Myocardial revascularization without extracorporeal circulation; Why hasn't it convinced yet?

Extracorporeal circulation has led to a great development in cardiovascular surgery during the last five decades. Its time-proven efficacy and safety have made on-pump coronary artery bypass grafting (CABG) the gold standard method of surgical revascularization. However, coronary revascularization on cardiopulmonary bypass and the accompanying aortic manipulation are related to plenty of deleterious complications. Therefore, off-pump CABG surgery was established to avoid complications. Nevertheless, despite the initial enthusiasm on this technique, only 20% of myocardial revascularization procedures worldwide are performed off-pump. Not only are off-pump cardiac procedures more technically difficult but also they do not provide better results in terms of graft patency, completeness of revascularization, repeat revascularization requirement, cost, and quality of life. Completeness of revascularization and anastomotic quality should not be compromised to avoid cardiopulmonary bypass.

A Single-Center Randomized Trial of Intraoperative Zero-Balanced Ultrafiltration During Cardiopulmonary Bypass for Patients With Impaired Kidney Function Undergoing Cardiac Surgery

OBJECTIVES

The authors investigated whether zero-balance ultrafiltration (Z-BUF) during bypass significantly improves clinical and cost outcomes or biomarkers of kidney injury for patients with preoperative kidney impairment (estimated glomerular filtration rate [eGFR]<60 mL/minute) undergoing cardiac surgery.

DESIGN

A single-center randomized controlled trial recruited, patients between 2010 and 2013, with a 12-months follow-up.

SETTING

Hospital.

PARTICIPANTS

One hundred ninety-nine patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

INTERVENTIONS

Patients were assigned randomly to receive zero-balance ultrafiltration (Z-BUF) or not, with stratification for degree of kidney dysfunction and diabetes.

MEASUREMENTS AND MAIN RESULTS

The authors assessed clinical efficacy and kidney function biomarkers. Cumulative probability of discharge from the intensive care unit (ICU) was assessed by Kaplan-Meier plots and was found not to be significantly different between the two trial arms (p = 0.61). After adjusting for EuroSCORE, diabetes, eGFR, cardioplegia types and type of surgery in a Cox proportional hazard model, hazard ratios (HR) for ICU length of stay between the Z-BUF and no-Z-BUF groups was not significantly different: HR (95% CI): 0.89 (0.66, 1.20; p = 0.44). In contrast, significant reductions in postoperative chest infections and the composite of clinical endpoints (death, strokes, and myocardial infarctions) in the Z-BUF group were observed. In addition, Z-BUF significantly abrogated the rise in the kidney damage markers urinary NGAL/creatinine ratio, urea, creatinine and eGFR during CPB and adverse events risks.

CONCLUSIONS

Z-BUF during bypass surgery is associated with significant reductions in morbidity and biomarkers of CPB-induced acute kidney injury soon after CPB, which are indicative of clearance of inflammatory/immune mediators from the circulation.

Tranexamic acid is associated with less blood transfusion in off-pump coronary artery bypass graft surgery: a systematic review and meta-analysis

OBJECTIVE

Tranexamic acid reduces blood loss and transfusion in on-pump coronary artery bypass graft (CABG) surgery. Compared with on-pump, off-pump surgery is associated with less blood loss and transfusion. Therefore, tranexamic acid may be less effective for off-pump surgery, and its safety profile may be different in this setting. The aim of this study was to determine the efficacy and safety of tranexamic acid for off-pump CABG surgery.

DESIGN

Systematic review and meta-analysis.

SETTING

University of Edinburgh.

INTERVENTIONS

The administration of tranexamic acid.

METHODS

A systematic review of randomized controlled trials administering tranexamic acid to patients undergoing off-pump CABG surgery. A meta-analysis of 24-hour blood loss, postoperative allogeneic transfusion, and thromboembolic events.

MEASUREMENTS AND MAIN RESULTS

Eight trials were identified. The lack of appropriate data limited the meta-analysis on blood loss. Tranexamic acid significantly reduced the overall risk of allogeneic blood component transfusion (risk ratio = 0.47; 95% confidence intervals, 0.33-0.66; p < 0.0001) and packed red blood cell transfusions (risk ratio = 0.51; 95% CI, 0.36-0.71; p = 0.0001). No association was found between tranexamic acid and myocardial infarction, stroke, or pulmonary embolism. Population sizes of meta-analyses ranged from 466 to 544.

CONCLUSIONS

Tranexamic acid reduces blood transfusion after off-pump surgery. Although no association with adverse events was found, the population sample size was too small to detect rare but clinically significant adverse events. A well-designed randomized controlled trial with an appropriate sample size is required to confirm tranexamic acid effectiveness and safety in off-pump CABG surgery.

No major differences in 30-day outcomes in high-risk patients randomized to off-pump versus on-pump coronary bypass surgery: the best bypass surgery trial

BACKGROUND

Off-pump coronary artery bypass grafting compared with coronary revascularization with cardiopulmonary bypass seems safe and results in about the same outcome in low-risk patients. Observational studies indicate that off-pump surgery may provide more benefit in high-risk patients. Our objective was to compare 30-day outcomes in high-risk patients randomized to coronary artery bypass grafting without or with cardiopulmonary bypass.

METHODS AND RESULTS

We randomly assigned 341 patients with a EuroSCORE > or = 5 and 3-vessel coronary disease to undergo coronary artery bypass grafting without or with cardiopulmonary bypass. Patients were followed through the Danish National Patient Registry. The primary outcome was a composite of adverse cardiac and cerebrovascular events (ie, all-cause mortality, acute myocardial infarction, cardiac arrest with successful resuscitation, low cardiac output syndrome/cardiogenic shock, stroke, and coronary reintervention). An independent adjudication committee blinded to treatment allocation assessed the outcomes. Baseline characteristics were well balanced between groups. The mean number of grafts per patient did not differ significantly between groups (3.22 in off-pump group and 3.34 in on-pump group; P=0.11). Fewer grafts were performed to the lateral part of the left ventricle territory during off-pump surgery (0.97 versus 1.14 after on-pump surgery; P=0.01). No significant differences in the composite primary outcome (15% versus 17%; P=0.48) or the individual components were found at 30-day follow-up.

CONCLUSIONS

Both off- and on-pump coronary artery bypass grafting can be performed in high-risk patients with low short-term complications. CLINICAL TRIAL REGISTRATION- clinicaltrials.gov. Identifier: NCT00120991.