subsequent studies with larger samples and prolonged follow-up are needed to evaluate it. TRIAL REGISTRATION: NCT05751200. The video showed the partial process of the XJ-procedure in managing the aortic root in the ATAAD surgery. The vascular graft was folded outward about 15 mm, and the eversion was intermittently sutured to the full layers aortic wall using 2-0 pad polyester sutures. Then, the eversion of the graft and aortic wall were continuously sutured in one more turn using 3-0 polypropylene sutures. (XJ-procedure, aortic root reinforcement combined with vascular grafts eversion and built-in procedure; ATAAD, acute type A aortic dissection.). (MP4 297097 kb).

Predicting New-Onset Postoperative Atrial Fibrillation Following Isolated Coronary Artery Bypass Grafting: Development and Validation of a Novel Nomogram.

OBJECTIVE: To select variables associated with new-onset postoperative atrial fibrillation (POAF) following isolated coronary artery bypass grafting (CABG) and develop a nomogram for risk prediction in a Chinese population. METHODS: The study retrospectively enrolled 4854 consecutive patients undergoing isolated CABG from February 2018 to September 2019, they were divided into derivation cohort and validation cohort with a 3:1 ratio according to the order of operation date. In the derivation cohort, significant variables were selected by use of the multivariate logistic backward stepwise regression analysis and a nomogram model was built on the strength of the results. The model performance was assessed in terms of discrimination and calibration. Besides, we compared the discriminative ability for POAF of the nomogram with established prediction models (CHA2DS2-VASc and HATCH scores) in the two cohorts. RESULTS: POAF occurred in 1025 (28.2%) out of 3641 patients in the derivation cohort, and in 337 (27.8%) out of 1213 patients in the validation cohort. A nomogram, composed of eight prognostic variables, namely age, sex, heart rate, hypertension, left ventricular ejection fraction (LVEF) <50%, left atrial diameter (LAD) > 40mm, estimated glomerular filtration rate (eGFR) level, and on-pump surgery, was constructed from the derivation cohort. The nomogram had substantial discriminative ability in derivation and validation cohorts with the area under the receiver operating characteristic curves (AUCs) of 0.661 (95% confidence interval, 0.642-0.681) and 0.665 (95% confidence interval, 0.631-0.699), respectively, and showed well-fitted calibration curves. Compared with CHA2DS2-VASc, HATCH and POAF scores, respectively, the nomogram had superior discrimination performance. CONCLUSION: We constructed a novel nomogram with improved accuracy for predicting the risk of POAF following isolated CABG, which might help clinicians predict individual probability of POAF and achieve effective prophylaxis.

Response of four evergreen savanna shrubs to an incidence of extreme drought: high embolism resistance, branch shedding and maintenance of nonstructural carbohydrates.

Extreme drought events are becoming frequent globally, resulting in widespread plant mortality and forest dieback. Although savanna vegetation cover ~20% of the earth's land area, their responses to extreme drought have been less studied than that of forests. Herein, we quantified branch dieback, individual mortality and the associated physiological responses of four evergreen shrubs (Tarenna depauperate Hutch., Maytenus esquirolii (H. Lév.) C.Y. Cheng, Murraya exotica L., Jasminum nudiflorum Lindl.) in a savanna ecosystem in Southwest China to an incidence of extreme drought during 2019 and 2020. We found that 80-100% of the individuals of these species exhibited branch dieback, whereas individual mortality was only found in T. depauperate (4.5%). All species showed high resistance to stem embolism (P50, water potential at 50% loss of hydraulic conductivity ranged from -5.62 to -8.6 MPa), whereas the stem minimum water potentials reached -7.6 to ca -10.0 MPa during the drought. The low water potential caused high native embolism levels (percentage loss of hydraulic conductivity (PLC) 23-65%) in terminal branches, and the remaining stems maintained 15-35% PLC at the end of the drought. Large within-individual variations in stem vulnerability to embolism were detected, and shedding of vulnerable branches could be a mechanism for shrubs to reduce water and carbon consumption. Overall, the content of total nonstructural carbohydrates (NSC) and their components in the stem were generally comparable to or higher than those in the rainy season in three of the four species. Because the leaves were turgor-less for most time during the drought, high NSC levels during the drought could be due to recycling of NSC from dead branches or translocation from roots. Our results suggest high tolerance of savanna shrub species to extreme drought, which could be facilitated by high embolism resistance in some stems and shedding of vulnerable branches to maintain individual water and carbon balance.

Left Ventricular Structure is Associated with Postoperative Death After Coronary Artery Bypass Grafting in Patients with Heart Failure with Reduced Ejection Fraction.

BACKGROUND: The relationship between abnormal left ventricular (LV) structure and adverse outcomes has been confirmed in diverse patient groups in previous studies. However, it remains uncertain whether LV structure has predictive implications in heart failure with reduced ejection fraction (HFrEF) patients with coronary artery bypass grafting (CABG). METHODS: This study retrospectively enrolled patients who had HFrEF and underwent CABG between January 2013 and July 2019. According to LV hypertrophy (LVH) and LV enlargement (LVE) assessed by echocardiography, patients were classified into four LV structure types: (-)LVH/(-)LVE, (+)LVH/(-)LVE, (-)LVH/(+)LVE, and (+)LVH/(+)LVE. RESULTS: A total of 435 consecutive patients (mean age: 59.4 ± 9.6 years; 14.9% female) were enrolled in the present study. Examined independently, either LVH (p < 0.001) or LVE (p < 0.001) was independently associated with postoperative mortality in multivariate analysis. When LVH and LVE were analyzed in combination, the risk of mortality after CABG was lowest in (-)LVH/(-)LVE and increased with (+)LVH/(-)LVE (odds ratio [OR]: 7.525; 95% confidence interval [CI]: 1.827-30.679, p = 0.004), (-)LVH/(+)LVE (OR: 7.253; 95% CI: 1.950-27.185, p = 0.003), and (+)LVH/(+)LVE (OR: 9.547; 95% CI: 2.726-34.805, p < 0.001), independent of other risk factors. Adding LV structural types to the baseline model gained an incremental effect on the predictive value for postoperative mortality (AUC: baseline model, 0.838 vs baseline model + LV structural types, 0.901, p for comparison = 0.010; category-free net reclassification improvement (NRI): 0.764, p < 0.001; integrated discrimination improvement (IDI): 0.061, p = 0.007). CONCLUSION: LVH and LVE were associated with an increased risk of postoperative mortality after CABG in patients with HFrEF. Categorizing LV structural patterns with LVH and LVE contributes to risk stratification and provides incremental predictive ability. Routine echocardiographic assessment of LVH and LVE is needed in clinical practice.

The number of myocardial infarction segments connected to papillary muscle is associated with the improvement in moderate ischemic mitral regurgitation.

Background: We evaluated whether the number of myocardial infarction (MI) segments connected to the papillary muscle (PM), as assessed using cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE), predicts whether moderate ischemic mitral regurgitation (IMR) improves after isolated coronary artery bypass grafting (CABG) to guide the choice of surgical strategy. Methods: A total of 54 patients diagnosed with coronary heart disease (CHD) complicated with moderate IMR who underwent isolated CABG were selected continuously in this retrospective study at Beijing Anzhen Hospital. All patients underwent preoperative LGE. The patients were divided into the IMR improved group (37 patients) and the unimproved group (17 patients) according to 1-year postoperative echocardiography. The factors associated with no IMR improvement after isolated CABG were analyzed. There was no trial registration and no publication of the study protocol. Results: The number of MI segments connected to PM was an independent risk factor for no IMR improvement after isolated CABG [odds ratio 4.39; 95% confidence interval (CI): 1.93-9.98; P<0.001]. The optimal receiver operating characteristic (ROC) curve cut-off value for no IMR improvement was ≥2 (sensitivity: 82.4%; specificity: 83.8%). Follow-up at 1-5 years (median, 2.8 years) showed that the incidences of major adverse cardiovascular and cerebrovascular events (5.4% vs. 23.5%; P=0.041) and New York Heart Association (NYHA) grade (P=0.026) were higher in the unimproved group. Conclusions: In patients with CHD complicated with moderate IMR, the number of MI segments connected to PM is an independent risk factor for no IMR improvement after isolated CABG. Mitral valve surgery should be performed simultaneously with CABG in patients with ≥2 MI segments connected to the PM.

Risk factors for acute kidney injury following coronary artery bypass graft surgery in a Chinese population and development of a prediction model.

BACKGROUND: Acute kidney injury (AKI) after coronary artery bypass graft (CABG) surgery is associated with significant morbidity and mortality. This retrospective study aimed to establish a risk score for postoperative AKI in a Chinese population. METHODS: A total of 1138 patients undergoing CABG were collected from September 2018 to May 2020 and divided into a derivation and validation cohort. AKI was defined according to the Kidney Disease Improving Global Outcomes (KDIGO) criteria. Multivariable logistic regression analysis was used to determine the independent predictors of AKI, and the predictive ability of the model was determined using a receiver operating characteristic (ROC) curve. RESULTS: The incidence of cardiac surgery-associated acute kidney injury (CSA-AKI) was 24.17%, and 0.53% of AKI patients required dialysis (AKI-D). Among the derivation cohort, multivariable logistic regression showed that age ≥ 70 years, body mass index (BMI) ≥ 25 kg/m2, estimated glomerular filtration rate (eGFR) ≤ 60 mL/min per 1.73 m2, ejection fraction (EF) ≤ 45%, use of statins, red blood cell transfusion, use of adrenaline, intra-aortic balloon pump (IABP) implantation, postoperative low cardiac output syndrome (LCOS) and reoperation for bleeding were independent predictors. The predictive model was scored from 0 to 32 points with three risk categories. The AKI frequencies were as follows: 0-8 points (15.9%), 9-17points (36.5%) and ≥ 18 points (90.4%). The area under of the ROC curve was 0.730 (95% CI: 0.691-0.768) in the derivation cohort. The predictive index had good discrimination in the validation cohort, with an area under the curve of 0.735 (95% CI: 0.655-0.815). The model was well calibrated according to the Hosmer-Lemeshow test (P = 0.372). CONCLUSION: The performance of the prediction model was valid and accurate in predicting KDIGO-AKI after CABG surgery in Chinese patients, and could improve the early prognosis and clinical interventions.

Development and Validation of a Novel Nomogram for Preoperative Prediction of In-Hospital Mortality After Coronary Artery Bypass Grafting Surgery in Heart Failure With Reduced Ejection Fraction.

Background and Aims: Patients with heart failure with reduced ejection fraction (HFrEF) are among the most challenging patients undergoing coronary artery bypass grafting surgery (CABG). Several surgical risk scores are commonly used to predict the risk in patients undergoing CABG. However, these risk scores do not specifically target HFrEF patients. We aim to develop and validate a new nomogram score to predict the risk of in-hospital mortality among HFrEF patients after CABG. Methods: The study retrospectively enrolled 489 patients who had HFrEF and underwent CABG. The outcome was postoperative in-hospital death. About 70% (n = 342) of the patients were randomly constituted a training cohort and the rest (n = 147) made a validation cohort. A multivariable logistic regression model was derived from the training cohort and presented as a nomogram to predict postoperative mortality in patients with HFrEF. The model performance was assessed in terms of discrimination and calibration. Besides, we compared the model with EuroSCORE-2 in terms of discrimination and calibration. Results: Postoperative death occurred in 26 (7.6%) out of 342 patients in the training cohort, and in 10 (6.8%) out of 147 patients in the validation cohort. Eight preoperative factors were associated with postoperative death, including age, critical state, recent myocardial infarction, stroke, left ventricular ejection fraction (LVEF) ≤35%, LV dilatation, increased serum creatinine, and combined surgery. The nomogram achieved good discrimination with C-indexes of 0.889 (95%CI, 0.839-0.938) and 0.899 (95%CI, 0.835-0.963) in predicting the risk of mortality after CABG in the training and validation cohorts, respectively, and showed well-fitted calibration curves in the patients whose predicted mortality probabilities were below 40%. Compared with EuroSCORE-2, the nomogram had significantly higher C-indexes in the training cohort (0.889 vs. 0.762, p = 0.005) as well as the validation cohort (0.899 vs. 0.816, p = 0.039). Besides, the nomogram had better calibration and reclassification than EuroSCORE-2 both in the training and validation cohort. The EuroSCORE-2 underestimated postoperative mortality risk, especially in high-risk patients. Conclusions: The nomogram provides an optimal preoperative estimation of mortality risk after CABG in patients with HFrEF and has the potential to facilitate identifying HFrEF patients at high risk of in-hospital mortality.

Biosensing Near the Exceptional Point Based on Resonant Optical Tunneling Effect.

Inspired by exceptional point (EP) sensing in non-Hermitian systems, in this work, a label-free biosensor for detecting low-concentration analytes is proposed, via a special multilayer structure: a resonant optical tunneling resonator. Due to the square root topology near the exceptional point, a recognized target analyte perturbs the system deviated from the exceptional point, leading to resolvable modes splitting in the transmission spectrum. The performance of the designed sensor is analyzed by the coupled-mode theory and transfer matrix method, separately. Here, the simulation results demonstrate that the obtained sensitivity is 17,120 nm/imaginary part unit of refractive index (IP) and the theoretical detection limit is 4.2 × 10-8 IP (regarding carcinoembryonic antigen (CEA), the minimum detection value is 1.78 ng). Instead of the typical diffusion manner, the liquid sample is loaded by convection, which can considerably improve the efficiency of sample capture and shorten the response time of the sensor. The sketched sensor may find potential application in the fields of biomedical detection, environment protection, and drinking water safety.