Non-invasive Ischaemia Testing in Patients With Prior Coronary Artery Bypass Graft Surgery: Technical Challenges, Limitations, and Future Directions

Coronary artery bypass graft (CABG) surgery effectively relieves symptoms and improves outcomes. However, patients undergoing CABG surgery typically have advanced coronary atherosclerotic disease and remain at high risk for symptom recurrence and adverse events. Functional non-invasive testing for ischaemia is commonly used as a gatekeeper for invasive coronary and graft angiography, and for guiding subsequent revascularisation decisions. However, performing and interpreting non-invasive ischaemia testing in patients post CABG is challenging, irrespective of the imaging modality used. Multiple factors including advanced multi-vessel native vessel disease, variability in coronary hemodynamics post-surgery, differences in graft lengths and vasomotor properties, and complex myocardial scar morphology are only some of the pathophysiological mechanisms that complicate ischaemia evaluation in this patient population. Systematic assessment of the impact of these challenges in relation to each imaging modality may help optimize diagnostic test selection by incorporating clinical information and individual patient characteristics. At the same time, recent technological advances in cardiac imaging including improvements in image quality, wider availability of quantitative techniques for measuring myocardial blood flow and the introduction of artificial intelligence-based approaches for image analysis offer the opportunity to re-evaluate the value of ischaemia testing, providing new insights into the pathophysiological processes that determine outcomes in this patient population.

Performance of a Novel Risk Model for Deep Sternal Wound Infection after Coronary Artery Bypass Grafting

Clinical prediction models for deep sternal wound infections (DSWI) after coronary artery bypass graft (CABG) surgery exist, although they have a poor impact in external validation studies. We developed and validated a new predictive model for 30-day DSWI after CABG (REPINF) and compared it with the Society of Thoracic Surgeons model (STS). The REPINF model was created through a multicenter cohort of adults undergoing CABG surgery (REPLICCAR II Study) database, using least absolute shrinkage and selection operator (LASSO) logistic regression, internally and externally validated comparing discrimination, calibration in-the-large (CL), net reclassification improvement (NRI) and integrated discrimination improvement (IDI), trained between the new model and the STS PredDeep, a validated model for DSWI after cardiac surgery. In the validation data, c-index = 0.83 (95% CI 0.72–0.95). Compared to the STS PredDeep, predictions improved by 6.5% (IDI). However, both STS and REPINF had limited calibration. Different populations require independent scoring systems to achieve the best predictive effect. As the STS, the REPINF external validation across multiple centers it’s important to guide healthcare professionals as a quality improvement tool in the prevention of DSWI after CABG surgery.

The Effect of Acute Kidney Injury on TGF-β1 and Smad3 in Patients with Coronary Heart Disease after Off-Pump Coronary Artery Bypass Grafting

Background. Acute kidney injury (AKI) is one of the most common and serious complications for coronary disease (CAD) patients, suffering from coronary artery bypass surgery (CABG). AKI occurs in nearly 30% of cardiac surgery patients, including CABG patients, affecting renal function, prolonging hospitalization time, and increasing all-cause mortality. TGF-β1 and Smad3 are sensitive biomarkers in evaluating kidney function. Therefore, comparing the TGF-β1 and Smad3 levels between the AKI patients and non-AKI patients after CABG surgery might have an important significance for identifying the risk degree of AKI and applying effective preventive measures after CABG surgery. Objective. This study aims at comparing the TGF-β1 and Smad3 levels between the AKI patients and non-AKI patients after CABG surgery to identify the risk degree of AKI and apply effective preventive measures after CABG surgery in clinics. Materials and Methods. A total of 25 proper patients, diagnosed as coronary disease (CAD) and undergoing AKI after CABG, were selected as the AKI group. The 25 participants, who did not suffer from AKI after CABG, were recruited using the case-control matching method in SPSS 25.0 software as the non-AKI group. Also, corresponding surgical specimens (tissues) and samples of blood were collected from them. Histopathological analysis and immunofluorescent microscopy of lesion artery and kidney of patients, who have been treated with kidney transplants, were performed on surgical specimens to find the pathological and histological change difference between the two groups. RT-PCR and Western blot were conducted to quantify the levels of TGF-β1 and Smad3 expression in serum for the patients of AKI and non-AKI groups, respectively. Results. Serious renal fibrosis was noted in patients of the AKI group. In addition, by H&E staining of the lesion artery, severe histopathological changes including smooth muscles proliferation with endothelial cell infiltration, focal degeneration and disruptions, and less collagen accumulation were found in the lesion artery of patients from the AKI group. Higher levels of TGF-β1 and Smad3 were observed in serum of patients of the AKI group. Conclusion: The increased levels of TGF-β1 and Smad3 in serum might be risk factors for triggering AKI for CAD patients undergoing CABG.

The study of the prevalence of vitamin D3 deficiency and its relationship with blood glucose level after coronary artery bypass graft operation among patients with diabetes

Objectives: Nowadays, vitamin D3 (VitD3) deficiency is among the most common dietary deficiencies around the world. Researchers have paid more attention to VitD3 because it is a vital element of the body and has a plausible relationship with various diseases such as diabetes mellitus type II. This study was conducted to examine the prevalence of vitamin D3 deficiency and its relationship with blood sugar levels in people with diabetes undergoing coronary artery bypass grafting (CABG). Methods: An observational study was conducted in 2017 in Shahid Madani Hospital, Tabriz, Iran, for 8 months. Due to the use of census sampling, only 115 patients with diabetes and open-heart surgery were enrolled in the study. A questionnaire collected information on the participants' demographics, medical history, VitD3 levels and blood glucose levels. Data were analyzed using SPSS ver. 25. Independent t-test was used to compare quantitative data, and chi-square test was used to compare categorical variables. Results: One hundred and fifteen out of 348 patients who had CABG surgery were diabetic. Moreover, 24.7% of patients with diabetes had VitD3 deficiency. The results of the coefficient-correlation test indicated that there was a significant relationship between the mean blood glucose level and VitD3 level (p < 0.05). Conclusions: The results of this study suggest that patients with diabetes can improve their blood glucose control after CABG surgery by taking sufficient VitD3. Therefore, it should be considered as a principle of the hospital operation to prescribe VitD3 prior to surgery for these patients.

A Nano-Based P1Cminimum Probe to Monitor Thrombosis in Grafts and Improve Cardiac Function After Coronary Artery Bypass Grafting Surgery

Magnetic resonance imaging is widely used to identify and monitor thrombi in grafted vessels following coronary artery bypass grafting surgery (CABG). We produced a biosensor, P1Cm-SPIO-Cy5.5, composed of P1Cm peptide, superparamagnetic iron oxide nanoparticles (SPIO), and polyethylene glycol (PEG), for use in MRI thrombus imaging. Activated platelets induced by adenosine diphosphate were used for combination tests in vitro. A rat model of common carotid artery thrombosis was used for anti-thrombus experiments in vivo. P1Cm-SPIO-Cy5.5 remains stable in vitro and has good anticoagulation capacity. It can bind specifically to activated platelets and thrombi. In rats that underwent bypass surgery, P1Cm-SPIO-Cy5.5 could detect and label thrombi over a long period, and prevent thrombosis in grafted vessels. P1Cm-SPIO-Cy5.5 improved cardiac function in rats following CABG surgery. P1Cm-SPIO-Cy5.5 is a potential sensor for use in MRI for the early diagnosis and prevention of thrombosis after CABG surgery.