Outcomes of On-Pump versus Off-Pump Coronary Artery Bypass Graft Surgery in the High Risk (AusSCORE > 5)

Less Invasive and Hybrid Surgical/Interventional Coronary Disease Management: The Future Is Now

Coronary artery bypass grafting (CABG) has evolved to become the criterion standard in elective revascularisation for coronary artery disease (CAD), particularly in patients with complex or multivessel CAD, left main involvement, diabetes mellitus, or left ventricular dysfunction. Despite the superiority of CABG in patients with the most advanced forms of CAD, a standard CABG operation, through a median sternotomy and with the use of cardiopulmonary bypass, carries well recognised challenges. In this article, we describe newer approaches, such as off-pump CABG, minimally invasive bypass grafting, robotic CABG, and hybrid coronary revascularisation, which we consider as necessary ways to minimise invasion, reduce recovery time, provide the benefits of arterial grafting to more patients, and offer alternatives to mitigate the adverse effects of conventional sternotomy and cardiopulmonary bypass.

Evidence-Based Determination of Cut-Off Points for Increased Cardiac-Surgery Mortality Risk With EuroSCORE II and STS: The Best-Performing Risk Scoring Models in a Single-Centre Australian Population

OBJECTIVES

Risk scoring models (RSMs) are commonly used for estimation of postoperative-mortality risk in patients undergoing cardiac surgery, but their prediction accuracy may vary in different populations and clinical situations. The prognostic accuracies of some RSMs have not yet been fully evaluated in the Australian population. In this retrospective observational study, our aims were to assess the performance of four contemporary RSMs, to identify the best RSMs for prediction of postoperative-mortality in the single-centre cohort, and to determine a statistical threshold for classification of patients with increased or "higher" mortality risk.

METHODS

The study population included patients who underwent cardiac surgery at Liverpool Hospital between January 2013 and December 2014. Demographic information was collected, and mortality risks were estimated with the ES2 (EuroSCORE II), STS (Society of Thoracic Surgeons Score), AS (AusSCORE total) and ASMR (AusSCORE multi-risk) RSMs. (Additive EuroSCORE) (AES) and LES (logistic EuroSCORE) were included for historical interest. Discrimination, the ability to stratify patients between mortality and no mortality outcomes, and calibration, the comparison of risk score estimated and observed outcome in the population, were evaluated for each RSM, to determine their predictive accuracy in the study population. Discrimination was assessed by the AUC (area under the receiver operating characteristic curve), and acceptable calibration by the p-value greater than 0.05 for the Hosmer-Lemeshow (H-L) test. The best AUCs in contempory models were compared using the DeLong test. For ES2 and STS risk scores, cut-off points, or thresholds, for patients at increased risk of mortality were derived using Youden's J-statistics, calculated from sensitivity and specificity of models in predicting mortality.

RESULTS

From a total study population of 898 patients, 738 had scores for all six RSMs. The three EuroSCORE risk models and Youden's J-statistics analysis included the total population. Of the models in contemporary use, ES2 had higher discrimination (AUC=0.850) in this population than ASMR (AUC=0.767, p=0.024) and AS (AUC=0.739) and non-significantly higher discrimination than STS (AUC=0.806, p=0.19). All contemporary models had acceptable calibration but the older LES (H-L p=0.024) did not. Estimated mortality was closest to observed mortality with the ES2 model. Both AES and LES over predicted mortality. The RSM with the highest discrimination in isolated coronary artery bypass graft surgery (CAGs) (AUC=0.847), isolated valves (AUC=0.830), and females (AUC=0.784) was the ES2 model. STS discrimination was highest in CAGs plus valve procedures (AUC 0.891), and males (STS AUC=0.891). Cut-off points for risk scores to define increased risk populations were 3.0% for ES2 and 1.7% for STS. Similar proportions of patients in each RSM (ES2-26% to STS-32%) were defined as higher risk by the model threshold score depending on type of procedure.

CONCLUSION

Among RSMs in contemporary use, ES2 and STS showed the best discrimination and acceptable calibration. Caution is recommended in specific subgroups. Increased mortality risk score cut-off points could be identified for these two RSMs in this single-centre cohort.

On-pump versus off-pump coronary artery bypass surgery for multi-vessel coronary revascularization

Background

This study aims to compare the operative and postoperative results of on-pump (ONCAB) and off-pump (OPCAB) coronary artery bypass surgery (CABG) for multi-vessel coronary revascularization (≥4 anastomoses).

Methods

From May 2018 to August 2019, a total of 120 patients (22.5% women, mean age 61.5±8.4 years) received either ONCAB (Group 1, n=60) or OPCAB (Group 2, n=60) for multi-vessel coronary artery disease (CAD). Preoperative left ventricular (LV) ejection fraction (EF) was 53.1%±8.4%. Median EuroSCORE II was 1.59 (interquartile range, 1.01–2.54). The median number of performed coronary anastomoses was 4 (interquartile range, 4–5), with equal distribution in both groups (P=0.4). All procedures were performed by highly experienced surgeons. The primary endpoints were overall survival at 30 days and freedom from severe adverse events (SAE), which included myocardial infarction (MI), coronary artery re-operation, and re-thoracotomy, caused by bleeding and stroke.

Results

The overall survival in both groups was 100% with no intraoperative OPCAB-to-on-pump conversion. The median procedure time was 169 min (interquartile range, 150–179 min) for Group 1 and 183 min (interquartile range, 169–205 min) for Group 2 (P<0.001). The overall freedom from SAE numbered 93.3% (98.3% vs. 88.3%, P=0.030). Postoperative MI rate was 2.5% (n=3) with no significant difference for either group (0 vs. 5.0%, P=0.100). One MI patient underwent a re-operation, and two other patients received a conservative treatment. A total of 2.5% (n=3) of patients underwent a re-thoracotomy on account of bleeding (0 vs. 5.0%, P=0.100); no anastomosis-related bleeding was detected. Blood transfusion was applied in 31.7% of patients (38.3% vs. 25.0%, P=0.090). A total of 1.7% of patients (1.7% vs. 1.7%, P=0.800) developed a stroke. Ventilation time, intensive care unit stay, and hospital stay were similar in both groups.

Conclusions

ONCAB showed superior freedom from SAE and shorter procedure times when compared to OPCAB for multi-vessel coronary artery revascularization.

Neural network imaging to characterize brain injury in cardiac procedures: the emerging utility of connectomics

Cognitive dysfunction is a poorly understood but potentially devastating complication of cardiac surgery. Clinically meaningful assessment of cognitive changes after surgery is problematic because of the absence of a means to obtain reproducible, objective, and quantitative measures of the neural disturbances that cause altered brain function. By using both structural and functional connectivity magnetic resonance imaging data to construct a map of the inter-regional connections within the brain, connectomics has the potential to increase the specificity and sensitivity of perioperative neurological assessment, permitting rational individualized assessment and improvement of surgical techniques.

Off-pump coronary artery bypass grafting in high-risk patients: a review

The role of off-pump coronary artery bypass (OPCAB) grafting in high risk patients remains controversial. While there have been studies showing the potential benefits of it, there is still a lot to be learned from the application of this technique in this sub-group of patients. The results of the different trials and papers that we reviewed seem to indicate a benefit in the OPCAB group. Despite of the fact that trials were significantly different in methodology, especially when choosing the risk score stratification tool or the cut-off to define high risk the literature seems to suggest a benefit from the use of OPCAB surgery. Here, we present a review which focussed on early and late outcome in high risk patients undergoing on- and off-pump coronary revascularization.

Outcomes of off-pump versus on-pump coronary artery bypass graft surgery in patients with severely dilated left ventricle

BACKGROUND

Currently, off-pump coronary artery bypass (OPCAB) grafting has been the standard procedure for surgical revascularization in patients with coronary artery disease (CAD). This study aimed to examine the safety and applicability of OPCAB compared with on-pump coronary artery bypass (ONCAB) in patients with severely dilated left ventricle.

METHODS

A retrospective study of giant left ventricle patients [left ventricular end diastolic diameter (LVEDD) ≥ VE mm] undergoing coronary bypass grafting from 2009 through 2015 at a single center was conducted. Preoperative and intraoperative risk factors, and postoperative outcomes were analyzed. Survival analysis was carried to analyze survival rate during follow-up.

RESULTS

A total of 24 patients underwent ONCAB, and 26 underwent OPCAB. Both groups had similar preoperative profiles. Two cases from each group died during in-hospital time. In comparison to OPCAB, there was longer operation and post-surgery intubation time and more renal dysfunction in ONCAB group (P<0.05). One-year survival between OPCAB and ONCAB were not significantly different (87.5% vs. 92.3%, P>0.05).

CONCLUSIONS

OPCAB is a safe and feasible alternative for CAD patients with giant left ventricle, offering a significant advantage over ONCAB with regards to renal function, operation duration and length of ventilation.